Discharged 12V battery

[Crod]

Hi All, interesting thread on ZapMap cafe yesterday that started with a photo of two guys apparently trying to jump start an eNiro from an ICE 12V battery. General incredulity all round until someone pointed out that they'd almost flattened the 12V battery of their Niro by leaving the heating on when the motor was off ( not in utilty mode). Kept getting "battery low " warnings but they knew the traction battery was almost full so they ignored the warnings until they finally realised what was happening and switched the drive back on just in time. I was wondering if there was any known heating/ driving configuration in MGs ( specifically ZS EV) that would cause the same potential problem?

 

[Ian Key]

I think the MG4 needs 30 minutes to charge the 12v battery so continuously doing short journeys will run it down eventually. I assume the ZS EV is the same.

 

[Lguk]

My understanding is the hv battery will kick in and top off the 12v so long as its above a certain %. This wasn't present on the early mg5s or ZS but was later patched in with a software update. A modern jump pack was listed as a good idea to carry in the vehicle for such cases where the 12v has been drained, which is usually someone sitting in the car with the heating/ac on at a charge point but in standby mode whilst the car charges.

 

[Crod]

Thanks both. I've found a thread from Oct 2020 that confirms the traction battery supplies 14.2V continuously to the 12V battery when the car is in engine operating mode. That fits with the 14V battery voltage I see when I'm driving. I like the idea of carrying a jump pack.

 

[MonsterMonster]

Our of curiosity what is the specification of the MG5 12v battery? I'm assuming they are smaller than those found in an ice car as it does not need cold crank amperage.

 

[Alb]