HV battery shut off - long term?

[lostindawoods]

Hi guys,

Keep getting the HV battery shut off issue every couple of weeks. Turn off and back on sorts it out very quickly within a few minutes, but I just wanted to know how others did with this long term? It didn't cause any other more serious issues or get worse/more frequent did it?

I have MG5 PFL LR Exclusive, got it 2nd hand after watching youtube reviews and really like it, but just worried about this one thing... I have a nightmare that it will somehow cut off on me while I'm on the motorway, but it's really only happened when first turning on after being parked stationary so far.

Only had the car a month, thanks for any advice guys.

 

[Jomarkh]

Hi, are you letting it wake up before selecting R or D?
I pause until it 'clunks' before selecting a gear as it doesn't like doing things too quickly.
I can normally get it going by selecting P then pressing the start button again with foot on the brake pedal.

 

[maskull]

I've had my MG5 PFL for 2 years and I've had this happen a couple of times in that time but not every couple of weeks . Funny thing is it happened to me today after two failed charging attempts on two different charging posts . On the second attempt the HV battery shut off came up . Got out the trusty 10mm spanner disconnected the 12 volt negative battery terminal for a minute or so , fault disappears ,moved to third charging post and charged without a problem .
Also as @Jomarkh says in the previous post don't rush the start up procedure process...it doesn't like it

 

[dragon2611]

Remember to be sure to press the foot brake when you press the start/on button or it won't close the contractors and you'll get that message.

The other times I've had that have been if something upsets the car whilst trying to charge at which point you either have to leave the car 10mins or so or disconnect the 12V battery to reboot everything.

 

[5teep]

Hi guys,

Keep getting the HV battery shut off issue every couple of weeks. Turn off and back on sorts it out very quickly within a few minutes, but I just wanted to know how others did with this long term? It didn't cause any other more serious issues or get worse/more frequent did it?

I have MG5 PFL LR Exclusive, got it 2nd hand after watching youtube reviews and really like it, but just worried about this one thing... I have a nightmare that it will somehow cut off on me while I'm on the motorway, but it's really only happened when first turning on after being parked stationary so far.

Only had the car a month, thanks for any advice guys.

There 'may' be an issue with your 12V battery charge dropping too low while the car is left overnight. Failing that do as suggested above and make sure you are not trying to make the car go too soon. If you can't solve it then book it in to get it checked, should still be under warranty.

 

[lostindawoods]

Yeah it happened again today. Brake pedal felt really firm, barely any give, 12V battery voltage dropped from the usual 14.1 V to 12 V. But off and on again fixed it, brake pedal as well loosened up like normal. Really strange this car... apart from this, I like everything else about it quite a lot.

 

[MickeySw]

Yeah it happened again today. Brake pedal felt really firm, barely any give, 12v battery voltage dropped from the usual 14.1 to 12. But off and on again fixed it, brake pedal as well loosened up like normal. Really strange this car... apart from this, I like everything else about it quite a lot.

You only see the 14.1V (provided by the HV battery via the CCU) when the car is READY (or charging).

However this only works, if your 12V Aux is able to provide the initial power to start the car. I would replace it (out of warranty anyway), if not just to rule it. Make sure you charge an even new 12V fully before you use it.

 

[JohnV6]

If it really shows 12V the battery when you follow the process below it is cream crackered. Replace it as it is c 30% efficient.

After you let the battery lie for a while disconnected....

If it reads 11.9 volts it is only 20% efficient

12.12v 40% efficient

12.3 volts 60% efficient

12.52 volts 80% efficient

12.72 volts 100% efficient

 

[lostindawoods]

Just took a reading of the battery with multimeter (bonnet open) and it read 12.6v when idle. That should be ok then right guys?

 

[dragon2611]

Just took a reading of the battery with multimeter (bonnet open) and it read 12.6v when idle. That should be ok then right guys?

Maybe, I think there have been cases of batteries showing an ok resting voltage but completely collapsing when any load is placed on them.

 

[maskull]

Maybe, I think there have been cases of batteries showing an ok resting voltage but completely collapsing when any load is placed on them.

Yes , I've had that happen on a previous car . I bad cell is all that's needed