I have had a 2020 Superb iV for a year, which has been charged via the granny charger and a 20amp capacity timer socket which I had installed in our front porch. But I have just noticed an instruction in the handbook saying that a timer socket should not be used.

The charger is rated for a 13amp mains and with my car set for reduced charge supply (about 7amp?) what is wrong with using a timer socket with a 20amp switching capacity?

Using a timer allows me to benefit from the cheap night time rate of Octopus GO, whilst limiting the maximum charge capacity of the battery in order to extend battery life.

If it's a plug in timer it's unlikely to be rated for 20A. You're probably better off with a wall mounted timer, similar to an immersion heater timer.

I can't see any reason why there should be an issue after that. Unless you've an extension reel.

Simply test / feel the timer for any heat whilst it’s charging - if it’s hot then stop using it but if you’re only pulling 7 amps then I doubt you’ll have a problem…….

Plug straight into the socket and set the timing in the car - mine is set to 0% minimum charge (so it doesn't start charging straight away) and then charge between 23:30 and 04:30 each night.