5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
Hi my 97 540i has developed a charging problem. I have searched the forums and tried various solutions but to no avail.
When I start the car everyhing looks good until about a minute of ideling then the no charge warning light starts flashing. The measurements on the batery are 12.3v to 12.4v. I have replaced the battery with a new one and have also gotten the altenator (air cooled one) tested, there was no problem with the test. I took the altenator out of the car to get it tested as I did not want to drive it like that (176km to test center).
I am thinking water has gotten in somewhere (serviced and washed the car prior to fault) or there is a loose connection somewhere?
I also drove the car (thinking water will evaporate) for 30kms, no charge light does go off at about 160km +/- 3000rpm.
I do also have a brake lining warning (waiting on parts) don't think that has anything to do with it though
Any sugestions welcome as I am at a loss. O and no I do not want to sell her as I still like the car alot
When ideling it is 11,80 but it looks like it is going down, before start it reads 12,11.
I am not sure where the altenator fuse is but I checked all fuses again and they look good (in boot and glovebox)
Altenator did test good well over 13 closer to 14 on bench, is something in the car making a differance?
Thanks for all the help darkhorse737 I checked the fuses and they are definitely good. I have also installed a new battery.
I did some investigation into alternators and found out that they have rectifiers and regulators. I think some the diodes on the rectifier have been damaged by some grass and insects I have found in the airpipe that cools it.
About half of the rectifier was totally blocked by the debris, that might have caused some of the diodes to over heat or short out. I can see discoloration on them.
Not sure if this is the case but I have ordered a new one from the agents at R7425incl about $ 929.86 (rip off) that is not installed I have to install and I also have to give them the old unit
I also disconnected the power terminal while the car was running and it keeps running but does die when the volts go below 8v. Alternator seems to supply less and less power as it runs.
I am not sure how they tested it on the bench and found it running good as it definitely doesn't run good in the car.
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