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Nema 6-20 install

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A friend just helped me install a NEMA 6-20 outlet in our SE Arizona garage! Total cost was about $70 and a 12 pack of Guinness:

25ft of 12-2 wire
20 amp breaker
6-20 outlet
box and cover plate.

We're using this EVSC and a J1772 to Tesla adapter:


which was formerly plugged into a NEMA 5-20 outlet via it's included NEMA 5-15 to 6-20 adapter.

We're now charging at 16amps and 233 volts = 3.7kw.
 
We're now charging at 16amps and 233 volts = 3.7kw.
So this is something I've been wondering about. Yeah 16*233 = 3700. But you don't really get 3.7 kwh into your battery for each hour of charging, do you ? There's some inefficiency in the charger, and it gets worse for the top 80 or 90% of charge level, right ? Are there widely-accepted numbers for those efficiencies ?
 
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A friend just helped me install a NEMA 6-20 outlet in our SE Arizona garage! Total cost was about $70 and a 12 pack of Guinness:
Nice work!

So this is something I've been wondering about. Yeah 16*233 = 3700. But you don't really get 3.7 kwh into your battery for each hour of charging, do you ? There's some inefficiency in the charger, and it gets worse for the top 80 or 90% of charge level, right ? Are there widely-accepted numbers for those efficiencies ?
When charging using any level 2 EVSE, the car uses about 500W to run computers, fans, etc. And there are conversion losses inside the car converting from AC to DC and changing the voltage to pack voltage. So, yes, you’d get about 3.2 kWh or so into the battery.
 
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