C4 B78 2.0 Blue HDi --- acceptable max voltage / alternator whine.

[onthecut]

I had noticed the last few days a slight whine, which varies but definitely engine rotation related. Plugging in the code reader to check something else, I was surprised to see a voltage of 15.2 / 15.3v on the reader, with the engine running. Double checked with voltmeter direct from the battery +ve and it hovers between 15 and 15.2v. Put a load on (lights, air con) drops it to a steady 14.3v.

The 15v figure seems quite high to me and I wondered if anyone has any thoughts ? I' m now guessing the whine is alternator generated. If it is too high, question is whether it's the alternator or some part of the control cicuit. The battery mangement box that sits ahead of the battery was replaced with a brand new piece about six months ago.
Is there any way to test the small device directly at the -ve terminal ?

Mike.

[Mihael_M]

The voltage is high and it seems to me that it is not because of the alternator but because of the BMB. Why was the previous one changed?
Have you tried to connect the obd reader? It can only be connected to the obd port.