charging problem... - United Bimmer Community

**smokeydub** · 04-12-2006, 06:10 PM

hello. I just bought a cheap '93 325i expecting to have to put some work into it. It had been sitting when I got it, and the battery was bad, so I brought a new optima red top and dropped that in it when I picked it up. The car started right away, and continued to run perfectly fine for several short drives over the rest of the day, but then this morning I woke up to find the battery completely dead (2-3 volts). It apears not to be charging, if I jump it it runs back down and dies within a minute or two. I haven't had a chance to jump it again or charge the battery to test things with it running.

Im guessing its a bad alternator or voltage regulator, but Im not very familiar with these cars at all, so I would greatly apreciate any advice or trouble-shooting suggestions anyone can give. Thanks :-)

**xsperf** · 04-12-2006, 08:15 PM

if i were you, i would test your alternator, see if there is an current coming from it, and if there is, well thats a whole different story, i am not exactly sure how to test a voltage regulator, but test that too just to make sure that it isnt the alternator

**tomctx** · 04-12-2006, 11:11 PM

If you can get it running, put a multimeter across the battery terminals and see if there is about 13.5 to 14 volts. If you don't have that, the alternator is bad. If there is an auto parts place near you, most will test your battery and alternator for free. meter needs to be on DC volts.

**smokeydub** · 04-13-2006, 03:05 AM

Thanks

Thats exactly what I planed on doing, just haven't found someone to jump me again yet, and I don't have a battery charger here. I should have just gone ahead and done it earlier when I had the chance.

I hope its the alternator, and I don't have to go on an electrical problem hunt.

Edit: Well, the alternator tested bad, so I just picked up a bosch 140 amp, about to stick it in right now.

**smokeydub** · 04-14-2006, 03:31 PM

ok, so before I installed the new alternator I checked for shorts with the multimeter, and there appears to be one. Both the alternator line and the positive battery terminal make a circuit to ground :-(

So, does anyone know of any particularly common places to check for a short? any common places for wire fraying? From searching around the net it I found a number of people complaining of this, but I never found anyone who said where they finaly found the short....

Storamin · 04-14-2006, 04:57 PM

Check in your trunk. Where the trunk open up on the left side should be a black plastic cover that covers a bunch of wires. Some people have had problems with those.

**xsperf** · 04-14-2006, 05:50 PM

i dunno of a common place, but i just wanna say glad u didnt immedietaly replace ur alternator, if you need any wiring diagrams, www.manualsunlimited.com has some VERY nice ones, or even www.alldata.com <-- not so nice wiring diagrams

**c1apton** · 04-14-2006, 08:02 PM

Trace the wiring off the back of the alternator. There's a common problem with that wiring becoming brittle & chaffing from heat & vibrations.

**smokeydub** · 04-15-2006, 11:39 AM

so, a little update....after reading around on forums and getting very frustrated trying to track down a short, I finaly decided maybe the relatively high resistance is caused by something that is supposed to be there (my meter reads around 16 from the red alternator wire or the positive battery terminal, but my meters acuracy is questionable). So I put a new alternator in, jump started again (yeah, I know, jumping is potentialy harmful to the ecu, etc), and checked the voltage at the battery....14volts, perfect......then after a few minutes and a drive around the block I check again and its down to 12v...it seemed to level out there until I turned it off, and then read 10v, maybe 40 minutes later went and checked again, and it was down to 6 volts and wouldn't crank. So Im pretty sure there is some major electrical leakage or a minor short somewhere.