I have an MG ZS EV registered Dec 2019. It's battery has now failed at under 22,000 miles . It had no service in 2021.

[Peter Docherty]

MG do have a policy re missed services which implies that if the missed service is irrelevant to the current problem, the warranty may not be invalidated. We are waiting to hear . If MG will not cover this, I would be interested to hear what others would offer as options. The car [even with intact battery] is probably worth only £7 to £8K so refitting a new battery probably wouldn't be worthwhile. I know that second hand batteries are available but [being 80] I am not in a position to be able to assess how good an option this would be. Am I faced with just selling the rest of the undamaged car to a breaker and spending money on a second hand MG with an intact service history ?
Any opinions or advice would be welcome. Peter.

 

[JohnV6]

Do you mean the 12v battery or the high voltage one?

 

[Gadget Geek]

Just wondering why it missed a service.

 

[Alb]

Welcome to the club Peter
I think it works in your favour that the missed service was 4 years ago rather than the most recent. If I were in your shoes, I'd be pursuing a legal remedy if they turned down the warranty claim but until you know, just remain polite and respectful.

 

[Lovemyev]

If we are talking about the 12 volt battery here then would be totally normal, however if it’s the traction battery here, then I would be extremely surprised by this, given that the car has only covered 22,000 miles ?.
Interesting to hear the circumstances of how this has been diagnosed / cause etc and by who ?.

 

[decrep]

If it's the traction battery what's meant by "fail"?

 

[Peter Docherty]

It is indeed the HV battery that has apparently failed. The Orange tortoise just appeared out of the blue, the battery having performed faultlessly up to that point. I cannot recall why there was no service in 2021. The service was eventually carried out 7 months late and it, and all subsequent services, have been normal. It was Covid lockdown time and life wasn't normal.

 

[Fokmg]

Hi
I am very sorry and suprised to hear about your issue. I would hold your ground, I would assume that at all the subsequent services the battery performance was checked and found to be perfectly ok. The mode of failure you describe was rather sudden and points to some form of component failure or a bad connection?

From your comments I assume that you have owned the car from new ?

Surely as an early user MG should show a great deal of consideration to your problem

 

[decrep]

so I assume the orange tortoise meant you could still drive but at a reduced speed?
This means the battery was still working to a certain extent.
Did it show a suddenly reduced state of charge?

I think some of us are a bit doubtful about a sudden failure of the battery itself, There could be other causes of the problem.

 

[Gadget Geek]

If the service was missed because of lockdown then I think you would have good grounds to have the warranty reinstated.

 

[DBedford]

Surely as an early user MG should show a great deal of consideration to your problem

I guess we all respect your comment. but they are business, not a charity, and if its not covered under warranty or by UK consumer rights, then its a hard life experience.

 

[Lovemyev]

It is indeed the HV battery that has apparently failed. The Orange tortoise just appeared out of the blue, the battery having performed faultlessly up to that point. I cannot recall why there was no service in 2021. The service was eventually carried out 7 months late and it, and all subsequent services, have been normal. It was Covid lockdown time and life wasn't normal.

This is unfortunate and very strange that the high voltage pack had suddenly completely failed given the cars low milage covered.
Has the car ever been left for long periods of time with the battery at a low state of charge.
Has the pack suffered from water ingress ?.
Who has diagnosed the fault and what is there views on what has caused this very unusual condition, as this is NOT normal !.

 

[Peter Docherty]

When this happened the battery was about 70% charged. The local MG dealership advised running the battery down to about 10% and recharging using the household 3 pin plug supply cable. I did this but no recharge occurred. I then drove the car to the dealership. Their service department tell that tests show that the battery is at fault. They are now preparing to strip the battery to discover the precise fault. There has been no recent collision. About 2 weeks prior to this event the car was at the MG dealers as the heating /AC fan was cutting out. Fan replaced.

 

[Lovemyev]

When this happened the battery was about 70% charged. The local MG dealership advised running the battery down to about 10% and recharging using the household 3 pin plug supply cable. I did this but no recharge occurred. I then drove the car to the dealership. Their service department tell that tests show that the battery is at fault. They are now preparing to strip the battery to discover the precise fault. There has been no recent collision. About 2 weeks prior to this event the car was at the MG dealers as the heating /AC fan was cutting out. Fan replaced.

Interesting ?.
The dealer recommending running the pack down to 10% SOC, then carry out a slow charge from the Granny unit.
This action may suggest that they thought ( at that time ) that if the cells if the pack where badly out of balance, then carrying out a charge from a low SOC could balance the pack and may help / correct the issue.
This is a “first port of call” in this type of situation. I am pretty sure that the dealer will be taking there instructions from MG Customer Service at this point.
They will be in total control here, offering clear instructions to the dealership on just what checks they need to be making and in a scripted way.
Giving the dealer the instruction to remove the pack, would strongly suggest that they are convinced that the problem is inside the pack.
The BMS control unit is housed inside the case of the pack, so could this be the cause of the problem ?.
More testing ahead I am convinced, a process of elimination here.
Unless there is obvious evidence of water ingress, I somehow think that the cells of the pack should okay .
The previous problem with the heater could be a clue that something was not 100% okay here.
Please keep us upto date on the progress !.

 

[Peter Docherty]

Many thanks for your helpful comments. I wonder if the following points to the source of the problem. While I was running the battery down (a mixture of driving the car and just running the a/C and heater) I noticed that when driving the battery performed completely normally for between 4 and 5 minutes before shutting down into power save mode. This happened every time I took it out.

 

[Slipstream]

Interesting ?.
The dealer recommending running the pack down to 10% SOC, then carry out a charge.
May suggest that they thought ( at that time ) the cells if the pack was badly out of balance. Carrying out a balance cycle, just may if correct the issue.
This is a “first port of call” in this type of situation. I am pretty sure that the dealer will be taking there instructions from MG Customer Service at this point.
They will be in total control here, offering clear instructions to the dealership on just what checks they need to be making.
Giving the dealer the instruction to remove the pack, would strongly suggest that they are convinced that the problem is inside the pack.
The BMS control unit is housed inside the case of the pack.
Could this be the cause of the problem ?.
More testing ahead I am convinced, a process of elimination here.
Unless there is obvious evidence of water ingress, I.somehow think that the cells of the pack should okay .
The previous problem with the heater could be a clue that something was not 100% okay here.
Please keep us upto date on the progress !.

As lovemyev says it would be very interesting to find out the cause of the problem. I've owned me EVs for five years and never seen this problem on this or other forums.

 

[decrep]

I wonder if the following points to the source of the problem. While I was running the battery down (a mixture of driving the car and just running the a/C and heater) I noticed that when driving the battery performed completely normally for between 4 and 5 minutes before shutting down into power save mode. This happened every time I took it out.

It's got to give somebody, that knows how the system works, a few clues.
The battery is obviously working OK if it's driving the car. but one of the sensors is picking up some sort of problem, and changing to save mode.
The diagnostics should tell the techs which sensor, and tell them where to look.

 

[Fokmg]

To my simple mind I wonder if there is a poor connection on the output of the Battery to the motor?
May be a bad connector or cable crimp that has a bit of resistance, after 4 -5 mins use it gets a bit hot resistance increases and send the system into alarm ? Interesting to find out if this happens every time that you try to run the car for about 5 mins ? What is the recovery time between being able to drive the car.

Recalling a bit of Physics
Power equals I squared times R. , (I = current and R= Resistance)

If a high power cable connection is a bit suspect the problems and observations made by yourself could indicate a fault of this nature could be the cause, and the battery may well be ok.

Look for the simple and obvious falts first

 

[Gadget Geek]

Could the battery pack heat sensor be faulty, thinking it is going to cook the battery and putting it into tortoise mode?

 

[Bam Bam]

I guess we all respect your comment. but they are business, not a charity, and if its not covered under warranty or by UK consumer rights, then its a hard life experience.

Sure, there isn't much loyalty in business. However, on the other hand businesses do operate with the idea of 'good will' and have a view to their reputation.