Everything you need to know about BMS & voltage balancing

Yes - good point. I’m unsure what impact longer term the issue and subsequent balancing may have - I suspect minimal but you’re quite right we don’t know and probably never will.
 
This is a good discussion and I have no doubt the video will be of benefit.

Two suggestions/requests from me

- keep it simple, high level and ideally describe in terms/technologies people are aware of. For example most people know about mobile phone battery issues - they drain faster when cold, the battery life is effected by number of charges and you may need to replace the battery if you don’t manage it properly

- put the salient points in a small reference document as not everyone will want to watch a video to find something they are searching for. It’s also easier to update a document if you find out something additional you want to add
 
Srp111 said:
Really ??
Click to expand...
Yep!!!!!

ECU Module version spreadsheet

I'll update this top post as more data is provided. In an attempt to figure out what the different versions of all the software do/cause, we are putting together a list of peoples car ecu versions. If you have the OBD2 device (currently being looked at in another post) or OVMS, please post your...
www.mgevs.com www.mgevs.com

Project OBD2 - Mobile App v1.2.1 and later

It's not Bluetooth ...it's WiFi...don't think it will work with the app. Is there a switch, I think some do both
www.mgevs.com www.mgevs.com
 
Yeah at least 3 users all after 12th Feb have had BMS ending in EU1.
It's build date appears to be 10th February.
Where as the mid Jan update as AO1 with a build date of 30th December.
 
JodyS21 said:
@Stuart Wright
I think there's a very important new development hopefully Miles can shed some light on - There's another new version of the BMS that has just appeared in the last week or 2!!!
Click to expand...
Not another update surely !.
We want to use our EV's as normally possible transport, not offering them up for software releases every couple of weeks !.
This can become very tiring.
 
Software errors are inevitable but they should never get to production. The MG test procedures need to be tightened up. Customer safety is paramount. Hopefully there are no other bugs lurking that could compromise that.

They also should have recalled those cars affected by the duff BMS. They shouldn't have left it to dealers to decide. I feel for some of the posters on here that have been badly affected....it's not on.

I really like my ZS EV but I would struggle to recommend MG to anyone else. That's a shame.
 
Stuart Wright said:
I hope Miles isn't in the firing line because he's working here for the benefit of MG owners and MG themselves.
It will probably take about a day to edit the video. I hope to publish over the weekend some time.

Here is the revised list of questions. They are organised so that they first explain the basics and then go deeper with the answer to each question leading into the next question.

In December 2020, a small number of MG ZS EVs had a software version installed which contained a bug which caused the batteries of the cars to become imbalanced. In this interview, Miles Roberts, Innovations Development Manager at Chorley Group answers the questions that MG ZS EV owners have about this software update, the effect it has, and what they should do about it.

  1. About the car’s software
    1. How is the software in electric cars different to the software in internal combustion engine cars?
    2. Do electric cars have more frequent software updates than ICE cars?
    3. How are software updates to MG electric cars installed?
    4. What changes to the ZS EV have been made with the various updates?
    5. How can a ZS EV owner identify what version of the software they have?
  2. About the BMS and cell voltage
    1. What does BMS stand for?
    2. What is BMS generally and why is it important?
    3. Can MG ZS EV owners see the battery health?
    4. What is the max and min voltage on the display and why is it there?
    5. What should the max and min voltage display read for the ZS EV?
    6. What if the voltage display reads something else?
  3. About battery cell voltage balancing
    1. What is battery cell voltage balancing?
    2. Does cell voltage balancing happen on all electric cars?
    3. What causes an imbalanced battery?
    4. When will ZS EVs usually need to have their battery balanced?
    5. Is battery balancing an automatic process?
    6. Does rapid charging create more of an imbalance than fast charging?
    7. Which particular ZS EV software update caused imbalanced batteries?
    8. Does this software update affect other MG models?
  4. Dealing with an imbalanced battery
    1. What impact will an imbalanced battery have on the car?
    2. Will having an imbalanced battery damage the battery or car?
    3. What should an owner who believes they have an imbalanced battery do?
    4. Have ZS EV owners with the particular software version been contacted to update it?
    5. What is the procedure for re-balancing the ZS EV battery?
    6. Why does balancing a battery take so long? Is there any way to speed it up?
  5. Current situation
    1. What is the latest version of the ZS EV software and when was it released?
Click to expand...
Looking forward to the video?
 
I have just had my BMS updated during service. After first charge and equalisation the voltage showed as 450V and range of132 miles in normal. I drove a short distance and recharged the car, The charging took 2 hrs (both on 'Granny charger) and equalisation at least 3 hrs. The voltage is now 455 and range 145. It looks as though I have the very latest BMS version
 
JodyS21 said:
@Stuart Wright
I think there's a very important new development hopefully Miles can shed some light on - There's another new version of the BMS that has just appeared in the last week or 2!!!
Click to expand...
We await with baited breath. Will this be in the video or conveyed earlier ?
 
PeteJ said:
I have just had my BMS updated during service. After first charge and equalisation the voltage showed as 450V and range of132 miles in normal. I drove a short distance and recharged the car, The charging took 2 hrs (both on 'Granny charger) and equalisation at least 3 hrs. The voltage is now 455 and range 145. It looks as though I have the very latest BMS version
Click to expand...
What date did you just get the BMS updated?
See the other thread:

Project OBD2 - Mobile App v1.2.1 and later

It's not Bluetooth ...it's WiFi...don't think it will work with the app. Is there a switch, I think some do both
www.mgevs.com www.mgevs.com

Thanks
 
I need some resources. Can anyone please send me
  • video of the charging light pulsing
  • video of the charging light solid
  • photo of the dash showing 449 volts
  • photo of the dash showing 455 volts
 
PeteJ said:
I have just had my BMS updated during service. After first charge and equalisation the voltage showed as 450V and range of132 miles in normal. I drove a short distance and recharged the car, The charging took 2 hrs (both on 'Granny charger) and equalisation at least 3 hrs. The voltage is now 455 and range 145. It looks as though I have the very latest BMS version
Click to expand...
not sure petej you have latest BMS update from jan 2021 as on the forum people indicated that the voltage had dropped to 450 ish after the update any one else clear on this..
 
Stuart Wright said:
I need some resources. Can anyone please send me
  • video of the charging light pulsing
  • video of the charging light solid
  • photo of the dash showing 449 volts
  • photo of the dash showing 455 volts
Click to expand...
Dash showing 449Volts
 

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