
Originally Posted by
Fuzzylogic
It works like this:
When you plug in the cable from the roadster, the EVSE sends a pilot signal to the Car, this pilot signal tells the roadster it can draw (in my case) Max 26A from the mains.
Then the charging starts, the Max current is set by the charger in the car to 26A.
By now varying the pilot signal you can change the current the roadster will draw, the car will respond to this signal within 5 seconds.
I use a kWh meter, with pulse output on the same phase as the roadster is on. On this phase there are a few other household items like the water cooker.
Let's say the water cooker is on, and draws 6A , Car is charging and draws 26A.
The pulses from the kWh meter tell the EVSE that currently 32Amps are drawn, that's 6 Amps too much.
So as soon as the current on the phase goes above 26A, the pilot signal to the roadster will change, and tell the roadster to draw 26-6=20 Amps instead.
Once the water cooker switches off, the current to the roadster will automatically change to 26A again.