12V battery and iSmart app

[mkpete]

I have a 2025 MG HS PHEV Trophy, which I bought 2 months ago when it was about 9 months old with 4000 miles.
What battery level do people find the iSmart app showing?
Mine often shows 12.2V, though it has gone up to 12.3V. It seems to lose about 0.1V each day when I have not used it for a couple of days (dropping to 11.9V) and I wonder if this is normal or whether there may be a problem with the battery.
I have read about 12V battery problems with other EVs and issues if they are left for a long time. Some only seem to charge when the car is being used, though the manual states:
When the vehicle is powered OFF and the system detects that the 12V battery is running low, the vehicle will automatically charge the 12V battery under certain
conditions to ensure the vehicle starts.

I have a dashcam but am relutant to connect it if I could end up with a dead battery.

I did notice one day that it increased overnight from 12.0V to 12.2V, suggesting that it may charge from the main battery sometimes.
If it does this then perhaps I need not worry!

Interested to hear what battery voltage others see on the app.

 

[Totti1001]

The app's display is not particularly accurate. As soon as you query the car via the app, the voltage drops slightly. Some control units are activated and even the interior lighting comes on. That's why the app shows you the low voltage.
I installed a battery monitor that transmits the voltage to my mobile phone via Bluetooth and also stores it for 70 days. That way, you can always see immediately if something is wrong. At 1:37 a.m., I queried the vehicle and the voltage dropped briefly.
Anything around 12.2V or higher is actually okay.

 

[BarrieG]

A number of people have spotted rhe manual note that the traction battery will charge the 12V battery if it gets low.
If it gives you any confidence, I have left .my car in an airport car park for three weeks with no ill effects.

 

[Noel]

You mention that you have a dash cam. I have Nextbase front and rear cams, which are active when the car is parked, and detect bumps. If the settings are not correct they discharge the 12V battery. What camera/s do you have?

 

[mkpete]

You mention that you have a dash cam. I have Nextbase front and rear cams, which are active when the car is parked, and detect bumps. If the settings are not correct they discharge the 12V battery. What camera/s do you have?

Hi Noel
I have the Nextbase 522GW with front and rear cameras.
I possibly made a mistake in having Halfords fit it. The guy turned up with a hardwire kit to connect to the fuse and an OBD connector. I told him that I did not want a permanent feed but discovered (no doubt because it was easier) that he had fitted the OBD kit. It was only some days later that I discovered that this is a permanent feed.
I have found a video on YouTube which suggests that if it is set up with Parking Mode ON but Auto Power Off OFF that is not supposed to drain the battery.

However, I have been relutant to connect the dashcam until I am happy with my battery.
From what I have read 12.2v indicates that the battery is not even achieving a 50% charge.

I would still be intersted to know what voltage other people are seeing on their iSmart app.

 

[Totti1001]

To prevent the battery from discharging through the dashcam, you need a hardwire connection cable. This is a small box that is connected to the continuous positive and ignition pulse. You can use the box to set how far the voltage is allowed to drop. If the voltage falls below the set value, the dashcam is disconnected from the power supply. I bought a kit like this for my Viofo dashcam back then.
However, I haven't used the parking mode yet.
But as I already wrote, you don't need to worry about your 12.2 V at all, that's still within the normal range.
If you have a measuring device, you can connect it directly to the 12 V battery. To get a real value, however, you have to lock the car and wait a few minutes.
It takes a while for all the control units to shut down.