Lothsahn wrote:DaveinOlyWA wrote:10%. It would be over 15% with 6.6

Thanks! Is that just due to parasitic drain from cooling pumps, etc, or is the 240V conversion inherently more efficient?

Its the BMS/LBC. Conversion efficiency between the voltages I don't know although 240 is likely a higher but probably not significantly so.

the issue is the inverter that changes AC from your wall to DC to store into the battery. The conversion creates a lot of heat so a cooling system is needed. This means pumps, etc. Now, the pumps do have variable speeds but not many steps which means power usage from the pump varies little between 120 and 240.

Add it up and you have a near equal level of power being taken from the wall that does not go to the battery. So its 250 watts. So you got 1440 watts coming in minus the 250 or 1190 watts or 82.6% of the power from the wall into the battery.

Take the 240 feed. It has several current options but if taking the max of 27.5 amps we have 6600 watts minus the same 250 or 6350 watts or 96% of the power from the wall into the battery.

Now, there are several other lesser factors to consider including battery temps, etc. including the losses that can go as high as 350 watts (more or less) and so on but even if we use the lower number for 120 volts and the higher number for 240 volts, the difference is still quite extreme.

Several years ago, (before LEAF Spy) I installed a utility grade meter inline with my EVSE and found a rough efficiency of

75% on 120 volt, 12 amp

83% on 240 volt, 12 amp

88% on 240 volt, 20 amp

Now the meter was analog so I logged only whole kwh readings. IOW; the efficiencies were determined from data collected over several weeks.