# Big 3 or Big 4 Upgrade?



## dsw1204 (Mar 23, 2015)

I am finally ready to do the Big 3 upgrade. Picked up a very nice kit...1/0 gauge, OFHC from GP Car Audio. If you're going to buy a kit, I'd look at these guys. But, I was checking out some Big 3 videos on Youtube and saw one on a Big 4. I didn't even know there was a Big 4. The video was stressing that, if you do the Big 3 you should go ahead and do this Big 4 upgrade.

Is doing the Big 4 upgrade that much better than doing the Big 3? What can you guys tell me?


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## DC/Hertz (Nov 27, 2011)

3 will be fine. Just make sure all connections are solid and the grounds are very clean.


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## gijoe (Mar 25, 2008)

Even big 3 is usually unnecessary. Improving the grounds is what matters, the big 3 also "upgrades" to the alternator to battery cable. Unless you install a high output alternator messing with this cable is pointless. It is already sized for the amount of current the alternator can produce. 

Whether it's big 2, big 3, or big 4 just focus on the grounds.


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## DC/Hertz (Nov 27, 2011)

Larger cable stores more power. It does help. Is it needed? Who knows but it does help. 
When I did SPL and chased every tenth of a db I would gain by adding a cable run from the front to the back. Even though the runs I already had where plenty for the demand. 
Same concept as the big 3.


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## gijoe (Mar 25, 2008)

DC/Hertz said:


> Larger cable stores more power. It does help. Is it needed? Who knows but it does help.
> When I did SPL and chased every tenth of a db I would gain by adding a cable run from the front to the back. Even though the runs I already had where plenty for the demand.
> Same concept as the big 3.


Cables don't store power (the capacitance is very, very low), a larger cable has less resistance, so more current can pass through, but it's already sized to allow as much current as the alternator can provide. Upgrading the cable will lower the resistance, but that won't matter unless the alternator cable is undersized (which won't be the case).


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## DC/Hertz (Nov 27, 2011)

So you have added cable runs and tested SPL scores? I don't think you have. 
Even adding the Big 3 has proven to gain on the termlab. Would you notice? I doubt it. 
Does it work? Completely.


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## gijoe (Mar 25, 2008)

DC/Hertz said:


> So you have added cable runs and tested SPL scores? I don't think you have.
> Even adding the Big 3 has proven to gain on the termlab. Would you notice? I doubt it.
> Does it work? Completely.


If the big 3 shows proven gains, as you claim, how do you know it had anything to do with the alternator cable, and not just the grounds? Replacing the cable does, on paper, lower resistance. More copper will do that. However, resistance isn't a problem in the alternator cable. Lowering the resistance slightly isn't going to improve anything. That cable moves current from the alternator to the battery, that's all it does. It is sized to be able to move as much current to the battery that the alternator can produce. Making this cable bigger does not do anything meaningful. Improving the grounds can make a big difference, but replacing the alternator cable doesn't.


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## DC/Hertz (Nov 27, 2011)

If you really want to open your mind and know the truth there a plenty of documented test showing how adding runs increased SPL. Ever so slightly but a gain is a gain. 
If you don't want to know you won't look for yourself.


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## gijoe (Mar 25, 2008)

DC/Hertz said:


> If you really want to open your mind and know the truth there a plenty of documented test showing how adding runs increased SPL. Ever so slightly but a gain is a gain.
> If you don't want to know you won't look for yourself.


I see how this is going to be. You won't offer any logical explanation to back up your claim. I am not an EE, but I've taken circuits 1, circuits 2, digital circuits 1, digital circuits 2, and electronics. I'm not an expert, but I have a more than basic understanding of this stuff. 

I don't have a problem being wrong, so if you can show me how upgrading that cable can help, I'm willing to learn. But, a bigger cable lowers the resistance, the lower the resistance the more current will flow from the battery. The cable is already sized to allow all of the current that the alternator can produce, making it bigger does not allow the alternator to pass any more current than it already can. The cable is not the limiting factor, the alternator is.

Again, if you can explain why upgrading that cable will help, I'm all ears. I'm wrong all the time.


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## DC/Hertz (Nov 27, 2011)

I did say it stores power. It does store electrons which will be more quick release. You said it didn't. So here we are. Even JL recommends it 

https://jlaudio.zendesk.com/hc/en-us/articles/204374080-The-Big-3-Wiring-Upgrade


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## danno14 (Sep 1, 2009)

Perhaps different verbiage will help

Merriam Webster- Store: a quantity or supply of something kept for use as needed.
"the squirrel has a store of food"
synonyms:	stock, supply, stockpile, hoard, cache, reserve, bank, pool; More
verb
1.
keep or accumulate (something) for future use.
"a small room used for storing furniture"
synonyms:	keep, keep in reserve, stockpile, lay in, put/set aside, put away/by, put away for a rainy day, save, collect, accumulate, hoard, cache; 


Cable does not "store" energy. It allows current to be transmitted from where it is stored (battery) or created (alternator), to where it is used. Larger wire of a given material will allow for greater transmission at a given voltage. Disconnect the wire from the alternator or battery, and you will soon find no electricity is left in the cable


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## Gouki (May 14, 2017)

I would also add that the OEM did not necessarily completely optimize the size of the cable for the rated power of the alternator, as evidenced by the puny (to us) factory ground cables found on most vehicles. Often times a vehicle is assembled to "function correctly", not "totally optimized for performance". Something, something, built to budget, something, something. 

I do agree that the grounds are most important, and a worthwhile upgrade for most cars. I am getting ready to build my own kit using 1/0 Knukonceptz Kolossus Fleks Kable on my M.


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## Rocketjones (Oct 23, 2008)

Gouki said:


> I do agree that the grounds are most important, and a worthwhile upgrade for most cars. I am getting ready to build my own kit using 1/0 Knukonceptz Kolossus Fleks Kable on my M.


The knukonceptz has a clean look. I used them for my grounds as well. One run from the far side firewall, ran past the turbo. For that piece I wrapped it in aluminum foil tape. It's held up for 6 months with no discoloration. Titties.


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## Marky (Nov 15, 2011)

The "stores power" was the problem. But all in all it gets the power there,or back to the battery so as far as that goes he's right.


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## gijoe (Mar 25, 2008)

Gouki said:


> I would also add that the OEM did not necessarily completely optimize the size of the cable for the rated power of the alternator, as evidenced by the puny (to us) factory ground cables found on most vehicles. Often times a vehicle is assembled to "function correctly", not "totally optimized for performance". Something, something, built to budget, something, something.
> 
> I do agree that the grounds are most important, and a worthwhile upgrade for most cars. I am getting ready to build my own kit using 1/0 Knukonceptz Kolossus Fleks Kable on my M.


OEM did NECESSARILY size the wire for the alternator. That's an absolute safety necessity. They could never afford the lawsuit that would occur when cars set fire because they put an alternators in the car that produces more current than the wire they put in to get the current to the battery. This cable does not need "upgrading" unless an aftermarket alternator is installed. 

The grounds are a different argument. There is value in improving the grounds because they were not sized for aftermarket gear. 

Adding an aftermarket stereo has no impact on the connection between the alternator and the battery. The maximum current of that alternator is no different with or without aftermarket amps, the cable is sized appropriately. 

*Even if I install 4,000 watt amps, my alternator will still only be able to produce 80 amps, so there is no need to change the cable unless you add an alternator that produces more current*


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## Ronn25 (May 25, 2014)

I think this would totally depend on the car? right? I've seen some older cars that the alternator wire looked very small even though it had a 100 amp alternator. Of course better grounds should help, Gm comes to mind about having poor grounds.


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## Marky (Nov 15, 2011)

gijoe said:


> OEM did NECESSARILY size the wire for the alternator. That's an absolute safety necessity. They could never afford the lawsuit that would occur when cars set fire because they put an alternators in the car that produces more current than the wire they put in to get the current to the battery. This cable does not need "upgrading" unless an aftermarket alternator is installed.
> 
> The grounds are a different argument. There is value in improving the grounds because they were not sized for aftermarket gear.
> 
> ...


That's not completely true. The OEM alternator and wiring is designed for the stock configuration. You push that alternator to maximum output for extended periods the wiring will be strained. Heat is the enemy any its absolutely a good idea to upsize ALL of the power and ground cables if you are running things to maximum output or pulling heavy amperages more then its designed for. Will it catch fire not likely, more apt to blow fuseable link or destroy diodes in voltage regulator to alt.

All the guys with 2003-2007 F250 trucks add a output cable to the passenger battery as well as adding supplemental grounds to improve on what Ford built stock.
So go for it, it will only help out the entire vehicle. 

I added larger cables and even put grounds on transmission and engine to frame. The new cars are very computer dependent and any help is wise. 

That's my input on this subject, not trying to start a argument in any way.


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## mmiller (Mar 7, 2008)

Big three in a moderately powered SQ system, is stupid, and a complete waste of time. The Big One is what's important, and an AGM battery is more than sufficient. People spending $300 to upgrade to wire the size of a pop can with a 100 Amp alternator, is nothing short of idiotic. And half the time people use ****ty CCA wire which brings it to a whole other level of stupid.

Upgrade the 12AWG battery to chassis Ground to a minimum 4 AWG and buy a good quality AGM battery. Zero need for anything else with a stock alternator.


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## lurch (Jan 20, 2014)

mmiller said:


> Big three in a moderately powered SQ system, is stupid, and a complete waste of time. The Big One is what's important, and an AGM battery is more than sufficient. People spending $300 to upgrade to wire the size of a pop can with a 100 Amp alternator, is nothing short of idiotic. And half the time people use ****ty CCA wire which brings it to a whole other level of stupid.
> 
> Upgrade the 12AWG battery to chassis Ground to a minimum 4 AWG and buy a good quality AGM battery. Zero need for anything else with a stock alternator.


X 2 if you ask me.
buy the biggest lump of AGM battery that will fit. 
lots of current and reserve in there and the posts don't corrode. 
buy some good battery clamps to go with it and a decent ground
cable and this combo performs. 
as mmiller says, this should be FIRST in a big three.


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## SkizeR (Apr 19, 2011)

Gouki said:


> I would also add that the OEM did not necessarily completely optimize the size of the cable for the rated power of the alternator, as evidenced by the puny (to us) factory ground cables found on most vehicles.





Ronn25 said:


> I think this would totally depend on the car? right? I've seen some older cars that the alternator wire looked very small even though it had a 100 amp alternator.


ohms law. i dont think ive ever seen a factory battery ground that was longer than a foot. i also dont think ive ever seen an alternator power wire that was never longer than maybe 5 feet. might be puny, but over that short run it can handle it no problem.


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## eviling (Apr 14, 2010)

gijoe said:


> Cables don't store power (the capacitance is very, very low), a larger cable has less resistance, so more current can pass through, but it's already sized to allow as much current as the alternator can provide. Upgrading the cable will lower the resistance, but that won't matter unless the alternator cable is undersized (which won't be the case).


Nothing's stored at level that surges enough to make difference. In went to school for electrical and that statement does not hold true. Its a charge that the system puts in the electrons in the copper but once its through its through its simply a difference in the level of resistance these elections have to go from point a to point b. A capacitor has semiconductors to achieve​ the charge they hold, without that it holds nothing even when the systems active it's holds the same charge as a live system and when its off its simply off. 


DC/Hertz said:


> I did say it stores power. It does store electrons which will be more quick release. You said it didn't. So here we are. Even JL recommends it
> 
> https://jlaudio.zendesk.com/hc/en-us/articles/204374080-The-Big-3-Wiring-Upgrade



Sent from my ONE A2005 using Tapatalk


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## LostnEye (Feb 18, 2016)

SkizeR said:


> ohms law. i dont think ive ever seen a factory battery ground that was longer than a foot. i also dont think ive ever seen an alternator power wire that was never longer than maybe 5 feet. might be puny, but over that short run it can handle it no problem.


 


gijoe said:


> OEM did NECESSARILY size the wire for the alternator. That's an absolute safety necessity. They could never afford the lawsuit that would occur when cars set fire because they put an alternators in the car that produces more current than the wire they put in to get the current to the battery. This cable does not need "upgrading" unless an aftermarket alternator is installed.
> 
> The grounds are a different argument. There is value in improving the grounds because they were not sized for aftermarket gear.
> 
> ...


Ohms law does play into car manufacturers wiring choices but adequate for normal usage of a stock car and adequate for how we intend to use them are not the same thing. I have yet to upgrade alternator wiring on any of my own cars, however I have upgraded headlight wiring on a couple cars that while adequate to the manufactures standards adding a relay with heavier gauge make an noticeable improvement in light output. Different cars will have different results based on lots of different factors. 

I am saying upgrading the charging wire on your 80 amp stock alternator will make a difference, no. I am saying you shouldn't assume it isn't a bottleneck if you are significantly changing draw in the system over what it was designed to do.


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## gijoe (Mar 25, 2008)

LostnEye said:


> Ohms law does play into car manufacturers wiring choices but adequate for normal usage of a stock car and adequate for how we intend to use them are not the same thing. I have yet to upgrade alternator wiring on any of my own cars, however I have upgraded headlight wiring on a couple cars that while adequate to the manufactures standards adding a relay with heavier gauge make an noticeable improvement in light output. Different cars will have different results based on lots of different factors.
> 
> I am saying upgrading the charging wire on your 80 amp stock alternator will make a difference, no. I am saying you shouldn't assume it isn't a bottleneck if you are significantly changing draw in the system over what it was designed to do.


It's pretty easy to tell. With the length, and gauge of the cable, you can measure resistivity. That will tell you straight up whether or not the cable can handle the maximum output of the alternator. You will not find an OEM cable that can't handle the rated output of the alternator.

Just 2' of 8awg wire can safely handle 160 amps. My cable is much shorter than 2', so that only means it can handle more than 160 amps. For a typical 80-100 amp alternator 10 awg would even be fine.


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## DC/Hertz (Nov 27, 2011)

eviling said:


> Nothing's stored at level that surges enough to make difference. In went to school for electrical and that statement does not hold true. Its a charge that the system puts in the electrons in the copper but once its through its through its simply a difference in the level of resistance these elections have to go from point a to point b. A capacitor has semiconductors to achieve​ the charge they hold, without that it holds nothing even when the systems active it's holds the same charge as a live system and when its off its simply off.
> 
> 
> 
> Sent from my ONE A2005 using Tapatalk


So you are saying when you turn off the car the battery magically sucks back in all the power from the cables connected to it? No, no it doesn't. 

Let's explain this. 
How can an amplifier that can draw a maximum of say 100 amps. It has a 4 foot run of 1/0 going to it which is more then enough for its demand. 
But they gain on the amp dyno buy having duel inputs. 
This has been tested buy I think droppin Hz on a YouTube dyno test. I don't remember the details but whatever wiring it had was more then enough before the dual inputs. Which I think the amp already had duels so it made it quad inputs.


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## LostnEye (Feb 18, 2016)

gijoe said:


> It's pretty easy to tell. With the length, and gauge of the cable, you can measure resistivity. That will tell you straight up whether or not the cable can handle the maximum output of the alternator. You will not find an OEM cable that can't handle the rated output of the alternator.
> 
> Just 2' of 8awg wire can safely handle 160 amps. My cable is much shorter than 2', so that only means it can handle more than 160 amps. For a typical 80-100 amp alternator 10 awg would even be fine.


Again, I am not saying anything is to be gained for on any individual basis but you are making assumptions as to what is under the hood of everyone who may read this threads hood. Car manufactures couldn't care less about those of us that modify their cars. They care about their shareholders. Every nut, bolt, and wire is scrutinized to save every penny, as those pennies add up to dollars per car and millions across a product line. 

What may be acceptable to not start a fire at the lowest bid might not be the optimal solution for those running much draw is all I am saying.


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## gijoe (Mar 25, 2008)

LostnEye said:


> Again, I am not saying anything is to be gained for on any individual basis but you are making assumptions as to what is under the hood of everyone who may read this threads hood. Car manufactures couldn't care less about those of us that modify their cars. They care about their shareholders. Every nut, bolt, and wire is scrutinized to save every penny, as those pennies add up to dollars per car and millions across a product line.
> 
> What may be acceptable to not start a fire at the lowest bid might not be the optimal solution for those running much draw is all I am saying.


You're missing the point. Modifying the car doesn't change anything with regard to this cable. The only modification that matters is if you add a high output alternator. You can add 1,000 amps to the trunk and that alternator will still only produce 80 amps, and that cable will still carry all of the current.


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## DC/Hertz (Nov 27, 2011)

Here this should end this argument. If added cable here made a huge gain then the same will apply to the big 3. As you can see by the length of the run it was plenty of wire from the start. 
Notice how the voltage drop was lower, power was 200 watts more. 
More cable the better proven right before your eyes. 

https://youtu.be/5RupFFAOx74


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## LostnEye (Feb 18, 2016)

gijoe said:


> You're missing the point. Modifying the car doesn't change anything with regard to this cable. The only modification that matters is if you add a high output alternator. You can add 1,000 amps to the trunk and that alternator will still only produce 80 amps, and that cable will still carry all of the current.


You're missing the point. You're assuming the wire does not add enough resistance to be noticeable with a large added draw because it is adequately sized as to not catch fire under the output the manufacture designed it to function. Will it make a different on most cars, I highly doubt it. 




DC/Hertz said:


> Here this should end this argument. If added cable here made a huge gain then the same will apply to the big 3. As you can see by the length of the run it was plenty of wire from the start.
> Notice how the voltage drop was lower, power was 200 watts more.
> More cable the better proven right before your eyes.
> 
> https://youtu.be/5RupFFAOx74


I can't watch the video at work. But just like my point above you can't assume the factory ground wire is that weak. If you are running 5k well then you should be upgrading your grounds. On my simple system running a single 5 channel I doubt I would see a difference.


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## claydo (Oct 1, 2012)

Here we go again.....sheesh peoples when will you learn enough about electrical theory to realize the load does not affect the alternator ( well except these days of "smart charging systems" where it will loaf if the loads are low, for economy reasons) because it is not the source of electricity in you car, the battery is. The alternators sole purpose is to provide an over voltage situation for the battery to charge.....that's it.....period. Get the largest, best quality battery you can, run the necessary gauge wire to your system from the battery, and everything will be hunky dory. A good battery can supply over 800 cca, your alternator more than likely produces 100 amps or less, like I said, it's just there to provide more than 12 volts so the battery can store it. Knowing this, do you think your puny alternator is really powering that bank of power hungry class a/b amps in your trunk, or do you think the battery might be carrying that load?

Here, read this thread and see what you think.......
http://www.diymobileaudio.com/forum...scussion/254377-big-three-ok-tell-me-why.html

Oh, and I'd like to add that references to guys with 10000 watt spl systems is not a logical way of thinking in our world, don't forget these same guys will skip fusing for another db.......not really applicable in a real world system.


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## gijoe (Mar 25, 2008)

DC/Hertz said:


> Here this should end this argument. If added cable here made a huge gain then the same will apply to the big 3. As you can see by the length of the run it was plenty of wire from the start.
> Notice how the voltage drop was lower, power was 200 watts more.
> More cable the better proven right before your eyes.
> 
> https://youtu.be/5RupFFAOx74


You are a stubborn one. There is no argument about whether or not more copper improves current flow. More copper means lower resistance, which means less voltage drop, and more current. We all agree there.

The argument is that it is a waste of time to change a cable that is already sufficient. The current source (the alternator) is only capable of producing a so many amps, we'll say 80-100 for our purposes. Adding more copper between the alternator and battery will reduce voltage drop, but why would that help? It won't. 

I fully understand why improving grounds helps, but can you explain why improving a 8 awg cable between the alternator and battery would make a difference? I'm all ears.


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## DC/Hertz (Nov 27, 2011)

+
Google Video














ERROR: If you can see this, then Google Video is down or you don't have Flash installed.




Well it appears more cable also helps when there is already enough cable. 
As proven in that video. 
But I know you won't watch it because you don't want to be wrong.
I hope you don't really think less voltage drop don't help


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## DC/Hertz (Nov 27, 2011)

claydo said:


> Here we go again.....sheesh peoples when will you learn enough about electrical theory to realize the load does not affect the alternator ( well except these days of "smart charging systems" where it will loaf if the loads are low, for economy reasons) because it is not the source of electricity in you car, the battery is. The alternators sole purpose is to provide an over voltage situation for the battery to charge.....that's it.....period. Get the largest, best quality battery you can, run the necessary gauge wire to your system from the battery, and everything will be hunky dory. A good battery can supply over 800 cca, your alternator more than likely produces 100 amps or less, like I said, it's just there to provide more than 12 volts so the battery can store it. Knowing this, do you think your puny alternator is really powering that bank of power hungry class a/b amps in your trunk, or do you think the battery might be carrying that load?
> 
> Here, read this thread and see what you think.......
> http://www.diymobileaudio.com/forum...scussion/254377-big-three-ok-tell-me-why.html
> ...


The alternator is there to run the car not charge the battery.


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## claydo (Oct 1, 2012)

DC/Hertz said:


> The alternator is there to run the car not charge the battery.


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## gijoe (Mar 25, 2008)

DC/Hertz said:


> +
> Google Video
> 
> 
> ...


Dude, we're talking about a fraction less voltage drop! A fraction! I did watch the video and it has nothing to do with the alternator cable, which is what we are discussing. It's just showing the different more highly resistive connections make, it's not relevant. We all know what more resistance does to current. 

You still don't seem to get my point. I am fully aware of ohms law. Yes, more copper will reduce voltage drop, how many times do I need to agree with that? What you wont listen to is that the voltage drop from the alternator to the battery is not a concern. Adding more copper will reduce the voltage drop in a circuit that already has very little voltage drop. If you increase the amount of copper from the alternator to the battery, you will reduce voltage drop. You will allow a fraction more current to flow from the alternator to the battery, and you will reduce heat by a fraction as well, neither matter. The amplifiers that you add don't matter in this case. 

If I get time this weekend I'll measure the cables in my car and I can show you the math. Running a second cable in parallel to the existing cable does not equate to any real world improvement. 

Do it yourself if you want. If you need me to walk you through the math you'll need to wait a while, my vacation starts in an hour.


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## gijoe (Mar 25, 2008)

DC/Hertz said:


> The alternator is there to run the car not charge the battery.


What charges the battery then, pixie dust?

You have proven over and over to be far too confident in your ignorance.


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## DC/Hertz (Nov 27, 2011)

Unhook the battery. The car will stay running until it runs out of gas. 
Y'all can't be serious. 

Got this and Clay stereotyping SPL people.


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## claydo (Oct 1, 2012)

Not stereotyping anyone.......have you or have you not seen the practice I mentioned?

Ok.....I think I can put a situation to you that will help you understand.....let's have a lil contest, theoretical of course, but let's take dd's largest badass sub amp....let's mate it with a couple of their beefiest subs in a big ol ported box.....ok, now let's times this by two......one for you, one for me.......I'll remove my old yellow top battery and hook my amp to it, directly, outside of the car........now you start your car and disconnect your battery and power your setup directly from your spinning alternator....now the fun begins, out comes the meter, let's do some burps......me off my yellow top, you solely off yer alternator........now let me ask you.....who wins, and explain why.


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## Bayboy (Dec 29, 2010)

Disconnect the battery while the car is running???? DON'T DO THAT!!! Good way to screw up someone's electrical system.


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## claydo (Oct 1, 2012)

Bayboy said:


> DON'T DO THAT!!! Good way to screw up someone's electrical system.


Lol....theoretical my friend, his alt would be dead within minutes.


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## Bayboy (Dec 29, 2010)

claydo said:


> +
> Google Video
> 
> 
> ...


I was referring to DC/Hertz's suggestion.... probably should have quoted it.


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## DC/Hertz (Nov 27, 2011)

Yes you can 100% unhook the battery while the car is running. It won't mess up anything period. Now if your car monitors the battery it will throw a check engine light. 

Clay if we did that my score might me higher because I will have a higher starting voltage. 
This all depends on the battery and the size of the alternator. 
A battery does not offer much above its 12v resting voltage. 
Fact.


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## Bayboy (Dec 29, 2010)

It won't mess up anything? Ahhhh... guess I was wrong. Yeah, you should go out and disconnect yours then jam the stereo to see how much difference it is. Maybe even turn on a few things while doing it. Headlights, a/c, etc... 

Sent from my SM-G900V using Tapatalk


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## DC/Hertz (Nov 27, 2011)

Man go ask a mechanic if you don't believe me. It will be fine. And if your stereo doesn't draw enough power to pull the voltage down to 12v it won't notice a difference.


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## mmiller (Mar 7, 2008)

DC/Hertz said:


> Man go ask a mechanic if you don't believe me. It will be fine. And if your stereo doesn't draw enough power to pull the voltage down to 12v it won't notice a difference.


I've been around and worked on cars since I was about 10, and some of my best friends that are "Techs". They're called tech's now, not Mechanic, it's not 1990. Sure it will run, how long before the Alternator smokes? Itll get hot enough to cook a steak within a minute. Do you know what is kills electronics,excess heat! I have seen countless times where a weak battery kill not only a good alternator but a new one. 12.4-12.6 is proper sitting battery voltage, I don't need YouTube, or Google to know that, such as an expert like yourself.

In new cars the electrical system is controlled by the ECU, it's constantly monitoring parameters through the electrical system giving and taking small amounts of current to different sensors and components, this is done to not only maximize the life of the components, but also to increase fuel economy. Unhooking it will do a hell of a lot more than just throw a no big deal MIL.

You know what's worse than no knowledge? Someone that has a little knowledge and thinks they know it all. Go unhook your battery every time you start your car for the next few days and let us know how long it lasts.


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## claydo (Oct 1, 2012)

DC/Hertz said:


> Yes you can 100% unhook the battery while the car is running. It won't mess up anything period. Now if your car monitors the battery it will throw a check engine light.
> 
> Clay if we did that my score might me higher because I will have a higher starting voltage.
> This all depends on the battery and the size of the alternator.
> ...


Whoa, I can't believe you came to that conclusion about our lil theoretical burp contest.....notice I said the biggest monster amp they have........you think your alternator has enough current to burp that beast as well as a big ol battery? I believe the first burp would be the end of your charging system.....I am of course assuming dd makes a monster spl amp here.....where the battery powered amp would produce several high current burps before the amp went into protect from under voltage. ....

Something tells me you don't know a s much about the relationship of current and voltage as you think you do.


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## DC/Hertz (Nov 27, 2011)

So if you get a dead cell in a battery which renders it useless you can't jump it off and drive it to autozone? 
Yeah you can. 

Clay a burp takes 2-3 seconds to get a reading. Many people run their charging systems down to as low as 9v during a hard day of demoing.


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## mmiller (Mar 7, 2008)

Yes, you can, and while you're there you may as well by a new alternator at the same time... When the parts guy gives you the new battery and tells you to fully charge it before you install it, ask him why so you can argue with him with Your mind numbing logic. You have no clue how an electrical system works on a modern vehicle, so instead of arguing with people, go do some research.


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## Jheitt142 (Dec 7, 2011)

As someone who does batteries for a living, you'll be very hard pressed to find a modern car that will run off alt output alone. There is way to much going on in the car and modern alternators just don't have the big numbers. You can boost it without a battery and it'll run for 30 seconds if you're lucky, then it will die. This happens more often in cars with terminals that have corroded away to nothing. 

A 93 civic may run just fine on the alt alone, but a 2017 has the same alt output with 10 times the load, it will not run without a battery. When I get to a newer car with a stone dead battery if I boost and unhook right away it dies every time. I have to leave the cables hooked up long enough to allow the battery to charge up a bit before the car will run on its own. It's also why modern cars are garbage for trying to recharge a battery. 


Sent from my SM-G930W8 using Tapatalk


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## Hoye0017 (Mar 23, 2010)

gijoe said:


> OEM did NECESSARILY size the wire for the alternator. That's an absolute safety necessity. They could never afford the lawsuit that would occur when cars set fire because they put an alternators in the car that produces more current than the wire they put in to get the current to the battery. This cable does not need "upgrading" unless an aftermarket alternator is installed.
> 
> 
> 
> ...




So this thread has been all over the place but I'd like to comment on this concept and why I don't think this statement is exactly true.

First, I also generally agree that for a ~1000w system, an alternator cable upgrade will make no difference. And this is probably true well beyond 1000w with today's amp's heavily regulated power supplies. 

That out of the way, I see the logic in your argument, GIJoe, but I don't agree with your understanding of the current capacity of an alternator or the way a Manufacturer protects that alternator and it's cable. An alternator's amp rating is not a hard ceiling, nor a constant. It does not "put out" amps, it only responds to the load presented to it and provides what it can in response. The lower the resistance of the load, the higher the amps it must provide.

Alternators ratings say what they are guaranteed to supply given a constant load. An alternator rated at 100 amps could see short dips in load resistance that will force it to provide more than 100 amps for short periods. It doesn't just stop at 100a and say "sorry, I can't go any higher." If that dip is too low or for too long, one of 2 things will happen:

A. The fuse or the fusible link between it and the battery/fuse box will blow, protecting the wire and alternator.
B. The alternator or it's rectifier will blow from too much current draw.

The point of all of this is that the OEM cable is actually spec'd to handle the maximum current DRAW that can be asked for by the OEM electrical systems. This is not necessarily equal to the maximum capacity of the alternator.

The alternator could be capable of 200a peaks but if the main fuse or fusible link between it and the OEM battery/fuse box is only rated at 100a, that OEM cable only has to spec'd to support 100a.

Now... the question is: where do you connect your aftermarket power cable? Before or after the alternator's fuse/fusible link? What could a big 3 upgrade do to the safety measures put in place by the manufacturer?


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## GEM592 (Jun 19, 2015)

claydo said:


>


yeah, this ^^^


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## dcfis (Sep 9, 2016)

How do you guys square your 1" diameter power wire with it running through puny blade fuses at the amp- heck even anl or maxi fuses are a fraction of a fraction the cross section of the 1" cable some run. I always chuckle with a buss bar with multiple Neon 1" Powa cables running through a row of 300 amp ANLs. Its staring them right in the eyes.


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## DC/Hertz (Nov 27, 2011)

The fuse is a very short area. That's why it doesn't make but a minimal difference.


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## DC/Hertz (Nov 27, 2011)

Hoye0017 said:


> So this thread has been all over the place but I'd like to comment on this concept and why I don't think this statement is exactly true.
> 
> First, I also generally agree that for a ~1000w system, an alternator cable upgrade will make no difference. And this is probably true well beyond 1000w with today's amp's heavily regulated power supplies.
> 
> ...


The point was the alternators job is not to charge the battery. It's job is to start the car. That's why batteries are chosen by cold cranking amps. 

As for removing the battery. We did it all the time in the late 90s to test if the fault was the battery or alternator that was bad. So yes they ran for at least long enough for us to determine the issue. 
Put a 300 amp alt on a civic and see if it cuts off. 
Most stock alts I see today are much larger then they where in the 90s. 
If you have like I do, a 300 capable draw and it stays over 14v when pushed I'm pretty sure it will be fine without the battery.


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## dcfis (Sep 9, 2016)

DC/Hertz said:


> The fuse is a very short area. That's why it doesn't make but a minimal difference.


So, do you admit its like spicing in a 10 awg wire to you Four Aught wire then?


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## DC/Hertz (Nov 27, 2011)

```

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dcfis said:


> So, do you admit its like spicing in a 10 awg wire to you Four Aught wire then?


Sure. For 1 inch. 1in of 10awg can carry a lot of current.


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## dsw1204 (Mar 23, 2015)

DC/Hertz said:


> 3 will be fine. Just make sure all connections are solid and the grounds are very clean.



Thanks, I'll just do the Big 3. I'm pretty sure I don't need to do it, I just want to do it.


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## DC/Hertz (Nov 27, 2011)

You should take some readings. Same song at a volume that's effecting the voltage before the 3 and after.


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## Hoye0017 (Mar 23, 2010)

DC/Hertz said:


> The point was the alternators job is not to charge the battery. It's job is to start the car. That's why batteries are chosen by cold cranking amps.




Ya lost me. It kinda sounded like you were saying the alternator's job was to start the car. I'm sure that's not what you meant.

Either way, the alternator's job is to both run the car's electrical systems while it's running and to charge the battery as needed. 

But that is not my point. My point is that the cable between the alternator and it's fuse is only spec'd to safely handle* the maximum current that the factory electrical system might ever pull. This is usually defined by the main fuse or fusible Link rating. This OEM maximum draw is also what decides a MINIMUM spec for the alternator. So, the rating of the alternator is not what defines it's conductor or fuse.

*"Safely handle" means that the current draw will not create enough heat to where the insulation would be compromised, nor cause it to combust. I suspect that most manufacturers give themselves plenty of headroom when spec'ing the cable gauge.

Remember that conductor resistance increases as it's temperature increases. So additional current draw beyond what is spec'd could create a higher voltage drop than that cable would normally produce. 

So this means that it's plausible that upgrading the cable between the alternator and battery could lower the voltage drop caused by the OEM cable. Whether or not this results in any SPL improvement depends on many more things. 

Just remember, for most modern cars, there is a fuse or fusible link between the alternator and the battery. When you go straight from the alternator to battery, you bypass this. This does not put the OEM cable at risk but it does remove some protection for the alternator. You no longer have a fuse that would blow before the alternator would.


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## GoneBassFishing (May 29, 2018)

I did the Big 3 upgrade and definitely noticed more power from the amp and today I did the 4th upgrade.


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## audiocholic (Dec 5, 2016)

hey friends, 

my car has a 125amp alt and a 70ah 760cca AGM Varta (now owned by johnsons same as Optima) battery 2018 march production.

with a Alpine PDX V9 feeding a Pioneer Stage 4 C172PRS comps actively and a infinity 120.9w sub would it be a waste of time to do the big 3?


labour cost here is peanuts probably 10usd at most for the install and another 10usd for 4awg ofc wire (6-7ft) so is it worth it for the upgrade at this cost or should I just stick to upgrading the ground only?


by the way does anyone know the c172prs tweeters rms rating and impedence?


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## MikeS (May 23, 2015)

audiocholic said:


> hey friends,
> 
> my car has a 125amp alt and a 70ah 760cca AGM Varta (now owned by johnsons same as Optima) battery 2018 march production.
> 
> ...


You only need the ground wires upgraded to match your amplifier power wire really. Another thing is to get the charging voltage up a bit for the AGM battery if charging system is not made for it. If you feel theres not enough juice in the battery the charging voltage may very well be the reason.
There was a difference starting the car after I installed some diodes to alt-s wire to trick the regulator to give out higher voltage.

Most cars have some sort of "smart" charging, with purporse of using less fuel = less charging. With those it's pretty much pointless to upgrade the oem wire from alternator.


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## audiocholic (Dec 5, 2016)

MikeS said:


> You only need the ground wires upgraded to match your amplifier power wire really. Another thing is to get the charging voltage up a bit for the AGM battery if charging system is not made for it. If you feel theres not enough juice in the battery the charging voltage may very well be the reason.
> There was a difference starting the car after I installed some diodes to alt-s wire to trick the regulator to give out higher voltage.
> 
> Most cars have some sort of "smart" charging, with purporse of using less fuel = less charging. With those it's pretty much pointless to upgrade the oem wire from alternator.




thanks for the reply,



just as you stated my car indeed does have whats called the intelligent battery system similiar to Honda's ELD system.


the alternator outputs according to whats being used so for instance if all is off it only puts out 12.6v .

if theres a heavy load such as a/c, headlights all being on at once it puts our 14.4v




I simply pulled the connector on this system and luckily only get a warning on the dash and nothing else such as limp mode etc. this allows for a steady/stable 14.4v's


I will do as you stated and upgrade the ground wire from battery to chassis of which looks like 8 or even perhaps thinner wire.


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