Going away for a week's holiday - do I power off the MG4 completely?

[captain678mg]

Sorry to revive this thread. After leaving my MG4 for a fortnight during a holiday, I returned to find the car completely dead. The central locking system and everything else wouldn't respond. I called the AA, and they jump-started the car with a 12V battery pack, which solved the problem. Once all the systems were back online, the main battery still showed an 80% charge. I spoke to an MG technician, who mentioned that the issue is with the small size of the 12V battery. Regardless of how much charge the main battery has, the car won't charge the 12V battery unless it's plugged in or the ignition is on. He also noted that the battery gets drained by over-the-air updates. Sadly I'm starting to feel this is going to be a game of Russian Roulette every time I go holiday. Carrying a 12v battery pack around seems like a horrible hack. It isn't good for the battery or the car to have 12v battery drained completely. Has anyone replaced the car battery with something bigger?

 

[tsedge]

Sorry to revive this thread. After leaving my MG4 for a fortnight during a holiday, I returned to find the car completely dead. The central locking system and everything else wouldn't respond. I called the AA, and they jump-started the car with a 12V battery pack, which solved the problem. Once all the systems were back online, the main battery still showed an 80% charge. I spoke to an MG technician, who mentioned that the issue is with the small size of the 12V battery. Regardless of how much charge the main battery has, the car won't charge the 12V battery unless it's plugged in or the ignition is on. He also noted that the battery gets drained by over-the-air updates. Sadly I'm starting to feel this is going to be a game of Russian Roulette every time I go holiday. Carrying a 12v battery pack around seems like a horrible hack. It isn't good for the battery or the car to have 12v battery drained completely. Has anyone replaced the car battery with something bigger?

Your technician is talking complete rubbish, which is itself sad and frustrating.

There are no over-the-air updates, MG have never released this functionality and have stopped talking about it in their promotional material. This was only ever for the Infotainment anyway.

The 12V battery is topped up by the HV battery whenever it needs to be and there are hundreds of members here on the forum with MG4s that have been perfectly fine left for weeks whilst they go on holiday. The only circumstances where the HV battery won't top up the 12V battery is if the HV battery is too low, but keeping the HV battery between 50-80% when you leave the car (as you did) is perfectly good.

So the problem here is you either have:

• One of the bugs in the MG software causing a parasitic drain, which is fixable with an update that your dealer should be able to provide.
• Something plugged into the car that drains power (e.g OBD2 reader) while it is away.
• A faulty 12V battery that is not holding charge.

Given that you've already been fobbed off with nonsense, I'd suggest taking it to a better and more helpful dealer that has more of a clue.

A 12V battery pack is an emergency fall-back only, but IS NOT needed if the car is working correctly. Don't accept the answers you've been given.

 

[Martinonline]

The technician may be using OTA to describe communication via the iSmart App. Other than that I agree with @tsedge, the technician is a little challenged in the knowledge department.

 

[tsedge]

The technician may be using OTA to describe communication via the iSmart App. Other than that I agree with @tsedge, the technician is a little challenged in the knowledge department.

That's true, they might have meant this. But you'd have to be obsessively and constantly using this to run the 12V battery down. Normally the car goes to sleep after something like 24-48 hours and can stay like that for weeks - unless something is keeping it awake.

 

[Rolfe]

Might a loose connection on the 12v also do this? (I left my car for over two weeks in an airport car park and just walked up to it and it started as if I'd only parked it to pop into the paper shop. Still at the same SoC as when I left it.)

 

[Lillemy]

So far no problems for me. Just left it like normal, with charge below 80%

16 days when I was in Peru last year, 15 days when I was in Nepal this year. And 22 days when I was at my sisters farm for the lambing period in april.

Never seen it below 13v on 12v battery so far.

 

[rjhfandclf]

That's true, they might have meant this. But you'd have to be obsessively and constantly using this to run the 12V battery down. Normally the car goes to sleep after something like 24-48 hours and can stay like that for weeks - unless something is keeping it awake.

As far as I am aware this is totally correct. But the issue I find often is that when I do try to contact the car through the app after not using it for several days, the app keeps telling me in a little black box: "The remote control instruction execution has failed. Try again later". Sometimes it works after several tries, but other times, it won't work until I unlock the car first. I know there are various threads about this here, and some have said it is due to going into a 'deep sleep'.

We are soon due to leave it untouched for four weeks, so I would like to be sure to be able to check-in just once in a while if possible, and at present, this is a concern. But we've decided to leave the car at home and take a taxi to the airport, since four weeks' parking is about the same as two 30-mile taxi trips these days!