Batteries drop to 11.9v overnight. How to find and fix the phantom power drain?

[SkwurlyFab]

I've been having a lot of trouble with a phantom power draw on my 04 Chevy 2500HD. I've got two XS Power D3400 batteries under the hood wired in parallel with a Mechman E-series 250a alternator powering them. My system consists of a Kenwood DNX-8120 HU feeding an Orion HCCA-D5000 sub amp, and a JL 300/4 amp for my mids. All 1/0 wiring with big 3 done.

I also have a Directed Smart Start alarm installed with the cell phone connection service, but it isn't activated right now (not sure if that makes a difference).

I will charge my batteries all day up to 13.1 volts, and by the next morning my volt meter is reading at 11.9v. Well below the 12.6v minimum charge. I'm quick to charge them back up, but I'm worried about damage over time and obviously this is a huge pain in the *** since I'm always worried my truck is gong to die.

I have no idea how to locate what is drawing all the power out of the batteries as the truck is parked. I have a multi meter I can use to test the system, but how do I figure out what component is actually draining the power?

At one point I noticed that my sub amp was staying on, since the red logo was lit up even when the truck was off. This seems to have gone away and I have been keeping an eye on it, but that is concerning.

I also noticed that my dome light stays faintly lit when the truck is off, locked, with alarm activated. I replaced the bulb with an LED so I don't think it can drain enough power to take two XS batts down to 11.9v, but if that is staying on, maybe something else in the system is too.

Any and all help would be appreciated! I searched through the forums for answers but couldn't find anything definitive so I had to post up.

 

[wew lad]

very easy, just find the wire you want to clamp and put the meter around it with the arrow pointing the direction the current is going

hardest part is going to be finding which specific thing is causing it. start by the battery to confirm the current draw is actually happening, then trace it back to the problem area. if you're lucky it'll be something simple like a light, if you're unlucky it'll be something hard like a bad component

 

[SkwurlyFab]

Will my multi meter be able to perform the tests outlined in the previously mentioned Youtube video that explains how to locate the circuit that's drawing the power?

 

[adulbrich]

Or you could un-plug everything aftermarket and each night plug one extra thing back in. When it starts dropping overnight again, you've found the issue

 

[Massive spl]

Or you could un-plug everything aftermarket and each night plug one extra thing back in. When it starts dropping overnight again, you've found the issue

Light the dome light that stays on all night lol duh

 

[adulbrich]

Light the dome light that stays on all night lol duh

Yeah, probably is the dome light.

Mine don't even work in my truck unless you press the buttons. They don't come on when you open the doors.

I say just take the dome light out, lol. Might be a door switch is bad

 

[wew lad]

i dont have a dome light, the bulb fell out and burned the plastic lol i need to go to a junkyard and get one

 

[Massive spl]

Yea I have no dome lights. I just use my visor mirror lights if I need lights. The dome lights rattled wayyy to much

 

[adulbrich]

I only use my dome lights when it's dark and I need to find something in my center console anyways, lol

 

[Jeffdachef]

fk the lights. Night vision goggles ftw

 

[SkwurlyFab]

I definitely need to figure out why that dome light is staying on. It's weird because it's not even fully on, it's barely on and visible at all. I've made sure that no switches are in the on position and I've sat in the truck for 15 minutes after locking it and setting the alarm and it never goes off. I don't think it could be a door switch because if it was, my Amp steps would stay in the down position, which they don't.

 

[inferno1985]

id def check your door sensors. you may have a broken one. does your truck give you any indication that your doors are OPEN when they are closed? like if my car is on and running and i open the door. my dome comes on and also on my dash it shows a car with the doors open.

also check glove box as well. put your phone in the glove box with video/camera mode and record you closing the glovebox to see if the light goes off.

yo can always just remove the bulb from the dome. if that solves the problem then it is probably a relay switch for the timed on/off interior lighting.

 

[SkwurlyFab]

If the door sensor was staying open, my retractable steps would stay down, which they don't, so I don't think its the door sensor.

I'll check the glovebox, I read about that somewhere else also.

I'm going to test the bulb and everything else this weekend while reading the amperage draw from the negative post of the battery. hopefully it's something easy and not impossible to find.

 

[wew lad]

ive never had any sort of problems like this with my chevy, its gotta be in your addons wiring somewhere.. start with that wiring.

 

[SkwurlyFab]

Oh I guarantee it's in the add ons somewhere. My wiring is all over the place after all the stuff that's been added over the years by several different installers. I wish I could just start fresh with a new truck, but money doesn't allow for that right now.

 

[avs20]

Your dome light is an easy fix. You need to wire a resistor to the bulb, or else it will stay on. I had to do this on my bed lights and dome light. Search Google for dome light resistor for whatever truck you have...I'm sure someone has already done all of the work in finding what works and what doesn't.