Battery? Alternator? Or wiring issue?

[gamehawk55 10+ year member]

Hey guys,

So I've got a bit of an issue right now where my amps in the back aren't getting the full voltage that I'm reading at the front. I can read anywhere from 13.8-14.4v up front either at the battery or the alt, or between BIG 3 ground and batt or alt. But my amps in the back are getting usually at least 1 volt less power. So my amps are usually only getting about 12.6v for some reason and I'm not sure whats causing that. I have SHOK 1/0 gauge ran from the front to the back on a 250A fuse. Also BIG3 done in SHOK 1/0. The wire in the front is being ran to a Knuconceptz KNF-60 fused distribution block in the back. I am using the block for Power and ground. The input power/ground to the KNF-60 is the SHOK wire and then using about 3.5' of 4awg KNU power and ground out to an AQ 200.2, and then also aprox 1' each KNU 1/0awg power and ground to a RF T2500-1BDCP.

The only reason I realised this was happening was because of the "BATT" gauge on the RF amp would read pretty low sometimes (12v) after playing music for a while. At first I just assumed it was a power hog, but then I found out my up front voltage was actually normal but the amps weren't.

So is this just a bad ground? Or maybe my battery too weak to keep up with the demand? Or the alt?

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[mylows10 5,000+ posts]

disconnect the battery from the alt ,and recheck the voltage ,may be just resistance as well.but that is a lot ,also check all the grounds ,there may be a loose power wire somewhere as well

 

[LosIsATool 5,000+ posts]

You're running a VERY power hungry big amp on the stock alt. you're lucky it's only dropping that much.

 

[gamehawk55 10+ year member]

disconnect the battery from the alt ,and recheck the voltage ,may be just resistance as well.but that is a lot ,also check all the grounds ,there may be a loose power wire somewhere as well

Disconnecting the battery from the alt is essentially just "shut the car off" is it not? And my resting "car off" voltages can get pretty low too after playing hard for like 20 minutes. Usually below 12v. And then turning the car on I'll only have like 12.8v at the amp. In the morning after being off for a while the amp gauge will read like 13.2-13.4v which leads me to believe this might just be my battery getting too weak to actually pass along the 14v from the alternator down that 1/0awg?. Is that possible?

I'm planning on a 310A singer alt and XS Power D3400 under the hood eventually. But for now could just replacing the battery with a Red top suffice? If thats where this power problem is coming from that is? The current battery is about a year old and been subjected to 1000w+ of car audio pretty much the entire time a few hours a day.

 

[LosIsATool 5,000+ posts]

If it was the battery it would be dropping lower.

 

[gamehawk55 10+ year member]

You're running a VERY power hungry big amp on the stock alt. you're lucky it's only dropping that much.

I'm not running the amp at anywhere near full power. It's tuned for 1000-1600w currently

 

[mylows10 5,000+ posts]

Disconnecting the battery from the alt is essentially just "shut the car off" is it not? And my resting "car off" voltages can get pretty low too after playing hard for like 20 minutes. Usually below 12v. And then turning the car on I'll only have like 12.8v at the amp. In the morning after being off for a while the amp gauge will read like 13.2-13.4v which leads me to believe this might just be my battery getting too weak to actually pass along the 14v from the alternator down that 1/0awg?. Is that possible?
I'm planning on a 310A singer alt and XS Power D3400 under the hood eventually. But for now could just replacing the battery with a Red top suffice? If thats where this power problem is coming from that is? The current battery is about a year old and been subjected to 1000w+ of car audio pretty much the entire time a few hours a day.

depending on which battery you have ,that may or may not be the problem .singer alts are nice i've sold quite a few here lately and will be getting one in my truck very soon as well

 

[LosIsATool 5,000+ posts]

I'm not running the amp at anywhere near full power. It's tuned for 1000-1600w currently

Lol that's a pretty wide range there. How did you come up with that number?

 

[gamehawk55 10+ year member]

Lol that's a pretty wide range there. How did you come up with that number?

Because I originally tuned it to put out aprox. 1600w with the volume on 28 and sub vol at 0 on the deck. Sometimes I run the sub vol lower like -5 or -8 depending on how I wanna listen to it.

And another weird thing is that even though the voltage guage on the amp looks like it's dropping ASTRONOMICALLY. My headlights BARELY flicker.....With my old audison LRX 5.1k the headlights would dim ALOT when I would slam on it. Especially when I played metallica or other rock music.

 

[gamehawk55 10+ year member]

YAY I found the problem. It was a loose ground. Today the voltage was soooo bad. Was below 12v this morning at the amp (11.3v) and I was like WTF OK this isn't right. So I was just checking some more stuff with the dmm and instead of putting the dmm prongs on the power and ground of the amp I put the positive lead on the amp power and negative lead on the chassis of the car. BOOM dmm read 13.8v. So I checked my actual chassis ground and it was loose. Fixed that and voyage shot right up to 13.8v STRONG. Now I can rip on my stereo at 1600W and it STILL doesn't fall below 12.4v. I know that's still kinda lowish but its better than 10v or lower. I could barely use my stereo the last couple days Cuz the voltage dropped so low I had to keep turning the subs down to compensate so it wouldn't go below 12v. And now after a bass note hits it shoots right back up to 13.8v on the BATT gauge instantly. So happy its not the battery or alt :-D

Just goes to show. Check ur grounds people. GROUND GROUND GROUND hahaha. Anyways thanks everyone for the help and hopefully this thread helps someone else one day.