Typical 12v battery level?

[welshlewy]

I’ve had my mg5 LR for about two months, and I’m sat in it waiting to AA assist, as it’s broken down with a system fault, hv battery shut off fault. It seemed to be caused by a dodgy GeniePoint charger at Morrisons, which caused my 12v to go from 14.1 to 12.1. This got me wondering, as I’m new to EV ownership, is 14.1ish typical for this car, as that’s what it’s showed since I had it?

 

[Alb]

That's a pretty normal voltage.
14+ Volts is the charger voltage. not the battery.

 

[Lovemyev]

You should see just over 14 volts when the car is in the READY mode and it will then be charging the 12 volt battery, from the large HV traction battery.
In STANDBY mode, with everything turned off, you are likely to see just over 12 volts on the battery.
My ZS EV is standing on the drive right now and the App is reporting a voltage of 13.3 volts.
This is normally around the 13.1 volts mark and the lowest I have seen is 12.7 volts.

 

[welshlewy]

Thanks, at least my car is normal on that front.

 

[Lovemyev]

While you are waiting, try locking up the car and walking away.
Some cars have recovered on there own, in due course.
If not, the AA guy may try the old disconnect the 12 volt battery and wait 15 mins and then reconnect.
Or if his diag machine will talk to the car, there maybe a genetic code reset he can try to clear any codes that are stored.
All of these things have been used on other cars.
Failing that, its a trip to the dealer to reset the fault codes stored.
Some Morrisons charges have been highlighted as troublesome in the past.

 

[welshlewy]

Thanks. I’ve tried leaving it for a while but it hasn’t helped, so hopefully AA can help out.

 

[Lovemyev]

Thanks. I’ve tried leaving it for a while but it hasn’t helped, so hopefully AA can help out.

Good luck and please keep us in the loop with the problem !.

 

[welshlewy]

Thanks, will do. I had a long journey planned for the weekend, so best this has happened today rather than tomorrow!

 

[Jomarkh]

Was this on a rapid charger and what percentage did you start and then finish on?

 

[welshlewy]

well the AA has arrived and he’s plugging in…

 

[welshlewy]

Was this on a rapid charger and what percentage did you start and then finish on?

It was a rapid charger. But it didn’t even connect properly, the charger failed as it was trying to connect, which made me think it was the charger that messed it up.

 

[welshlewy]

Was this on a rapid charger and what percentage did you start and then finish on?

It didn’t even connect properly, the charger failed as it was trying to connect

 

[welshlewy]

He can’t get the car to communicate with his diagnostic pad. 12v disconnect comes next

 

[welshlewy]

Battery disconnect didn’t work either. Awesome.

 

[Prof1967]

This has come up as an issue previously usually where people have been sat in the car listening to their radio when charging.

If you press the start button twice without your foot on the brake the display will show a voltage of 12 to 13 volts. You can then use the infotainment system but it will be drawing power from the 12 volt battery and as with an ICE car this can drain the battery. If the voltage gets too low it can cause an HV shut off.

If you plan to stay in the car while charging and use the infotainment you need to put your foot on the brake and press the start button twice and the voltage should then show 13 to 14 volts. The car will then take power from the HV battery to keep the 12 volt battery topped up.

 

[welshlewy]

Thanks, I’ll bear that in mind. It’s fixed now, AA were able to clear the code

 

[Prof1967]

Battery disconnect didn’t work either. Awesome.

Does he have a 12 volt booster? If he connects this to the 12 volt battery then it should allow the HV battery to engage and you should be able to get going.

Some people carry these boosters as a matter of course as it is common on many EV;s (even TESLA's) for the HV battery to not engage if the 12 volt runs down.

 

[welshlewy]

All working now, clearing the code worked a treat. Thanks everyone for your help!

 

[NickG]

@welshlewy I had the exact same issue when charging. Couldn't get it to work and after about 10 mins of trying gave up. But during that time I locked / unlocked the car and pressed Start a number of times. However, possibly not always pressing the brake. The car was on with radio and also AC as it was 27c! The battery was showing 12.2v and I had the System Fault and HV Battery has been Shut Off errors rendering the car useless. The AA guy fixed it by plugging in to the OBD and although no error codes showed selected 'Clear Errors' and car back to Ready.

He did try plugging in a booster which sent the voltage to 12.6v and that didn't work. He did a quick battery disconnect but only for about 15 seconds which I'm guessing isn't enough.

It would be nice to know if there is a way to do this without having to call a 3rd party if that's all it takes to fix this.

 

[Gomev]

This has come up as an issue previously usually where people have been sat in the car listening to their radio when charging.

If you press the start button twice without your foot on the brake the display will show a voltage of 12 to 13 volts. You can then use the infotainment system but it will be drawing power from the 12 volt battery and as with an ICE car this can drain the battery. If the voltage gets too low it can cause an HV shut off.

If you plan to stay in the car while charging and use the infotainment you need to put your foot on the brake and press the start button twice and the voltage should then show 13 to 14 volts. The car will then take power from the HV battery to keep the 12 volt battery topped up.

I think you may be confusing pressing the start button once and twice.
Without using the footbrake pressing Start once to put into ACC(essory) mode will show 12v and will turn off after a couple of minutes. Pressing again into ON mode will connect to the HV and voltage will show 14v and will remain on.
No need to apply footbrake.

The Start button
The operational status displays are as follows:
Indicator Off (OFF)
If the switch has not been operated and there are no
indicators illuminated, the power system is OFF. The power
electric door mirrors remain operational.
Yellow Light (ACC)
Pressing the START/STOP Switch without the footbrake
being applied whilst the vehicle power system is OFF will
place the system in the ACC state, this will illuminate the
yellow indicator in the switch button. The ACC position
allows operation of certain ancillaries such as power
windows.
Green Light (ON/READY)
• Whilst in the ACC state, pressing the START/STOP
Switch without the footbrake being applied will place
the system in the ON state, the green indicator will
illuminate. This will allow some electrical systems to
operate.
• Pressing the START/STOP Switch with P selected and
the footbrake applied will place the vehicle in the
READY state, the green indicator will illuminate. This
indicates that all electrical systems will operate and the
vehicle is ready to be driven.
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