12v battery level

[Kithmo]

I've read in various places that the 12v battery gets charged up when you're charging the HV, is this so ?
The reason I ask is, yesterday when I did my first home charge (top up) on my Pod Point the first thing I noticed was the 12v battery level was down a notch when I started the car. It had been sat at the 14v mark all the time previously, but after the charge it was at the next notch down (13v ?) when I first put the car in READY mode. It crept back up to the 14v mark after about 30 seconds, whereas it normally goes to the 14v mark straight away and did so today when I started it up.
This made me think maybe the 12v doesn't charge up with the HV.

 

[Frank]

I've read in various places that the 12v battery gets charged up when you're charging the HV, is this so ?
The reason I ask is, yesterday when I did my first home charge (top up) on my Pod Point the first thing I noticed was the 12v battery level was down a notch when I started the car. It had been sat at the 14v mark all the time previously, but after the charge it was at the next notch down (13v ?) when I first put the car in READY mode. It crept back up to the 14v mark after about 30 seconds, whereas it normally goes to the 14v mark straight away and did so today when I started it up.
This made me think maybe the 12v doesn't charge up with the HV.

Hi Kithmo,

Just charge your car up EVERY night with the podpoint home charger no matter what the SOC and you will NEVER have to worry about the 12v bty. Problems arise when one sits in a car park waiting for returning shoppers and listening to the radio too long when not in the ready mode. I just keep it in ready mode when doing this, minimal drain on the HV battery when doing this and unlike a ICE car does not cause any noise or emission pollution, but more importantly stops the 12v battery getting drained and the radio WON'T turn off every 10 minutes or so as it does (to protect the 12v bty) when not in the ready mode. In ready mode off course as well as listening to uninterrupted radio you can have the A/C or heating on as well.

Regards

Frank

PS Don't worry about the HV battery being charged every night it will NOT harm it. The Battery Management System on the car protects it from overcharger and being too drained.

 

[DangerousDoug]

I carried out a test on my MG soon after I got it, to answer this very question. I put a multimeter across the 12v battery and recorded it's voltage before and after starting a charge (the car was able to charge when locked but with the bonnet open). The battery voltage was 12.8v before charging started, then jumped up to 14.2v when charging commenced. Therefore the 12v battery does indeed get charged as you charge the HV battery.

 

[KasEV]

@Kithmo,
You observation about the 12 volt indicator going down a bit then after 30 seconds settling higher after a charge is absolutely normal. There are slight voltage fluctuations as the system resets.
These fluctuations are always small and last only a few seconds so absolutely nothing wrong with your car.

 

[Kithmo]

I wasn't worried about there being anything wrong, as it went back up to 14v, I was puzzled as to why it was lower when I first started it. Having checked again what it does is, on pressing the start button it does the gauge sweep thing then settles at 14v, showing READY on the screen. After maybe 5 or 6 seconds it drops to 13v, then after about 30 seconds it goes back up to 14v. This seems pretty normal, as you said, powering up all the systems. So I guess what's happened is I didn't notice it drop to 13v before and just saw the initial 14v.