94 Cavalier, good battery, goes dead, clock stay on

[MikeS144]

ok. I am working on a 94 cavalier. The battery if left connected will be stone dead over night. If I charge it over night with the battery disconnected from the car it holds a charge just fine. As long as I unhook it from the car it holds a charge.

Now.... the clock on the radio never goes out. is it supposed too? I am suspecting the ignition switch. anybody had any experience with this problem and/or replaced the ignition switch?

Thanks a bzillion.

[J-Ri]

The clock should go out, but that alone wouldn't kill a good battery over night.

Connect an ammeter (preferably a clamp-on meter just because it's easier) on one of the battery cables. It should read .05A or less. When you find it's higher, pull the fuses one at a time until the reading drops to an acceptable level. Remember to remove any light bulbs that need to be on while testing (under hood, dome, glovebox, or whatever

[MikeS144]

I connected my ammeter between the negative cable and post. with the radio fuse in I am seeing .25 amps. with the fuse out it's down to .01 amp. That doesn't seem like enough current to kill a battery over night. I think I may have a bad battery after all. I'm going to put it in my van for a couple days to see.

[brcidd]

0.250 amps (250 milliamps) is too much-- manufacturer's recommendation is no more than 50 ma-- A single relay will draw 150 ma and can cause a car not to start overnight-(been there, done that)- yours is more than that- so therein lies your problem- something on that circuit is on all the time-- have you added aftermarket equipment- like a new radio, some remote keyless entry modules, or a remote starter? how about lights, or charger connections- anything changed since this happened? Has anyone worked on it since this started?

Just some things to ponder- other than that, you need to start seperating wires on that circuit to finally find the draw. A good wiring diagram is essential.