HV Battery Shutdown

[Rolfe]

Had similar faults on my zs ev. Rejected it and got money back. MGs are rubbish!

Your profile says you're still driving one...

 

[andymgzs]

The fault - sudden loss of power and rapid deceleration as you desperately try and get to the hard shoulder. It might coincide with being in cruise and then braking.

Car needs to come to a full stop. Place in park. Foot on brake and car says ready and power is restored

I have had the car for three months. The car had this fault three times in the first two weeks. AA disconnected battery and fault seemed to stop. Happened a fourth time and took it into MG who updated the software. Just happened for a fifth time so it's not fixed.

Very dangerous. Has anyone else had this fault or had it resolved?

The AA are excellent- my zs ev has had this fault countless times. AA fix each time and mg say nothing wrong. I now avoid motorways because this happened to my son on a smart motorway. Very dangerous.

 

[andymgzs]

Had similar faults on my zs ev. Rejected it and got money back. MGs are rubbish!

Interesting- I tried like hell to get MG to accept fault but they would not. HV failures and battery capacity. Their diagnostics are really bad.

AA and this forum know more about MGs than MG.

 

[Rusty168]

Hi
As the car has had this same fault 3 time I would start looking into having it replaced with a new car. The person work with used to be a BWW sale Manager for some years and this used to be the rule, now I do not know if covers all makes but look in to it.

It's through a lease company. The lease company and broker are taking no responsibility. I don't own the car so can't send it back. Intend on letting MG look at it again next Wednesday. Second time it will have been in. If it happens after that then I will push to have it replaced. Cheers R

 

[Rich D]

Sounds very similar to my experience in terms of issue with the car and the dealerships ability to diagnose & repair. As everything is under warranty it’s “sounds” like the dealers get pretty poor support from MG themselves.

 

[Shavian]

Rusty168 - that sounds horrible. My only “HV Battery Disconnect” warnings have come while public charging on a 350Kw rapid charger. Car failed to connect first time, and then went “oops, don’t like this” when I retried. Wife not happy as we were some way from home in the evening. Called MGAA to recover us. Just as he turned up I tried a further start and this time it worked as advertised, very embarrassing! I then had the Tesla update applied (for £95 - daylight robbery) and charged successfully on Tesla superchargers a couple of times. Next time I used an IONITY 350Khw charger again, and the same thing happened - HV disconnect and total shutdown for about 30 mins. Wife not happy again. I then took the ZS to the dealer for diagnosis and they found a Record of a ‘historic spike’ in the computer indicating the past failure. They wiped this off and I have since had no trouble. Wife still not happy, so we replanned our trip to France by using her smelly ICE car instead! I think the lesson is to only use public chargers of up to 100Kwh : the car only wants to charge at about 60, so there’s no point in using a pokier charger anyway.

 

[Cfish]

The fault - sudden loss of power and rapid deceleration as you desperately try and get to the hard shoulder. It might coincide with being in cruise and then braking.

Car needs to come to a full stop. Place in park. Foot on brake and car says ready and power is restored

I have had the car for three months. The car had this fault three times in the first two weeks. AA disconnected battery and fault seemed to stop. Happened a fourth time and took it into MG who updated the software. Just happened for a fifth time so it's not fixed.

Very dangerous. Has anyone else had this fault or had it resolved?

I have had it happen three times since the end of April - each time after braking when going fairly fast. I have fixed it each time by getting out, locking and getting back in again. Very dangerous and very frightening. Anyone else?

 

[Derek clark]

I have had it happen three times since the end of April - each time after braking when going fairly fast. I have fixed it each time by getting out, locking and getting back in again. Very dangerous and very frightening. Anyone else?

I've had this and other faults, 28 in all. Returned my EV and got all my money back.

 

[andymgzs]

Yep same with mine. MG dismissed it consistently because computer said no problem. Not funny breaking down on a smart motorway. AA know more about MG than MG!
Mine goes back in December and I finally get rid of it!

 

[Martinonline]

Instead of getting out etc have you tried power down option on the info screen - car icon, safety tab.

I think I read somewhere that the HV battery is designed to disconnect in an accident. This must involve a negative accelerometer and perhaps that is faulty. Could also be linked to airbag control. Whatever it is a major fault that needs fixing.

 

[Sid Mr old banger]

My situation seems slightly different than possibly others, inasmuch as I have an MG4 Trophy. I have had it six months and this is the fourth time my car has stopped dead with no power, complete system shut down. On the last occasion there was a car behind me but managed to stop. There was no warning or slowing down, just stopped.

I had to get out of the car, go through the simulation of locking the car, then get back in and the car started up again. I have been fortunate in as much as if I had been on a motorway it could have caused a multiple pile up (plus myself dead}. Do you feel that I would be safe in this car?

 

[Rolfe]

Welcome to the forum, although it's bad that it's under these circumstances. Have you reported this to your dealer, and if so what did he say?

 

[Ian Key]

My situation seems slightly different than possibly others, inasmuch as I have an MG4 Trophy. I have had it six months and this is the fourth time my car has stopped dead with no power, complete system shut down. On the last occasion there was a car behind me but managed to stop. There was no warning or slowing down, just stopped.

I had to get out of the car, go through the simulation of locking the car, then get back in and the car started up again. I have been fortunate in as much as if I had been on a motorway it could have caused a multiple pile up (plus myself dead}. Do you feel that I would be safe in this car?

Check the 12V battery terminals are tight and as @Rolfe says take it to your dealer as there might be a software update needed.

 

[tsedge]

Loose connection, software problem or a faulty module are the likely culprits.

 

[andymgzs]

Loose connection, software problem or a faulty module are the likely culprits.

Just tell MG that you want a car that works.

Their customers service is poor and they do not deal with recurring issues.

I do admire this blog and the ingenuity of the bloggers but really MG are accountable for fault finding and fixing their cars.

Fortunately my lease finishes early December and that will be a good day.

 

[andymgzs]

My situation seems slightly different than possibly others, inasmuch as I have an MG4 Trophy. I have had it six months and this is the fourth time my car has stopped dead with no power, complete system shut down. On the last occasion there was a car behind me but managed to stop. There was no warning or slowing down, just stopped.

I had to get out of the car, go through the simulation of locking the car, then get back in and the car started up again. I have been fortunate in as much as if I had been on a motorway it could have caused a multiple pile up (plus myself dead}. Do you feel that I would be safe in this car?

NO.
And don’t accept no from MG.
This has happened on smart motorway and trust me it’s not safe.

 

[Shavian]

The HV battery disconnect on my ZS Trophy has happened twice, but only when plugging in to a rapid (100+ Kwh) non- Tesla public charger. Frustrating and inconvenient but not dangerous like the frightening incidents described above. In both cases I summoned assistance from MGAA, and in both cases the fault corrected itself after 30 minutes just as the AA arrived - how embarrassing! Only issues were an angry wife and loss of faith in public chargers. I very rarely need to use them, and now only use Tesla chargers when they are available.

 

[andymgzs]

The HV battery disconnect on my ZS Trophy has happened twice, but only when plugging in to a rapid (100+ Kwh) non- Tesla public charger. Frustrating and inconvenient but not dangerous like the frightening incidents described above. In both cases I summoned assistance from MGAA, and in both cases the fault corrected itself after 30 minutes just as the AA arrived - how embarrassing! Only issues were an angry wife and loss of faith in public chargers. I very rarely need to use them, and now only use Tesla chargers when they are available.

Thanks for insights. My lad has had this issue several times with public chargers. It’s not the fault of the charger in my opinion - it’s how MG had coded charger management.

 

[Snowy]

I can't remember ever posting a review, however things are so bad with the MG4 I am compelled to make other drivers aware.
I leased an MG4 in November 2023 and things have gone from bad to worse.
Within 4 weeks of having the vehicle the car did an emergency brake on a busy main road and then shut down, there was nothing in front of me and how the car behind avoided going into the back of me I really don't know. I contacted GH and was told they had no appointments available for 2 weeks and no hire vehicles available
Over the next couple of days I made the decision to carry on driving and kept my journies local, a few days later unbeleivably the same thing happened in the exact place as before. Shaking and upset I immediately called Glynn Hopkins and was told that this probably happened because it had been stored in the memory from the previous incident ! WTH
After several more telephone calls to the dealer Glynn Hopkins Romford (shocking customer service) the car was eventually taken to Manor Park East London for repairs I was informed of 2 things firstly that the sensor may have been dirty and secondly the car had not been calibrated properly !
During the 4 days I had a hire vehicle via Europe Cars, which GH collected on the 4th day however they did not inform Europe Cars and for over a month I received daily messages and telephone calls informing me that bailiffs action would be taken be unless I paid £800.00 as apparently the car had been placed in a compound. Despite me informing EC that I did not have the hire vehicle during the times they were quoting they were insisitent that I was responsible and should pay, this went on for over a month and GH did nothing to rectify the matter, telling me that they had tried to phone EC but noone was picking up
Eventually I managed to speak to EC Head Office and explained everything thankfully they sorted out the problem stating GH had not responded to any of there requests for the date the vehicle had been returned (GH denied this) and therefore the reason EC were hosling me responsible.

Anyway back to the MG4 last Saturday I was driving down the A13 a notoriously busy road and the amber phone flashed up on the screen stating system failure within seconds a red phone flashed up stating consult handbook the car then completely lost power and shut down, a lorry was behind me and thankfully he didn't go into the back of me. I am releived that I was in the slow lane but it still could have caused a very bad accident. As you can imagine I have lost all faith in this car it is an accident waiting to happen
I have been driving for 42 years and always been a confident driver, this car has caused me to feel extremely nervous as I never know what will happen as the car is so unpredictable.
By the way the AA were called and he admitted to have virtually no knowledge on this electric vehicle
Also GH have told me that they have no knowledge of any problems with the MG4 Trophy LR and said not heard of any other unhappy customer, I suggested he look on You tube as so may people reprting failures with car shutting down

 

[andymgzs]

Very typical I’m afraid. My ZS EV goes back on the 6th December and that will be a good day.
I have no problem with GH - I think they have a very bad pass from MG. You cannot maintain a car on a shoe string and the problem resolution goes back to China (assumption).
Leased mine new and at first visit told I had to pay for a software upgrade, many defects, breakdowns - some dangerous. However, computer say no faults!

Make sure you get AA cover - they know the most about these cars and how to fix them.