ml350owner2012

What is the normal operating voltage measured at the cigar lighter? I've been monitoring the voltage using a digital voltmeter and have found that the voltage can range from 12 volts to 14.7 volts no matter what the engine loading. Most other cars (domestics) that I have measured seem to run around 13.5 volts steadily. Since I am planning to install a ham radio transceiver that expects 13.5 volts I need to know if this is normal operation for the ML or do I have a charging system issue?

MBtech1098

Yes that sounds pretty normal. Part of the BLUE EFFICIANCY is a modified charging strategy. The CDI control unit will command minimum charging output during acceleration and cruising when possible. The CDI will command maximum charging output when you are in a state of decel. This in a sense is like regenative charging and allows lower fuel consumption.

ml350owner2012

Thanks for the input. Since the car is new my guess was it's some new charging strategy. Fortunately, low battery voltage is a common issue with ham radio installations and there are several solutions out there. They are DC/DC converters that maintain a 13.6 volt output regardless of the input, at least until it drops below a safe level for starting the vehicle. Guess I'm in the market for one now!

Thanks very much for your help,

Harold