Post your MG ZS EV battery SOH data please

In my case, the SOH was at 100% till around 26,000 kms and 2 years. Then it started dropping rapidly by around 1% per 1k kms or each month. Now at 30k kms, it is 95.6%. I am really worried about this rapid drop. Voltage difference is 0.018V.
 
Lobogris said:
In my case, the SOH was at 100% till around 26,000 kms and 2 years. Then it started dropping rapidly by around 1% per 1k kms or each month. Now at 30k kms, it is 95.6%. I am really worried about this rapid drop. Voltage difference is 0.018V.
Click to expand...
Maybe it doesn't start showing a drop initially due to reading the top buffer ?
 
@JodyS21

My SOH started dropping below 100% only quite recently, I went back to this thread to learn more.

Looks like timing (mileage) of the first drop varies, but then it quite quickly approaches ~95%. I haven't seen anyone's post that is significantly below. How did your car go in the last 6 months since you first posted this?
 
Peter WA said:
And another drop: 20298 km, SOH 96.89%
Click to expand...
Hi Peter, I know this dropdowns are very frustrating.
Mine also had a dropdown again to 96,37% @ 15968 Km and 19 months of use. Typical is that it every time drops with exact 0,20%, maybe my OVMS module is calculating same this.
I treated my battery like a baby all the time, everytime charged to 80% and 1 to 4 to 100% for balancing.
I know another user who did exactly the same and same milage and age and is still having 99,6% SoH.
I wonder why some people still have excellent SoH and other don’t.
I know the main factor is high temperatures and charging with high currents, but that is not the case here.
I hope the degradation wil get more stable in time, I read that from other EV users.
Maybe it could help to get the BMS software from january 2021 which is having more top protection buffer for the cells.
The basic BMS is charging to 4,22 V per cell which is much too high.
This means charging to the limit what li-ion can handle.
The latest BMS sotware is charging the HV battery to 449V instead of 455V
That is 449 : 108. = 4,15V per cell which is much better for the battery.
But why do I still have trouble then, I charge to 80% which results in 436V HV voltage.:(
BTW how many range you have when charged to 100% SoC with an average temperatur of 20° C?
Just in ECO mode with hvac on.
When I bought the car this was ca. 260 Km.
 
Johnberg51 said:
Maybe it could help to get the BMS software from january 2021 which is having more top protection buffer for the cells.
Click to expand...
My previous Gen1 ZS EV ran on the factory software for about 12 months, then it got updated to the Jan15th 2021 BMS update.
At just over two years old and almost 20,000 miles, the car would hit 153 miles of range in normal mode and Regen level 3.
This was after a full charge and balance and everything turned off in the car.
99.9% of our charging needs, where performed at home on our wall box.
I estimate that the SOH of the HV battery was sitting at around 94% ( ish ).
 
When they say 72 KWh capacity, 68 KWh usable range, this is not only to cover the fact that 0% in reality 5% because the battery is not very happy about being fully discharged.

They probably also reserve a bit for the top, to keep the SOH at 100% for longer when the car is new.

This is why it does not drop in the first months / year, and when it does, it suddenly drops a bit every 1000 miles.
 
hmadsen said:
When they say 72 KWh capacity, 68 KWh usable range, this is not only to cover the fact that 0% in reality 5% because the battery is not very happy about being fully discharged.

They probably also reserve a bit for the top, to keep the SOH at 100% for longer when the car is new.

This is why it does not drop in the first months / year, and when it does, it suddenly drops a bit every 1000 miles.
Click to expand...
This is completely true, but we have to remember that when the Jan 15th 2021 update was released, it increased the size of the top buffer ( over the original factory software ) at the head of the pack anyway.
You would therefore think that the reduction in the predicted milage / range would be slower to decrease in the cars running on the latest BMS update ?.
All manufactures report a slightly reduced size of the battery pack and build in a slightly larger upper buffer to the pack.
They know the HV battery will disclose battery degradation quicker when new, but will be lower in the subsequent years.
So, in order to avoid blind panic to new EV owners, they aim to conceal this initial degradation.
 
Excusive Bought April 2020
26000 miles @ 94.08 SOH
Fully charged @ 92.7%
Max voltage 448.75
Max Cell Voltage 4.162
Min Cell voltage 4.148
Battery Temp 7c

Car is fully charged overnight on local 7kw for around 9-10h @ least twice a week & a 4-5h top up charge once a week.
Under 20 Rapid charges since bought if that & maxed out @ around 90%.
Never charged on the Granny Charger.

Car had Comfort Update as well as the charging with door open update & HV fuse update.
Never had the major BMS Issue or update.
Car has been great overall aside from minor interior niggles & poor quality driver seat cover.
 
I am seeing a pattern now of slight battery degradation across both my original Gen1 ZS EV and other owners with similar mileage covered and age of the car.
My previous ZS EV was just over 2 years old and covered almost 20,000 miles.
Almost exclusively charged at home from our wall box.
The car never suffered from the “Buggy” software, but had the Jan15th 21 BMS update.
Comfort 2 update also.
Our range after a full charge and balance and in normal mode was a constant 153 miles.
I estimate our SOH to be very similar to yours.
 
No degradation yet on the factory BMS at 20 months old and 4k miles.
100% SOH
Fully charged:
97% SOC
456.25V
151 miles GOM (not reset trips)
Cell max = 4.231V
Cell min = 4.183V
(imbalance = 48mV)
I'm hoping the GOM gets higher later when the weather is warmer more often.
I got a reading of163 miles in the Summer and 158 a couple of months ago, now dropped to 151.
 
Kithmo said:
No degradation yet on the factory BMS at 20 months old and 4k miles.
100% SOH
Fully charged:
97% SOC
456.25V
151 miles GOM (not reset trips)
Cell max = 4.231V
Cell min = 4.183V
(imbalance = 48mV)
I'm hoping the GOM gets higher later when the weather is warmer more often.
I got a reading of163 miles in the Summer and 158 a couple of months ago, now dropped to 151.
Click to expand...
The low mileage is likely to support the higher SOH of the battery.
The more mileage covered, means more charging sessions.
I think the age of the car has very little impact on the SOH of the HV battery.
A relative has a Gen1 ZS EV that is about 18 months old.
He is a low usage case with only 6,000 miles covered.
His SOH is likely to be 100% also.
 
SOH = 93.55%
27 months old, 27,000 miles
Probably around 40 rapid charges during its life
approx once per month charged to 100%, the rest of the time to around 80%
 
Johnberg51 said:
Hi Peter, I know this dropdowns are very frustrating.
Mine also had a dropdown again to 96,37% @ 15968 Km and 19 months of use. Typical is that it every time drops with exact 0,20%, maybe my OVMS module is calculating same this.
I treated my battery like a baby all the time, everytime charged to 80% and 1 to 4 to 100% for balancing.
I know another user who did exactly the same and same milage and age and is still having 99,6% SoH.
I wonder why some people still have excellent SoH and other don’t.
I know the main factor is high temperatures and charging with high currents, but that is not the case here.
I hope the degradation wil get more stable in time, I read that from other EV users.
Maybe it could help to get the BMS software from january 2021 which is having more top protection buffer for the cells.
The basic BMS is charging to 4,22 V per cell which is much too high.
This means charging to the limit what li-ion can handle.
The latest BMS sotware is charging the HV battery to 449V instead of 455V
That is 449 : 108. = 4,15V per cell which is much better for the battery.
But why do I still have trouble then, I charge to 80% which results in 436V HV voltage.:(
BTW how many range you have when charged to 100% SoC with an average temperatur of 20° C?
Just in ECO mode with hvac on.
When I bought the car this was ca. 260 Km.
Click to expand...
I know battery health is definitely affected by unfavourable charging regiment etc, but I think luck also plays a big part in battery health - no battery cells are ever really identical, could have a pack with some above average cells or a pack with some below average cells…
 
JodyS21 said:
I know battery health is definitely affected by unfavourable charging regiment etc, but I think luck also plays a big part in battery health - no battery cells are ever really identical, could have a pack with some above average cells or a pack with some below average cells…
Click to expand...
I seem to have a pack with one high cell.
The high cell (MU04) reads 4.23V, the rest are all 4.18-4.19V. :confused:
 
Kithmo said:
I seem to have a pack with one high cell.
The high cell (MU04) reads 4.23V, the rest are all 4.18-4.19V. :confused:
Click to expand...
Is this Vmin - Vmax from one of the 9 CMU’s?
You have the BMS software which reduces HV voltage to 449V instead of 455V?
4,23 V is based on a 455 V battery pack (455 : 108)
This should getting lower after equalizing.
BTW 50 mV cell difference is nothing to worry about, MG claims 100 mV is allowed.
 
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