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View Full Version : E34 Killing Batteries



dsio
05-01-2005, 09:51 PM
Ive got a pair of red E34s here, one automatic, one manual, and over the last few days both have been giving me grief. The automatic needed the LKM solder fix to be done, and now the manual is killing batteries.

It discharged its first battery, which was a very new and extremely large, and then was unable to start. The car had been left sit with nothing left on and just died overnight. The battery was replaced with a BOSCH extra high capacity euro battery, which worked. The battery worked for a period of time, until my mother left the parkers on overnight, which completely discharged the battery. It was reading around 7V when i got to it. When I charge it, it eats 4 amps continuously, and never actually charges, and this is the exact same thing that happened to the first battery after it died. They both sit at 4 amps and never charge.

Since then, I took the BOSCH back under warranty and had it replaced, but now its done the same thing to a 3rd battery.

I did a check to see how much current was flowing when the car was all off. The current starts at 4 amps, then goes down to 30mA and sits there for the most part. I removed and replaced each fuse one at a time, and it never moved from 30mA. I just dont get how its doing that.

What is bugging me even more, is that my E30 is also doing the same thing, although at a slower rate. My E30 is drawing current at a continuous 70mA, and slowly kills a battery. I can deal with that because it takes several days to do it, and ill figure that out, but the E34 is doing it overnight.

I dont know if this helps or not, but the E34 is also idleing very very rough when its cold in particular, but also sometimes when its warm. At 3000-4000 revs, it makes a loud clicking sound like a gear missing some teeth as well. If anyone can explain either of these problems I would greatly apreciate it. We have bought three of these BMWs (never had BMWs before) over the last 6 months, and both of the E34s as well as the E30 are electrically pathetic. I hope this isnt something I will have to get used to.

632 Regal
05-01-2005, 11:34 PM
if the alternator has a bad diode it will discharge the battery either fast or over time and cause running problems if the battery is low.

Anthony (M5 in Calgary)
05-02-2005, 09:25 AM
...for an E34. I'd be happy if mine was that low.

From what I've seen the chime module is a common culprit for mysterious draws but with 30mA your car should stay charged for 2 weeks without a problem. I've also seen the window switches illuminated in a 535 after being shut off overnight.

I have a discharge problem with my M5 which I suspect is some module that intermittently fails to switch off. I have the car on stands right now and the battery died after 3 days. After a charge 2+ weeks ago it is still charged now. Whenever I put the battery charger on, the most it dumps in is 3-4A. Weird.

Anthony