I have an odd problem with a 1994 Grand Am. The battery will not draw any current from a battery charger when the positive & negative cables from the vehicle are connected to the battery. If I disconnect the leads and connect the charger directly to the posts, then it draws current perfectly and charges completely.
Any thoughts why the battery will not draw current when the cables are connected?
Thanks!
If the battery is in good enough shape to start the car or you're using a manual charger, I have no idea. But in the case of a weak battery and an automatic charger, the car may be causing the voltage to drop below 6-8V, the typical threshhold required for automatic chargers to work because they're designed to not spark when connected to the battery.
That usually means there is a black oxide coating either on the posts or the terminals causing a bad connection.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Dirty battery cables.
Mike,
That was one of the first thoughts I had, but I wire brushed the cables and posts and the problem persists. The battery is in good shape and the car starts strongly.
I'm just stumped.
Jas> That usually means there is a black oxide coating either on the posts or
Try a water and baking soda mix - clean the entire battery!!
The fact that your charging makes me wonder if your alternator diodes are up to snuff. Test cars throwback voltage, if the alt. is putting out, I'm stumped. No alt. output makes me suspect the diodes.
Throwback test tools VOM
Connect VOM to Battery should read approx 12 volts
Start engine, with engine running, test battery voltage, should be approx 13 or so volts. Same voltage means no output, higher voltage means charging OK
Umm, he is not using the alternator....
Mike
Paul wrote:
Yea, and 12 volts is essentially a dead battery. And 13v won's really charge one well. Too much guessing and approximation to help.
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