Efficiency of DCQC?

[TimLee]

What is the efficiency of DCQC?
I drove 66.6 miles and did DCQC at Eaton unit that showed 11.0 kWh in 26 minutes, 52 seconds.
6.05 miles per kWh if there were no losses.
But some portion of this from the grid power is converted into heat in the LEAF battery.
Has someone carefully measured the efficiency of DCQC?
Is it a function of battery temperature?

 

[RegGuheert]

We can estimate the losses in the battery since others have measured the resistance of the battery. I'm going from memory, but I recall the LEAF battery resistance is about 90 mohm when new. If we use an average voltage of around 375V and a charging power level of 48 kW, then the charging current is about 128 A. At that current level, about 1.5 kW would be dissipated in the resistance of the battery. We might be able to imagine up to another 500 W dissipated elsewhere in the LEAF including pumps and other wiring resistive losses, so a total loss of about 2 kW when new. That would give an efficiency of about 96% when new.

I woul expect losses could double as the battery degrades, so perhaps efficiency could drop to around 92% for an older LEAF.

 

[DaveinOlyWA]

but full rate charging only happens for lower half of the pack and no pump losses since DC bypasses the inverter. after that it drops off pretty fast so we are looking at something even higher. Reg! thanks for the math!

 

[DaveinOlyWA]

I am starting an experiment to find out but fear that it may not be as easy a task as simply collecting data and crunching numbers. The reason I am doing this is the flurry of new Nissan fast chargers installed in my area that don't tell you how much charge you received...kinda really sucks actually...

so I will be collecting the data to analyze but since the charge rate varies so much, have to wonder if starting SOC, ambient temps, battery temps and ending SOC will play any significant roles in the efficiency?