[DanMZe90]

Hi,

I run Carly BMW on my 2005 330D to do diagnostics fairly regularly. For the last few weeks I have been getting an 'overvoltage' error. I have had the car for 4 years and I believe the original battery was in it and due for replacement, even though the voltages were pretty much correct at idle and running.

I purchased a genuine BMW battery from Cotswold BMW with the same output as mine and fitted it today. The Carly app did not recognise it as a different to what was in it already but allowed me to register it as the same kind of battery. I haven't been for a spin in it but have had it idling to a) clear faults and b) re-run the Carly diagnostics a number of times. I am still getting an overvoltage error. Should I see how it is after I've done a few runs to work over the week or is it pretty much now pointing at the voltage regulator or alternator?

If it is the latter where do I get the voltage regulator from? Cotswold BMW don't sell it separately so do I buy that second hand or refurbished? The same goes for the alternator, at £430 it is rather expensive new so is it Ebay or some other place that does refurbs?

Any help much appreciated as always!

Thanks

Dan

[Dormermike]

Depending on the alternator you've got, you can usually replace the brush pack and or regulator.

What voltage whilst the engine is running?

[DanMZe90]

Hi, idle it is 12.78 and running it is around the 14.19 - 14.35 mark, max I saw it go to was 14.39. I just cleared the codes again and ran diagnostics and not showing the fault but not sure it happens on the way to work or a longer run. Will check tomorrow evening, hopefully it sorted itself out.....

[Dormermike]

12.78 is too low at idle

[DanMZe90]

Thanks, that's what the 'old' battery I took out was registering too. Do you think this points to the regulator/alternator then?

Thanks

Dan

[DanMZe90]

Sorry, I've been a bit of an idiot. 12.78 is switched off and not idling...doh!

[DanMZe90]

OK, panic over as overvoltage disappeared and hasn't reared its ugly head again this week so putting it down to bad battery.

Thanks

Dan