Mg5 long-range 12V not charging

[splreece78]

Hi all..

I do 1 HR journeys daily and also plug in overnight

The below image is from 7am after an overnight charge....no schedule restrictions so has been plugged in constantly...50% charge

Isn't the 12V meant to charge as well.. I'm sick of panicking every morning that the battery won't be charged.. already had RAC out once to jump it as it fully discharged while I was away.

Only 2 yrs old

 

[MickeySw]

Isn't the 12v meant to charge as well.. I'm sick of panicking every morning that the battery won't be charged.. already had RAC out once to jump it as it fully discharged while I was away.

Yes, the CCU will charge the 12V battery every time the HV battery is connected (READY or charging). What voltage does it show when READY?

Only 2 yrs old

You can try to do a HW reset, but most likely you’ll need to replace it.
The quality of the stock 12V battery isn’t great, hence the reason it’s only covered by a one year warranty?

 

[Jomarkh]

Keep a 12V pack in the car. It doesn't take much to kick the CPU into ready mode.

 

[kevin ellard]

Are you by any chance having trouble with the radio? If so then disconnecting the 12V battery for a couple of minutes might fix both things.
By the way, I think the 12V only gets charged while the car is in ready mode or charging. Once the main battery has stopped charging it also stops charging the 12V.

 

[5teep]

Nothing wrong with 13.8v surely or am I missing something?

 

[rjb1970]

Nothing wrong with 13.8v surely or am I missing something?

13.8 with the lights on is normal, 14.0 without, so this looks ok.

 

[MickeySw]

Nothing wrong with 13.8v surely or am I missing something?

The 13.8V is supplied by the DC/DC section of CCU and is not indicative of the 12V battery health.

Starting the car with HV battery disconnected will ensure that all low voltage circuits are powered directly by the Aux battery.

If its voltage drops quickly below 12V consider replacing it rather sooner than later.