Reduced Power - MG UK Deny Fault.

[Lovemyev]

Hi, I got the car in September 2020 and when it had it's first service last year I had asked them to update the BMS as my car has to be locked to charge on the AC chargers. They said it was all updated but my car still has to be locked to charge on the 7kw chargers.

There is another "Tick Box" section in the BMS update that needs completing to obtain A/C charging with the doors unlocked.

The below quote, is taken from the "MG EV Owners Club".

Charging unlocked/locked update for ZSEV​

The ZSEV has always supported unlocked charging on CCS (rapid chargers) and in 2020 a software update was released to add this function to charging on type 2 (6.6 kWh fast chargers). You are less likely to want to sit in your car for this slower charging, although it can still be occasionally useful. This is a side update to the BMS update: specifically to the EVCC module of the car. Once this is installed, the car will charge both locked or unlocked.

 

[SRMiller07]

Cheers guys, I tried to call the garage this morning but couldn't get through but am over that way on Friday so will stop off and have a chat with them. Hopefully it'll be a simple as getting me onto the most up-to-date software/BMS.

 

[SRMiller07]

There is another "Tick Box" section in the BMS update that needs completing to obtain A/C charging with the doors unlocked.

The below quote, is taken from the "MG EV Owners Club".

Charging unlocked/locked update for ZSEV​

The ZSEV has always supported unlocked charging on CCS (rapid chargers) and in 2020 a software update was released to add this function to charging on type 2 (6.6 kWh fast chargers). You are less likely to want to sit in your car for this slower charging, although it can still be occasionally useful. This is a side update to the BMS update: specifically to the EVCC module of the car. Once this is installed, the car will charge both locked or unlocked.

Ah, might be why it got missed then at the last service. Will ask again as it'll be handy when on the public chargers and I want to sit in the car (or if I've forgotten something in the car and have to unlock it and restart the charge)

 

[rpannell]

function to charging on type 2 (6.6 kWh fast chargers).

You would have thought and hoped that MG would understand the difference between kWh and kW. What is a 6.6kWh charger???

 

[SRMiller07]

If you firmly believe that the car is at fault you should engage an independent qualified engineer to liaise with your MG dealer and review the advice they have recieved from MG UK.

The engineer's report will then provide you with a clear direction in which to take your issue - if the engineer agrees with MG then the issue would be closed; in the event the engineer disagrees then you have the basis for leverage with MG to either repair or reject the vehicle or to begin legal proceedings (which should always be a last resort).

Or you could just sell it - with the delivery delays I'm sure that it would go for top-dollar anyhow (is that allowed in the UK if there was a PICG against it?).

I did look the other day and I paid £22k for my exclusive and the same age/mileage today still seem to be going 2nd hand for £24-25k! Have debated just trading it in for the newer LR version as the uplift in cost isn't massive.
I'll give the dealership a chance to update the car before I go any further, only seems right to give them the chance to rectify it.

 

[Lovemyev]

The BMS update has been covered extensively on the forum and @Miles Roberts CG has very kindly proved owners with a LOT of information regarding dates / effects of "Buggy" software etc etc.
There is a HUGE thread covering the BMS issues already on the forum.
You can do some simple checks of your dash instruments yourself, when you have received the car back from the dealer.
Try to find a dealer who has plenty of experience in applying the BMS update successfully.

 

[BarryH]

I have a fairly early car, delivered January 2020. I have never experienced any reduction in power at any SOC, and I have run the battery down to virtually nothing.
I think there must be a fault somewhere if you get reduced power. It could be some protection device operating to prevent a system shutdown. Similar to "get you home" mode in ICE cars.

My ZS too was delivered in Jan 2020 and had multiple updates through until August that year and the last BMS update was in July/August which was a good BMS. But it was in Nov/December that there was a bad BMS update to European cars which I missed thankfully and when buggy BMS update was discovered MG suspended all updates until it was sorted around mid-January and I had my 1st Annual Service and Comfort 2 upGrade first week of Feb by which time MG Dealers were updating the Buggy BMS. but as @Kithmo says your car could have slipped through the net.

 

[WAC 768]

Hi, Newbie here. Did you every get to the bottom of this as I seem to be having a very similar experience with my ZS where it will limit/reduce power without any warning. It usually happens when down to 2 bars but this morning when I did the school run it was at 3 bar and still limited power. It's a bit worrying, and have been caught out on this, as I don't find out I have limited power until I pull out onto the main road which is a 60 and slightly up hill. I then find out I have a max 60-65% power.
I try to leave the car plugged in over night once a month to balance but can't believe that it doesn't tell you when it drops. Even happens when I have been driving for a while, get to 2 bar and then drops power. This is usually a few miles before the low battery light comes on.
We have a Zoe and that doesn't limit the power at all when either cold or low (granted I'm usually driving slow anyway when it's flashing red ;-) )
I don't know if I should take this up with the dealership or what?
Cheers

Hi, i gave MG UK (Spoke to them directly) every chance to fix the car and in the end they stated there's too many
variables and at this point the dealers hands were tied, so in the end i sold it on and actually bought a Zoe and this works fine and as expected. My ZS battery was fully balanced, with all the latest BMS updates and the problem was clear enough, when the pack is cold and the first warning appears the reduction starts, once at operating temperature (after many, many miles) the car even at 8% (shown at charger) provides 100% of the power....

Remember if you charge your car every night (I couldn't) then this problem is never noticed, simply because:
1) You've started @ 100%, done a long journey (pack will be at optimal temp) - 100% power
2) You've driven short jorneys and covered only 50 miles during the day and then put the car on charge over night - 100% power.

Your dealer will be clueless and they will contact MG UK, who or unless they have a fix (doubt this very much) you are stuck. Legal action is possible ans was a path i was looking into but then comes the point, once started you should not drive the car and depending on when you initally started the claim, they may not offer you the full price.

You could try here and they were going to take my case but i'd sold the car before they contacted me.
Make a complaint - Resolve your dispute - The Motor Ombudsman

Sorry I cannot give you positive news but this is the reality of your situation.