Long term effects of bad BMS?

[peter]

Is there any info known about the potential long term impacts of having the bad BMS software? I.e. after fully balancing and recovering to 449v, does the battery still hold 42.5kwh or has the BMS caused any long term deterioration?
I don't have the equipment to take any exact readings but wondering if anyone with the ovms hardware can confirm.
My experience having been badly affected by the bad BMS is a small drop in battery capacity but my method is crude. I drove from 100% down to 7%, I divided number of miles by my KW/h consumed to get total KW/h consumed, then divided by 0.93 to gross up for remaining 7%.
It worked out at 40.5kwh total capacity, so a little less than it should be. Anyone else have any info on this?

 

[Lovemyev]

Is there any info known about the potential long term impacts of having the bad BMS software? I.e. after fully balancing and recovering to 449v, does the battery still hold 42.5kwh or has the BMS caused any long term deterioration?
I don't have the equipment to take any exact readings but wondering if anyone with the ovms hardware can confirm.
My experience having been badly affected by the bad BMS is a small drop in battery capacity but my method is crude. I drove from 100% down to 7%, I divided number of miles by my KW/h consumed to get total KW/h consumed, then divided by 0.93 to gross up for remaining 7%.
It worked out at 40.5kwh total capacity, so a little less than it should be. Anyone else have any info on this?

I can not comment if there are any long term affects by having the “Buggy” software installed.
MG say that the HV battery will recover to 100%.
But of course they would say that, I guess.
The new BMS released on 15th Jan 21 does appear to have increased the space at the top of the battery, that’s for sure, this can be felt because the Regen braking is stronger even when the battery is reporting as being 100% fully charged.
The Regen needs somewhere to go, so the buffer has to be in there hiding to accept it.
The Regen is more linear now I find.
On the previous OEM software, the Regen was fairly weak when the battery was fully charged.
I think MG have slightly reduced the capacity of the pack, in view of the longer term life of the unit, maybe ???.

 

[JodyS21]

Is there any info known about the potential long term impacts of having the bad BMS software? I.e. after fully balancing and recovering to 449v, does the battery still hold 42.5kwh or has the BMS caused any long term deterioration?
I don't have the equipment to take any exact readings but wondering if anyone with the ovms hardware can confirm.
My experience having been badly affected by the bad BMS is a small drop in battery capacity but my method is crude. I drove from 100% down to 7%, I divided number of miles by my KW/h consumed to get total KW/h consumed, then divided by 0.93 to gross up for remaining 7%.
It worked out at 40.5kwh total capacity, so a little less than it should be. Anyone else have any info on this?

No idea, the exact capacity/available capacity is a bit of a mystery, all we can do it try to extrapolate things such as you have tried to.

To be honest your 40.5kWh figure doesn't matched up with what others have seen.
You're doing an AC charge and using the kWh reported by your AC charger/meter, this should be about 10% higher than what is actually put into the battery due to AC-DC losses etc, so at your calculation it'd mean more like 36.5kWh total - which surely cannot be right?

Actually I don't get your calculations now, did you mean "KW/h"? or kW per Mile from the trip?
If you reset your trip etc then that 40.5kWh is a valid figure to come up with. It DOES [edit] sound a bit low.
We don't know how regen is taken into account in the trip either btw.
Where did you get the 7% from?

Were you fully balanced so def at full capacity?

 

[peter]

I took all readings from cars display. Took total miles and divided by miles per KWh to find how many kWh the journey consumed.
I knew the 7% remaining because I plugged it in right after journey and that's what the display said.
40.5kwh capacity is not bad but it is advertised at 45khw and I believe 42.5 is meant to be available for use. Hence I think there has been a small amount of deterioration caused by the battery issue.
It would make sense this could happen as we are warned leaving battery at 0% for long periods causes deterioration. The bad BMS caused some of the cells to not charge, i.e. stuck at 0% thus I expect there is some deterioration in those cells.
I'm not too unhappy as vast majority of the lost range has come back, but seems there is a small long term impact.

 

[JodyS21]

I took all readings from cars display. Took total miles and divided by miles per KWh to find how many kWh the journey consumed.
I knew the 7% remaining because I plugged it in right after journey and that's what the display said.
40.5kwh capacity is not bad but it is advertised at 45khw and I believe 42.5 is meant to be available for use. Hence I think there has been a small amount of deterioration caused by the battery issue.
It would make sense this could happen as we are warned leaving battery at 0% for long periods causes deterioration. The bad BMS caused some of the cells to not charge, i.e. stuck at 0% thus I expect there is some deterioration in those cells.
I'm not too unhappy as vast majority of the lost range has come back, but seems there is a small long term impact.

Thats the first time anyone has said the bad bms caused some of the cells to not charge/stay at 0%
I think everyone else as far as we're aware has fully recovered after having the bad bms.

I would highly recommend getting a cheap (<£10) OBD2 bluetooth dongle and use app to check your SOH%, plus confirm all the cell voltages.

 

[Lovemyev]

Thats the first time anyone has said the bad bms caused some of the cells to not charge/stay at 0%

This is news to me also ?.
I was of the opinion that only SOME cells in the pack, had fallen below the value of other cells.
Numerous balancing cycles was required to bring up the value of lower cells in the pack.
You would have though that having a few certain cells at almost zero or extremely low, would cause other issues.
Of course @Jody21 is totally correct, a SOH check on the HV battery would flash up any cells that had extremely low readings.
The dealer would also be able to see these values of course.
Some owners who have been badly affected by the "Buggy" software, have actually witnessed the affect on their packs and now seen them recovered after the latest BMS was installed.
@Mike would you like to briefly explain what you have seen both pre and post BMS update please.
I do know you have facts and figures that supports the fact that the pack in your car is now back to normal.
Thank you in advance.