Battery Drain


New Member
Oct 4, 2009
Martinez, Ga
I'm looking for some tips or obvious things to look for in my situation. I have a 93 LX and the battery keeps going dead on me. I thought it was just the puny stock alternator not keeping a charge on the battery, but I can hook up my battery charger and put a full charge on it and two days later it is completely dead. The only thing I can think of is, before I bought it, someone put in a triple cluster in the center vent and there is a battery gauge that seems to run straight off of the battery. I know certain things like the computer and radio memory use constant voltage to retain their memory, but would this gauge be enough to kill the battery after a couple of days? I've also noticed a hard start situation, but I'm assuming this is related to the battery issue also, where I'll turn the key to start and the motor turns over slowly at first and then faster a couple of time then starts. Maybe it just a crappy battery. What does everyone think?
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Hook a test light up between your battery's negative post and the ground cable. If you have a drain, which most cars do because of computer, clock, stereo, etc., the light on the test bulb will light up. Remove your fuses one by one until the light goes out and that will help you identify the circuit. Once you have the circuit, you can narrow your search from there.

Good luck
I had the same problem, It was the vanity mirror light in the sun visor. I found the light on while the car was parked in a dark garage. Hope this helps.
By battery gauge do you mean Volts? This should not be hooked up directly to the battery but to a switched source (like the radio). If the gauge is hooked directly to the battery then it is probably running down your battery. Current has to flow thru it in order for it to read. It should not show anything with the key off.
i have the same issue...put in a 200a alternator..charged it up...went out a month later (its in storage for the winter) and its dead...i did notice a "rust inhibitor" electronic device under the hood on the drivers side up by my camber plate thats always on...dont know if everyone has one or not but thats what i think mine might be...let me know if you figure it out..
I'll have to check the vanity lights... I thought at first it was the latch for the hatch cause I didn't close the hatch all the way one night and killed the battery myself, but since then, I've checked that and that's not it. To answer crjpony, yes, it is a volts gauge and it reads whether the key is on or not. I am in process of moving the gauge senders back to the cluster (the guy disconnected the oil and temp cluster gauges to put them in the center vent plus a voltage gauge in the center vent), so hopefully that will clear up the problem.

I do have a new 3g alternator that is going in soon, I would like to just figure this out before I install it.
Do you have an alarm on the car? I've got an old Viper on mine that works when it wants to and if I'm storing the car for a while, I've got to disconnect the battery or the alarm will drain it.
Along the same lines of what Qwomack said, you can use a DMM instead of a test light. This way you can see how much draw there is (since there is always some transient draw in the system, and there are multiple sources). You should not see more than about 100 mA without the alarm on. When doing the testing, be sure the underhood light and interior lights are off.

If the draw is rather large, first disconnect the alt's charge cable. A bad alt diode will allow a large backfeed.

Good luck.
What brand is your battery?
Date purchased?

First thing before you start killing yourself for an electrical gremlin is to just take the battery to be tested. It's free and easy at any parts store.
If it is, avoid cheap chain store batteries, i've had pepboys batteries last 6 months and diehards last 7 years.
LOL, I'm kinda ashamed to say it, but I have not changed the battery since I bought the car, the date sticker on the battery is 6/09, but the bad part is the battery is an el cheapo wal-mart battery. I was looking at swapping over to a DieHard AGM or the original Odyssey AGM.
Unfortunately , the weather has not been cooperating with me lately, every time I get a moment to mess with the car, it starts raining... I'm starting to feel like I live in London. :)
Most batteries out there come from one of three manufacturers.

Battery longevity has a lot to do with maintenance.
To answer crjpony, yes, it is a volts gauge and it reads whether the key is on or not.

ok thats your problem right there. the previous owner connected the gauge or gauges to a direct power source. you need to disconnect this and hook it to an ignition power sourse, so it only has power w/key on. once this is done, use a dvm (digital volt meter) to see how many milli-amps you have with the key off, as stated above, less than 100 ma would be fine. i suspect once you remedy the hack job done by the PO, you will be fine :nice:
I was able to disconnect the gauge last night and took some readings. I think my DMM is messed up, but the initial reading was 2.5A before I disconnected my gauge, and was 460mA after disconnecting the gauge. I'm going to get another meter to verify this.
Phantom Battery Drain

For years, I've been haunted by this battery drain problem on my '06 Mustang GT. Other members suggested the trunk light (which I've since removed) and stereo amp. I turn off the AC and radio when parked and this seemed to help but not always.

I keep the car on a battery tender since the car is not driven much. However, sometimes I notice the tender is charging for hours despite taking the car out for a short period. I cannot find a significant current draw with a amp probe. However, if I briefly reset the ignition (i.e., cycle the power on and off with the car key), the problem instantly resolves. Hence, some electrical system is not being properly shutoff when the car is turned off. I suspect a bad relay.
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