murraydeluxxxe

I went away for four days, came back and the battery was completely dead. (completely! no weak interior lights, no half-hearted starting, etc.)

It's a new-ish battery (year old), it started fine before i left (well, it did have to crank a little) and it only takes a quick jump to get it to start.

Any thoughts on what could drain a battery in a sitting car?

RandyJ75

Lots of things could drain the battery, one night I noticed that my underhood lights were on with hood closed! Its a bad idea to jump a Corvette, better to charge the battery. If that does not work, remove the battery and take it back to were you bought it and have them test it. I just had a two year old Optima Red top died on me today, what a POS battery, it was a PITA the whole time I owned it, always going dead.

murraydeluxxxe

Thanks for advice!

CSS996

Are your connections good? Three times on three different vehicles I have attempted to start them and NOTHING happened. I simply jiggled the battery cables, and they started right up. Cleaned and tightened the connectors after that and no issues.

murraydeluxxxe

Connections are clean and tight!

jfb

Current, amps, coulombs per second, electron flow, THAT is what makes lead acid batteries go dead! You have excessive leakage current and you should measure it and compare it against GM's edict that it shouldn't exceed 50 milliamps. Remove the negative cable and connect an ammeter from the neg cable to the neg battery terminal and wait for the courtesy lights to time out, then switch down the full scale reading on your ammeter and see what the leakage current is. My 87 measures 27 ma. and the battery stays up. Then pull the courtesy fuse so you can keep the passenger door open while you remove one fuse at a time while looking at the ammeter. If you find a fuse that causes a current drop, then you need to look further at that circuit to find the leakage current. At night check the underhood lights, vanity mirror lighjs, door map lights, center console light. Do you have a radar detector, CB radio, aftermarket alarm or radio or audio amp? Check em.
Also, jumping to get a start doesn't charge the battery up and a dead battery draws a lot of current for awhile and the alternator supplies this large current which heats the alternator and shortens its life. Dead batteries take a long time to charge up, so always use a battery charger to charge a battery up, not the alternator.

murraydeluxxxe

Wow, great advice and explanation.