Battery Drain ???'s

I'm getting battery drain from something. Need some suggestions on what to check. The only acc I have connected to the battery is a Heavy duty wire harness for the headlight, that runs through relays in stalled 6+ years ago, no trouble. All acc are off . Doors shut good interior light off. Stereo is off, & does not have constant power. I just replaced my 6+ year old Optima a couple of weeks ago w/ an Oddesy 1200, because it started losing volts, but now the new Oddesy is doing the same, just not as bad. Truck had sat for a few months, but started right up until recently. Last night, I had to jump it, only had 6V. Drove it around charged up to 13.08V. Metered it this morning, & I was at 12.58V. I've cleaned terminals @ battery end. Alt is still charging battery. I'm going to look at Batt cable ground @ engine block & connection to starter. No other mods have been done from the time it was sitting & still starting , until just after memorial day when I installed the front Detroit (no electrical impact) Any other ideas :banghead: :dunno:

I'm glad you're having to look for it and not me.

Sounds like you could have a short somewhere that is drawing current. Use a multimeter to test various circuts to find one with a draw even though the switch is off. Might not be easy.......

First, you should remember that a battery will self-discharge when it sits, and it will do so more as it ages, and more so again if it's been allowed to go really dead during its lifetime. 12.58 volts is the correct voltage for a sitting battery.

If you still suspect a current drain, get an ammeter good for 20 amps DC or so - preferably an auto-ranging digital one, and disconnect one of the battery leads. Now complete the circuit again through the ammeter. You should now see an ammeter reading, showing the amount of the current drain. If possible place the ammeter where you can see it from within the car, or have an assistant with you. Now get in there and pull fuses, one by one. If it's a circuit that is covered by a fuse, you should see the current drop when you pull the right fuse. If your XJ is a 91 or up, don't forget that there's another bunch of fuses in the engine compartment.

If you still don't find the source by pulling fuses, you'll have to start looking for wiring faults elsewhere, but I'm guessing you'll find something. A common issue is some small light somewhere, such as the glovebox or the vanity mirror, burning unnoticed, or perhaps a fault in a stereo component that stays energized.

edit: I forgot to mention that since there are things like the clock, and perhaps an alarm, always energized, there will always be a tiny current drain even when things are all right. If you're going to store a modern vehicle for a matter of months you really need to disconnect the battery.

Goatman said:

I'm glad you're having to look for it and not me.

Click to expand...

Thanks alot Hurray for Goatman, Screw me :laugh: Yeah I don't envy myself either.

Yeah, it looks like I'm losing 1/2v a day, so it should be real fun to find :nosmile:

Well thanks again guys. I'll try the fuse trick.

Rob