Trouble staying at 14v

[InspectahDeck]

Hello -

I have a XS D3400 powering a Sundown saz 1500 and a DC Lvl4 15, I also did the big 3.

This setup worked good for about 6 months, battery barely went below 14v.

The past couple of weeks however, the battery struggles to stay above 11-12v even with no music playing. After a while of driving it will slowly go up but usually just sits a bit below 14v, no music.

Trying to troubleshoot what is going on, I was thinking it was the alt, but I went to the shop today and the alt tested out fine. So now I am thinking is the battery going bad?

Ideas are appreciated, but as of now I cant play any music with the voltage so low.

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[Full Tilt 10+ year member]

At least you're being smart about it, lol. Don't break your shit.

A few questions; what vehicle is this in? You said the battery struggles to stay above 11-12v, that's not a great sign. Did you notice that while sitting still or driving down the highway?

How old is the D3400? Is that the only battery in the car?

 

[InspectahDeck]

The D3400 is the only battery in the car, had it for about 6 months as well.

The voltage stays low whether im city or highway driving, even idling. After a while of driving it will climb up into the 13s. It seems to be getting progressively worse so as of now I am not even playing music.

 

[Full Tilt 10+ year member]

The D3400 is the only battery in the car, had it for about 6 months as well.
The voltage stays low whether im city or highway driving, even idling. After a while of driving it will climb up into the 13s. It seems to be getting progressively worse so as of now I am not even playing music.

If the alternator tested fine, I'd definitely look into the battery going bad. If you bought it new, I'd be surprised to see it failing already. I'm not sure if you have any sort of warranty on it or not.

If it's used, well, you know how that can go.

 

[shizzzon 10+ year member]

I would get an ammeter and clamp the alternator at max output on sine wave to see how much current is coming out of the alternator, then do the same with the battery.

Perhaps a section of the rectifier is gone in the alt..

2nd, it just started getting warmer in the colder states recently.

Colder weather allows charging system to charge at higher voltages.

PCM controlled alternator probably doesn't want to even be above 13.8v on warmer days.

Dropping into 11s even if everything was perfect sounds like either you have no battery in the rear or your FRAME is terrible and you need dedicated ground run from front to rear to maintain charging while under load.

I would also manually charge the AGM using the correct charger just to ensure the battery is topped off, especially since it's already dug into the 11s recently.

I would also load test the battery too.

If i remember correctly, a 100A load test on a fresh charge should show mid 11s on drop with slow rise to high 11s.

XS Power can confirm this, i'm just rattling it off from memory.

 

[wew lad 5,000+ posts]

if only dc clamp meters weren't so expensive^...

is this voltage drop at the battery terminals or elsewhere?

 

[InspectahDeck]

if only dc clamp meters weren't so expensive^...
is this voltage drop at the battery terminals or elsewhere?

Terminals

 

[adulbrich 5,000+ posts]

Connection possibly rattling loose somewhere?

Hopefully your vehicle isn't PCM controlled. I hate that.

Sounds like an alternator issue, but you said it tested fine. Battery shouldn't be bad after 6 months.

 

[wew lad 5,000+ posts]

short somewhere