.4 volt voltage drop

[Sequoia_Bass]

I'm about to switch my grounds to 4/0 grounding to the frame. But for now i am using the cars floor as my ground and i'm getting a .4 volt drop compared to my battery voltage. My amps cut out at high volume i'm assuming because of the grounds. Will i see improvement when i switch over to the 4/o wires? and does bad grounding cause amp problems like i mentioned?

[WalledSonic]

>I'm about to switch my grounds to 4/0 grounding to the frame. 

If you are changing from a chassis ground to a frame ground anyway, then you can measure your voltage drop and report back your findings.

[audiofanaticz]

Depending on what you have now for wiring, its most likely the positive run of wire that has a lot of resistance causing the .4 voltage drop from the battery.

A proper chassis ground will have little resistance in the chassis (unless your running 5,000+ watts rms), and very little resistance in the wire since the ground wire is so short.
It has been tested that a decent rear chassis ground is better and has lesser resistance than a negative run of wire from the front to back (as long as you are under 5,000wrms or so).

But who really knows since you didnt say what your current wire size and type it is, nor have you said your amplifier model and what ohm load its wired at, and if you have additional batteries.

Realistically a .4 volt drop is not enough to kick your amp into protect, so there is something else severely wrong with your install.
Most amps will not protect due to low voltage until the low 9 volt range, so unless your car battery is 9.4 volts dropping to 9 volts I highly doubt that is the issue.

What can cause the amp to go into protect is loose connections on the positive wire, the fuse connections (if you have any), the ground wire. The amp will also protect if your running it under its lowest stable ohm load. It can also protect due to the gain, bassboost, or both being turned up too high. Another thing that may cause the amp to protect is if you have any stray speaker wires touching each other on the amps speaker output terminals, or on the subwoofer.

[rocking.that.eclipse]

I think that every build that I have ever worked on has had some voltage drop over the length of the vehicle. 

Heck even with 8 runs in my blazer I saw a 0.1V difference in voltage from right off alternator to the back battery bank

 

[audiofanaticz]

Yea, there is really no way around it. .4 volts is not that bad (if its under load).

The only solution is to keep running more wire until you reach the point of diminishing returns. Hell some db drag street class competitors have 20+ runs of wire going through the car just to get rid of every little bit of resistance.

But as I stated with my post, without knowing any real information at the problem at hand who knows what is up. A .4 volt drop shouldn't be kicking an amp in to protect, so Im assuming other factors are at play here.

If we knew the current type of wire (cca/ofc), the size of the wire, the length of the wire, the actual amperage draw, the front voltage, the rear voltage at the amp you could actually calculate out what the needed upgrades would be.
 

[Sequoia_Bass]

I have 2 4/0 ofc positive wire runs each one is 17 feet long each fused at 150 amps(for now until i get new alts) i have 4 american bass ph4000mds each one wired a 1 ohm, i have 2 bus bars one for positive and one for grounds. running 4 gauge from the buss bars to the amps. The amps only have 4 gauge inputs and i tried 1/0 adapters but the positive and negative terminals on the amp are side by side and the adapters would touch so i don't use them. I currently have all gains at 8oclock position, i know this isn't a volume knob but since i only have 240 amp alt and stock battery i keep all gains down. otherwise id have to keep radio low for it not to overpower alt,wich would result in quiet mids and highs. 

im running 4 gauge grounds straight to car floor not to buss bar for now. i still need to buy a tool to cut hole in car for the 4/0 wiring thats when i will switch over to buss bars and frame grounding.  but currently i get a .4 volt drop from back without any load... and the amps(or amp) will cut out at "high" volume. one(or maybe multiple) of the subs. will make a poping noise simuaneounsly when the amps cut off. i think one of the amps might have bad cap?

[audiofanaticz]

You cant use normal reducers, you need to find reducers that have an offset. Knukonceptz has them (but one set screw will be upside down like shown in their pics), Toolmaker Metalworkz, and Jims Machineworx both make their own style of them as well (and can be bought in copper but costs more).

Sky High also makes them, but from my expirence with their 4/0 to 1/0 reducers is they are really thin where the setscrew is and stripped out a couple very easily without much force.

Example:

http://www.knukonceptz.com/sp/set-screw-gauge-reducer-0-to-4-gauge/

 

 

 

[audiofanaticz]

Typically a proper set amp gain is usually in the 8 to 11 oclock range for clean output (of coarse it will vary some depending on many things, but its just as a rough idea on where they are normally set at).

Since those amps are "minis" with a 4awg power input, then I can say that your issue is not due to only using 4awg grounds. 
The fuse rating on those amps are 150 amps each which should easily be handled with 4awg wiring as long as the 4awg wire is copper and under 10 feet per run.

So you can easily rule that out as being the problem (unless your using cca wire, and the 4awg power/grounds are longer than 10 feet).

Now you said you had a stock battery (which is up front under the hood Im assuming).
Im willing to bet this is your problem.
You are trying to supply damn near 8,000 watts rms with 500-600 amp continuous draw when turned up to the point amps turn off.
That is more power than your alternator is able to put out, which is causing you to eat up what little reserve the factory battery has in it. Not to mention you also have to power whatever electronic accessories that maybe on in the vehicle (which can be 60-100 amps alone) on top of that huge current demand from the stereo.

In all honesty, I am surprised your stock battery hasn't failed yet, or your alternator hasn't blown from trying to charge a fairly dead battery, which can over load the alternator causing it to run exceptional hot until it melts any internal plastic components and/or starts on fire.
 

[Sequoia_Bass]

I will order some offset adapters! and what i don't get is that my voltage doesn't get very low before the amps cut out, roughly 11.4 volts or so. But i'll reduce gains until i upgrade electrical. After i do grounds i'll see if that helps any. Now that i remember, my friend borrowed one of my AB ph4000s and it would also make the subs pop, but his voltage stayed above 12volts