MG ZS EV 12V Battery

[Coulomb]

Why is my car occasionally giving a warning of a possible low charge (with the "engine" off) when I open the boot lid, yet the battery reads out at 12.65 ?

I assume that the boot lid motor is a fairly substantial 12V load. So if the 12V battery has high internal resistance, then with a heavy load the battery voltage would sag significantly, triggering the low battery warning.

High internal resistance can happen for several reasons. It may be that a good long charge from an external 12V battery charger will help. A charger with a good desulphation stage might help more. It's not clear to me whether the cheaper chargers claiming a desulphation capability are any good. I'd like to experiment with this myself, as the ZS 12V battery is getting old, and the MG4 12V battery had a very deep discharge for a day or so.

 

[Steptoe]

Earlier in the thread I posted that I had fitted a new battery after getting the low voltage warning but similarly after a few weeks I found I was getting the same warning with the new battery!

After some thought I realised that this might be because at that time I was making lots of very short runs, about 800 yards, parking up, then driving home. I no longer need to do this so am driving 'normal' distances again so have concluded that the short drives were not replacing the watts used in the start-up process.

Wonder if I have replaced a perfectly good battery......

 

[Tom Hartley]

Earlier in the thread I posted that I had fitted a new battery after getting the low voltage warning but similarly after a few weeks I found I was getting the same warning with the new battery!

After some thought I realised that this might be because at that time I was making lots of very short runs, about 800 yards, parking up, then driving home. I no longer need to do this so am driving 'normal' distances again so have concluded that the short drives were not replacing the watts used in the start-up process.

Wonder if I have replaced a perfectly good battery......

Wondering the same here but still, thank you for your past assistance

 

[Maximus]

Which AGM one did you find that works for your MG.

Lucas LF027 Is the battery fitted for me by Chorley Group as a replacement for my MG ZS EV 2020 model. LF027 Lucas Fusion AGM Car Battery 12V 60Ah | Car Batteries US | Duco Car Parts UK

 

[Maximus]

This is the ready mode - if you just press the START button and don’t put your foot on the brake, you go into ‘Accessory’ mode and you’ll see a lower charge state for the 12V - if it’s complaint, it’ll usually not go past 12…
Other than that, you could always pop the bonnet and stick a meter on the battery connections and read the DC voltage…

Yes agreed. I used the TopDon BT200 to test the battery and you will get a lot more on the health of the battery.