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Recent BMS update

Mark Holmes

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Essex
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MG ZS EV
I purchased my car in March 20 and have the comfort 2 software added in May, but since then the car hasn’t been back to the dealer for any updates. My first service is due next week and I’m concerned that the new BMS update will still cause me problems, okay my car shouldn’t have any balancing issues, but do I have the right to say I don’t want it installed as my current BMS seems to be working fine, why did they look to update it anyway, what were they trying to accomplished with the version that went wrong. Do you have any advise on this matter?
MilesperKWH - Would be interested in you thoughts and comments as an MG dealer....
 
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I hadn't had issues with the BMS before it was updated, I went to the dealer for fitting the green plates and they applied the update without asking me anything, they scanned the car and several updates were available for my car.
 
I'm going to ask them only to apply any absolutely necessary safety related updates when I take mine in July and see what they say. I don't need unlocked charging.
 
I love my Mg but I’m confused/bemused about next updates. Booked it in for service today and asked for some clarity on battery update issues and was told I would have to charge it 100 times after update to clear issue. I told them not to do the update and asked why would they even offer it .confused.com
Noticed this on another thread.
 
I hadn't had issues with the BMS before it was updated, I went to the dealer for fitting the green plates and they applied the update without asking me anything, they scanned the car and several updates were available for my car.
Do you have problems with you car since the updates?
 
Surely the dealerships must get release notes from MG for software updates. I’m thinking that the latest update is designed to further protect the HV battery pack and improve longevity. It seems to reduce top end voltage. The bugs contained in previous updates have further clouded the issue but it may well be that this latest update was coming anyway. If you were fortunate enough not to have the bug filled update then the battery balance fiasco may well not apply to you. Come on MG provide some clear guidance to your customers!
 
Fortunately, I'm getting the same range and mileage consumption as before the update, but voltage dropped to 450v.
That’s reassuring as some are now complaining of loss of power once they reach below 40%, which worries me even though I’m not a boy racer it’s still nice to expect the car to perform on an equal keel, particularly if pulling out of junctions or on to a busy roundabout..
 
Surely the dealerships must get release notes from MG for software updates. I’m thinking that the latest update is designed to further protect the HV battery pack and improve longevity. It seems to reduce top end voltage. The bugs contained in previous updates have further clouded the issue but it may well be that this latest update was coming anyway. If you were fortunate enough not to have the bug filled update then the battery balance fiasco may well not apply to you. Come on MG provide some clear guidance to your customers!
Agree we need more information, hence why I’ve invited Miles from Chorley to comment if he can.
 
That’s reassuring as some are now complaining of loss of power once they reach below 40%, which worries me even though I’m not a boy racer it’s still nice to expect the car to perform on an equal keel, particularly if pulling out of junctions or on to a busy roundabout..

WAC 768 said:
Interesting and wonder if this could be a common problem, post update, which if you charge daily and don't let the SOC go below 40% you would never notice this...
True as I am getting terrible mileage at the moment so doing tests and coincidently am running my battery low and checking things and now literally just noticed this while driving now , and came to check of it was happening to anyone else as I put my foot flat and get nothing .. well max limited on all modes , even when I turn esp off
 
That’s reassuring as some are now complaining of loss of power once they reach below 40%, which worries me even though I’m not a boy racer it’s still nice to expect the car to perform on an equal keel, particularly if pulling out of junctions or on to a busy roundabout..
I haven't noticed any loss of power, indeed last monday I rapid charged mine and I arrived at charger with 9% SOC remaining.
 
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I purchased my car in March 20 and have the comfort 2 software added in May, but since then the car hasn’t been back to the dealer for any updates. My first service is due next week and I’m concerned that the new BMS update will still cause me problems, okay my car shouldn’t have any balancing issues, but do I have the right to say I don’t want it installed as my current BMS seems to be working fine, why did they look to update it anyway, what were they trying to accomplished with the version that went wrong. Do you have any advise on this matter?
MilesperKWH - Would be interested in you thoughts and comments as an MG dealer....
The latest (January) version of the BMS update is the same one as they are now installing in the factory. The previous issue has been ironed out. The new BMS may offer better regen from 100% charge, and better overall pack longevity due to reduced top end voltage.
 
The latest (January) version of the BMS update is the same one as they are now installing in the factory. The previous issue has been ironed out. The new BMS may offer better regen from 100% charge, and better overall pack longevity due to reduced top end voltage.
Cheers Miles your response offers me much more confidence, thank you for taking the time to reply.
 
MG has made some adjustments to the ZS EV battery pack voltage limits to increase pack longevity, but maintain the range. The new maximum voltage will be around 449/450V (assuming no loads on like climate etc). The minimum voltages have been adjusted to keep the range equal. This may also allow the car to have better regeneration from 100% charge.
 
MG has made some adjustments to the ZS EV battery pack voltage limits to increase pack longevity, but maintain the range. The new maximum voltage will be around 449/450V (assuming no loads on like climate etc). The minimum voltages have been adjusted to keep the range equal. This may also allow the car to have better regeneration from 100% charge.
Thanks for the update. Do you know if this BMS update is planned to be installed across all customers cars that don’t currently have this version installed? I guess some will be concerned that not having the latest BMS update may adversely affect their battery pack longevity. Is it an update that dealers will contact customers about or will it be installed at service time? I guess it’s not a chargeable update? Thanks again for posting your reply - it’s great and very refreshing, that you take time out to provide more clarity.
 
I had the BMS update in Nov just before the lock down which obviously has reduced use of the car. I opted to get the update done as we are on OctopusEnergy but we have been disappointed in that the result of the update did not allow charging to start with the doors unlocked although we found that we could unlock the car with the handle button and it would remain charging. My second issue was the main reason for getting the update was the ability for delayed charging. Well it did it once, that was it, never again. To this date it only ever did that one delayed charge, this has made going on to OctopusEnergy pointless really. Although we have not noticed any reduction on power and our battery charges to 456volts I am now of the opinion that the update was not fully successful, well it’s not an opinion, I know it was not successful.
 
It sounds like you need the January 2021 update. I too have never taken advantage of the 5p Octopus tariff
 
I had the BMS update in Nov just before the lock down which obviously has reduced use of the car. I opted to get the update done as we are on OctopusEnergy but we have been disappointed in that the result of the update did not allow charging to start with the doors unlocked although we found that we could unlock the car with the handle button and it would remain charging. My second issue was the main reason for getting the update was the ability for delayed charging. Well it did it once, that was it, never again. To this date it only ever did that one delayed charge, this has made going on to OctopusEnergy pointless really. Although we have not noticed any reduction on power and our battery charges to 456volts I am now of the opinion that the update was not fully successful, well it’s not an opinion, I know it was not successful.
To get the charging whilst unlocked, you need the EVCC (onboard charger) updating, then the BMS after.
 
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