# Amps and car's charging system



## Jeff Young (May 19, 2010)

How do I know if my proposed new car stereo system is too powerful for 
my car's chaging system.? One guide I read says this -

In addition to matching the amplifiers to your speakers, you'll also need to
match the amplifier to your car's charging system. If your amplifiers draw more
current than your alternator can produce, you need to back down on the
amount of amplifier power you add to your car or beef up your charging
system, which is expensive.

I'm not sure how to do this.

Thanks, 

Jeff


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## bkjay (Jul 7, 2009)

What are planning to put in and how many amps is your alternator? Most cars these days can handle the additional load.


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## t3sn4f2 (Jan 3, 2007)

The battery is part of the "charging system". In fact, it has a few times the output current potential (FOR MUSIC!) as an alternator has. You only need to worry about drawing more power then your alternator can replenish over a time and that the battery can take the discharge stress.


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## MarkZ (Dec 5, 2005)

Don't worry about it unless your vehicle's electrical system is unusually small or your audio system is unusually loud or inefficient.


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## Jeff Young (May 19, 2010)

Right now I'm considering putting this in my 2000 Dodge Caravan: 

HEAD UNIT - Alpine CDA-117 
FRONT SPEAKERS - Morel Elate 6 (2-way or 3-way) 
REAR SPEAKERS - Hertz (still debating whether to fill)
AMPLIFIERS - Rockford Fosgate T400-4 & Rockford Fosgate T400-2
SUBWOOFER - 2 Pioneer TS-SW1001S2

I appreciate all help and advice. 

Thank you, 

Jeff


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## bkjay (Jul 7, 2009)

You should be good to go.I think you have around 90-130 amp alternator in your ride and thats plenty. Make sure you upgrade all your grounds and alt. power wire.


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## t3sn4f2 (Jan 3, 2007)

bkjay said:


> You should be good to go.I think you have around 90-130 amp alternator in your ride and thats plenty. Make sure you upgrade all your grounds and alt. power wire.


Why the alternator power wire? Is the alternator going to put out more current then it is rated for now that there is a larger load on it?

I'd say the only thing he has to worry about it pulling down the battery charge level down to a critical point too often. Where it starts to loose it's ability to recharge completely and maintain that lesser charge.

Take a drive down to Sears and get a Diehard PLATINUM (not gold....Platinum), maybe upgrade the ground, and enjoy*.*


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## MarkZ (Dec 5, 2005)

cajunner said:


> it stands to reason that wire selection by the manufacturer is a time-based quotient, that is based on the stock needs of the car, and with the addition of a high power stereo the current flow will _over time _ be much higher, causing any resistance to flow to heat up the wire, and increase the voltage drop.
> 
> I believe that the short path between alternator and battery is debatable whether an improvement can be had for the cost, but in that debate I also believe that a big cable should be able to take a larger current flow without deteriorating over time, as the greater conductor content will spread the heating aspect of the current across a much greater area, and the oxidation that occurs with heating will be reduced as a result.


 It's hot under the hood.


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## MarkZ (Dec 5, 2005)

Have you done the calculations? The temp produced by the engine far exceeds the temp produced by current. Look at it in terms of energy.


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## t3sn4f2 (Jan 3, 2007)

cajunner said:


> *it stands to reason that wire selection by the manufacturer is a time-based quotient, that is based on the stock needs of the car, and with the addition of a high power stereo the current flow will over time  be much higher, causing any resistance to flow to heat up the wire, and increase the voltage drop.*
> 
> I believe that the short path between alternator and battery is debatable whether an improvement can be had for the cost, but in that debate I also believe that a big cable should be able to take a larger current flow without deteriorating over time, as the greater conductor content will spread the heating aspect of the current across a much greater area, and the oxidation that occurs with heating will be reduced as a result.


If that was the case, the manufacturer would make sure to included a specific warning that any aftermarket accessories will void the warranty since the heavier load would cause more stress to the alternator due the increased resistance in the undersized wire. 

Make more sense that they would spend a few cents more on a $20,000 car and use a safe gauge. Then they would not have to worry about making that problematic claim or having to filter through all those warranty claim of people who blew the alternator prematurely and put everything back to stoke in order to get it fixed.

8 gauge is enough for any alternator out there. Do you know of any with less then 8?


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## MarkZ (Dec 5, 2005)

Dude, joules is the magic word here...

And no, I've NEVER felt a power wire heat up with current flow. Not that I'd be able to tell with it sitting in a 160deg engine compartment!


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## t3sn4f2 (Jan 3, 2007)

MarkZ said:


> Dude, joules is the magic word here...
> 
> *And no, I've NEVER felt a power wire heat up with current flow. Not that I'd be able to tell with it sitting in a 160deg engine compartment!*


x2. I've only felt improper connections heat up.


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## t3sn4f2 (Jan 3, 2007)

cajunner said:


> you would think, wouldn't you?
> 
> haha..
> 
> ...


k, look at it this way. Would you agree that an 8 gauge *5 foot* in length wire (most a bat to alternator run will be) is large enough for even a 120 amp alternator? Do you know of any 120amp oem alternators that have anything smaller? Any 80 amps even? What will a 6 or a 4 give you?


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## MarkZ (Dec 5, 2005)

Yeah, but have you done the calcs yet? 

I'll get you started. An 8ga wire is 0.00063 ohms per foot. If you drew 50A through that wire all day long*, Joule's law says that it would dissipate 1.575w. This is being dissipated by a foot of wire.

How hot will it get? Well, here's a test. Take a wirewound resistor, which might be as wide as an 8ga wire and is probably only 3 inches long, and dissipate 0.4w through it (1/4 of the power since it's 1/4 the length). Can you feel it heat up?

* = You're not drawing 50A DC from your alternator. Your speakers, amplifiers, and alternator would burn up long before that happened -- they're all made with tiny gauge wire inside wrapped in coils.


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## t3sn4f2 (Jan 3, 2007)

cajunner said:


> maybe I'm not being clear here, all I'm saying is that if you think the alternator to battery wire that came with your car is good enough, it probably is, and if it does go bad it's an easy fix, granted.
> 
> But most of us would use a larger gauge to run 18 feet to an amp rack that is drawing 150 amps or so at max volume, from the battery and it's because of the voltage drop factoring in.
> 
> ...


I've had many old +10 year cars in my life (hand me downs from the original owners) that had the original OEM cables and never seen one alternator cable fail from direct heat or oxidation. 

My old 94 explorer with 100,000 plus miles on it had the alternator go bad on it and the cable and connecter were pefectly fine just weathered looking. And thats in this Miami heat and salty air.


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## t3sn4f2 (Jan 3, 2007)

And also, once corrosion starts on a copper wire, it stops and does not continue further in to the connector or wire. The corrosion forms a protective skin. This is why copper pipes last FOREVER!


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## MarkZ (Dec 5, 2005)

cajunner said:


> I'm sorry, but the calcs aren't my real world experience, and as such I would never rely on numbers in a book if my wire is getting hot, and the book says it's not supposed to.


Right, but if your wire's getting hot, and it's not supposed to, then it's time to figure out WHY it's getting hot rather than dismiss it as violating the laws of physics.

Seriously, if you're seeing 8ga wires get HOT, and it's not due to something near it (like an engine ), then you better put your troubleshooting hat on because something is seriously wrong with the install.


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## MarkZ (Dec 5, 2005)

Well, we'll agree to disagree then. It's a pointless endeavor to upgrade the wiring, in my view. If you can provide some measurements to support your stance, I'd be happy to look at them. Because the laws of physics ain't on your side, bud.


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## bkjay (Jul 7, 2009)

Wow what the hell did I start LOL!. Ok first that was my opinion. Now to the facts. A charging system is only good as it's weakest link. Now would any run amp with a 80 amp fuse with a 8 gauge wire? NO! even if it was as short as 5 feet. Can you.YES.But you may or may not get the most out of your amp. Same with the OEM wire.It was designed for the equipment that came with the car. Not saying it's not going to work without upgrading the alt. wire but why not do a simple thing and get it out the way.


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## bkjay (Jul 7, 2009)

MarkZ said:


> Well, we'll agree to disagree then. It's a pointless endeavor to upgrade the wiring, in my view. If you can provide some measurements to support your stance, I'd be happy to look at them. Because the laws of physics ain't on your side, bud.


Voltage travels threw path of least resistance. So under load a 4 gauge wire is going to have less resistance than a 8 gauge Fact.


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## bkjay (Jul 7, 2009)

Don't get me wrong OP may have no problems.But in the long run his charging system will be happy for it. Another thing changing your power along with grounds helps big time with dimming headlights.


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## bkjay (Jul 7, 2009)

Why would upgrade the battery when the car starts the battery is no longer needed.


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## MarkZ (Dec 5, 2005)

bkjay said:


> Wow what the hell did I start LOL!. Ok first that was my opinion. Now to the facts. A charging system is only good as it's weakest link. Now would any run amp with a 80 amp fuse with a 8 gauge wire? NO! even if it was as short as 5 feet. Can you.YES.But you may or may not get the most out of your amp. Same with the OEM wire.It was designed for the equipment that came with the car. Not saying it's not going to work without upgrading the alt. wire but why not do a simple thing and get it out the way.


Why the hell wouldn't you run the amp off the 8ga wire? What's going to happen if you do? Let's answer that question.

Have you ever measured current draw of an amplifier while playing music? If you haven't, you have no business having an opinion on this matter! 

The reason I say this, as cold as it may sound, is because an amp does not draw 80 friggin amps. So let's stop thinking that you hook your amp up and WOMP ... massive DC current flow. The amp draws its maximal current when you turn it on. After that, it draws according to what the music dictates. Your speakers, with their 22ga voice coil wires, and your amps, with their 26ga secondary traces and their 20ga input chokes, are going to burn out long before your 8ga power wire goes up 2 degrees. [And I'm not even talking about the silicon in your amp that heats up a lot FASTER and is a lot more vulnerable to heat than copper!]

If you think your 1000w amp is delivering 1000w constant into your speakers, I have news for you. 

So seriously guys, stop with the "my amp draws 80A" crap. Time-averaged (which is the only thing that matters when talking about temperatures), your 1000w amps are probably drawing somewhere on the order of 12A at full bore. 8ga wire is more than adequate enough to handle that kind of current. The romex in your house that you sleep alongside is smaller than 8ga. Are you up at nights worrying if it's gonna set the house on fire the next time your refridgerator kicks on?


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## MarkZ (Dec 5, 2005)

bkjay said:


> Don't get me wrong OP may have no problems.But in the long run his charging system will be happy for it. Another thing changing your power along with grounds helps big time with dimming headlights.


Actually, the _opposite_ is true. If your amps draw more current (and virtually all of them WILL with more voltage at their terminals), then it increases dimming problems.

Although, as I mentioned, the difference between 4ga and 8ga will be negligible.


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## bkjay (Jul 7, 2009)

Did you miss the part when I said yes you can run it from 8 gauge.


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## bkjay (Jul 7, 2009)

MarkZ said:


> Actually, the _opposite_ is true. If your amps draw more current (and virtually all of them WILL with more voltage at their terminals), then it increases dimming problems.
> 
> Although, as I mentioned, the difference between 4ga and 8ga will be negligible.


So doing the big three makes your lights dim more? Because thats all I recommended. But I didn't want to confuse OP with terms.


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## bkjay (Jul 7, 2009)

MarkZ said:


> Why the hell wouldn't you run the amp off the 8ga wire? What's going to happen if you do? Let's answer that question.
> 
> Have you ever measured current draw of an amplifier while playing music? If you haven't, you have no business having an opinion on this matter!
> 
> ...


Thats 120 volts in house, now that drop the current big time sorry. Just like 24 volt systems run half the current of 12 volts


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## MarkZ (Dec 5, 2005)

So you don't think anything in your house draws 12A?


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## bkjay (Jul 7, 2009)

MarkZ said:


> Why the hell wouldn't you run the amp off the 8ga wire? What's going to happen if you do? Let's answer that question.
> 
> Have you ever measured current draw of an amplifier while playing music? If you haven't, you have no business having an opinion on this matter!
> 
> ...


You can run a 1000w amp on 8 gauge wire, but do you.


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## MarkZ (Dec 5, 2005)

Haha what the hell is that even supposed to mean?


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## t3sn4f2 (Jan 3, 2007)

bkjay said:


> Wow what the hell did I start LOL!. Ok first that was my opinion. Now to the facts. A charging system is only good as it's weakest link. Now would any run amp with a 80 amp fuse with a 8 gauge wire? NO! even if it was as short as 5 feet. Can you.YES.But you may or may not get the most out of your amp. *Same with the OEM wire.It was designed for the equipment that came with the car.* Not saying it's not going to work without upgrading the alt. wire but why not do a simple thing and get it out the way.


Oh I get it. They couldn't spring for a slightly larger wire but they put an over sized alternator that will never be used to it full potential. I see :laugh:


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## bkjay (Jul 7, 2009)

MarkZ said:


> Haha what the hell is that even supposed to mean?


My point is If you have a chance to upgrade why not? You might not believe me but yours ago my 89 accord alt. tested at 89 amps 13.8 volt. After alt.wire and ground upgrade tested 96 amps at 14.2 volts. Also my idle voltage went up too. So thats why I say why not.


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## Knobby Digital (Aug 17, 2008)

Test it again after it gets hot under the hood on a summer day.


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## lycan (Dec 20, 2009)

just a side note, while i'm watching the drama 

When conductors, or semiconductors, are dissipating electrical power as heat, the resulting _average_ temperature of the conductor can be calculated by the thermodynamic equivalent of Ohm's Law ... where *heat flow* is analogous to _current_, and *temperature* is analogous to _voltage_. The schematic diagram is pretty simple : you've got a current source representing heat flow, forcing heat through a thermal impedance. One side of this impedance is connected to "ambient temperature", the other side is the conductor whose temperature we are interested in 

The temperature of the conductor is then :

Conductor Temp = (power dissipated in watts)*(thermal impedance) + ambient temperature

One thing to note : a large ambient temperature does not really "over-ride" the temp rise due to power dissipation by the conductor ... instead, the effects are _additive_. Power dissipation by a conductor raises it's temperature _above ambient_, by an amount that depends on its thermal impedance. If ambient is "hotter", that certainly doesn't help!

Point being : the ambient rise may be significantly _larger_ than the (heat flow)*(thermal impedance) product ... but it's ultimately the SUM that's important, not just the bigger one.


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## t3sn4f2 (Jan 3, 2007)

bkjay said:


> My point is If you have a chance to upgrade why not? You might not believe me but yours ago my 89 accord alt. tested at 89 amps 13.8 volt. After alt.wire and ground upgrade tested 96 amps at 14.2 volts. Also my idle voltage went up too. So thats why I say why not.


.3 whole volts? 

Well considering that an unregulated amp will typically get a 25% increase in power from 12 to 14.4 volts (ie 1dB, the minimum change a human can perceive), you then got a whopping *~.1dB*. That seems worth it.


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## bkjay (Jul 7, 2009)

t3sn4f2 said:


> Oh I get it. They couldn't spring for a slightly larger wire but they put an over sized alternator that will never be used to it full potential. I see :laugh:[/QUO
> 
> For what the car came with what they have is no problem.
> We see this all the time cars with high horse power motors with junk trans.


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## bkjay (Jul 7, 2009)

t3sn4f2 said:


> .3 whole volts?
> 
> Well considering that an unregulated amp will typically get a 25% increase in power from 12 to 14.4 volts (ie 1dB, the minimum change a human can perceive), you then got a whopping *~.1dB*. That seems worth it.


Now I did not measure volt at the amp. under load .I must admit

All we are talking about is a peace of wire not buying a head unit or something.
Again why not?


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## MarkZ (Dec 5, 2005)

lycan said:


> One thing to note : a large ambient temperature does not really "over-ride" the temp rise due to power dissipation by the conductor ... instead, the effects are _additive_. Power dissipation by a conductor raises it's temperature _above ambient_, by an amount that depends on its thermal impedance. If ambient is "hotter", that certainly doesn't help!
> 
> Point being : the ambient rise may be significantly _larger_ than the (heat flow)*(thermal impedance) product ... but it's ultimately the SUM that's important, not just the bigger one.


This is true. But when ambient>>electrical temp, then the temp ~= ambient.


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## MarkZ (Dec 5, 2005)

bkjay said:


> Again why not?


Who needs one extra chore in life? I make a point of only doing things to my audio system that will make a difference.


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## t3sn4f2 (Jan 3, 2007)

bkjay said:


> Now I did not measure volt at the amp. under load .I must admit
> 
> All we are talking about is a peace of wire not buying a head unit or something.
> Again why not?


I guess. Why not then clean the bugs off your cars front bumper. The reduced drag does in fact increase acceleration and gas mileage. It's not that much to ask, just a bucket with soupy water and a sponge. If it didn't do ABSOLUTELY anything, then I would say it was a waste of time.

_I'm_ being ridiculous?


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## ryan s (Dec 19, 2006)

Quick! Go check your exhaust hangers! Bet they've never been changed...and it could stop your exhaust from adding just a teensy vibration while driving. 

/sarcasm


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## lycan (Dec 20, 2009)

MarkZ said:


> This is true. But when ambient>>electrical temp, then the temp ~= ambient.


just didn't want anyone thinking something like : "who cares if the electrical power dissipation causes the wire temp to increase by _fifty degrees_ ... when the engine causes the wire temp to increase by a _hundred_?"

The answer to this silly hypothetic is : cuz the wire will now be 150 degrees hotter


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## bkjay (Jul 7, 2009)

Well OP here you go! Not sure if this helped LOL!


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## t3sn4f2 (Jan 3, 2007)

bkjay said:


> Well OP here you go! Not sure if this helped LOL!


And good luck searching other thread on this topic. We've made sure they all end like this! :devil::laugh:


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## bkjay (Jul 7, 2009)

t3sn4f2 said:


> And good luck searching other thread on this topic. We've made sure they all end like this! :devil::laugh:


Why is the truth so funny lol!


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## MarkZ (Dec 5, 2005)

cajunner said:


> yes!
> 
> I knew I was right...
> 
> ...


You were talking about the wire heating up. Now you're talking about bad connections heating up.


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## Volenti (Feb 17, 2010)

cajunner said:


> I also said that the wire heats up near the connections where resistance occurs!
> 
> it's a matter of heat conducting down the wire...
> 
> ...


Hot enough to melt the solder out of those crappy glass 3AG fuses so often used, if not melt the entire fuse holder it's self, seen it many a time.


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## t3sn4f2 (Jan 3, 2007)

hhhmmmm........cables with heatsinks built in! I'm gonna be rich! Nobody steal the idea, it's mine.


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## t3sn4f2 (Jan 3, 2007)

Volenti said:


> Hot enough to melt the solder out of those crappy glass 3AG fuses so often used, if not melt the entire fuse holder it's self, *seen it many a time*.


On improper terminations.


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## MarkZ (Dec 5, 2005)

Didn't you just say yesterday that the resistance of the circuit is dominated by the connections? So why is bigger wire helping you in any appreciable way in that case?


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## kyheng (Jan 31, 2007)

Well, I'm using 1/0AWG for my power cable..... But when the connections gets dirty over time, I will get a 2V drop from battery till my amp.


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## t3sn4f2 (Jan 3, 2007)

cajunner said:


> it's important to understand, that the connecting parts of a circuit where large transfers of energy are occurring, have to physically dissipate heat well to withstand long-term use.
> 
> *that's why you see such massive castings being used on distro blocks, when a much smaller casting would suffice to simply hold the conductors in place and provide continuity.*
> 
> ...


What?! 

The massive block of material is so that you can have multiple massive cables on one input and so that the set screw doesn't rip the thread hole apart. Look at an equivalent single fuse single in/out 0 gauge fuse holder, any one, there is no massive block there because its not needed. All there is is enough material to make a strong screw base and a large enough slot for the wire gauge. 

And thats for set screws. Look at ring terminal fuse holders. All there is a A BOLT! on a plastic plate. Just what is needed to hold the ring terminal to the fuse. 

This is the fuse panel in my house. Not very massive for the inputs something with 10+ kilowatt potential.

View attachment 18473


How about ring terminals even, look how small the cross-sectional area is of the part that links the crimp sleeve to ring on a 0 gauge verity.


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## MarkZ (Dec 5, 2005)

good connections = negligible resistance = no temperature change
bad connections = higher resistance = possible temperature change

If that's all you're saying, then we're in agreement. But before you continue to go on this kick about big wire and big connections, PLEASE, I beg of you, go measure the resistance of all these things you're talking about. What you'll find is that you probably don't have the equipment to do it. Why? Because most typical meters measure small fractions of an ohm as 0 ohms.

A better way... send 50A through these connectors you're talking about. See if they heat up.

Controlled lab conditions, cajunner. The observations you've made are undoubtedly true -- I have no reason to doubt you -- but the conclusions you're drawing from them are whacky.


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## ryan s (Dec 19, 2006)

So what you're saying is...

My 8 year old wiring kit should be **** by now.
The plastic covers on my "cheap" distro blocks should have melted long ago.
The fuse holder should be a lump of plastic.
4ga for ~110A of current is insufficient due to heat waste.

Right? 

Cause my stuff certainly doesn't get warm under use. The power wire under the hood has faded insulation, but it's just less blue than the rest of the wire.

I'm with Mark and t3sn4f2 on this one...


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## MarkZ (Dec 5, 2005)

cajunner said:


> you might have 110 amps of current drawn in peaks, but over time even an average draw of 50 amps for a steady pull (which is, hard to take on most reasonably efficient systems, on your ears...) will eventually begin to show heat degradation. It's a matter of time, though.


Actually 50A _average_ would kill more than just your ears. It would kill your amps, speakers, and alternator long before your wire got the opportunity to heat up.

It's important for you to keep in mind that this hardware is by far the LARGEST piece of metal in the chain. The alternator's coils are much smaller, the amplifier's traces are much smaller, and the speaker's voice coil is much smaller. They've also got a small radiating surface area because of their geometry.

And I have to bring up the point I brought up many posts ago... if some of these connectors are in the engine compartment, which is usually the case for most cars, then any effects of temperature due to current are going to be dwarfed by the heat generated by the engine! Not only that, but it's going to get a lot hotter in a car trunk in the summer than the heat generated by proper terminations.

IOW, ambient temperature rules, temperature generated by current drools. 

My suspicion is that your experience comes from crap terminations that had either become horrendously corroded or partially blown fuses.



> my laboratory is the real world.
> 
> I'm not drawing conclusions, I'm saying I've felt hot connectors and blocks even when the wire was new, even when the screw was tight, even when the mechanical part of the process was done perfectly! One reason, is the dissimilar metals. another is the conductivity of pot metal castings, and thin plating on those Chinese parts, that resemble good equipment but really aren't..
> 
> that's not drawing conclusions, that's observation and testing in car, with my hand pulling the conductor against the mechanical clamp of the connector and witnessing a tight and solid connection, and yet the distro block is hot!


No, the conclusion part comes from what you're attributing this temperature change to. You're not simply stating your observations. You've come up with an elaborate mechanistic explanation that just doesn't obey the laws of physics.


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## ryan s (Dec 19, 2006)

cajunner said:


> did I say you had "cheap" distro blocks?
> 
> geez, people are getting touchy..
> :laugh:
> ...


 I threw it out there that I use cheap distro blocks (Stinger HPMs...$10 each) and have used even cheaper Knus in the past. Per what you've posted, they should have fused to the power wire by now or something.

I do know about peak current draw, but where is the limit on degradation according to you? My wires _should _be needing replacement per your theory...but they don't. Surely I should have been noticing power loss years ago, living in a sometimes humid, salted-roads, snow/rain on the ground half the year state! (sarcasm).

And the whole 2000w on 8ga wire thing doesn't make any sense in this context. Actually, it doesn't even relate to the OP of the thread at all :laugh: I can only gather that you say to run bigger wire and connections to fight heat and degradation from heat. Would this not already be taken into consideration for online calculators? Wouldn't that mean I _should _go to bigger wire? Wouldn't that mean we _all _should go up in wire size?

Still running my stock underhood wiring from 1998, with almost 153k on them  No melting or burning in the 4.5 years I've had it.



MarkZ said:


> IOW, ambient temperature rules, temperature generated by current drools.


:laugh:


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## ryan s (Dec 19, 2006)

I have speaker wire that failed from corrosion (the cheapest wire you could find)...

So what's the argument now? That you've seen things we mere mortals could only imagine in our deepest, darkest fantasies? :laugh:

There's no debate about wires becoming ****ty in cars. That I've seen, as well...cracked insulation, excess corrosion, fraying at connections...


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## MarkZ (Dec 5, 2005)

cajunner said:


> I think it is good to run within the recommendations that you can find on BCAE, I'm not saying anyone should run bigger than that, just that there is viable proof that running small wire is a system design no-no..


Where is this proof?

You already said that the connections dominate the resistance, not the wire. Then you keep bringing up wire size. 

This is the most confusing discussion I've ever seen on DIYMA. You're all over the map here.


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## MarkZ (Dec 5, 2005)

Have you gone and measured the resistance yet?


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## MarkZ (Dec 5, 2005)

Electrically.


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## MarkZ (Dec 5, 2005)

cajunner said:


> I'm doing one better, I'm measuring the physical manifestation of high resistance, if it didn't heat up the wire/block, then I wouldn't have a pot to pee in, would I?


No, you're not doing one better. You're choosing ignorance. Rather than MEASURE what could be responsible for your observations, you're making baseless conclusions.

IOW, you're *assuming* that you know the answer rather than confirming the answer with a simple measurement. And that's why everyone's been telling you that your conclusions are wrong.

It's starting to look more and more like you're not actually interested in getting to the bottom of your observations, which makes me wonder if you're just arguing here to save face.


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## lycan (Dec 20, 2009)

another sidelight, just for fun 

Can't really compare power wire for an amplifier, to the gauge wire used for speaker coils  Two reasons, i think :

1. The currents are _significantly_ different. Quick example : 4-channel amp, delivering 4x100W to four, 4-ohm loads. Each load receives 5A (rms) current. However, input current to power amplifier (assuming 12V supply, and 67% efficiency) is 50A. That's an order-of-magnitude difference.

2. Voice coil heating is _not_ an insignificant effect. Power compression is a real issue for many drivers/applications. Sadly, simply increasing voicecoil gauge is not that simple ... increased moving mass, wider gap needed, etc. Point being: voicecoil heating is a problem, with no trivial solution.

Actually, I too suspect that the _contacts_ for the power wire are the _real_ problem : these "junctions" are where the most _loss_ (voltage drop, and heat) will be found. These pressure-only contacts are quite lousy, from a real surface-area perspective. It's why I advocate a separate ground wire for power : not that the ground wire itself has lower impedance than the entire chassis ... it's that the ground wire has lower impedance than the entire chassis _plus the two contacts to it_.

But here's my punchline: fatter wires usually allow for larger contacts


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## MarkZ (Dec 5, 2005)

Larger contacts are inconsequential. The quality of the contact has more to do with the quality of the junction than the actual surface area of the contact. IOW, a large corroded contact sucks compared to a small clean one.

Not that any of it matters. If it's a clean contact, it won't have an appreciable resistance. If it doesn't have an appreciable resistance, it won't get hot. One only needs to drag the digital meter out and hear it beep.


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## lycan (Dec 20, 2009)

MarkZ said:


> Larger contacts are inconsequential. The quality of the contact has more to do with the quality of the junction than the actual surface area of the contact. IOW, a large corroded contact sucks compared to a small clean one.
> 
> Not that any of it matters. If it's a clean contact, it won't have an appreciable resistance. If it doesn't have an appreciable resistance, it won't get hot. One only needs to drag the digital meter out and hear it beep.


now that's funny!

Hearing a "beep" from a digital multimeter is _hardly_ the "acid test" for a good contact. You'll get a 1 volt drop from 20 milliohms at 50 amps. I promise you, my multimeter will "beep" if it measures _twenty thousandths_ of an ohm ... but i'd hardly consider a 1 volt drop at each power contact to be "acceptable" !! 

Larger contact area is a _good thing_, when it comes to lowering contact resistance. And a large, clean one wins over a small, clean one


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## MarkZ (Dec 5, 2005)

lycan said:


> now that's funny!
> 
> Hearing a "beep" from a digital multimeter is _hardly_ the "acid test" for a good contact. You'll get a 1 volt drop from 20 milliohms at 50 amps. I promise you, my multimeter will "beep" if it measures _twenty thousandths_ of an ohm ... but i'd hardly consider a 1 volt drop at each power contact to be "acceptable" !!
> 
> Larger contact area is a _good thing_, when it comes to lowering contact resistance.


Well, it's not a _bad_ thing, if that's what you think I'm implying.

20 mohms is nothing.


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## lycan (Dec 20, 2009)

MarkZ said:


> Well, it's not a _bad_ thing, if that's what you think I'm implying.
> 
> 20 mohms is nothing.


20 mohms is nothing ... as far as your multimeter is concerned.

20 mohms is HUGE ... if there's 50 amps flowing from a 12 volt supply : 1 volt drop, and 50 watts of heat.

That's the whole point !!!


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## MarkZ (Dec 5, 2005)

If 50 amps are flowing from your 12v source, then you'd better hit ebay and buy some new amplifiers...only after you've located the fire extinguisher.


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## lycan (Dec 20, 2009)

MarkZ said:


> If 50 amps are flowing from your 12v source, then you'd better hit ebay and buy some new amplifiers...only after you've located the fire extinguisher.


What number do you prefer ... 10 amps? 20 amps? Do you pick your amplifiers based on the ability of a beeping multimeter to ensure a good contact on the power lead? 

I've a got a lovely Class A tube amp that draws 25 amps at idle ... no fires yet! And the sub amp isn't even powered-up yet.

And you'd better stay _far_ away from the SPL crowd, if you think 50 amps of current draw is fire-department excessive


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## lycan (Dec 20, 2009)

Let's pick 20 amps of current ... 50milliohm will STILL cause a 1 volt drop, and 20 watts of heat at the contact.

Will your multimeter "beep" for 50 mohms? Is that loss at the contact acceptable?

Is 20 amps of current from your 12V supply a ridiculous, excessive amount of current?


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## MarkZ (Dec 5, 2005)

You use a number of different strategies if you're building an SPL system. Obviously a lot of what's said in this thread, or even this forum in general, doesn't apply. I don't see the value in presenting hypotheticals that have no real bearing on actual use.

The notion that larger wire is required to use connectors large enough to not get hot is laughable, and I'm surprised you seem to be taking that stance. Connection problems bad enough to actually cause things to get hot (in comparison to engine compartments, trunks, etc) tend to be the result of corrosion and crappy mechanical design/failure.

You two are being pennywise and pound foolish in this matter.


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## lycan (Dec 20, 2009)

MarkZ said:


> You use a number of different strategies if you're building an SPL system. Obviously a lot of what's said in this thread, or even this forum in general, doesn't apply. I don't see the value in presenting hypotheticals that have no real bearing on actual use.
> 
> The notion that larger wire is required to use connectors large enough to not get hot is laughable, and I'm surprised you seem to be taking that stance. Connection problems bad enough to actually cause things to get hot (in comparison to engine compartments, trunks, etc) tend to be the result of corrosion and crappy mechanical design/failure.
> 
> You two are being pennywise and pound foolish in this matter.


20 milliohms at 50 amps = 1 volt drop, and 50 watts of heat
50 milliohms at 20 amps = 1 volt drop, and 20 watts of heat

And as already discussed, the temp rise from this heat flow is : dependent on thermal impedance, and _additive_ to ambient.

Yes ... i maintain that surface area is your best friend, for minimizing the loss (heat, or voltage) at these lousy (unwelded) pressure contacts.

I honestly don't see anything laughable about that.

What's laughable is the "beeping multimeter" comment ... as the true "measure" for a good power contact.


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## MarkZ (Dec 5, 2005)

I hate to ruin the joke for you, but you're taking that comment out of context.

I hope you've upgraded your blower wiring to 1/0 and used $50 connectors. Your car's a tinderbox! None of these pigtails have enough surface area.


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## lycan (Dec 20, 2009)

MarkZ said:


> I hate to ruin the joke for you, but you're taking that comment out of context.
> 
> I hope you've upgraded your blower wiring to 1/0 and used $50 connectors. Your car's a tinderbox! None of these pigtails have enough surface area.


I'm arguing in favor of establishing an acceptable loss ... 1 volt being too much.
I'm arguing that _increasing_ surface area at a pressure-only contact is a good thing, because it _reduces_ resistance.
I've presented some numerical examples that your mulitmeter would consider "nothing", that would still be quite significant at the current levels of interest.

As far as I can tell, you've argued that none of it matters. The engine compartment is hot anyway, listen for the beep, voicecoil wire is small gauge so power wire can be too, and large contact area doesn't matter because a small _clean_ one is better than a big _dirty_ one (still scratching my head on that orthogonal variable).

Anyway ... i think we can all agree that any ill-effects of poor wiring, or poor contacts, are definitely _quantifiable_.

So i'll take my leave now  Adios !


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## MarkZ (Dec 5, 2005)

lycan, this isn't the first time in this thread where you haven't followed my point that controlling for unimportant stuff means nothing in comparison to things that actually matter. It was true with the ambient temperature thing, which you seemed to accept earlier. And it's true with the fact that corrosion and mechanical factors trump surface area. You're correct that all of these factors are additive, and I never implied that they weren't. But if a>>b, then a+b = a. My stance throughout this thread has been that a>>b.

Specifically, in the absence of corrosion and mechanical issues, the surface area provided by the 8ga wire and connectors is MORE THAN ADEQUATE for the job! If the corrosion and mechanical issues become bad enough to where you start generating heat, then it's really not going to make a bit of difference whether this corrosion is sitting in a 4ga connection or an 8ga connection. You're still fuct either way.


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## lycan (Dec 20, 2009)

arrrghhh ...

Mark, i understand the argument you are _trying_ to make. I understand that a+b=a, if b<<a. However, a+b does NOT equal a, if a & b are comparable. And many of your comparisons that try to demonstrate that "b<<a" are just plain faulty. For example :

1. Amplifier power traces. If we consider voltage drop as the figure-of-merit, we must consider LENGTH as well as cross-sectional area. The high-current, primary-side power traces in a well-designed amp are what, maybe a few inches long? The power cable from the battery/alternator to the trunk may well be 20x that length. Therefore, to generate a COMPARABLE voltage drop, the power cable run needs to have 20x the cross-sectional area. If we want the voltage drop in the power cable to satisfy "b<<a", then you're looking at maybe 200x the cross-sectional area of the traces in the power amp (or, the wires many manufacturers use instead of low-cross sectional area traces). Does 8 gauge wire satisfy this 200x constraint? I didn't do the math, but anyone can ...

2. Voicecoil wire. We've already shown that the currents in the voicecoils are ~10x _less_ than primary-side power amp current. Furthermore, the voicecoils MUST have some DC resistance, to perform their function, or else the power amp won't be happy driving it  Finally, heating of voicecoils is _not_ an insignificant problem. It's simply a bad comparison, based on current levels and function.

3. Temperature rise at points of contact. I don't know the thermal impedances involved  but we _have_ shown that "tens of amps" flowing through "tens of milliohms" are capable of generating "tens of watts" (a couple specific examples are above), and quite possibly a voltage drop on the order of one volt. I would not be at all surprised to find that a contact, with probably less than a square inch of area, dissipating tens of watts would indeed be quite warm to the touch ... and, noticeably hotter than ambient! Now, i'll be the first to admit that i have not _established_ that an 8 gauge contact would create "tens of milliohms" of resistance ... but your comment that 20 mohms is "nothing" (to you, and your multimeter) is just not accurate, at these current levels. So again, you have simply not demonstrated that "b<<a".

And we haven't even begun the discussion of current-induced corrosion at the surface of two dis-similar metals in a pressure contact, and the possibility that _larger_ surface area = _lower_ current _density_, which may very well _slow_ the rate of corrosion. In other words, i think (but i'm not certain) that a _larger_ contact area will reduce corrosion (at least, the galvanic type).

All i'm saying is this : It is all quantifiable  But we must resist the temptation to draw conclusions from faulty parallels & analogies  I'm NOT saying that we must always use 1/0 power wire, but i'm also recognizing that 8 gauge power wire is not satisfactory for all applications. It's not even "always" satisfactory, i submit, for those applications that most in this hobby would consider "reasonable".


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## MarkZ (Dec 5, 2005)

lycan said:


> arrrghhh ...
> 
> Mark, i understand the argument you are _trying_ to make. I understand that a+b=a, if b<<a. However, a+b does NOT equal a, if a & b are comparable. And many of your comparisons that try to demonstrate that "b<<a" are just plain faulty. For example :
> 
> 1. Amplifier power traces. If we consider voltage drop as the figure-of-merit, we must consider LENGTH as well as cross-sectional area.


But voltage drop _isn't_ the figure of merit. The discussion is about temperature. Voltage drop can be an indicator of how much energy a hunk of metal is going to dissipate (at least if we know its resistance...), but ultimately it comes down to _energy_ with respect to _geometry_. A small trace is going to dissipate more energy per unit length than a large wire. So, if his argument was that an 8ga cable was insufficient at shedding heat, then I argued that the relatively small primary side traces are even more insufficient (heatsinks & thermal insulation notwithstanding -- see my comments about ambient, for example).



> 2. Voicecoil wire. We've already shown that the currents in the voicecoils are ~10x _less_ than primary-side power amp current. Furthermore, the voicecoils MUST have some DC resistance, to perform their function, or else the power amp won't be happy driving it  Finally, heating of voicecoils is _not_ an insignificant problem. It's simply a bad comparison, based on current levels and function.


Again, context is key. I used voice coil wire as an example of something that, according to his theory, should degrade even more quickly over time due to temperature. And in fact, it does (although it's usually not the wire itself, but rather the adhesives, lacquers/insulators, etc). Anyway, I brought up VCs in the context of corrosion/breakdown stemming from heat, which was cajunner's main point through most of the thread.



> 3. Temperature rise at points of contact. I don't know the thermal impedances involved  but we _have_ shown that "tens of amps" flowing through "tens of milliohms" are capable of generating "tens of watts" (a couple specific examples are above), and quite possibly a voltage drop on the order of one volt. I would not be at all surprised to find that a contact, with probably less than a square inch of area, dissipating tens of watts would indeed be quite warm to the touch ... and, noticeably hotter than ambient! Now, i'll be the first to admit that i have not _established_ that an 8 gauge contact would create "tens of milliohms" of resistance ... but your comment that 20 mohms is "nothing" (to you, and your multimeter) is just not accurate, at these current levels. So again, you have simply not demonstrated that "b<<a".


Not to sound like a broken record here, but you're taking me out of context again. My meter comment was actually intended to portray the opposite of what you think it was -- I said earlier in the thread that most typical meters simply can't resolve low enough resistances to be able to measure these sorts of things that we've been talking about! That's when I suggested that he run higher currents through these things so that he can actually make the measurements more accurately!

Edit: Here's my quote - "_But before you continue to go on this kick about big wire and big connections, PLEASE, I beg of you, go measure the resistance of all these things you're talking about. What you'll find is that you probably don't have the equipment to do it. Why? Because most typical meters measure small fractions of an ohm as 0 ohms. A better way... send 50A through these connectors you're talking about. See if they heat up._"

Also, as I pointed out "warm to the touch" is irrelevant. _Hot_ is what we're trying to find. This is when I brought up the point about the temperatures under the hood and in the trunk in summertime. "Warm to the touch" isn't going to cause problems if these connectors and wires are being subjected to 160F temperatures or higher. Yes, it's additive, but if you're pushing things to the limits already to where a few degrees is going to make a difference, then something is _wrong_.



> And we haven't even begun the discussion of current-induced corrosion at the surface of two dis-similar metals in a pressure contact, and the possibility that _larger_ surface area = _lower_ current _density_, which may very well _slow_ the rate of corrosion. In other words, i think (but i'm not certain) that a _larger_ contact area will reduce corrosion (at least, the galvanic type).
> 
> All i'm saying is this : It is all quantifiable  But we must resist the temptation to draw conclusions from faulty parallels & analogies  I'm NOT saying that we must always use 1/0 power wire, but i'm also recognizing that 8 gauge power wire is not satisfactory for all applications. It's not even "always" satisfactory, i submit, for those applications that most in this hobby would consider "reasonable".


And I think that's where we disagree.

One of the "faulty parallels & analogies" you haven't addressed is the one I brought up about the blower (or other high current accessories) and stock wiring/connectors. If these aren't a problem, then I don't see how you can suggest that 8ga wiring in typical audio applications would be a fire hazard!


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## eviling (Apr 14, 2010)

well this is an ideal topic for me.


i need to beef up my alt in my car, it's probobly only puping 65-75 amp's and my system is drawling way more than that, the fuse ratings of everything in my car is over 160 amp's alone. my voltages are dropping. i need to beef it up to get the proper power out of my system. 

does anybody know any large companys that do rewindings, or any local shops if you're from my area?

car is a 1999' suzuki esteem 1.6L SD


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## lycan (Dec 20, 2009)

MarkZ said:


> One of the "faulty parallels & analogies" you haven't addressed is the one I brought up about the blower (or other high current accessories) and stock wiring/connectors. If these aren't a problem, then I don't see how you can suggest that 8ga wiring in typical audio applications would be a fire hazard!


simple ... I didn't mention fire hazard, _you_ did. Re-read the last page or two. YOU mentioned fire hazard, if your audio system is drawing 50 amps of current.

Regarding the blower & other accessories, i'm sure the wiring is designed with the application in mind : how much current does the blower draw, and how much voltage drop is acceptable ... to a fan?

And why can we extend that conclusion ... in terms of resultant wire gauge ... to any & all audio systems?


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## kyheng (Jan 31, 2007)

Well, on a normal listening system, you really don't need alot of power. Do you need a full 100W of power to your tweeters without frying your ears? This same goes to others.


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## lycan (Dec 20, 2009)

kyheng said:


> Well, on a normal listening system, you really don't need alot of power. Do you need a full 100W of power to your tweeters without frying your ears? This same goes to others.


no, it doesn't.

100 watts to a tweeter with 98dB efficiency is NOT the same as a 100 watts to a midbass (or subwoofer) with 86dB efficiency.

I know there are those who are happy with a stereo that draws no more than ~10 amps from the vehicle's electrical system. I'm just saying that this does not categorically describe everyone in the hobby.

EDIT : and ... will you design your power wiring for average, normal listening ... or the "peak" times when you really want to crank it?


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## kyheng (Jan 31, 2007)

lycan said:


> no, it doesn't.
> 
> 100 watts to a tweeter with 98dB efficiency is NOT the same as a 100 watts to a midbass (or subwoofer) with 86dB efficiency.
> 
> I know there are those who are happy with a stereo that draws no more than ~10 amps from the vehicle's electrical system. I'm just saying that this does not categorically describe everyone in the hobby.


Obviously, you never try spending more time to understand truely what I meant. But I'm not that happy this time you never pull out some math calculations which means nothing.


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## lycan (Dec 20, 2009)

kyheng said:


> Obviously, you never try spending more time to understand truely what I meant. But I'm not that happy this time you never pull out some math calculations which means nothing.


huh ????


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## ryan s (Dec 19, 2006)

cajunner said:


> True, but I'm trying to demonstrate what happens over time cumulatively, and some people do run their systems at high power for hours, blowing and changing out their amps but not the wiring... but that's not the point I'm trying to make with the experiment. I want to see if the same rate of heat conductance is true for both circuits, I propose the larger gauge system will have a lower end temperature, and a slower rise to temp than the small gauge circuit will. And the power is a static 100 amps.
> 
> the thing is, we can make an experiment that shows heat build-up in terminals, but what we can't do is show the microscopic pitting and conductor oxidation that occurs over long periods when exposed to conditions conducive to galvanic element migration. You have salt air, you have un-protected copper in a terminal, and you have time.
> 
> ...


This is where my flags go up. Is the basis of your argument that heat from resistance (poor connections, cheap materials, too small wire) causes premature failure of wire? Is this in a nutshell?

So you're saying...buy big wire and it'll last forever (*bolded*)...but what about the elements you mention (underlined)? All of a sudden your wire is not subjected to the same elements everyone elses' is? Or if it is subjected to the elements, it _won't break down because it's a bigger gauge_? Forever is a strong word.

Am I understanding this right?


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## kyheng (Jan 31, 2007)

^^Haha, sometimes people stay too long in a small room and forgot about real world......


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## kyheng (Jan 31, 2007)

^^When current flows, it do generate heat. But is good if you can define the subjective term "hot". Rather than keep on arguing on the subjective terms, why not specify the temperature correctly in numbers? For me, 70°C is cold. Or for you, 30°C is hot? If this is the case, all of us can keep on arguing on this until the sun rises from west.


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## lycan (Dec 20, 2009)

kyheng said:


> ^^When current flows, it do generate heat. But is good if you can define the subjective term "hot". Rather than keep on arguing on the subjective terms, why not specify the temperature correctly in numbers? For me, 70°C is cold. Or for you, 30°C is hot? If this is the case, all of us can keep on arguing on this until the sun rises from west.


already been discussed. Current flow & resistance determine _heat flow_, thermal impedance is needed to calculate _temperature rise_ over ambient.

So ... what's the thermal impedance (or conductivity) of a copper wire? Of a copper-to-chassis contact?


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## ryan s (Dec 19, 2006)

cajunner said:


> buy big wire, and the need to upgrade is non-existent.
> 
> buy big wire, and the wire will last longer than small wire in a high current application.
> 
> ...


Or find amps that work with your current power wire and/or are more efficient (alternator output generally comes into play before wire, given that wire is properly sized).


If my 4ga ever managed to get to the point where it would heat enough to cause damage (outside moisture/salt, both of which have caused their share of corrosion in this car), my alternator would already be ****ting the bed since it's only rated for 80A max.

All the microscopic stuff doesn't jive with my pragmatism. Possibly "pragmatism" may be too strong of a word for this context, but I've been running the same wire since high school, in 2 very different cars, with more setups than I can count. I know this wire isn't going to last forever, but if it was _really _that much different..._really _that important...we'd all have double-ought gauge power wire since that would be the ultimate "buy once" solution. At least in this thread.

If it ain't broke, don't f with it. If a wire corrodes, regardless of gauge, it gets replaced. Perhaps I've said all I can...it's like talking politics


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## lycan (Dec 20, 2009)

ryan s said:


> Or find amps that work with your current power wire and/or are more efficient (alternator output generally comes into play before wire, given that wire is properly sized).
> 
> 
> If my 4ga ever managed to get to the point where it would heat enough to cause damage (outside moisture/salt, both of which have caused their share of corrosion in this car), my alternator would already be ****ting the bed since it's only rated for 80A max.
> ...


ryan ... how much current does your audio system draw from the supply (alt/batt), through your 4 gauge wire? Feel free to estimate, or report any measurements. Average, and "full tilt" ... for any of the systems you've installed.


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## ryan s (Dec 19, 2006)

lycan said:


> ryan ... how much current does your audio system draw from the supply (alt/batt), through your 4 gauge wire? Feel free to estimate, or report any measurements. Average, and "full tilt" ... for any of the systems you've installed.





cajunner said:


> But it's fun politics, because science is fighting physics....
> 
> I too don't like the supposition that I can't see what's physically deteriorating because it is happening on a microscopic level, but it is happening...
> 
> ...


This is the point where I shrug my shoulders. All I really care about wire is that it doesn't corrode _within a reasonable time_, is flexible, has a decent jacket, is what size it claims it is, and is preferably cheap.

Like the people on camera forums who sit and fret about lines of resolution and such...it never interested me. If it works for me, awesome. If it doesn't, time for Plan B.

Too pragmatic for minutiae, if you will. Use good quality stuff of the right size...that's what I care about.


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## MarkZ (Dec 5, 2005)

lycan said:


> simple ... I didn't mention fire hazard, _you_ did. Re-read the last page or two. YOU mentioned fire hazard, if your audio system is drawing 50 amps of current.
> 
> Regarding the blower & other accessories, i'm sure the wiring is designed with the application in mind : how much current does the blower draw, and how much voltage drop is acceptable ... to a fan?
> 
> And why can we extend that conclusion ... in terms of resultant wire gauge ... to any & all audio systems?


It seems there's quite a bit of miscommunication here. Fire hazard has been the whole point of cajunner's posts, which you were apparently defending. I'm sorry if I attributed that argument to you. I had assumed that with the discussion of parts heating up, you were on board with that.

And no, I'm not extending 8ga to "any and all" audio systems. Of course not. There are applications which might require bigger wire. I'm arguing against the notion that 8ga is going to deteriorate into a pile of ash in most DIYMA members' systems.


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## MarkZ (Dec 5, 2005)

cajunner said:


> MarkZ, I propose to you an experiment, since you are adamant that you are correct:
> 
> Take an average amplifier power circuit, break it down, and reproduce it in your 'lab'.
> 
> ...


That wasn't me. That was t3.


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## MarkZ (Dec 5, 2005)

lycan said:


> no, it doesn't.
> 
> 100 watts to a tweeter with 98dB efficiency is NOT the same as a 100 watts to a midbass (or subwoofer) with 86dB efficiency.
> 
> ...


Lycan, in the context of this discussion, peaks don't mean a damned thing. 10A, time-averaged, is a lot of current. By an admittedly rough approximation, 10A would correspond to roughly 800w of system power WITHOUT clipping (assuming 10dB crest factor, 60% amplifier efficiency, 13.5v).


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## MarkZ (Dec 5, 2005)

cajunner said:


> high temperature epoxy coats voice coil copper, and it's baked on normally, or it fails.


I've been told otherwise by a guy representing Alumapro. I'll try to dig up that post. It was from a long time ago.



> my point, is that OVER TIME, the cumulative effects of using small gauge wire that is good enough when you install it, may not be good enough 5 or 10 years down the road, and if you live in a salt water marsh, it may only be 1 year...
> 
> before the effects of corrosion from heat and elemental weathering combine to destroy the current capacity of your terminal set.
> 
> ...


I think you're going to great lengths to try to make the point. Now you're dragging in moisture, humidity, salt, high heat environments, and so forth. I also think the more and more you rely on these things, the less of a difference wire gauge makes in the face of all these environmental factors. Again, what you haven't demonstrated is that 8ga wire, compared to 4ga, 2ga, 1/0, or whatever, is significantly more prone to being influenced by these factors.

I've already told you several pages ago that we agree that (1) connections tend to dominate the resistance; and (2) bad connections can cause problems! We disagree that bigger wire and bigger crimps prevent these problems.


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## MarkZ (Dec 5, 2005)

cajunner said:


> Warm to the touch, is a hot/cold cycle.
> 
> hot/cold cycling contributes to several things, in a small crimped connector:


Better heat your garage at night and cool it in the daytime. And whatever you do, don't park it in the sun. Ride a bike to work. 

You're grasping at straws.


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## t3sn4f2 (Jan 3, 2007)

cajunner said:


> aren't you saying an 8 gauge wire circuit typical of amplifiers, is not going to heat up more than a 1/0 gauge circuit, when passing the same amount of current over a long duty cycle? The experiment should determine who's right here...


Just to be clear, he's only saying I used the house wire example, not him.


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## lycan (Dec 20, 2009)

MarkZ said:


> Lycan, in the context of this discussion, peaks don't mean a damned thing. 10A, time-averaged, is a lot of current. By an admittedly rough approximation, 10A would correspond to roughly 800w of system power WITHOUT clipping (assuming 10dB crest factor, 60% amplifier efficiency, 13.5v).


huh?

First of all, what do you mean by "system power" ... it's certainly NOT the average power, determined by the product of rms current & rms voltage. Ten amps of _average_ current into a 60% efficient amplifier means 130 watts _average_ power input (at 13 volts DC), and a whopping 78 watts of _average_ power output (these terms are non-ambiguous) ... for your _entire system_, subs included. Yeah, i know ... 78 watts of real, average power translate into hundreds of "music watts"  Did you recently get a job in the marketing department of a power amp manufacturer?

Secondly, peaks are VERY important for voltage drop considerations! I'm surprised at you, honestly  

Or are you still discussing thermal considerations, as the ONLY concern when sizing power wire & connectors?

I certainly wouldn't use "music watts", the avoidance of fire, nor the blower motor wiring in my Honda (my blower motor draws 18 amps, or less, at full speed btw) as the guidelines for sizing my audio power wiring & connectors!

This has gotten way beyond silly ... i'm gone.


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## kyheng (Jan 31, 2007)

lycan said:


> already been discussed. Current flow & resistance determine _heat flow_, thermal impedance is needed to calculate _temperature rise_ over ambient.
> 
> So ... what's the thermal impedance (or conductivity) of a copper wire? Of a copper-to-chassis contact?


I don't give a s*** if this has been discussed. I only see "this is hot, that is generating heat, this is very high resistance" and other kind of rubbish(subjective) talks. It means nothing, especially from you(again, where's all you maths when I'm expecting some?). I want to see some numbers, then we continue on this. Else it is meaningless. 
When I'm asking questions, I'm expecting some answers, when I'm asking objective questions, please answer them objectively. Don't give me some subjective answers or the other way round. This is what I've been see on how you reply to others. Are you good? Well, from other people maybe, but for me, you are no other than a coward.


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## thehatedguy (May 4, 2007)

How did AC carrying wires get mixed into all of this? The power and ground wires are the only DC sources in the audio chain. Everything else is AC current...like your house. From what I remember of physics, AC lines can use a smaller conductor per amperage than DC. The windings in the alternator, traces on the amp boards, and voice coil wire all deal with AC power.

I don't get the analogy.


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## kyheng (Jan 31, 2007)

cajunner said:


> my low-tech explanation on this, is that hot is defined by such a temperature change that the physical, static stress on the conductor and the connector, effects a physically different operating condition.
> 
> if that crimp is not that tight, hot comes sooner, as the mechanical force that contains the wire is less, meaning that less conduction can be achieved through the finite space of the inside of a ring terminal's crimp section.
> 
> smaller crimp, smaller wire, larger temperature gradient in working conditions based simply on less conducting area, this seems intuitive to me?


Again, where's the numbers to prove your statements? Wouldn't it abit dumb when you can do all sort of lab experiments but you can't provide any real world numbers? 

By your defination on hot, I feel abit funny also, can ~80°C in the engine bay change the shape of the terminals? And talk about resistance, how many % will that 80°C affects? 10%, 20% or even 50%? Really, the most I can see is 0.1V drop with my engine running after travel for 30 minutes. Will this affects the overall performance? I really in doubt.


----------



## kyheng (Jan 31, 2007)

thehatedguy said:


> How did AC carrying wires get mixed into all of this? The power and ground wires are the only DC sources in the audio chain. Everything else is AC current...like your house. From what I remember of physics, AC lines can use a smaller conductor per amperage than DC. The windings in the alternator, traces on the amp boards, and voice coil wire all deal with AC power.
> 
> I don't get the analogy.


Agree with you on this, I also lost, when lycan and cajunner brought out all those rubbish..... 
From my limited knowledge on electronics, AC is using voltage as carrier while DC is using current as carrier.


----------



## lycan (Dec 20, 2009)

kyheng said:


> I don't give a s*** if this has been discussed. I only see "this is hot, that is generating heat, this is very high resistance" and other kind of rubbish(subjective) talks. It means nothing, especially from you(again, where's all you maths when I'm expecting some?). I want to see some numbers, then we continue on this. Else it is meaningless.
> When I'm asking questions, I'm expecting some answers, when I'm asking objective questions, please answer them objectively. Don't give me some subjective answers or the other way round. This is what I've been see on how you reply to others. Are you good? Well, from other people maybe, but for me, you are no other than a coward.


What a ****ing idiot.

I'm so sorry ... i didn't meet your expectations, and provide the exact answers you were looking for. Please, oh please, forgive me !! I promise to try harder, and do better, next time. I promise !!

Oh wait ... i already _have_ provided some math in this thread, including the thermodynamic equivalent of Ohm's law, for converting heat flow into temperature. So we _all_ see, that it doesn't much matter what answers are provided, since you've demonstrated a complete inability to read & understand even the simplest of concepts.

In other words ... you wouldn't understand the answers, even if _they were read aloud to you_.

Another *******, added to the ignore list


----------



## TREETOP (Feb 11, 2009)

lycan said:


> What a ****ing idiot.
> 
> I'm so sorry ... i didn't meet your expectations, and provide the exact answers you were looking for. Please, oh please, forgive me !! I promise to try harder, and do better, next time. I promise !!
> 
> ...


*ZING!* 


(reading along while taking a break from swapping out the stator in my 275A alternator, which is connected to my batterie*s* with 1/0 power wire- they're also grounded with 1/0 to the engine block, the vehicle frame, _and_ the body) :laugh:


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## bkjay (Jul 7, 2009)

reading along while taking a break from swapping out the stator in my 275A alternator, which is connected to my batteries with 1/0 power wire- they're also grounded with 1/0 to the engine block, the vehicle frame, and the body)

1/0 power wire why? Just use 8 gauge! lol!


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## kyheng (Jan 31, 2007)

cajunner said:


> you misunderstand, when I say "changed the physical" I mean expansion of the metal parts, to the degree that the wire is no longer held in the same physical force of compression.
> 
> also, your engine running, and voltage dropping after 30 minutes, is likely an observation of a car computer circuit at work, as most charging systems have a command set of instructions to drop from the 14.4V of charging current to a 13.8V maintenance condition, as continuing to charge at 14.4V will overheat a battery over a long period.


So now you mean that the heat will cause significant expansion to cause big voltage drop, that's something new that I will delete it from my brain ASAP after replying you. Or you never bolt them properly? Alot of factors that will contribute to high voltage drop accross. 

Nope, my car's alternator can only supply me 13.8V normally. The 13.7V I measure is on my amp after a 20ft run of power cable.


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## TREETOP (Feb 11, 2009)

bkjay said:


> reading along while taking a break from swapping out the stator in my 275A alternator, which is connected to my batteries with 1/0 power wire- they're also grounded with 1/0 to the engine block, the vehicle frame, and the body)
> 
> 1/0 power wire why? Just use 8 gauge! lol!


LOL sure, 8ga for 3kw of amplification.  8ga would just be a loooong fusible link.

I may be an exception, but that shows that there's not a one-wiresize-fits-all-scenarios answer. I see people speaking in absolutes in this thread, mainly on the side of leaving the stock wiring alone. Well, there are plenty of reasons that just wouldn't work for me.


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## TREETOP (Feb 11, 2009)

cajunner said:


> It would be nice to know how much actual watts are lost to heat in that 1/0 application, through the various 1/0 connecting parts.


Honestly I have better things to concern myself with. If I was running 3kw on stock electrical, or if I had 3 batteries and an 8ga charging wire, or even if I had my current setup but without upgraded ground wires, then I'd have something to contemplate. As is though, I've set up the foundation planning around worst case scenario, thus there's no worries now or in the future.


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## MarkZ (Dec 5, 2005)

cajunner said:


> wow... I didn't see that coming.
> 
> for my calculations, I see someone bumping "bass I love you" for an hour, and I suspect their 2kw amplifier is drawing 4kw, as it is 50% efficient at 1 ohm, and if it's clipping it's drawing 6kw to get 1.5kw each to two subs in a daily driver...
> 
> so 6kw, what's the amp draw on that?


A lot.

Who around here has 6kW of amplification? Their poor alternator!!

Like I mentioned to werewolf, several other design considerations are involved when putting together SPL vehicles. I also mentioned to him that I wouldn't suggest 8ga wire for all applications, and I sure wouldn't suggest it to someone with 6kW of amplification endeavoring to play bumpin' bass songs with 50% efficiency amps clipped all to hell.

Please stop manufacturing unrealistic hypotheticals to try to make your point. I gladly concede that those types of extreme listening habits require a different strategy.


----------



## MarkZ (Dec 5, 2005)

lycan said:


> huh?
> 
> First of all, what do you mean by "system power" ... it's certainly NOT the average power, determined by the product of rms current & rms voltage.


Right. I think you know what I meant by "system power". You can do the calcs just as well as I can. 

If you want me to spell it out, if you add up the power ratings of your amps (assuming they're fairly accurate), you'd come out to about 800w given the parameters I provided. Like I mentioned, 10A is a very ballpark estimate of what the current draw might look like. And I would argue that 10A is nothing to shake a stick at, even though you don't think much of it. Obviously everybody's mileage varies, but I think it's a far better estimate of what's really going on than your 50A nonsense.



> Ten amps of _average_ current into a 60% efficient amplifier means 130 watts _average_ power input (at 13 volts DC), and a whopping 78 watts of _average_ power output (these terms are non-ambiguous) ... for your _entire system_, subs included. Yeah, i know ... 78 watts of real, average power translate into hundreds of "music watts"


You know better than this.



> Secondly, peaks are VERY important for voltage drop considerations! I'm surprised at you, honestly
> 
> Or are you still discussing thermal considerations, as the ONLY concern when sizing power wire & connectors?


Lycan, that's exactly what I'm still discussing, _because that's the topic at hand_. And before you go blaming me, I wasn't the one who introduced it!


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## MarkZ (Dec 5, 2005)

thehatedguy said:


> How did AC carrying wires get mixed into all of this? The power and ground wires are the only DC sources in the audio chain. Everything else is AC current...like your house. From what I remember of physics, AC lines can use a smaller conductor per amperage than DC. The windings in the alternator, traces on the amp boards, and voice coil wire all deal with AC power.
> 
> I don't get the analogy.


Current is current. If an AC line passes 10A of current, it will dissipate the same amount of energy as the same line passing 10A of DC. This is the beauty of the RMS calculation. There's nothing magical about AC.

How much current does your microwave draw? What about your washing machine? What about your car audio system?

I don't know the answers because I don't know what appliances you have, whether or not they're on 220, and what type of audio system you have. But I don't think it's inconceivable that they all draw about the same amount of current. Yet, one camp is worried about the structural integrity of the wire in one case but not the other. And as much as cajunner wants to deny it, the words "wire failure" and "burnt" have a certain connotation.


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## MarkZ (Dec 5, 2005)

TREETOP said:


> LOL sure, 8ga for 3kw of amplification.  8ga would just be a loooong fusible link.
> 
> I may be an exception, but that shows that there's not a one-wiresize-fits-all-scenarios answer. I see people speaking in absolutes in this thread, mainly on the side of leaving the stock wiring alone. Well, there are plenty of reasons that just wouldn't work for me.


I hope you're not referring to me, because I've _explicitly_ said otherwise. Several times, even.


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## MarkZ (Dec 5, 2005)

Reminder:

Before everyone continues crawling up my ass about this 6kW - 8ga thing that I supposedly said, I'd like to remind everybody what my first post in this thread was:



MarkZ said:


> Don't worry about it unless your vehicle's electrical system is unusually small or your audio system is unusually loud or inefficient.


So, please, stop with the straw man arguments. If you have to manufacture things, I'll consider that an admission that you have no valid argument and I won't respond to those things.


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## TREETOP (Feb 11, 2009)

MarkZ said:


> I hope you're not referring to me, because I've _explicitly_ said otherwise. Several times, even.


Wow. There were 146 replies before mine, 145 not counting one that was me. Yet somehow you think I'm referring to you? Paranoid much?


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## lycan (Dec 20, 2009)

Mark, in post #103 you responded to my statement that 8 gauge is NOT suitable for all applications, by saying "that's where we disagree". The only conclusion is that you think 8 gauge wire is suitable for all audio applications.

As far as the 50 amp number I offered, it was intended to demonstrate that YOUR statement that 20mohm resistance being "nothing" is NOT accurate, for possible current levels of interest ... peak, or average. I then offered 20 amps, and 50mohm. I then asked YOU to pick a "reasonable" current ... and you didn't respond.

But as far as 50 amps being "nonsense" and "fire department" worthy in an absolute sense ... again, these are YOUR quotes ... i disagree. I suspect that we've got at least one hobbyist, IN THIS VERY THREAD, who really does need to size his power wire & connectors with _at least_ 50 amps of power current in mind.

Power levels that might be nonsense to YOU, do not necessarily apply to everyone.


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## MarkZ (Dec 5, 2005)

lycan said:


> Mark, in post #103 you responded to my statement that 8 gauge is NOT suitable for all applications, by saying "that's where we disagree". The only conclusion is that you think 8 gauge wire is suitable for all audio applications.


It's too bad that you're stooping so low. I expected more from you. That you would even suggest that I would think 8ga wire is suitable for all audio applications is pretty insulting.

In case you're wondering, the sentence that I quoted and that I "disagreed" with was this one: "[8 gauge] is not even 'always' satisfactory, i submit, for those applications that most in this hobby would consider 'reasonable'." That was the end of the quote and then I said I disagree.

But sure, that must mean I'm saying 8ga is suitable for every audio application ever conceived.



> As far as the 50 amp number I offered, it was intended to demonstrate that YOUR statement that 20mohm resistance being "nothing" is NOT accurate, for possible current levels of interest ... peak, or average. I then offered 20 amps, and 50mohm. I then asked YOU to pick a "reasonable" current ... and you didn't respond.


Apparently, "By an admittedly rough approximation, 10A would correspond to roughly 800w of system power WITHOUT clipping (assuming 10dB crest factor, 60% amplifier efficiency, 13.5v)." doesn't count as a response. So how's this instead?










Better? 



> But as far as 50 amps being "nonsense" and "fire department" worthy in an absolute sense ... again, these are YOUR quotes ... i disagree. I suspect that we've got at least one hobbyist, IN THIS VERY THREAD, who really does need to size his power wire & connectors with _at least_ 50 amps of power current in mind.
> 
> Power levels that might be nonsense to YOU, do not necessarily apply to everyone.


You mean, this mystery hobbyist might be running a system that I would consider "unusually loud or inefficient"? Gee, I wonder if I would suggest 8ga to him or if I'd suggest he upgrade his wiring? If only I had said something earlier in this thread that would provide a clue as to how I would respond to the mystery hobbyist!


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## lycan (Dec 20, 2009)

MarkZ said:


> It's too bad that you're stooping so low. I expected more from you. That you would even suggest that I would think 8ga wire is suitable for all audio applications is pretty insulting.
> 
> In case you're wondering, the sentence that I quoted and that I "disagreed" with was this one: "[8 gauge] is not even 'always' satisfactory, i submit, for those applications that most in this hobby would consider 'reasonable'." That was the end of the quote and then I said I disagree.
> 
> ...


I also expected way more from you in this thread ... WAY more. 

Without quantifying "unusually loud" or "inefficient", any results or recommendations are meaningless. And as i've said, we've got at least one user in this very thread ... who must be the extreme exception in all of car audio hobbyland, i suppose ... for whom 50A of current draw is not "nonsense" (nor is he calling the "fire department" on a regular basis), someone for whom 8 gauge power wire isn't going to work.

I didn't mean to insult you, i just read the words that you wrote. 8 gauge won't cut it for me either ... this, based on objective analysis (including, but not limited to, the things i've already offered in this thread). How many hobbyists would it take to move the discussion away from the "unusual"? That's rhetorical, don't bother an answer.

I tried to steer the discussion to something quantifiable, to no avail 

Yep ... i expected way more from you too.

EDIT : your comprehension and reasoning skills are deteriorating with every single post in this thread. It was ME who offered 10 Amps first (actually, ~10 amps in post #110) when i got no response from a 50 amp or 20 amp offer. You didn't offer it in response to my unanswered query. But your silly cartoon does do a good job of defending your style in this thread.


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## t3sn4f2 (Jan 3, 2007)

thehatedguy said:


> How did AC carrying wires get mixed into all of this? The power and ground wires are the only DC sources in the audio chain. Everything else is AC current...like your house. From what I remember of physics, AC lines can use a smaller conductor per amperage than DC. The windings in the alternator, traces on the amp boards, and voice coil wire all deal with AC power.
> 
> I don't get the analogy.


I mixed it in! Incorrectly :blush:


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## MarkZ (Dec 5, 2005)

lycan said:


> I also expected way more from you in this thread ... WAY more.
> 
> Without quantifying "unusually loud" or "inefficient", any results or recommendations are meaningless.


No ****. This is why, in the many many threads in this forum where people are asking about upgrading their wiring, I take each situation individually. And in each case, my opinion is based on loudness and efficiency.



> And as i've said, we've got at least one user in this very thread ... who must be the extreme exception in all of car audio hobbyland, i suppose ... for whom 50A of current draw is not "nonsense" (nor is he calling the "fire department" on a regular basis), someone for whom 8 gauge power wire isn't going to work.
> 
> I didn't mean to insult you, i just read the words that you wrote. 8 gauge won't cut it for me either ... this, based on objective analysis (including, but not limited to, the things i've already offered in this thread). How many hobbyists would it take to move the discussion away from the "unusual"? That's rhetorical, don't bother an answer.
> 
> ...


Actually, I mentioned 12A long before you even posted in this thread. But it's my reading skills that are being called into question?

I think your biggest problem in this thread is that you haven't read all the posts, which is why you're doing so sucky at understanding context, and the posts you _have_ read you haven't read carefully.

That's me giving you the benefit of the doubt.


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## lycan (Dec 20, 2009)

MarkZ said:


> No ****. This is why, in the many many threads in this forum where people are asking about upgrading their wiring, I take each situation individually. And in each case, my opinion is based on loudness and efficiency.
> 
> 
> 
> ...


have you been drinking? That's me, giving you the benefit of the doubt.

The number in your silly cartoon is 10, not 12, and you drew it as a "supposed response" to the number that was offered ... by me. So yeah ... it's your reading skills that need some help.

But let's cut the ********, and avoid the sweeping generalities (like, there's no way 50A DC is being drawn from your alternator ... because the tiny wires inside your amplifier would fry).

Here's a specific example, and it's not "unusual" or "atypical":

- McIntosh MCC204 Class AB amp, 4x50W, driving two tweets: 4 ohm, 92dB efficient; and two rear channels: 4 ohm, 88dB efficient.

- McIntosh MCC302 Class AB amp, 2x150W, driving two midbass drivers: 4 ohm, 88dB efficient

- McIntosh MCC301M Class AB amp, 1x300W, driving a single 12" sub (sealed enclosure): 4 ohm, 85dB efficient

Total rated output power is 0.8kW. Yes, three McIntosh amps is not "typical" ... i chose them because all necessary specs are readily available  The key point is that an 800 Watt (full rated power) audio system is NOT unusual.

The car is 2004 Honda Civic, amps mounted in the trunk. The driver likes a variety of music, and although he doesn't listen to rap all the time, he does like to lean on the volume every now & then  Windows up, and windows down. Very typical dude.

He wants your help on wiring. Key questions :

1. Do you recommend any upgrades to the factory wiring ... battery & alternator?
2. Do you size the amplifier power wiring for only 10 or 12 amps of DC current draw, total, from the alternator/battery (these are the numbers you've claimed, as yours, for a typical ... i.e., not unusual ... audio system)?
3. Do you recommend anything larger than an 8 gauge power wire, for all amps included?

Finally ... if you care to indulge me ...

4. Do the power traces and "little wiring" inside the McIntosh amps burn up, when the amps are being tested by McIntosh at full rated power delivery?

You can use any rules you think are appropriate for sizing power wire : peaks, averages, heat, voltage drops, music crest factors ... whatever you like.

You've made some sweeping generalizations in this thread, and now you're arguing against generalities. So let's get specific


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## RangOH (Jul 25, 2009)

wow can i just get a summery of what went on in this thread.. my ADD did not like this thread. 

you people have gotten way too bent out of shape about this stuff.


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## MarkZ (Dec 5, 2005)

lycan said:


> have you been drinking? That's me, giving you the benefit of the doubt.
> 
> The number in your silly cartoon is 10, not 12, and you drew it as a "supposed response" to the number that was offered ... by me. So yeah ... it's your reading skills that need some help.


Haha ok, you win. 12A instead of 10A. Such a huge difference.

But you're right, I never offered any opinion about what a "reasonable" current would be. 12A ... 10A ... I was all over the map! 



> 1. Do you recommend any upgrades to the factory wiring ... battery & alternator?
> 2. Do you size the amplifier power wiring for only 10 or 12 amps of DC current draw, total, from the alternator/battery (these are the numbers you've claimed, as yours, for a typical ... i.e., not unusual ... audio system)?
> 3. Do you recommend anything larger than an 8 gauge power wire, for all amps included?


Sure. 8ga would be perfectly safe. I wouldn't expect it to break down or "burn up". But if you've read my posts here over the years, you'd probably find that I'd ask how long the length of wire is (a question I asked as recently as a few days ago when a similar question was posed), so that I can make some assessment of the voltage drop.

But it's important to keep in mind that these are two _very different_ issues. The temperature of the cable (the issue that cajunner had focused on and *what this thread has been about since page 1*) is one issue, and whether or not maximal voltage is being presented at the amp's terminals is another issue. One is safety, the other is mostly performance.



> 4. Do the power traces and "little wiring" inside the McIntosh amps burn up, when the amps are being tested by McIntosh at full rated power delivery?


They would before the 8ga supply wire does.

As you'll notice throughout this thread, it's been my stance that the 8ga wire will not "burn up" unless the system was "unusually loud or inefficient". You have apparently come down on the side that there's a likelihood that it will. So I'd like to hear the answer to your own question -- would you expect the 8ga cable to "burn up" before the primary side traces, switching transistors (which I referred to earlier in the thread generally as "the silicon"), fuses, or anything else in the amp?


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## lycan (Dec 20, 2009)

nicely evaded.

I'll answer my own questions :

Total idle current for these three Class AB amps is : 3 x 2.5 amps = 7.5 amps
Total current, at rated power, for these three Class AB amps (@12V) is : 135 amps
(subtracting idle current, yields an average efficiency around 55%).

The user likes to lean on the volume knob every now & then. Personally, I would not design the power wiring based on a MAX DC current draw of 10~12 amps ... *especially when the idle current alone chews up more than half of that*, in this VERY TYPICAL system.

No ... i may not be overly concerned about delivering the full 135 amps, i might be convinced a factor of two away from that (50 watts will never be delivered to the tweets, ever, for example). But i wouldn't want the power wiring, the cheapest pieces of the puzzle, to be the weak link in power delivery when the user wants to crank it. And I'll never use less than 10x _lower_ than full rated power when sizing cables and connectors. Call me crazy.

*My conclusion : 10~12 amps of DC current delivery is NOT satisfactory for a typical audio system, all amplifiers combined.*

(by the way, i told you how long the cable was : i defined the car, and told you the amps were in the trunk. I also asked for battery/alternator upgrades, which included the option for an additional battery in the trunk. You had everything you needed, to answer the questions).

To address your point : no, an 8 gauge power wire will not ignite with this current delivery. Of course, I asked to use _any and all_ concerns for sizing the wire ... a point nicely evaded, or ignored (it's OK ... nobody is obligated to answer that which is asked).

Oh ... i'm pretty sure we can agree that when McIntosh tests the MCC301M for full, rated power delivery, the *50A DC* current draw doesn't fry the tiny little traces inside. Someone stated otherwise, for ALL power amps in a system (not just one) in post #21:

"_You're not drawing 50A DC from your alternator. Your speakers, amplifiers, and alternator would burn up long before that happened -- they're all made with tiny gauge wire inside wrapped in coils._"

I think the OP has all the info he needs, for an informed decision.


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## MarkZ (Dec 5, 2005)

lycan said:


> nicely evaded.
> 
> I'll answer my own questions :
> 
> ...


I'd like to say you cleverly capitulated on virtually all of the points in this thread, but your backpedaling was too transparent for me to call it "clever".

Yes! Of course the 8ga wire is not a safety hazard in this proposed system! It won't "burn up", "fail", or whatever words cajunner had used to describe this catastrophic event he was warning us about and that you were defending. Finally you agree on that point, and hopefully that puts to rest all this talk about wire temperatures and such.

I'm not really sure why you think that I was designing a system around 10-12A "max current draw". As I'm sure you know, the 8ga wire will withstand current draws that far exceed that number. At least, I hope you know that. The 10-12A number was what I called a "very rough approximation" or "ballpark" estimate of the typical time-averaged draw we might expect from an 800w amplifier. I used it to illustrate the point that seemed to evade you and a couple of the others -- although your amps may be rated to draw a lot of current, the actual draw when listening to typical music in a typical fashion is significantly lower than the irrelevant max current draw figure that everybody was citing. It appears you're now on board with this. Progress!


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## TREETOP (Feb 11, 2009)

MarkZ said:


> The 10-12A number was what I called a "very rough approximation" or "ballpark" estimate of the typical time-averaged draw we might expect from an 800w amplifier... ...although your amps may be rated to draw a lot of current, the actual draw when listening to typical music in a typical fashion is significantly lower than the irrelevant max current draw figure that everybody was citing. It appears you're now on board with this. Progress!


Call me dense, but why would anyone plan their electrical upgrades around volume 15 knowing that their volume goes to 35? And how is max current draw "irrelevant", when the system is fully capable of drawing it? 
Wouldn't it be wiser to plan for worst case and not worry, than know every time you get an itch to "crank it up" that you have a weak link preventing you from getting optimum voltage at your amplifier(s)? Personally I'd rather not tax a smaller wire, even for seconds, with a load that a larger wire will handle more adequately. Better safe than possibly sorry I'd think, I'd rather not press my luck (I used up all my luck when I was young).


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## lycan (Dec 20, 2009)

MarkZ said:


> I'd like to say you cleverly capitulated on virtually all of the points in this thread, but your backpedaling was too transparent for me to call it "clever".
> 
> Yes! Of course the 8ga wire is not a safety hazard in this proposed system! It won't "burn up", "fail", or whatever words cajunner had used to describe this catastrophic event he was warning us about and that you were defending. Finally you agree on that point, and hopefully that puts to rest all this talk about wire temperatures and such.
> 
> I'm not really sure why you think that I was designing a system around 10-12A "max current draw". As I'm sure you know, the 8ga wire will withstand current draws that far exceed that number. At least, I hope you know that. The 10-12A number was what I called a "very rough approximation" or "ballpark" estimate of the typical time-averaged draw we might expect from an 800w amplifier. I used it to illustrate the point that seemed to evade you and a couple of the others -- although your amps may be rated to draw a lot of current, the actual draw when listening to typical music in a typical fashion is significantly lower than the irrelevant max current draw figure that everybody was citing. It appears you're now on board with this. Progress!


oh dear 

i didn't say "max current draw" ... at least, in the quoted post.

i DID say "max DC current draw". The DC, or average, current draw will be a function of the volume knob. Agreed?

*Do you expect the typical system i presented, all amplifiers combined, to EVER draw more than 10~12 amps of DC current? If so, what do you expect the max DC current to be, under worst-case user scenarios as presented?*

*What do you expect the PEAK current to be?*

*What criteria would YOU use ... ALL things considered ... for selecting the power wire size?*

You can use thermal only, DC current in a "worst case" scenario, or peak current & peak voltage drop in a "worst case" scenario.

I'll forget everything that's been posted about amplifier traces burning up, 50A DC being nonsense and fire-department worthy, etc.


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## lycan (Dec 20, 2009)

TREETOP said:


> Call me dense, but why would anyone plan their electrical upgrades around volume 15 knowing that their volume goes to 35? And how is max current draw "irrelevant", when the system is fully capable of drawing it?
> Wouldn't it be wiser to plan for worst case and not worry, than know every time you get an itch to "crank it up" that you have a weak link preventing you from getting optimum voltage at your amplifier(s)? Personally I'd rather not tax a smaller wire, even for seconds, with a load that a larger wire will handle more adequately. Better safe than possibly sorry I'd think, I'd rather not press my luck (I used up all my luck when I was young).


That's pretty much what i'm thinkn 

Especially when wire is the cheapest component in the chain!

I really will give Mark the benefit of the doubt ... we need to get away from burning wires as the only concern in sizing power wires. Let's see if he answers my last post.


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## MarkZ (Dec 5, 2005)

TREETOP said:


> Call me dense, but why would anyone plan their electrical upgrades around volume 15 knowing that their volume goes to 35? And how is max current draw "irrelevant", when the system is fully capable of drawing it?
> Wouldn't it be wiser to plan for worst case and not worry, than know every time you get an itch to "crank it up" that you have a weak link preventing you from getting optimum voltage at your amplifier(s)? Personally I'd rather not tax a smaller wire, even for seconds, with a load that a larger wire will handle more adequately. Better safe than possibly sorry I'd think, I'd rather not press my luck (I used up all my luck when I was young).


No one was talking about vol 15/35.


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## TREETOP (Feb 11, 2009)

MarkZ said:


> No one was talking about vol 15/35.


It was obviously a hypothetical set of numbers that I pulled out of my ass, to represent your "actual draw when listening to typical music in a typical fashion" vs. your "irrelevant max current draw figure". It applies just fine. We're now talking about volume 15/35.



lycan said:


> That's pretty much what i'm thinkn
> 
> Especially when wire is the cheapest component in the chain!


Exactly. If cost is the reason not to use larger wire, then someone's in the wrong hobby. Electrical is the last thing I'd consciously choose to shortcut on.


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## MarkZ (Dec 5, 2005)

lycan said:


> oh dear
> 
> i didn't say "max current draw" ... at least, in the quoted post.
> 
> i DID say "max DC current draw". The DC, or average, current draw will be a function of the volume knob. Agreed?


I know. If it's helpful, rephrase my sentence to read: "I'm not really sure why you think that I was designing a system around 10-12A 'max DC current draw'."



> *Do you expect the typical system i presented, all amplifiers combined, to EVER draw more than 10~12 amps of DC current? If so, what do you expect the max DC current to be, under worst-case user scenarios as presented?*


Sure, it will draw more than 10A during some songs and some passages within songs. I think the choice of 8ga gives us enough wiggle room to accommodate that. As I've tried to point out to you several times now, my "10A" number wasn't intended to be an upper limit or anything like that. It was a...what was the word?..."ballpark" figure that I brought up to try to defeat all the "50A" and "80A" nonsense that had been going on in this thread. The add-up-your-fuses crowd needs to be reminded of this every so often.

Don't tell me you're going back on the safety hazard thing. I don't think I can handle more games...



> *What do you expect the PEAK current to be?*


Explain why it's relevant.



> *What criteria would YOU use ... ALL things considered ... for selecting the power wire size?*
> 
> You can use thermal only, DC current in a "worst case" scenario, or peak current & peak voltage drop in a "worst case" scenario.
> 
> I'll forget everything that's been posted about amplifier traces burning up, 50A DC being nonsense and fire-department worthy, etc.


I already answered this question a few posts ago. I use safety and voltage drop as the useful electrical parameters. Personally, I also weigh cost, physical size and space constraints, and probably most importantly, what kind of terminals are on the amps or distro blocks. I don't generally consider it a good idea to try to squeeze big ass cable into a small screw terminal if I can help it.

But this line of questioning is all a diversion from the original topic. I'm not saying that anybody who doesn't use 8ga is making a bad decision and will burn in hell. I'm saying that 8ga is a safe and reasonable selection for many, if not most, of the applications we talk about in this forum.


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## MarkZ (Dec 5, 2005)

TREETOP said:


> It was obviously a hypothetical set of numbers that I pulled out of my ass, to represent your "actual draw when listening to typical music in a typical fashion" vs. your "irrelevant max current draw figure". It applies just fine. We're now talking about volume 15/35.


No, really. You're not understanding.

I laid out all the parameters in that earlier post. I had used maximum unclipped volume. 35/35, if that's how your system is set.



> Exactly. If cost is the reason not to use larger wire, then someone's in the wrong hobby. Electrical is the last thing I'd consciously choose to shortcut on.


There isn't a single time in this thread where I said not to use larger wire. I said that it's very often unnecessary.


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## TREETOP (Feb 11, 2009)

MarkZ said:


> No, really. You're not understanding.
> 
> I laid out all the parameters in that earlier post. I had used maximum unclipped volume. 35/35, if that's how your system is set.


I guess you're right, I'm not understanding- but like most everyone here I'm unwilling to admit it's because of a fault of my own. 

I'm reading where you're talking about "regular listening level", and I'm assuming that means regular listening level. NOT 35/35. 
Or is your setup tuned to play at "regular listening level" at 35/35, and you're assuming that's what others do?
"Regular listening level" for my setup is in the mid-20s somewhere. My volume goes to 62 at the head unit. My setup plays cleanly and unclipped (and *very loud*) at 62. But that's how I have it set up. My ears would likely become permanently damaged within 20 minutes if I drive around at 62, so obviously I don't (think My Bloody Valentine concert but with full clarity), but I have the capability and the electrical to back it up.


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## lycan (Dec 20, 2009)

MarkZ said:


> I know. If it's helpful, rephrase my sentence to read: "I'm not really sure why you think that I was designing a system around 10-12A 'max DC current draw'."
> 
> 
> 
> ...


fair enough. i do disagree, and i would recommend heavier power wire for most users on this forum.

For our purposes, i'd say it's fair to describe the current waveform with two key parameters : average, and peak. They BOTH depend on the volume setting, as well as the signal, of course. For sinewaves, the peak/average ratio is obviously smaller than for typical music. I think we would agree on all these points.

The PEAK current draw is relevant ... NOT for thermal or safety considerations, i ABSOLUTELY agree ... but for calculating the PEAK voltage drop in the power supply wiring (cables & connectors). When a music peak slams in, you wouldn't want your voltage drop (on a connector, for example) in that instant to be excessive ... or your "peak" my be compressed by the power amp.

So I submit that, while average current is fundamental to thermal concerns, the peak current is very important for sizing wire & connectors.

And i would also submit that, for the typical system that i presented, most users would find themselves cranking the volume knob to a level of DC (average) current that is SIGNIFICANTLY larger than 10~12 amps ... with PEAKS even substantially larger than that, naturally.

But yes, i ABSOLUTELY agree ... no fire hazard will occur, if you choose 8 gauge wire for all the power amps combined. If and where i suggested otherwise, i apologize and stand corrected


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## MarkZ (Dec 5, 2005)

TREETOP said:


> I guess you're right, I'm not understanding- but like most everyone here I'm unwilling to admit it's because of a fault of my own.
> 
> I'm reading where you're talking about "regular listening level", and I'm assuming that means regular listening level. NOT 35/35.
> Or is your setup tuned to play at "regular listening level" at 35/35, and you're assuming that's what others do?
> "Regular listening level" for my setup is in the mid-20s somewhere. My volume goes to 62 at the head unit. My setup plays cleanly and unclipped (and *very loud*) at 62. But that's how I have it set up. My ears would likely become permanently damaged within 20 minutes if I drive around at 62, so obviously I don't (think My Bloody Valentine concert but with full clarity), but I have the capability and the electrical to back it up.


I'm sorry if I was unclear in my explanation. I think my numbers and calcs were straightforward though. IIRC, I said an 800w amp, 13.5v, -10dB RMS song will draw approx 10A time-averaged at full unclipped output. If your system is 800w, and it's set to clip at 35/35, then yeah, I'm talking about 35/35.


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## MarkZ (Dec 5, 2005)

lycan said:


> fair enough. i do disagree, and i would recommend heavier power wire for most users on this forum.
> 
> For our purposes, i'd say it's fair to describe the current waveform with two key parameters : average, and peak. They BOTH depend on the volume setting, as well as the signal, of course. For sinewaves, the peak/average ratio is obviously smaller than for typical music. I think we would agree on all these points.
> 
> ...


Great, I think we're at least on the same page now.

And while I agree that peak current is valuable when it comes to calculating peak voltage drops, I think it should be tempered by the fact that peaks are smoothed to some extent by the switcher/rail caps. If we wanted to calculate a good estimate of peak, we'd time window the envelope of the signal appropriately. And this of course varies from amp to amp.


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## Oliver (Jun 25, 2007)

MarkZ said:


> What do you expect the PEAK current to be?
> 
> Explain why it's relevant.


I would use it to help ascertain that the design parameters have been met

If I am expecting a heavy or beefy amount of current to travel through the wires at a low voltage of say , maybe 10V or 9V [ which would increase the amount of amperage ] I'd want the wires to be large enough to handle this flow.


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## lycan (Dec 20, 2009)

MarkZ said:


> Great, I think we're at least on the same page now.
> 
> And while I agree that peak current is valuable when it comes to calculating peak voltage drops, I think it should be tempered by the fact that peaks are smoothed to some extent by the switcher/rail caps. If we wanted to calculate a good estimate of peak, we'd time window the envelope of the signal appropriately. And this of course varies from amp to amp.


It's a fair point about the capacitance ... i was considering mentioning it while I was typing. I suspect most amps don't have enough capacitance to supply a substantial portion of the current needed for a good kick drum slam, for example ... but i recognize the point.

I am in favor of adding some low ESR capacitance, by the way, to the primary side of the power amp's switching transformer  Brax (and somebody else, but i forget who) allow a connection directly to the transformer primary, bypassing the inductance that's usually in series (internal to the amp) with the battery connection (RF choke type thing). I know that caps are a whole other can of worms  but if done properly (big if) i think there can be some benefit ... for exactly this type of concern.


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## MarkZ (Dec 5, 2005)

a$$hole said:


> I would use it to help ascertain that the design parameters have been met
> 
> If I am expecting a heavy or beefy amount of current to travel through the wires at a low voltage of say , maybe 10V or 9V [ which would increase the amount of amperage ] I'd want the wires to be large enough to handle this flow.


Hahaha you should be the _last_ person commenting in this thread. You just told a guy this morning that he needed to run _two_ 8ga runs to his 300w amp. You're exactly who I had in mind when I said that a lot of the upgrade advice given in here is completely unnecessary.


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## MarkZ (Dec 5, 2005)

Oh brother, not this again.

You win, cajunner. Congratulations.


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## Oliver (Jun 25, 2007)

:laugh:


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## MarkZ (Dec 5, 2005)

That had been obvious all along.


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## MarkZ (Dec 5, 2005)

cajunner said:


> something not so obvious, is that anyone who wants to travel further down the road from where you have been going, is going to assume that if 8 gauge wire is suitable for most systems, then what's the harm in using 10 gauge wire?


Or even 12ga wire, or 14ga, maybe jump right to 20ga!

Holy straw man, batman! Please, stop trying to characterize my position.



> not so obvious, when this guy is going to buy a used amp on ebay that says, "Orion HCCA 250" and reads, 100 watts RMS.
> 
> "this amp kit is good for amps from 10 to 100 watts RMS" written on the 10 gauge advertisement.


Or maybe someone's gonna buy a "1000w" Rockwood amp, which is really only a 50w amp, and will insist on running 1/0 gauge to it.

Power ratings are often misleading. I've been saying this in car audio forums for 12 years.



> so this cat hooks up and then starts with his brother in law's dual 2 ohm 12's.
> 
> wires everything up in parallel, because that's the way the amp has the most power, you know how he knows? because he tried it all the other ways....
> 
> ...


Sheesh. You and the burning wire. Get over it already.

Oh wait! But when you say "burnt", you don't mean burnt! How silly of me.


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## lycan (Dec 20, 2009)

so after i've calmed down a bit ...

first, my apologies to Mark. He really doesn't drink all _that_ much  and not nearly as much as i need to 

Seriously, i was out of line more than once in this thread, and me sorry 

And i do know where he's coming from, in this sense : there is a tendency (at least, for those less well-acquainted with our hobby) to believe that if you hook up a 100W amp to a speaker, then the speaker is "getting" a 100W all the time. And that you should add up fuse ratings, to determine power wiring. It's our job to educate otherwise 

Also, it really _would_ be the rare system indeed, that would cause an 8 gauge power wire to catch fire. Doesn't mean that's the _only_ concern for sizing power wire, of course ... and Mark knows this very well.

Finally, all of us would agree that these concerns readily lend themselves to an objective analysis ... perhaps a new thread that thoroughly & methodically explores ALL concerns is in order (if it doesn't already exist)? We would also agree that each system must be analyzed on it's own ... no single rule is applicable for all.

Mark, you know i respect you and what you've contributed to this forum. Please accept my apologies.


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## MarkZ (Dec 5, 2005)

Lycan, I appreciate the kind words. Some of your posts in this discussion seemed to me to be uncharacteristic of the normally pragmatic approach you usually take in discussing these issues. I'm a prick 90% of the time, so I guess I didn't depart from the norm much. 

I think a tutorials thread would be a welcome addition, although I think the bcae site already has a decent section on wire.


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## MarkZ (Dec 5, 2005)

cajunner said:


> there are pretty good reasons why I was so adamant about not encouraging people to use 8 gauge wire in their systems as a baseline for accepted practices, some of which never made it into the discussion.
> 
> I think this discussion has made the lines a little more clear, but something to guard against is the mindset of a new-to-car audio layman, who reads this and takes away the following:
> 
> ...


You're doing god's work. Thanks for straightening that MarkZ character out. You've saved countless babies from their fiery demise today.

Edit: kittens too.


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## kyheng (Jan 31, 2007)

lycan said:


> Let's pick 20 amps of current ... 50milliohm will STILL cause a 1 volt drop, and 20 watts of heat at the contact.
> 
> Will your multimeter "beep" for 50 mohms? Is that loss at the contact acceptable?
> 
> Is 20 amps of current from your 12V supply a ridiculous, excessive amount of current?





lycan said:


> 20 milliohms at 50 amps = 1 volt drop, and 50 watts of heat
> 50 milliohms at 20 amps = 1 volt drop, and 20 watts of heat
> 
> And as already discussed, the temp rise from this heat flow is : dependent on thermal impedance, and _additive_ to ambient.
> ...


So this is the "ohm's law" that you said.... But under what condition? What's the wire being used? The quality? The lenght? Really, Ohm's Law are good to give us some picture when we are doing wiring jobs. But with all other factors remains assumption, do it really reflects on real life applications? I in doubt.



lycan said:


> no, it doesn't.
> 
> 100 watts to a tweeter with 98dB efficiency is NOT the same as a 100 watts to a midbass (or subwoofer) with 86dB efficiency.
> 
> ...


Obviously, you are a real dumbass, will a person pick a tweeter with 98dB efficiency to match with a midbass (or subwoofer) with 86dB efficiency? I won't and I don't know what you are trying to prove here



lycan said:


> I also expected way more from you in this thread ... WAY more.
> 
> Without quantifying "unusually loud" or "inefficient", any results or recommendations are meaningless. And as i've said, we've got at least one user in this very thread ... who must be the extreme exception in all of car audio hobbyland, i suppose ... for whom 50A of current draw is not "nonsense" (nor is he calling the "fire department" on a regular basis), someone for whom 8 gauge power wire isn't going to work.
> 
> ...


And under what ground you can simply label another person just like you labeled me? Just because you can type in some Ohm's Law where everybody can simply get it from Wiki or other website while others normally won't do like this?


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