Things are different when you charge your EV from a Level 3 DC fast charger, as there is no need to convert the current from AC. Data to verify how much lower losses are when DC fast-charging isn’t readily available, but they should be about 10 percent.
Our own Tom Moloughney calculated DC fast-charging losses while topping up his Tesla Model 3 a few years back from an Electrify America station and using a CHAdeMO to NACS adapter. He charged the Model 3 from a 7 percent state of charge to 57 percent, which put about 35.5 kWh back into its battery pack, and he calculated that about 3.5 kWh of that were losses. He estimated that had he charged from flat to full, total losses would have been around 7 kWh, or about 10 percent of the vehicle’s usable battery capacity at the time.
If the fast charger in question is designed to run at 800 volts and it charges an 800-volt EV, then losses should be lower, although this needs to be tested and verified before actual loss numbers are presented.