Stevelionking

Have had a new battery fitted with a original.
Started it up thinking it would be ok wasn't taking too much notice of voltages? but when ignition was on 12.4v then it dropped below 10v on crank up, then it shot up to 16volts then all the alarms came on as before, transmission faults, run flat indicator etc. then voltage went down to 12.1/2
I was trying to film what was happening but my battery ran out at the crucial point.
I charged my battery up and filmed it again but after the faults have come up on start up it doesn't appear again until the following morning.
When I started it the second time the voltages were as follows
Ignition on 12.4volts
Start cranking up went down to around 9v for a second
Then when engine was running was 12.1/2
Drove round the block and even when revving didn't go over 12.2v. What do you think? alternator.
I now have another problem that has occored since they fit my new battery.
As soon as I put the ignition on (Restraint Systems) Function of airbags, belt tensioner and belt force limiter faulty.
The bloke at the garage said just press the idrive and it goes off. But the seatbelt and airbag alarms are still on the dash in red.
I don't want to fall out with the garage owner untill I can get these things sorted. Can changing the battery cause this?
Sorry to be a pain. Steve

Gilgorm

This does sound like the alternator. I believe the voltage regulator is part of the alternator and it could be at fault. Perhaps someone with more knowledge could comment. I had an MB with this problem when the voltage regulator failed so the entire alternator/regulator had to be replaced.

pcy

Voltage regulator can be replaced without having to replace entire alternator.
Mechanics may recommend to replace the entire alternator [along with the regulator] since the alternator may also be on it's way out due to age of the alternator/car - note that you would have to remove the alternator from the car to replace the voltage regulator.

sanjsanj

at 16 volts, my instinct immediately says voltage regulator. Be careful, it can fry all your electronics, and is probably the reason for your seatbelt warnings now.

Does this work: http://imgur.com/a/ch1Fz ?

It might be something to help your source a voltage regulator, which can be replaced on it's own. Although you may find replacing the whole thing with one from a breakers more economical. Get your money back for the battery! I hate have-a-go mechanics!

Did you have a look at the error codes stored on the car? that should have told you about the voltage being too high in the first place...

Stevelionking

Hi, the voltages are all over the place at on stage it went to 18volts so not risking it any longer. Having the alternator taken off this afternoon and taking it to be checked and repaired. Should have it back tomorrow. Thursday it goes in to BMW to have the BST fitted as a recal. Still got problem with Restraint Systems just hoping when it goes in to BMW they can shine some light on it.
Thanks again for your help, will let you know how it is after I have had the alternator put back on.
Steve

balbs

2004??? Maybe the MPM in the bottom of the spare tire area got wet?

Stevelionking

Just to thank everyone especially Sanjsanj for thier help.
Changed alternator, cured all faults transmission, battery, windows etc, changing the battery caused airbag & restraint warnings but after the warnings were taken off everything is now ok
Thanks, Steve