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I was talking with an electrician doing some basic wiring at my house and mentioned that I'm getting an EV. He told that his relatives came to visit and wanted to charge an EV at his house. He had dual 230 V sockets that were otherwise identical but one was more worn than the other. The EV charged extremely slowly from this one socket, but once they switched to the other one, then it started charging normally (I assume at ca 2 kW).

Now I've got an EV myself. I first plugged it into a socket which had a 2-way socket multiplier and the car said it will take more than 24 h to fully charge from ca. 20% SoC (39 kWh Nissan Leaf.) Then I removed the socket multiplier/adapter and it started charging at the expected rate (ca. 2 kW).

This has me wondering: How does an EV regulate how much current can it pull?

Does it measure resistance in the circuit before starting to charge and determine the maximum current it can draw, or is there another way to intelligently not trip the fuse or set the socket/wires on fire?

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    \$\begingroup\$ Yes, in general, it's measuring the voltage droop as it increases the current. \$\endgroup\$
    – Dave Tweed
    Mar 18, 2023 at 16:08

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There are different mechanisms, not just in the EV itself, but also in the charging interface module.

They include circuitry to measure mains plug temperature rise, and will prevent it from overheating by communicating to the EV that it should charge with less current.

And of course the EV can measure how much voltage drops and if too much drop then charge with less current.

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    \$\begingroup\$ Indeed maybe the smarts are in the charging module. It uses something called Nissan EVSE which probably has some sort of detection built in. But I was indeed wondering about the technique that could be used to determine max safe cureent that can be run through the circuit without damaging it. Charging stations with plugs such as CHAdeMO and such include lines for data which probably take care of limiting the current. \$\endgroup\$ Mar 18, 2023 at 17:09

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