MG4 Dead !!

[schaud]

Thanks, I’ll take a look at it but do you think that if I don’t do anything and leave the car while I’m away it will be dead when I return? I know its hard to give a definitive answer but roughly how long could you leave the car and expect it be be ok when returning?

 

[someguy]

Thanks, I’ll take a look at it but do you think that if I don’t do anything and leave the car while I’m away it will be dead when I return? I know its hard to give a definitive answer but roughly how long could you leave the car and expect it be be ok when returning?

You might be close to the limit, according to the manual, you need to disconnect the 12v battery if you’re leaving it for a month, and you need to charge it every 3 months:

Note: It is recommended to set the power mode to READY for more than half an hour every week to help extend the service life of the battery. When the vehicle will not be used for an extended period (more than 1 month), it is recommended to disconnect the battery negative terminal clamping pile head. Make sure that the vehicle power system has been turned off before connecting or disconnecting the negative battery cable. (Page 291)

If the vehicle is not going to be used, parked, or stored for a long time it is necessary to charge the vehicle at least once every 3 months. During this time, the High Voltage battery state of charge should not be allowed to drop below 50%. (Page 295).

 

[Paulmg5]

A newish battery might survive 3 winter months but as suggested connect a battery trickle charger (one that monitors the battery charge) i hve one for my classic MG

 

[Chr1sB]

Just an update on the original issue … MG have run diagnostics on the 12v and there doesn’t appear to be any long term damage as it is still reporting that a good near new battery.

Alas however, MG cannot access any of the vehicle’s diagnostics to be able to find out what software levels are on the car, whether there are any error messages etc etc. Garage now awaiting a ‘fix’ to enable their diagnostic tools to be able to ‘see’ my car and find out the state of play. (Apparently it does on all their other cars in the garage when mine went in).

The garage has also said that I may never find out what has caused the sudden drain of the 12v … how re-assuring!!

Just as a point of interest for some users potentially… before the 12v went dead .. I had no radio and the Nav would ‘brick’ ie the audio directions would continue, but the visual display directions would freeze. After the battery died ie was effectively disconnected … both these functions now work without an issue !

I don’t want to suggest this as a fix for those that have similar issues with their infotainment system as I don’t really know what I am doing with car electronics… but I did find it an interesting consequence.

 

[Ian Key]

Just an update on the original issue … MG have run diagnostics on the 12v and there doesn’t appear to be any long term damage as it is still reporting that a good near new battery.

Alas however, MG cannot access any of the vehicle’s diagnostics to be able to find out what software levels are on the car, whether there are any error messages etc etc. Garage now awaiting a ‘fix’ to enable their diagnostic tools to be able to ‘see’ my car and find out the state of play. (Apparently it does on all their other cars in the garage when mine went in).

The garage has also said that I may never find out what has caused the sudden drain of the 12v … how re-assuring!!

Just as a point of interest for some users potentially… before the 12v went dead .. I had no radio and the Nav would ‘brick’ ie the audio directions would continue, but the visual display directions would freeze. After the battery died ie was effectively disconnected … both these functions now work without an issue !

I don’t want to suggest this as a fix for those that have similar issues with their infotainment system as I don’t really know what I am doing with car electronics… but I did find it an interesting consequence.

I think disconnecting the battery helps clear the memories of the individual components one of which might be loading in the wrong order so confusing the others. A bit like giving someone a set of directions but missing a left turn out. They get there eventually but it's the long way round.
Reconnecting it gives a clear set of instructions in the right order.

 

[dickturpin]

Just got back from 4 days away and the car is dead- ie won’t respond to App or key fob and whilst I can get to the emergency key I can’t turn it in the lock. Car left with 60% battery. Any ideas what to do now ??

Try disconnect twelve volt battery then reconnect

 

[Alb]

This happened 3 weeks ago! Read the whole thread.

 

[Deleted member 10041]

Just an update on the original issue … MG have run diagnostics on the 12v and there doesn’t appear to be any long term damage as it is still reporting that a good near new battery.

Alas however, MG cannot access any of the vehicle’s diagnostics to be able to find out what software levels are on the car, whether there are any error messages etc etc. Garage now awaiting a ‘fix’ to enable their diagnostic tools to be able to ‘see’ my car and find out the state of play. (Apparently it does on all their other cars in the garage when mine went in).

The garage has also said that I may never find out what has caused the sudden drain of the 12v … how re-assuring!!

Just as a point of interest for some users potentially… before the 12v went dead .. I had no radio and the Nav would ‘brick’ ie the audio directions would continue, but the visual display directions would freeze. After the battery died ie was effectively disconnected … both these functions now work without an issue !

I don’t want to suggest this as a fix for those that have similar issues with their infotainment system as I don’t really know what I am doing with car electronics… but I did find it an interesting consequence.

Hopefully it's a one off

 

[Hallix73]

So do we need something like this in the boot, would hate to come back from holiday to airport car park and find rhe car dead!!
Booster

 

[Ian Key]

So do we need something like this in the boot, would hate to come back from holiday to airport car park and find rhe car dead!!
Booster

For piece of mind it might be worth it and you only need enough power to wake the car up although I think I'd prefer to get one from a UK supplier. https://amzn.eu/d/f4MzMCU

 

[Michael A]

Just got back from 4 days away and the car is dead- ie won’t respond to App or key fob and whilst I can get to the emergency key I can’t turn it in the lock. Car left with 60% battery. Any ideas what to do now ??

Most probably your 12V battery has gone flat. Suggest to call AA or RAC etc to jump start it then drive it for 1/2 hour and finally fully charge and balance your main battery (which in turn should also charge your 12V battery).
Above are the recommendations of AA for my MG ZS EV as I had the same problem but AFTER having the sign on my radio screen “Radio Module Disconnected” which, again according to AA, was the main reason for draining my 12V battery.
I also had some difficulties to unlock the car with the physical key but managed in the end.

 

[Deleted member 10041]

Mate the OP was 3 weeks ago

 

[Cocijo]

Battery might be flat by now…. Again…

 

[Elec Car Aust]

Am I right in thinking the 12v battery is only charged when the car is "on" or charging?
If so leaving it parked up for a number of days, especially in cold weather, will flatten the 12v battery so in the OP's case plugging the car into a charger will recharge it.

Yes same as petrol car. EV needs to be 'in' to charge 12 volt.

 

[Elec Car Aust]

Buy a 12 volt lithium jump starter for just these occasions when the 12 volt is dead.

 

[Chr1sB]

Battery might be flat by now…. Again…

Thankfully not

 

[troopercooper]

Yes same as petrol car. EV needs to be 'in' to charge 12 volt.

The manual seems to disagree:

The 12V battery SOC (State Of Charge) is constantly monitored, when the vehicle is power OFF it is possible, under certain conditions, that the HV battery will automatically charge the 12V battery to ensure the vehicle starts. This function will activate and switch off automatically.

 

[Hallix73]

Could that be the Intelligent Battery setting that people are switching off as they say it increases range?

 

[siteguru]

No - that's intelligent battery heating(/cooling)

 

[Ayoull]

Lifted my bonnet today to see how much rubbish can accumulate above the undertray following seeing how bad a Tesla was on FB when they took the frunk out (looked like a forest floor)

My negative battery terminal was virtually off and a slack as a....

Had to get the spanners out push it down and nip it up