kingjames788

i'm new to forums don't know how it really works but i'm having a battery problem alternator is fine when the car is off the battery still goes dead no lights are left on or anything I can not figure out what it is

Professur

M'kay ... There probably should be some punctuation in there, but we'll work on that later. What I'm getting is that your car will start and run, but not charge the battery. Have you taken the battery around to the local parts store and had it tested? How old it is?

When you charge the battery and put it back in the car ... what voltage numbers are you seeing across the terminals, and from positive to chassis ground?

kingjames788

This is a new battery and when the car is running it stays charged. The problem comes when I leave the battery hooked up over night it goes dead like something is left on but everything is off.

Tedd Thompson

Did the old battery do the same thing? And have you tried removing the positive cable at night then reattach to see if it has held a charge, sometimes new doesn't equal good anymore. Check the output of the alternator to see what its actually putting out, if the car is running only off the battery the alternator would be shot ....Tedd

Professur

Ah, voltage leak. Gotcha. They've got these neat little sensors that detect voltage in wires without poking a hole in the insulation. With everything off, start with checking the draw on the main power lead. Is there anything that doesn't work well now? Electric mirrors or windows? Chaffed wires going through metal is the first thing I look for.

kingjames788

I will check to see if there is a power drain most likely it is a few other people told me the same. I'm currently taking apart the dash to check the wiring, also i'm going to take apart the fuse box and test everything. I hate wiring replacing a motor is easier to me. I'm going to rebuild the motor and transmission first time for both the engine is 94 350 chevy and 350 transmission/

Professur

I agree fully. But then, that wiring is 30 years old. Nothing lasts forever. Personally, when a car gets over 25 years old, I seriously start considering a new wiring harness as preventative maintenance. Sort of like rebuilding a stock tranny ... you spend the money before it fails to avoid the hassle of dealing with the eventual failure. At least our cars only have a dozen or so circuits with maybe a few hundred feet of wiring. Not like today's cars with 4 fuse boxes and bundles of 40+ leads per wiring loom.