Real Wh/mi and Charge Efficiency
My car reports a lifetime 282 Wh/mi over 14,900 miles. (I've never reset one of the trip counters).
A while back I began to wonder how realistic the car's energy figure was and installed a meter on my chargepoint circuit at the consumer unit. I reset the second trip counter in the car. Since installing the meter last September I have done 4,420 miles and the car tells me I have used 1,290 kWh averaging 292 Wh/mi.
However, my meter has logged 1439.3 kWh over the same period. Teslafi tells me I have added a further 190.8 kWh at Superchargers and other destinations totalling 1630.1 kWh for a real 368.8 Wh/mi. I don't do much pre-conditioning or sentry use. I supect most of the difference is down to charging inefficiency.
At 368.8 Wh/mi, my 'real' Wh/mi is around 26% more than the car reports. I wonder how typical this is? Of courrse my achieved Wh/mi is also much higher than the WLTP figure used in calculating the advertised range - but we all knew that already!
For what it is worth Teslafi reports that I have used 1,549 kWh over the same period and added 1,439 kWh. TeslaFi must calculate power usage from the current and voltage reports from the car which will not include power losses between my meter and the car and may not include some of the losses within the car. However, I might have expected the TeslaFi 1,439 added kWh to be closer to the car's reported 1,290 kWh. It is a pure coincidence that my home meter's 1,439 kWh matches the total power added according to TeslaFi!
Has anyone else done any similar comparisons?
Note that with an ICE, the fuel logged by the fuel supply pump is definitely very close to the fuel added and the fuel used if no leaks!