Why is my voltage drop so awful?

[Bumpin' Goalie 10+ year member]

Most common sense things have been mentioned such as ground, connections, etc. It is not normal nor confidence-inspiring to have such a severe drop occur through a short run of wire.

So I'll ask a rather overlooked question. What are you measuring voltage with? A self-detecting device or an adjustable device? Stinger meters, for example, have to be calibrated to be accurate.

Just food for thought.

Best wishes Still.

 

[hatedonmostly 5,000+ posts]

Most common sense things have been mentioned such as ground' date=' connections, etc. It is not normal nor confidence-inspiring to have such a severe drop occur through a short run of wire.
So I'll ask a rather overlooked question. What are you measuring voltage with? A self-detecting device or an adjustable device? Stinger meters, for example, have to be calibrated to be accurate.

Just food for thought.

Best wishes Still.[/quote']

Using a dmm...

Well, in order to ground the rear battery to the frame I had to undo the run of wire from the rear battery to the amp. Shit sucks, I didn't have enough wire.

Doing the rear battery to the frame I was dropping a little less, like 0.03v, and after playing a song for a while full tilt the voltage would stay above or at 12v. But that's on music, so could very well be due to the song.

Rear battery stays at 12.8 or higher, and honestly I don't know why that is dropping so low either.

I'm just gonna do a jumper from the amps' ground to the rear battery's frame ground, and see if that helps. I've eliminated every other possible option.

 

[hatedonmostly 5,000+ posts]

Just to clarify, here is what I have done:

+ 1/0 from front battery + to rear battery +, fused on both ends at 250A.

+ 1/0 from rear battery + to distro block input.

+ 4 and 8 from distro block output to amps 12v terminal.

- 4 and 8 from amp ground terminal to the first ground point, which is the grounded to the cab of the vehicle.

- 1/0 from rear battery - to the second ground point, the frame of the vehicle.

- 1/0 from the first ground point (cab) to the second ground point (frame) to connect the two grounds.

Still seeing 12.0 regularly. Really don't know what else there is to do from here...I shouldn't see any drop with this big *** battery...

 

[Stalin-ohaulic]

So basically, if you don't have a HO alt up front, no matter how much reserve you have in the rear, you're always going to have voltage drop?

If you exceed the amount of current the alt can produce while keeping the voltage up then yes. There is nothing else in the system capable of 14.4v. Caps DO charge up to 14.4v, but don't store enough of a charge to help at all.

 

[hatedonmostly 5,000+ posts]

If you exceed the amount of current the alt can produce while keeping the voltage up then yes. There is nothing else in the system capable of 14.4v. Caps DO charge up to 14.4v, but don't store enough of a charge to help at all.

I had a buddy who was running 3k with two 110ah batts, factory 110A alt and no big three done. He would stay above 13.5 unless he was playing full tilt for prolonged periods of times, and the reason why he would drop is because his alt wasn't charging fast enough.

If I'm running 1/3rd the power he has, with 1/2 the reserve, why am I dropping so bad, when his reserve was keeping up fine? I feel like I should have great voltage, I have a fucking 88ah battery and am only using 1k...yet dropping lower than he ever did.

 

[Pyro_By_Nature 5,000+ posts]

I only read the first and last page, but here's my suggestion. Fix your ground!!

The best thing you could do is to get another run of 1/0 from the front battery to the back, and ground the amp to that battery as well.

 

[9515ROB 10+ year member]

your batteries might be bad they might charge up fine but not like a load on them your alternator might not be big enough to run your car and your system

 

[hatedonmostly 5,000+ posts]

I only read the first and last page, but here's my suggestion. Fix your ground!!
The best thing you could do is to get another run of 1/0 from the front battery to the back, and ground the amp to that battery as well.

I'm grounded the the frame.

True, but the last thing I want to do is spend more money on this shit if I'm about to tear it all out because nothing has done any good so far.

your batteries might be bad they might charge up fine but not like a load on them your alternator might not be big enough to run your car and your system

I was getting the same voltage with the rear battery not hooked up, and with a different rear battery hooked up.

Regardless of the alternator, I should have plenty of reserve in that rear battery to keep up with a measly 1kW.

 

[9515ROB 10+ year member]

get a alternator

 

[hatedonmostly 5,000+ posts]

Regarding what I had said, which battery do you think it is? Front?

 

[Lakota 5,000+ posts]

Didn't read the whole thread, but will comment on one thing: The voltage throughout your car should be very close to the same value, no matter where you read. If there really is a difference in 1 volt from the front to the back, then you have a wiring problem. Your car is wired in parallel, and the connections should all have very low resistance. In a true parallel circuit, the voltage is the same everywhere.

 

[benzmansl65amg 10+ year member]

Bad ground

 

[hatedonmostly 5,000+ posts]

Didn't read the whole thread, but will comment on one thing: The voltage throughout your car should be very close to the same value, no matter where you read. If there really is a difference in 1 volt from the front to the back, then you have a wiring problem. Your car is wired in parallel, and the connections should all have very low resistance. In a true parallel circuit, the voltage is the same everywhere.

That leads me to believe that it's either the fuses, the fuse holders, or the ring terminals...I've reused the ring terminals multiple times by resoldering, could that possibly be it?

 

[Pyro_By_Nature 5,000+ posts]

I'm grounded the the frame.
True, but the last thing I want to do is spend more money on this shit if I'm about to tear it all out because nothing has done any good so far.

Your first sentence is precisely why you should have a dedicated run of 1/0 for the ground. A 20' run of 1/0 is much more conductive than the body of your vehicle.

 

[Stalin-ohaulic]

I had a buddy who was running 3k with two 110ah batts, factory 110A alt and no big three done. He would stay above 13.5 unless he was playing full tilt for prolonged periods of times, and the reason why he would drop is because his alt wasn't charging fast enough.
If I'm running 1/3rd the power he has, with 1/2 the reserve, why am I dropping so bad, when his reserve was keeping up fine? I feel like I should have great voltage, I have a fucking 88ah battery and am only using 1k...yet dropping lower than he ever did.

LOL... no you didn't. Your friend had a battery that defied the laws of physics? HA... phial.