App control of cabin heater - mains or battery?

[Striker]

If the car is connected to the charger (7KW) but has completed it's charge and then I turn on the cabin heater remotely, does the heater run from the battery or the mains?


Edit..

I can answer my own question, as I tried it tonight
It does heat from the mains

My car was sat at "charging stopped", at the 90% that I’d set it to

I turned on the windscreen blower via the app, on the charging screen it showed “Charging” 3.5KW

 

[Gooose]

It that because it’s using the battery for heating so dropping the battery level which kicks in the charging?