I’m just curious as to what the battery voltage should be reading at with just the ignition on? Thanks

On my FL2……12.2 volts……just checked…21h15 …....
Fairly new battery…..did 140 ml run yesterday……….not used today…….question answered….. FL2 SD4 HSE Lux Auto MY 2012— current
D2 TD5 HSE Man MY 1999 470kmls….gone 2014 ….lovely engine..chassis rotten
D1 300TDI Man MY 1996 56kmls….gone 1999…D2 much better
Wife’s FL1 1.8P MY 2001 32kmls …gone 2007…has Mini since.

I’m not sure if I understand the question

Are you asking

- Key on Engine off (if yes then go with what Pete wrote)

Or

- Key on Engine on (then it’s complicated)

Note: The voltage output of the battery will fluctuate based on the load and with key on engine off the load could be extremely variable. (Heated seats, Radio, Sat Nav, Bluetooth, defrost, cabin fan, radiator fan, fuel pump and more)

I would not try to measure voltage that way. Instead I would switch on the headlamp for 30 seconds or however ever long they stay on using the key fob and then check the voltage. Something like this would give a consistent measurement.


Let’s assume that Pete did not understand the question and that you were asking for key on engine on then you need to look at this chart

Click image to enlarge