Battery grounds with multiple batteries

[cheezy]

Hello, recently added a second battery to the system for whatever reason, I've never had any good ground spots in my 96 truck club cab other then the seat bolts which worked for my speaker and sub amp for a while but now however, the second AGM battery hooked up to the same bolt is like naaaaahhhh... my bass amp cuts volume then comes back after 6 seconds etc.... so now I'm in a predicament as to do i run another gauge run from the front battery negative to the rear AGM? I've read mixed reviews online i guess... i am from Old times where sure everyone thought you needed less then 18" for a battery ground, however, nowadays I see 80,000 watt rides with 12 runs of 4/0 negative from front battery to rear banks...

 

Just wondering if this will solve my problem or has solved above else's problem of similar to what I'm going through before I go get another run. 

 

Again, will running another run of wire from my front battery, that is grounded to the chassis, all the way to my rear AGM be a sufficient enough ground for the AGM?... Also, i have 2 amps grounded of the AGM now as well.  Thanks. 

Edited March 29, 2025 by cheezy

[Joe X]

As long as you use the proper gauge you can run ground from battery to battery no problem, in fact is the best ground you can have and in a truck the line will not be that long, just make sure gauge is what is needed.

 

Also don't forget big 3, it's extremely important.

[Reegster]

Run a battery isolator if you plan to add extra batteries in your vehicle. 

I would think that you amp cutting out is a capacitance problem not a grounding problem.

Running cable from the front of your vehicle to the back is fine for the 12v+ but the entire body and chassis is a ground.

A long ground wire directly to the battery might get you slightly better power (SLIGHTLY) but it will very likely cause inducted noise. 95% of inducted noise is usually from improper/poor grounding in a DC electrical system.

Burp trucks and SPL guys don't give a rats ass about engine whine, alternator hum, or ground loop noise. They are not listening to the system for audio quality, they are looking for max output.

They can run multiple long run ground cables if they want (again only a minor improvement electrically) because they don't care if it creates a small amount of whine or hum.

As previously prescribed: definitely do a big 3 upgrade and also consider adding a capacitor.

[Loudsinglecab]

On 12/16/2025 at 4:37 PM, Reegster said:

Run a battery isolator if you plan to add extra batteries in your vehicle. 

I would think that you amp cutting out is a capacitance problem not a grounding problem.

Running cable from the front of your vehicle to the back is fine for the 12v+ but the entire body and chassis is a ground.

A long ground wire directly to the battery might get you slightly better power (SLIGHTLY) but it will very likely cause inducted noise. 95% of inducted noise is usually from improper/poor grounding in a DC electrical system.

Burp trucks and SPL guys don't give a rats ass about engine whine, alternator hum, or ground loop noise. They are not listening to the system for audio quality, they are looking for max output.

They can run multiple long run ground cables if they want (again only a minor improvement electrically) because they don't care if it creates a small amount of whine or hum.

As previously prescribed: definitely do a big 3 upgrade and also consider adding a capacitor.

 

[Loudsinglecab]

Isolators are worthless unless you plan on leaving the engine off while bumping..
I run 4/0 + and - front to back in my S10 for a four 15 setup and it is a SQL setup with zero alt whine ECT..
If you know what you are doing you do not have issues ..
My best advice is be careful who you get your advice from lol

Edited December 21, 2025 by Loudsinglecab