Author Topic: Melting battery (Read 2644 times)

idunnoadam · « **on:** May 02, 2011, 06:40:58 PM »

I have a 91 318i. I recently had an alternator die on me so i replaced it, jumped it and now it starts and runs fine except i have a check engine light on and a battery which the multimeter says is getting 17 volts at idle. It smells like sulfer too, so somethings not right. I replaced the alternator(and regulator) again along with a new battery. Same thing. Today after work, with the car running, i removed the ground strap from the battery and the car died. Anyone got any ideas where I should look for problems?

jrobie79 · « **Reply #1 on:** May 02, 2011, 08:38:39 PM »

try posting on the electrical section of r3vlimited.com might get an answer faster there, its an e30 specific forum (all models including m42s)

ak96ss · « **Reply #2 on:** May 03, 2011, 06:35:20 AM »

While removing the negative cable may work to check alternator function on a '69 Buick, it is not a good idea with the electronics in today's cars (i.e., anything since roughly 1981 or so, when computers started to make an appearance....).

You stand a good chance of cooking something expensive when you do that.

Sounds like a bad voltage regulator to me, even though you replaced it. I'd have the new alternator tested at a parts store as a starting point.

DesktopDave · « **Reply #3 on:** May 03, 2011, 06:55:35 AM »

+1, I think the rebuilt alternator has a bad regulator. There are a lot of things that'll drop the system voltage on a car, but only the regulator can fail higher than the usual 13-15vdc our cars run at.

You can take a shot at the CEL by doing the stomp test (you know...key to position 1, don't start the car, stomp the gas pedal five times in ten seconds). If it's on all the time, the car sensed a significant problem. Mine comes on every now & then. Usually it's an O2 sensor problem, often related to leak in the intake..