# Should I ground my amplifiers directly to my battery?



## iregret (Jul 27, 2009)

I'm in the middle of my build up and something occurred to me. I bought 4 gauge wire for my amplifiers. My sub amp can accept it, but my other amps can not. They're PQ10s and it looks like the largest wire I can use will be 10 gauge. 

So I've got like 20 feet of 4 gauge black wire that I can't use.

Now I've ran 2 gauge wire from my battery to a 200 amp circuit breaker, then to a fused distribution block for the amplifiers.










Since I have this extra wire I figured I'd go ahead and run it directly to the battery, and then from the battery directly to the chassis.

I've seen in amplifier wiring kits where the ground wire is always smaller gauge than the supply wire. I don't usually buy kits so I always used the same sized wire.

Will me using 2 gauge for power and 4 gauge for ground be okay?

Good idea? Or bad idea?


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## bassfromspace (Jun 28, 2016)

Your ground should be 3ft long max.


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## emilime75 (Jan 27, 2011)

It's better to try and keep your wire runs as short as possible.


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## iregret (Jul 27, 2009)

That's what I thought.

I'll ground the battery to the frame. The chassis is probably a better conductor anyhow. It just so happens that all my gear will be grounded to the same point. No problem with that right?

I thought about it after I posted. What if, for some crazy reason failed and when I tried to start the truck there was a short and all that current went through the amplifiers by accident. That would suck!

Now, if there were a second battery near the amplifiers would you guys want to ground it to the battery then? Assuming the second battery was isolated from your starting battery.


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## Pimpnyou204 (Jul 13, 2011)

Out of curiousity would sanding down the portion where your spare tire screws down into be an ok ground to use?


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## Sound-In-Waves (Jan 22, 2012)

If you're grounding your amps to anything to try an prevent noise, it would be the alternator. Thats where the alternator whine would come from. I can disconnect my battery and still have alt whine but if I disconnect my alternator then the whine should go away. However I would recommend like everyone else keeping grounds as short as possible. All my grounds are 6 inches or less and I haven't had any problems with whine.


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## Sound-In-Waves (Jan 22, 2012)

And no I would not use the spare tire screw point, most likely its welded on to the frame.


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## eviling (Apr 14, 2010)

bassfromspace said:


> Your ground should be 3ft long max.


not true, it's just prefered.


emilime75 said:


> It's better to try and keep your wire runs as short as possible.


^ proper statment 

but yeah, no reason to make the run when the car has plenttttttttttttttttttttttttttty of conductivity to ground to the car. at the very most perhaps re-enforcing the ground from battery to car is much easier, and cheaper. it is what most of us do, the big 3 or some **** i think they call it. I'd show you mine, but i used black tech flex and it just blends in with the tubing and **** of my engine so it's hard to even see what i did. but make sure you attach to the engine and the car not just the car. granted the engines mounting blocks would in your mind be enough, their genraly painted and such. depending on the car.


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## [email protected] (Jun 12, 2008)

Grounding to the battery is done all the time, with no ill effects. Especially for high current demands. There is no real max length of a ground, thats just absurd. 

I wouldnt ground everything with 4 gauge if my power run was 2 gauge anyways.


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## eviling (Apr 14, 2010)

I believe its done with extreme SPL systems but for sq purposes its useless to run a ground through.

Sent from my EVO using Tapatalk 2


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## prettysweetsounds (Jul 26, 2011)

ground to the chasis. it's easier and effective.


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## [email protected] (Jun 12, 2008)

eviling said:


> I believe its done with extreme SPL systems but for sq purposes its useless to run a ground through.
> 
> Sent from my EVO using Tapatalk 2


Whats useless about getting the least voltage drop? Running it back to the front does that. Resistance should never be a problem as long as you run the proper gauge wire for the application. I am not saying everyone should run it to the front. But saying they need to be as short as possible is not correct.


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## Orion525iT (Mar 6, 2011)

prettysweetsounds said:


> ground to the chasis. it's easier and effective.


Unless your battery is under the rear seat .


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## [email protected] (Jun 12, 2008)

Orion525iT said:


> Unless your battery is under the rear seat .


Ya, I had a Audi before and it was under the seat, made it all alittle easier.


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## jonbuilds (Jul 8, 2012)

iregret said:


> Since I have this extra wire I figured I'd go ahead and run it directly to the battery, and then from the battery directly to the chassis.
> 
> I've seen in amplifier wiring kits where the ground wire is always smaller gauge than the supply wire. I don't usually buy kits so I always used the same sized wire.
> 
> ...


Typically the things you should emphasize for grounding are:
Secure, clean connection points, terminals, screws, etc...sand off any paint or rust proofing so you can see clean metal at your chassis connection point.
Make sure are grounding to chassis/unibody.
Keep ground runs short if practical, use same gauge wire as power feed.

BUT....
I can tell you I have seen some horrible ground runs that were just good enough to make everything turn on. It's the little things that can make the difference for long-term reliability, avoiding ground loops, etc.

UNLESS..
you have an old corvette, which may need to have the chassis "bonded" to prevent ground loops and associated noise when installing in a fiberglass body.

Grounding back to the battery typically will not provide any noticeable benefit, but only your ears and wallet will know and care about the difference, and you are the decider!

Best of luck
Jonathan


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## TAMUmpower (Jan 29, 2010)

It's also easier if you have a bimmer and ur battery is maybe 2 feet from ur amps...

I go direct to the post since its right there. Not gonna drill holes in my car unless I have to


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## RC Audio (Mar 12, 2012)

I have been installing professionally for some time now and I have heard many different arguments on this subject. Personally I only ground the amplifier at the battery if I am doing an amp in a vehicle which does not have a metal chassis, and I think maybe on a couple of occasions I have done it on a bwm or mercedes where the battery is right there and the run is very short. Knowing the basics about 12vdc electrical systems, it does make sense that you want the ground path to be a short as possible because obviously the further the distance the more resistance, however, I have wondered myself if the current was traveling through an adequately sized cable vs. the vehicle's chassis over the same distance, then isn't it the same thing? I don't know the correct scientific answer to that, but I do know that it is impractical to run a wire (esp. if it is a 4ga, 2ga, or 0ga) when you already have a perfectly usable ground path available (the chassis) as long as you properly ground the wire (i.e. mount to primary metal, clear the surface of any non-conductive material, and make sure the connection is %100 tight ). 

When I choose a grounding point I always try to find a usable factory bolt, I avoid drilling holes whenever I can because I find it pointless to hack up a car when there is a perfectly usable ground already there via a factory bolt. As far as noise, as long as there isn't a big voltage drop between the grounding point and the batteries negative terminal, then you will not have noise (at least no noise from ground loop, you can still pick up radiated noise through the rca's or crossovers of course).


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## JohnnyTwoTone (Sep 7, 2008)

It's weird that we even use the word "ground" in the case of cars.

"What if, for some crazy reason failed and when I tried to start the truck there was a short and all that current went through the amplifiers by accident. That would suck!"

Current shorts to the source. If your amp was properly bonded than there's no reason to believe that the current would run TO the amplifier, in case of a short.


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## CaptainMorgan (Jan 13, 2012)

I just put my battery in my trunk so I can hook everything up directly . I use a circuit breaker on my main run so if I overdraw from the alt I don't strand myself with a car that can't run, just reset the breaker.

I do like how it was pointed out that the common advice on short grounds isn't always true. A large ground wire can easily have less resistance than the chassis of a car.

I do have a slight alternator whine I need to get rid of, but I have an idea as to that. There is one other specific change I want to make that hopefully will solve my issues.


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## Golden Ears (Jul 18, 2010)

I have a Mercedes with the battery in the trunk on the passenger side- in the rear quarter panel well. Lots of amps. MC4000 on the rear wall- and 300 watt mono blocks on each rear quarter panel, and another 400 watt amp on a sliding drawer. 

I was thinking of adding a second battery in the mirror image location on the drivers side. 

How would I connect that? 

1. Should I use an isolator to reduce the load on the alternator?

2. Should I just parallel the batteries so I get more amperage? This is not an SPL car..I just want longer key off run time.

3. If I do this two battery set up. What should my wiring scheme look like? Should I run two circuit breakers and two fuses into a single distribution block? OR should I just parallel the batteries and run whatever amp is closer to each battery to reduce resistance?

4. I want to run power and ground to my head unit so they all ground to the same point to reduce noise... (I have noise now- ironically caused by wiring of a unnamed former IASCA judge) this is what Whittledge (he has ZERO noise) does with his sprinter. Will running that long of a lead from the rear cause issues? Should I just measure resistance with a multi meter and call it a day...and ground close to the head unit? 

5. With 2000 watts of McIntosh amplification should I change the grounding strap from my engine to chassis to a thicker gauge? Or is current flow there not a concern?


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## gravel (Jun 24, 2012)

Maybe its unnecessary, but I like to run a substantial (#8 or bigger) ground wire from the engine block to the battery, the battery ground, the head unit ground and end up at the amp ground. Ensures that the grounds all have as little resistance as possible. Started doing this years ago when I had a noisy system that wouldn't respond to the normal "bare sanded metal, stout and tight connection" grounding methods. Might be overkill, but I see no potential problems, my stuff is always quiet and it makes me feel good..


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## CaptainMorgan (Jan 13, 2012)

gravel said:


> Maybe its unnecessary, but I like to run a substantial (#8 or bigger) ground wire from the engine block to the battery, the battery ground, the head unit ground and end up at the amp ground. Ensures that the grounds all have as little resistance as possible. Started doing this years ago when I had a noisy system that wouldn't respond to the normal "bare sanded metal, stout and tight connection" grounding methods. Might be overkill, but I see no potential problems, my stuff is always quiet and it makes me feel good..


Ideally every component to an audio system should be grounded back to the same point, which obviously should have a good path to the battery (low resistance). As you say at worst what you're doing is overkill, and definitely ensures no noise.


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## Richv72 (May 11, 2012)

they sell adapters to make a wire smaller at the connection also, so just run the 4 to the chassis and use an adapter if you want to not waste the wire.


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## adrenalinejunkie (Oct 17, 2010)

Since we're on the topic. The '01 S10 Blazer has steel frame that I can get too by simply drilling a hole on the body. Would getting to the frame through the rear be the same as getting a 15Ft ground cable from the rear to the under hood battery? I think yes since the battery is grounded to the frame, but thought I'd ask to confirm since many of you have more expirience then me.


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## bigguy2010 (May 18, 2010)

On a full frame vehicle, use it as the ground. On a unibody I can see a reason to do this. Not for current carrying capacity but to ensure a great ground. Don't have to worry about drilling a hole and sanding the paint down. Also skipping spot welded sheet metal as your substrate. 

By running ground to the battery would you see any improvement in noise floor? Or would it possible introduce noise because the ground wire is running all the way up front? I've always found this idea interesting.


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## CaptainMorgan (Jan 13, 2012)

bigguy2010 said:


> By running ground to the battery would you see any improvement in noise floor? Or would it possible introduce noise because the ground wire is running all the way up front? I've always found this idea interesting.


The only way to give a sure answer is to measure the resistance or the run both through the frame and through the wire. If the run with the wire is a large enough wire to have less resistance than just going through the frame then it is a win for sure.


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