HV battery shut-off

[bobh]

I have a ZS trophy connect with a 51kWh battery. Most times when I try to start I get 2 warning lights. "High voltage battery pack cutoff warning" and "low voltage battery charging system malfunction warning". Often there is also a brief message that states "HV battery shut off". If I press the brake and start button again it usually clears the warning lights and all is ok. Can anyone suggest what there problem might be? Thank you.

 

[bobh]

Note that the 12V battery has been tested and is in very good condition.

 

[Gadget Geek]

Ah . . . I was going to sugget changing your 12V battery. Back to the deaer then if you are certain the 12V is in good condition. (Was it load tested?)

 

[Lovemyev]

If you intend to check the voltage ( power ) in your 12 volt battery under the bonnet with a volt meter, then just ensure have the car completely closed down and wait about 15 minutes to ensure all of the modules have fully closed down.
Now take a reading across the battery or even better, consider disconnecting the negative terminal ( 10mm spanner ) and THEN check the STANDING voltage.
If it's under 12 volts, then your battery will require a really good charge or it could have a dead cell or is self discharging due to a fault.
An additional check would be testing for a phantom drain, but this a little more involved.
A lot of people jump to the conclusion, that because you have a MASSIVE traction battery under the car, then the12 volt battery will never go flat !.
Not so unfortunately, and it is easy to get caught out on EV's and is always a vey good place to start, when trying to figure out why suddenly random odd warning messages are appearing on the dash ?.
These can be triggered by a low SOC in the 12 volt battery and can result in fault codes being stored.
Low / fault 12 volt batteries on EV's are the very first port of call in the diagnostic process and are pretty easy to rule out.
Your local Halfords etc will only be too happy to check your 12 volt battery for free.

 

[bobh]

Not sure what tests were done, but was told it was in perfect condition.

 

[Lovemyev]

Who carried out the tests, was it done in the manner described above ?.
You could ask for another opinion and then use both studies and preset them to the dealer ??.

 

[Coulomb]

Most times when I try to start I get 2 warning lights. "High voltage battery pack cutoff warning" and "low voltage battery charging system malfunction warning". Often there is also a brief message that states "HV battery shut off". If I press the brake and start button again it usually clears the warning lights and all is ok.

It's possible that you might be rushing the start-up process. This is a well known and discussed problem; search for others' solutions, or just try waiting a few seconds before pressing the start button. Then gradually reduce the wait time until you find the point where it doesn't like it.

 

[bobh]

It's possible that you might be rushing the start-up process. This is a well known and discussed problem; search for others' solutions, or just try waiting a few seconds before pressing the start button. Then gradually reduce the wait time until you find the point where it doesn't like it.

When I first had the car, I used to get problems due to rushing. I learned to be more deliberate. I have had the car for over a year, and the problem occurs almost every time now, when I power on the car.

 

[Chris H]

I get this about one in 5 starts (2024 Trophy Connect) - the battery light stays on and I get a message about HV battery. I have to power off and back on again (a bit like Windows 3.1) and always worked the 2nd time. I worry at some point it may just decide to not start at all.
I mentioned it to the dealer when I took it in but they said it couldn't be reproduced, so couldn't be arsed to try to find out what was causing it.

 

[bobh]

I get this about one in 5 starts (2024 Trophy Connect) - the battery light stays on and I get a message about HV battery. I have to power off and back on again (a bit like Windows 3.1) and always worked the 2nd time. I worry at some point it may just decide to not start at all.
I mentioned it to the dealer when I took it in but they said it couldn't be reproduced, so couldn't be arsed to try to find out what was causing it.

It started off being very occasional for me, but now it is almost every time.

 

[fred12345]

It started off being very occasional for me, but now it is almost every time.

Why don't you try the trick with disconnecting 12v battery for a few minutes in hope that clears any potential glitch? See what happens ...

 

[bobh]

Why don't you try the trick with disconnecting 12v battery for a few minutes in hope that clears any potential glitch? See what happens ...

Thank you for suggestion. Just tried that, but problem remains.

 

[fred12345]

Thank you for suggestion. Just tried that, but problem remains.

When is the next service due? If you can live with it until then, you could mention it to the MG garage, might be something they could fix without too much trouble.. You have AA cover from last service?

Maybe worth recording it on your phone so you can share your video with them (and here, might help identify what's going on)

I know you mentioned 12v battery was tested but quite a lot of problems seem to be caused by 12v batteries misbehaving ...

Found this but not sure if you can get anything out of it ??

Vehicle control system fault : HV battery shut off

Just had this happen to me with my new style zs. Charger wouldn't engage then crashed. Had to faff with the car to get it to release the cable. Went to find another charger and the car is throwing errors about the HV battery. Currently waiting for the RAC. Seen some comments about it...

www.speakev.com

AND

 

[bobh]

When is the next service due? If you can live with it until then, you could mention it to the MG garage, might be something they could fix without too much trouble.. You have AA cover from last service?

Maybe worth recording it on your phone so you can share your video with them (and here, might help identify what's going on)

I know you mentioned 12v battery was tested but quite a lot of problems seem to be caused by 12v batteries misbehaving ...

Found this but not sure if you can get anything out of it ??

Vehicle control system fault : HV battery shut off

Just had this happen to me with my new style zs. Charger wouldn't engage then crashed. Had to faff with the car to get it to release the cable. Went to find another charger and the car is throwing errors about the HV battery. Currently waiting for the RAC. Seen some comments about it...

www.speakev.com

AND

I am booked into garage in about 4 weeks time. I have taken photos. Had problem over a year, so will probably be ok until then.

 

[Jto]

If you intend to check the voltage ( power ) in your 12 volt battery under the bonnet with a volt meter, then just ensure have the car completely closed down and wait about 15 minutes to ensure all of the modules have fully closed down.
Now take a reading across the battery or even better, consider disconnecting the negative terminal ( 10mm spanner ) and THEN check the STANDING voltage.
If it's under 12 volts, then your battery will require a really good charge or it could have a dead cell or is self discharging due to a fault.
An additional check would be testing for a phantom drain, but this a little more involved.
A lot of people jump to the conclusion, that because you have a MASSIVE traction battery under the car, then the12 volt battery will never go flat !.
Not so unfortunately, and it is easy to get caught out on EV's and is always a vey good place to start, when trying to figure out why suddenly random odd warning messages are appearing on the dash ?.
These can be triggered by a low SOC in the 12 volt battery and can result in fault codes being stored.
Low / fault 12 volt batteries on EV's are the very first port of call in the diagnostic process and are pretty easy to rule out.
Your local Halfords etc will only be too happy to check your 12 volt battery for free.

Hi Lovemyev
I had seen something in a post this morning about shortcutting the start can course this which I not seen before and as you are most knowledgeable person on here I asking it ou could explain this as I am picking a new ZS next Saturday and will starting from scratch so cramming in all can.

 

[Lovemyev]

Hi Lovemyev
I had seen something in a post this morning about shortcutting the start can course this which I not seen before and as you are most knowledgeable person on here I asking it ou could explain this as I am picking a new ZS next Saturday and will starting from scratch so cramming in all can.

Thank you for your kind comments but just to put the record straight, I am definitely NOT not one of the most knowledgable people on this forum, that is 100% for sure.
I ( like others ) have owned both models of the ZS EV and have lived with its good and bad points along the way ?.
I am more than willing to share MY own experiences with other members, who may find it some benefit to them.
Firstly, I think it is safe to assume we are taking about a ZS EV here of course, as some people do incorrectly post questions on here on the ICE version of the ZS.
A couple of pointers towards protecting your 12 volt battery ( SOH ) State Of Health ).
Yes - You are totally correct with regards to following the start up procedure correctly, if you rush this process, the car WILL complain and is likely to throw up fault codes on the dash panel and may even refuse to drive !.
So - Enter the car, put your foot on the brake pedal firmly and keep it pressed !.
Press the START button and you will feel the pedal slightly sink, keep the pressure applied.
The info ( radio ) unit will boot and the car will give out a "bong" to indicate it has finished booting successfully, you will also see a green READY status in the dash panel.
Select the direction you wish to travel with the gear selector and then release the foot brake, when you are ready, by pressing the GO pedal it will release the hand brake and then off you go.
If you have the info unit ( radio ) running while you are parked up ( longer than 5 minutes ) then I strongly suggest that it is safer to leave the car in READY mode while parked up.
Why - Because in READY mode the 12 volt battery IS receiving a charge, in the aux / standby mode it is not.
This can result in depleting the battery and it will then refuse to boot up into READY mode when you are ready to leave.
Hope this make sense .
I am sure you will have other questions about the ZS EV and the members of this forum are only to willing to help - Enjoy.

 

[Jto]

Thank you for your kind comments but just to put the record straight, I am definitely NOT not one of the most knowledgable people on this forum, that is 100% for sure.
I ( like others ) have owned both models of the ZS EV and have lived with its good and bad points along the way ?.
I am more than willing to share MY own experiences with other members, who may find it some benefit to them.
Firstly, I think it is safe to assume we are taking about a ZS EV here of course, as some people do incorrectly post questions on here on the ICE version of the ZS.
A couple of pointers towards protecting your 12 volt battery ( SOH ) State Of Health ).
Yes - You are totally correct with regards to following the start up procedure correctly, if you rush this process, the car WILL complain and is likely to throw up fault codes on the dash panel and may even refuse to drive !.
So - Enter the car, put your foot on the brake pedal firmly and keep it pressed !.
Press the START button and you will feel the pedal slightly sink, keep the pressure applied.
The info ( radio ) unit will boot and the car will give out a "bong" to indicate it has finished booting successfully, you will also see a green READY status in the dash panel.
Select the direction you wish to travel with the gear selector and then release the foot brake, when you are ready, by pressing the GO pedal it will release the hand brake and then off you go.
If you have the info unit ( radio ) running while you are parked up ( longer than 5 minutes ) then I strongly suggest that it is safer to leave the car in READY mode while parked up.
Why - Because in READY mode the 12 volt battery IS receiving a charge, in the aux / standby mode it is not.
This can result in depleting the battery and it will then refuse to boot up into READY mode when you are ready to leave.
Hope this make sense .
I am sure you will have other questions about the ZS EV and the members of this forum are radio only to willing to help - Enjoy.

Thanks just the normal start up I have to do, I am able to set off in the PHEV before it’s finished booting up but yes in the ZS EV I will wait until it’s finished booting up.
The 12v battery should last a lot longer than 5 mins listening to the radio it should draw that much power. My thinking is the car been stored for some time even if the battery is disconnected it can still lose some voltage, and if you do only 3 to 4 miles in a day the battery can not recover its voltage, I do a 16miles round trips 5 days a week to work and back and it takes around 45 minutes each way per day so hopefully this will keep the battery well topped up. The other thing I may do is put the 12v on a charger on the drive just to give a boost.

 

[Lovemyev]

The 12v battery should last a lot longer than 5 mins listening to the radio it should draw that much power

I was being super cautious quoting 5 mins of course, but just remember you may have other 12 volt powered items drawing from the battery also, so playing safe with the car in READY mode is my preferred option.
You are not a high mileage user and using the car in the winter months with HVAC / lights / wipers etc can be challenging for your battery.
Providing a top up charge from a smart battery charger is good practice periodically.
Many EV owners opt to carry a battery booster pack under the drivers seat for back up reasons.
I would recommend buying one myself.
Yes you have MG ( AA ) Assistance with your car, but a long wait for a jump start could be avoided if you have your own battery booster.

 

[bobh]

I have a ZS trophy connect with a 51kWh battery. Most times when I try to start I get 2 warning lights. "High voltage battery pack cutoff warning" and "low voltage battery charging system malfunction warning". Often there is also a brief message that states "HV battery shut off". If I press the brake and start button again it usually clears the warning lights and all is ok. Can anyone suggest what there problem might be? Thank you.

I have found that pressing the brake firmly and being slow and deliberate when starting, results in no problems.

 

[PVperson]

If you intend to check the voltage ( power ) in your 12 volt battery under the bonnet with a volt meter, then just ensure have the car completely closed down and wait about 15 minutes to ensure all of the modules have fully closed down.
Now take a reading across the battery or even better, consider disconnecting the negative terminal ( 10mm spanner ) and THEN check the STANDING voltage.
If it's under 12 volts, then your battery will require a really good charge or it could have a dead cell or is self discharging due to a fault.
An additional check would be testing for a phantom drain, but this a little more involved.
A lot of people jump to the conclusion, that because you have a MASSIVE traction battery under the car, then the12 volt battery will never go flat !.
Not so unfortunately, and it is easy to get caught out on EV's and is always a vey good place to start, when trying to figure out why suddenly random odd warning messages are appearing on the dash ?.
These can be triggered by a low SOC in the 12 volt battery and can result in fault codes being stored.
Low / fault 12 volt batteries on EV's are the very first port of call in the diagnostic process and are pretty easy to rule out.
Your local Halfords etc will only be too happy to check your 12 volt battery for free.

I solved my "system fault" HV battery cut-out, that had disabled the (MG5 jan 2021) car for several days.
As I'm an electronics engineer, with knowledge of EV's and their foibles, I remembered I'd been driving an hour in heavy rain, and something HV may have got wetter than usual.
So, after being recovered home, I put the car on axle stands, starting warming things up with a fan heater, and put the LV battery on charge, of course. that evening I instructed an AA patrol to come with MG software support on their tablet. the (elderly) mechanic arrived, and started finding and clearing faults. He didn't think he'd get it running... he cleared a few most suspicious was the "HV motor controller fault" also a load with the ABS, probably because I'd disconnected the LV battery (which never dropped below indicated 12.1V (actual 12.4V at the battery) which failed to clear it. There was also a fault on the BMS, which may have had a bearing. I did keep asking him to reset (turn off/on) the car after each fault, so I could isolate which one caused it, but he cleared about 20 faults, then reset, and Hey! Presto, "clunk-clunk" of the HV contactors closing.
My best idea was leaving a 1kW fan heater blowing into the motor for an hour, certainly dried it throughly. wierd it's got a furry jacket on it!!! (especially when it's water cooled...) Saved me a lot of time and money, especially on hire cars and trains to the airport next week..