Charging Problem

[tAgC]

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

[darkhorse737]

check your fuses... especially the alternator fuse. if ok,

1) measure ur voltage across the battery ignition OFF; then,
2) with engine idling, measure again voltage across your battery terminals...

in step 2, you should be reading 13.5 volts or higher. less than 13.5 - it's time to replace alternator

have fun ;-)

[tAgC]

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?

[darkhorse737]

11.8volts on idle. hmmm...

bench test proves your alternator is fine.... but the 11.8volt reading tells me that the alternator isn't pushing the 13something volts into your battery.

There's such a thing as an alternator fuse, try and locate that. Also retrace your wiring. if u bench tested your alternator, very possibly you forgot to hook a wire or two back in the right place ;-)

[darkhorse737]

btw, the fuse/s for you alternator are fuses 15 & 18.

I strongly suggest you have your battery checked also. very possible, you have 1 or more dead cells and cannot hold or accept the alternator charge.

[tAgC]

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.

[darkhorse737]

$929.xx what??!!!... WHOA!.... they're available here for half that price with a limited lifetime warranty... *goodness

[tAgC]

Yes I have seen the price during my searches. I am being ripped off badly I think. I am going to phone around some more today maybe I can find it cheaper. I also hope that does solve the problem.

[iamcreepingdeath]

that's a nasty avatar.

[tAgC]

Now I know why nobody reads my posts
No seriously I like horror movies and this was a screen shot I took from Staying Alive.
Come to think of it your handle fits my avitar

[tAgC]

Installed the new alternator today, got 10% disount, helps a little problem is now solved yipee