battery ground be too good?

hey, I've got a system with approximately 350 amps (max) of power from fuse ratings, and my question is after I did the big 3 with better wire (2/0) on my truck the battery has a spike in voltage after burst of (usually higher freq) bass notes. The only conclusion i could come up with was that the resistance of my ground wire for the big 3 is less than that of the power wire (1/0 x 2) allowing for a current build up in return creating voltage spikes? any help would be greatly appreciated, thanks.

The voltage spikes also get up to 16volts putting both amps into protect mode. and one of my amps grounds are hooked directly to the battery. So the spike isn't only going through the truck.

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I can't hear you!

Partly correct perhaps.
Your +12V resistance may be too high.
But your ground cannot be too low. It never can be.
Just as +12V resistance can never be "too low".


There is no such thing as "current build up" as you put it.
It is simple V=IR. No delays or capacitance etc.


I presume you are saying that this system never "spiked" before, but since Big-3'ing (ONLY!), it now spikes?

I added the Big 3 and the voltage started spiking, then I added an HO alternator and and it basically just spikes a lot easier (lower RPM).

one thing i did notice was i have a Frame to Cab ground wire (which i upgraded as well). most vehicles only have chassis, engine block, and battery. I measured the resistance inside the cab and its about 1.5 ohms. The engine block 0.6 ohms and chassis 0.6 ohms. I know this has to be a part of the problem but I dont know if i should just start creating grounds.

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I can't hear you!

The cab is 1.5 Ohms resistance to the battery ground or alternator etc?

So 350Amps x 1.5R = 525 Volts?
Or if running 10 Amps, that's a 10 x 1.5 = 15 volt drop?


Yes - I think you may have a wiring problem!!

it's 1.5ohms to the battery negative yeah. But what do i need to achieve a lower resistance in the cab?? Does the current want the easiest route back to the battery negative? or to the alternator?

these are the ground wires that I standardly upgraded.

Battery-engine block
Battery-chassis
chassis-engine block
frame-cab

I would think the Cab would use a better ground source than the frame. should I trying hooking the battery negative directly to cab?

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I can't hear you!

The grounding principle behind the BIG 3 is fat cables (good ground) between the engine (ie, alternator ground), the battery -ve terminal, and the body.
That assumes the (heavy) loads are grounded to the body, else battery -ve. (Engine too, but that is rare except for starter motors.)

It is meant to ensure good grounding (fat cables; low resistance) between the load and the power sources (battery or alternator).


If you stick extra things between those grounds, or it you ground you load to something else, it is implicit that those need to be included.

In short (pun intended), if you have battery, alternator, chassis & body and cab (as I have where body = tray), then heavy ground between ALL of them.

Despite iron and steel being a far inferior conductor to copper (steel can be 3%-15% the conductivity of copper), because of the cross-sectional area of engine or body or chassis steel involved, they are usually the path of least resistance.
Hence rarely is a cable from battery or alternator ground direct to the load ground better than via chassis etc.
But that assumes good grounding (eg, the Big 3).

Only when the load-cable-connector-bolt-body-bolt-connector-cable-connector-bolt-chassis-bolt-connector... etc to battery or alternator is risky or breaks down is a direct connection better. IE - the connector-bolt-conductor path may become high resistance.
Or (obviously) when the cable length from battery/engine to the load is less than or similar to the intermediate paths.


And you may have found one of the reasons people with big amps have a (second) battery next to the amp.