Prolonged parking effect

[GJMG4 North]

Thought that there may be some interest in my recent experience of the impact on the battery of being parked up for a prolonged period.

We were lucky enough to be able to get away for a longer than normal holiday this summer, this meant we'd be parking the MG4 Trophy for approx 6 weeks and to be honest I had some concerns about what we'd be coming back to. The included AA support did give me some piece of mind as I locked the door and headed to the airport terminal but I needn't have worried. On our return, and after 6 weeks sitting outside, the traction battery was at exactly the same % as I'd left it (61%) and the 12v ddin't miss a beat when we fired her up again. All in all I'm delighted with the way the car performed, and happy to have ticked off another of the anxiety topics.

Just wondered if others have had similar experience with their cars, or did I just get lucky?

 

[webhiker]

I have had the same experience after 7 weeks. I just wasn't so lucky that it was caused by vacation, but by hospitalisation

 

[tsedge]

Mine has been exactly the same, no problems.

Am thinking about changing the 12V battery at the next service, 3 years, just as a precaution.

 

[Kithmo]

Leaving a good SOC may have something to do with it. According to the manual, the HV will keep the 12v topped up.

 

[EvTek23]

In the Service and Maintenance section of the handbook it says if left for more than 3 months then the HV battery should have at least 50% charge, (and to charge it every 3 months), and then goes on to say that it must not be left for more than 7 days at less than 50% charge.
With regards to the 12v battery and it's charge, it says that the car should be put into ready mode for half an hour every week, and if the car is not being used for more than a month to disconnect the negative of the battery.
However in the Forward of the handbook it talks about the constant monitoring of the battery and under certain conditions charging the 12v battery automatically, with the proviso that the HV battery is not left in a low state of charge (presumably <50% although not stated) and it will reduce the driving range.
These two parts are at odds with one another, as the Forward would suggest that the 12v battery should almost never go flat if the above conditions are met, and the battery is not faulty by the intelligent charging procedure. But then in the Maintenance section the belt and braces approach of disconnecting the 12v battery, which is recommended many vehicle manufacturers if the car is not used for a long period of time.

 

[Kithmo]

From the user manual page 23:
Intelligent Charging
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.
Note: The system will suspend intelligent charging if a
fault is present, when starting or the vehicle is being
charged by an external device.
Note: The driving range will be reduced after
intelligent charging.
Note: The intelligent charging function is suspended
when the high voltage battery is in a low SOC.

 

[Rolfe]

Really useful that they tell you exactly what that "low" SoC is. Oh wait...

 

[Kithmo]

Really useful that they tell you exactly what that "low" SoC is. Oh wait...

And what the, "under certain conditions" are.

 

[tsedge]

And what the, "under certain conditions" are.

Presumably they can be exactly stated since they are certain.