battery voltage range whilst engine is running?

[Benz270cdi]

hi everyone I was after a bit of info please if anyone has access to wis? Do you know what the voltage range should be at the battery when the engine is running at idle please? Any help much appreciated and thanks in advance, oh and the car is a w209 270cdi.

 

[BlackC55]

14-14.4v

 

[Benz270cdi]

I have just replaced the battery as I think the original had a bad electrode in it , I got the battery voltage up on the instruments and went for a drive and started putting load on electrical system with heated seats , heaters etc voltage dropped to 13.8 so replaced the battery before I looked at replacing the alternator, car now starts sweet at voltage at idle is 14.5v I have not been for a drive yet and loaded the system to see what the voltage is with the new battery