Why is my voltage drop so awful?

[RAM_Designs 5,000+ posts]

There is obviously high resistance between the rear batt and the amp. If you're dropping .2 and there is no current being drawn, that is bad. In a parallel circuit the voltage should be the same. It's only once you start drawing current that the resistance of the wire should become evident. You need to either shorten the run from the back batt to the amp, or shorten the ground or both... or tighten something. It's right there. It can't be anything else.

This.

How are you grounding your amp and where is it grounded to? I assume you're sending the ground from the amp to the rear batt and grounding the batt somewhere, correct?

 

[hatedonmostly 5,000+ posts]

This.
How are you grounding your amp and where is it grounded to? I assume you're sending the ground from the amp to the rear batt and grounding the batt somewhere, correct?

Unfortunately, no. Amps are grounded in the cab and batt is grounded in the bed... //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[Buck 5,000+ posts]

hmm...that might be your problem

 

[SpeedEuphoria 10+ year member]

I say grounding also

BUT

Whats the voltage with the car on? I never saw that, but prob not the issue as from what I under stand with the truck not running your getting a V drop of almost 1volt(from 12.6x down to 11.8v) or is that with the truck running, which would mean something is no good.

May have to run another 1/0 ground up to the front

 

[stereohead69 10+ year member]

You said your wire you bought off of Ebay what is the brand of wire since i know that companies like Pyramid,Rampage,Legacy,Lanzar to name a few when you buy from them a 4 guage kit when you get it its more like 8-10 gauge i dont know if that might be your prob but i would check it out.

 

[l7runner 10+ year member]

Ground amps to the rear batt.

If possible do a ground run from front to rear batt. This should solve all of your issues.

 

[hatedonmostly 5,000+ posts]

hmm...that might be your problem

Ground amps to the rear batt.
If possible do a ground run from front to rear batt. This should solve all of your issues.

Indeed, it seems so....

I say grounding alsoBUT

Whats the voltage with the car on? I never saw that, but prob not the issue as from what I under stand with the truck not running your getting a V drop of almost 1volt(from 12.6x down to 11.8v) or is that with the truck running, which would mean something is no good.

May have to run another 1/0 ground up to the front

Oddly, voltage with the car on is only 13.6 with the car warmed up. Pretty shitty.

But yes, the voltage drop I described was with the car on.

You said your wire you bought off of Ebay what is the brand of wire since i know that companies like Pyramid,Rampage,Legacy,Lanzar to name a few when you buy from them a 4 guage kit when you get it its more like 8-10 gauge i dont know if that might be your prob but i would check it out.

When did I say anything about eBay in this thread? //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif I run Knukonceptz everything...

 

[Imtjnotu 5,000+ posts]

RUN 0 gauge and check all ur grounds also get a dmm and check ur alternator

 

[hatedonmostly 5,000+ posts]

Okay, so:

-Grounded the amps at the battery, didn't help.

-Tossed in a buddy's 110ah battery to see if it was the battery was bad, I was still dropping to 12v. So rear battery I had in must be fine.

-Took the rear battery out, and the voltage drop did not change at all, or at least, very very little. Still dropping to 11.8-9.

-Checked various voltages. At full tilt I'm dropping to 11.8 at the amp, 12.0 at the in side of the distro for the amp, and 12.8 at the rear battery. Somehow I'm losing 1v between the battery and the amp, yet why should I even be dropping to 12.8 at the battery in the first place?

Alt not charging perhaps? If not then I give up

 

[Stalin-ohaulic]

Okay, so:-Grounded the amps at the battery, didn't help.

-Tossed in a buddy's 110ah battery to see if it was the battery was bad, I was still dropping to 12v. So rear battery I had in must be fine.

-Took the rear battery out, and the voltage drop did not change at all, or at least, very very little. Still dropping to 11.8-9.

-Checked various voltages. At full tilt I'm dropping to 11.8 at the amp, 12.0 at the in side of the distro for the amp, and 12.8 at the rear battery. Somehow I'm losing 1v between the battery and the amp, yet why should I even be dropping to 12.8 at the battery in the first place?

Alt not charging perhaps? If not then I give up

So you connected the amp to the rear batt, and there was still a voltage difference? If so, your wires are either too long or you have a bad crimp or something is high resistance there. Also, batteries only charge up to about 12.6, how the hell could they help keep your voltage up above that? lol

 

[hatedonmostly 5,000+ posts]

Yes, a small difference. All my connections are soldered...

I'm talking about with the car running.

 

[RAM_Designs 5,000+ posts]

Where exactly is your rear batt grounded in the bed?

 

[hatedonmostly 5,000+ posts]

To the bed of the truck, paint sanded and bolted down. I know it's not to the frame, but my frame is rusty and I didn't think it mattered because I was getting the same resting voltage on both batteries.

 

[ThatChevyGuy 5,000+ posts]

my alt is 136a, stock battery, random ebay 4 guage wire, AQ1200D amp, 14.4 volts.BIG 3??? who needs it???

seriously idk whats wrong, i just measured mine yesterday and i got literally 14.4 -14.2 volts right at the amp, i ran a single long wire from batt under all my side panel stuff, all the way to the amp. no fuses, no distro block.

Idiot.

 

[branham1127 10+ year member]

You need to listen to people and ground your rear battery somewhere else. The bed of a truck is not a good ground. Many people (such as yourself) fail to realize how important the ground is in a car electrical system. I really think this will solve the problem of the voltage difference.