e39 540i alternator and battery question - BMW Forum

HardStep · 10-06-2005, 07:30 PM

Hi,
my 540i ha been standing in garage for a while and today the battery was dead, when tried to crank the engine.
Last time when running i noticed headlights going lighter with higher rpm-s and also instrument cluster behaving same way. So i suspected faulty alternator. Now there has been 2 weeks from last time i run the car and as i said, battery was dead.
Is there a way i could check the alternator, if its faulty or not?
Also when i bought the car, it got another battery installed by seller, and i quess it might have been some junk.
As i understand, remanufactured alternator is like a lottery, but how much do the new ones cost? (rem are about $250?).
Also what battery should i get for a 1997 540i?
Thanks guys.

superdeadman · 10-06-2005, 09:04 PM

go to http://bmwtips.com and click on tips & tricks to look at replacing your battery at a cheaper price
also on that same site, there's an e39 forum tab that will take you straight to roadfly's forum... its the best place to go to to get help with your issue

///Matt · 10-06-2005, 10:31 PM

I had my alternator replaced on my 97 540i at 160,000mi and cost me about $300...Honestly, it was well worth it as a lot of little electrical issues disappeared, including my alarm that would go off randomly and like you, the headlights would dim and brighten with acceleration.

billB · 10-07-2005, 09:00 PM

I installed an INTERSATE battery for $90...Fits in the trunk--with a groove for the bracket, and Works as good as the dealers!!

sp0rky · 10-11-2005, 12:54 PM

The size of the e39 batter always makes me laugh.

Does this car *really* need a battery that large?? I can't think of too many other car's who have one like that!

///Matt · 10-11-2005, 01:18 PM

I agree with you Sp0rky...It is a lot of overkill! I guess because BMW decided to put electronics all over, they freaked out and decided to put in a battery that takes up half the trunk.