Flat battery, what could the cause be.

[janitor]

I woke up this morning to a flat 12v battery on my mg zs ev mk1,AA turned up and jump started it, all seems fine, i normally leave the wirelessly CarPlay dongle and the obd2 reader connected, do these draw power when the car is shut down, or is it just the cold weather that has caused it, dropped to less than 5c last night, the coldest since I got the car in march, AA recommend booking it in to mg as a precaution, which I will do in the mornin, just wondering if its anything I’m doing that’s caused it.

 

[Gadget Geek]

Usually it's totally random and without warning. Lots of threads on it if you use the search.

12v Battery Charging

Page 23 of the manual states Intelligent charging (of the 12v battery) is suspended when HV battery is in low state of charge. Sadly it doesn't state how low.

www.mgevs.com

Low voltage battery discharging

Car is a ZS Trophy LR, just under a year old. We have started seeing messages that the "Low voltage battery needs charging, do not leave car more than 3 days unused." Or words to that effect. Yesterday evening we parked up with the battery registering 13.8V. Later in the evening it was down to...

www.mgevs.com

12V Battery charge low - do not park for more than 3 days.

I was pleased to find that the BM12V battery monitor stores its records and gives the app the history when it reconnects. Nice. I was also pleased to see that whenever I challenge the 12V (by doing an iSmart scan, for example) it returns to its original charge. So, after a day of monitoring...

www.mgevs.com

 

[Jomarkh]

I woke up this morning to a flat 12v battery on my mg zs ev mk1,AA turned up and jump started it, all seems fine, i normally leave the wirelessly CarPlay dongle and the obd2 reader connected, do these draw power when the car is shut down, or is it just the cold weather that has caused it, dropped to less than 5c last night, the coldest since I got the car in march, AA recommend booking it in to mg as a precaution, which I will do in the mornin, just wondering if its anything I’m doing that’s caused it.

The 12v battery on an EV doesn't have a large capacity so doesn't take much extra connected to it to drain it.