@Pascal - As others say, do not use
anything (e.g. a 'timer', or extension cable) unless it is designed for EV loads. Even if the device says it is OK for high amps (e.g. 13 amps) remember that you will be putting a large current constantly for many (e.g. 5) consecutive hours. Most electrical-sockets/devices were not designed to take large load for many hours. Make sure the socket that you are plugging the granny charger into is of good quality, and monitor it over the first few days/weeks that you use it (make sure it does not discolour).
- Basically, imagine plugging in a kettle and switching it on permanently for many hours. Any poor quality conductive parts (e.g. connections in the socket etc) will get hot/cold and expand/contract and could start sparking etc.
That said, I have a 10 amp (I
deliberately chose one that did not do any higher ampage!) granny charger, and I have had no issues whatsoever, and I am really pleased with it. I use it for 5 hours at a time, to take advantage of 12am-5am off-peak electricity tariff. My granny charger has no 'smart' capabilities - it is simply on or off. Instead, the car decides when to start/finish the charging.
=> So all I had to do was set up my MG HS
(configured either using the infotainment screen, or via the iSmart app) to only charge between 12am and 5am.
Personally, I see no reason to purchase a 'smart' granny charger. Instead, just use the car's built-in scheduling capabilities to decide when to charge.
Enjoy your new MG! (It's a great car!)