I have a Model 3 SRP and a Polar home charging unit, which is on the Economy 7 circuit. This means charging only starts at 1230 and finishes at 0730; which is fine for me. But every now and then, for no reason I can find, it doesn't charge at all. The storage heaters and the immersion heater are on the same circuit, so I know that it does come on every night. Could anyone suggest a reason why this happens? I wonder if I plug the car in too early and it somehow disengages after several hours waiting for the current to arrive.