Advice required about 12V battery

[Aitch1]

On quite a few occasions when starting the car, I get a 'reminder' to turn off the large screen because the battery is low. Can anyone advise me how the electrics work, in that I thought the 12V battery was charged by an alternator each time the car was run. Which battery runs the heating and aircon? I've had the car from new, 2024, had no problems, fully serviced and clocked up 9498 miles. My mileage averages 42 to 46 mpg in winter, and 58 to 62 in spring/summer. Well pleased with all aspects of the car. Any help would be appreciated. Aitch

 

[MG Clive]

I can't claim to know exactly how the system works, but the MG3 Hybrid doesn't have an alternator, the 12 volt battery is charged from the High Voltage Battery, but only when the car is switched on (Ready), and the A/C is run by the 12 Volt Battery.

 

[mgpooter]

Yes basically the 12v battery runs all the normal things they always did.
...and the heat comes from the engine (when it warms up)