Determining Charging time to compute amperage

[devmach-e]

My ChargePoint is set to 40 amps and it charges my MME at 9.6 kW. It charges my son's 2019 Bolt at roughly 8 kW (32 amps). However, a level 2 AC EVSE can't tell a EV anything (it doesn't have two-way communication like a DC fast charger does) ... the car's internal charger controls it.

I can assure you that the EVSE (level 2 or 1) does tell the car useful information: the maximum amount of amperage that the circuit that the EVSE is on can safely supply. It's called the pilot signal. The car will then charge at the lesser of what the EVSE is advertising, or what the car's internal charger is capable of drawing. I.e on a car that has a maximum capability of 7.68 kW (32A) plugged into an 80A unit it will only pull 32A. If that same car is plugged into an EVSE that is capable of 16A, it will only draw 16A.

See https://en.wikipedia.org/wiki/SAE_J1772 for more information on how there is some bi-directional capabilities via the Pilot signal.

Sponsored