MJBelcher500

Does anyone know why the dash display shows a lower battery voltage than a reading taken at the battery terminals with a voltmeter?

My 2006 E55 shows 12.0 volts on the dash display, but 12.5 volts at the battery terminals. Seems like a fairly large difference.

machild

The dash reported voltage is based on wherever the voltage sensor is located which may not be at the battery. That sensor may be where the relay is located that is to switch on the backup battery for emergency braking requirements if the main battery is insufficient. That relay is located near the backup battery under the hood. The difference between the measure you took at the battery and the dash could be voltage drop due to other draws present at that time.