MG4 totally dead after service

[lancylad]

Took my 73 plate MG4 for its first service yesterday. Told them that I had been having a few issues with infotainment system & asked if there was an update.
When I collected, they said they couldn't find any issues but had factory reset to clear everything and start again.
Plugged in the charger when I got home.
Came to car this morning and car wouldn't open with either key.
Managed to gain entry manually with the physical key, but car totally dead. No lights at all, not even handbrake control light.
Waiting for MG garage to ring me back, but not hopeful. They didn't seem concerned at all.
Anyone any ideas what I can try ?
Thanks

 

[Silver estate]

Has an interior light been left on and flattened the 12v battery ?

 

[Bricktop X PWR]

Took my 73 plate MG4 for its first service yesterday. Told them that I had been having a few issues with infotainment system & asked if there was an update.
When I collected, they said they couldn't find any issues but had factory reset to clear everything and start again.
Plugged in the charger when I got home.
Came to car this morning and car wouldn't open with either key.
Managed to gain entry manually with the physical key, but car totally dead. No lights at all, not even handbrake control light.
Waiting for MG garage to ring me back, but not hopeful. They didn't seem concerned at all.
Anyone any ideas what I can try ?
Thanks

Do you have a voltmeter?

See what your 12volt battery is reading.

 

[PeteC]

It sounds like the 12V battery has drained for some reason. The 'Emergency Starting' section of the manual shows how to connect jump leads to power up from another car. Alternatively you could call the AA as MG give you membership.

I had mine die once and since then I have carried a small booster pack in case it ever happens again (which it hasn't).

 

[Tig170]

Sounds like they have just disconnected the 12v ? (their so-called factory reset), and not fully tightened up the connectors again.

 

[Silver estate]

Sounds like they have just disconnected the 12v ? (their so-called factory reset), and not fully tightened up the connectors again.

Could be

 

[lancylad]

Thanks for all the replies. Only just got back home to take another look at it.
Yep, looks like the 12V battery is dead. Reading 4.7V while connected, and only recovered to 6.5V when I disconnected the leads.
I never even considered the battery this morning - I just automatically thought they had screwed something up at the MG garage when they serviced it and "reset everything".
I guess that might still be the case. Seems very coincidental that they did a reset and I have a dead 12V battery next morning !!
Can't get to the battery easily to jump start from another car either - my car parked up against the shed to the front.
Will have to call breakdown tomorrow I guess !
Cheers everyone ?

 

[Coulomb]

Reading 4.7V while connected,

That battery won't last, and needs to be replaced. Jump starting might work, but the car is unlikely to restart even ten minutes later. If it does, leave the car in ready mode for half an hour or so, to give the battery a reasonable chance at temporary recovery.

Rather than jump starting or calling a breakdown service, can you get an ordinary 12V car charger on it? An overnight charge will give it the best chance of temporary recovery. That's if the charger will charge it when the voltage is that low.

It's possible that whatever they did at the service caused the auxiliary (12V) battery to die. If so, you might be able to get them to replace the battery. I'm pretty sure that there is only one year warranty on the auxiliary battery. But note that it's also possible that the battery just died and it's a total coincidence, perhaps triggered by whatever they did, but it might have happened a day or two later anyway. So they'll probably wiggle out of that. It still might be worth asking them. Finally, it's possible that the DC-DC isn't recharging the auxiliary battery any more. Check the battery voltage if and when you get it into ready mode; it should read some 14V or slightly more. Obviously even a new auxiliary battery won't last long if the car doesn't charge it.

Don't assume that a new 12V battery will be fully charged. It has likely sat on a shelf for weeks or months, and they gradually lose charge.

 

[Muffler]

As a thought, and subject to having a V2L adaptor and suitable charger on hand - has anyone jump-started their MG4 using the main (HV) battery?

 

[Coulomb]

has anyone jump-started their MG4 using the main (HV) battery?

That should happen automatically via the DC-DC. It's like an alternator in an ICE car.

But the problem is that with a really dead auxiliary battery, you can't get the car to ready mode, or run any menus, or even unlock the car door electrically. Use the emergency mechanical key to unlock if needed.

 

[lancylad]

My car is on a lease at work so it's covered by breakdown service. The AA came and started it with a battery booster on the 12V battery. Seems to have sorted it. But like some have said, I have reservations on how good that battery will now be. I suspect it will be knackered. I will just have to see how it goes I suppose.
Cheers again everyone. ?

 

[MGDriver]

Thanks for all the replies. Only just got back home to take another look at it.
Yep, looks like the 12V battery is dead. Reading 4.7V while connected, and only recovered to 6.5V when I disconnected the leads.
I never even considered the battery this morning - I just automatically thought they had screwed something up at the MG garage when they serviced it and "reset everything".
I guess that might still be the case. Seems very coincidental that they did a reset and I have a dead 12V battery next morning !!
Can't get to the battery easily to jump start from another car either - my car parked up against the shed to the front.
Will have to call breakdown tomorrow I guess !
Cheers everyone ?

You should never ever jump start an ev with another car, it should always be started with a small booster pack, using another car will almost every time blow fuses and completely brick the car

 

[siteguru]

If the other (ICE) car engine is already running then it should be OK. The problem is connecting up then starting the other car. That's why you should never jump start an ICE using an EV.

 

[Astral]

What if an EV is already running?

What if you disconnect the positive lead, can you then jump start another car?

 

[siteguru]

Never jump start an ICE car via an EV. The circuits on an EV aren't (usually) designed to withstand the very high voltage spikes cause by the ICE car's starter motor firing up (because an EV never has to deal with such spikes so they don't add in such protection circuitry to save cost).

 

[Astral]

sure, but if you disconnect the battery from the EV then you can use the battery itself to help somebody?

 

[siteguru]

Probably. But then you (they) would be better off with a dedicated jump starter pack. ?‍

 

[Astral]

Sure, but who has one? I don't and I don't know anybody who does

 

[PeteC]

Sure, but who has one? I don't and I don't know anybody who does

I've got a small booster pack that claims to jump start ICE cars, although I've not used it for that. I bought it when my MG's battery died while we were away from home. It brought the car back to life with no problem. Always carry it in the car now. I know I'm not alone on this forum in having one.

 

[Astral]

It's rare, and even if you do have it, you have to maintain it in order for it to be of any use in a specific scenario.