Post your MG ZS EV battery SOH data please

[JodyS21]

This morning I checked my SOH, it is disapointing
17.500 km
1 year old car
SOH 96,52%
Just to remaind I post my SOH 2 months ago and it was 99,56% and it have 14.600km. Since then it was mostlly fast charging but tis is crazy, even if I fast charge it isnt more than 1C off the battery. I found spec that says charge discharge 1C at 3500 cycles it should have more than 80% capacity remaining. Are those batterys that are in our cars so bad or Iam not realistic and it should be souch. On my previous ev cars I dint have possibillity to check this.
How is this SOH on other cars??

It is kinda worrying, but we just don't know what it'll end up like after 50k miles/80k km. Hopefully it is not a linear degradation, it's not supposed to be from what I've read, but one can't help but be concerned when we see the figures.
My cars SOH has done pretty much the same as yours, suddenly dropped at about the same mileage/kms.

 

[miko]

Is there any car with greater milage? 40.000 50.000 km/miles, what is their SOH?

 

[rpannell]

View attachment 4512

I'm going to try to pull together some data regarding battery State Of Health, we now have cars about that have done a reasonable mileage.

These are the bits that I think would be good to know:
SOH %
Mileage done
Car age (since registered)
Rought percentage of DC (Rapid) charges vs AC charges.
How many times do you think you've charged to 100%
GOM shown in Normal(3) after a 100% charge, with both trips reset (car started without brake pedal pressed/under no load) (this gives a good indication of SOH if you haven't got access to OBD2 data)

Mine, to start things off:
SOH 97.27%
10.5k miles
7 months old
5% Rapid charging (5 Rapids done, about 100 AC charges)
About 84 charges to 100%
GOM 159miles

SOH 94.84%
21,500 miles
22 months old
About 25% of miles done using rapids but only 10% of charges (as lots of small charges on non-rapid chargers)
Only charged to 100% if going on a long journey - say 18 times per year.
Usually charge is between 25-75%, charged on a granny.
GOM 154 miles (after full reset) in N

 

[Mark Holmes]

SOH 94.84%
21,500 miles
22 months old
About 25% of miles done using rapids but only 10% of charges (as lots of small charges on non-rapid chargers)
Only charged to 100% if going on a long journey - say 18 times per year.
Usually charge is between 25-75%, charged on a granny.
GOM 154 miles (after full reset) in N

That’s about the same as mine with 24500 miles

 

[rpannell]

That’s about the same as mine with 24500 miles

I suspect that most of the degradation is related to time rather than distance covered in that time, so most of the early cars will be around the same figure.
It does look as though most cars will have a 70-80% SOH at the end of their 7 year guarantee, assuming no catastrophic failure in the meantime.

 

[Johnberg51]

@JodyS21
Thank you very much Jody for posting this topic, I was looking a long time for SOH data from other MG users.
On the Dutch forums I also asked for this data and got it from about 4 users and everybody was having still 100% SOH. Even captain DIY in the warm Thailand is still having 100% after about 20.000 km.
My SoH dropped down to 99% after one year of driving with 9000 km and a few months later again to 98%. After updating OVMS I can read one digit more and at he moment it is 97,6% (car 16 months old).
I got the feeling I was the only one with this problems and was not so happy, but now I read your topic it seems I am not the only one.
I wonder how much difference there is from several users.
I love accelarating with the MG, powermeter to 100%, but I think the battery does not like this too much.
I also have a very high cell voltage delta (62 mV), in the garage they said up to 100 mV is OK, but what I read it should be not more then 20 mV.
Could this cause battery degradation?
I am interesting in the voltage value’s of other users, especial those with low SOH.
I always charge with 13A granny to 80%, 4 times and then one time to 100% for balancing. Also 100% when making a long trip. Rapid chargers only used 3 times. Battery 100% = 455V.
I have BMS 0823600P09 from the day I bought the car.
Balancing is starting at 99,8% and takes only 9 minutes, is this normal?
The milage after charging I can see in the OVMS app, this value is matching with eco-mode with hvac on, normal start.
With this settings, last summer it was 262 km in june with SOH still 100%.
At the moment it is going down, but this is also due to the colder weather.
When you look at this website 97,6% SOH is actually very normal after 16 months.
Nissan Leaf 2017 is about the same as my MG, but Kia Soul 2017 is much better.

Geotab - EV Battery Degradation

Geotab

storage.googleapis.com

A pity this site is not so complete, but after some time it will come.
OK, here some screenshots of my data.

 

[Kithmo]

My SOH is still 100%, but my cell imbalance is just over 40mV and has been since I first started checking it just over a year ago.
I think the 20mV imbalance figure is just what most people are reporting, not a recommendation. As long as your imbalance hasn't got, or doesn't get any worse, I don't think it's anything to worry about.

 

[Johnberg51]

As long as your imbalance hasn't got, or doesn't get any worse, I don't think it's anything to worry about.

On may 27 it was 54 mV, october 62 mV

 

[ARvanHAS]

SOH 99.8%
27.6k km / 17.1k miles
17 months old
15% Rapid charging
About 140 charges to 100%
GOM 236km / 146miles (N / HVAC on)

 

[JodyS21]

@JodyS21
Thank you very much Jody for posting this topic, I was looking a long time for SOH data from other MG users.
On the Dutch forums I also asked for this data and got it from about 4 users and everybody was having still 100% SOH. Even captain DIY in the warm Thailand is still having 100% after about 20.000 km.
My SoH dropped down to 99% after one year of driving with 9000 km and a few months later again to 98%. After updating OVMS I can read one digit more and at he moment it is 97,6% (car 16 months old).
I got the feeling I was the only one with this problems and was not so happy, but now I read your topic it seems I am not the only one.
I wonder how much difference there is from several users.
I love accelarating with the MG, powermeter to 100%, but I think the battery does not like this too much.
I also have a very high cell voltage delta (62 mV), in the garage they said up to 100 mV is OK, but what I read it should be not more then 20 mV.
Could this cause battery degradation?
I am interesting in the voltage value’s of other users, especial those with low SOH.
I always charge with 13A granny to 80%, 4 times and then one time to 100% for balancing. Also 100% when making a long trip. Rapid chargers only used 3 times. Battery 100% = 455V.
I have BMS 0823600P09 from the day I bought the car.
Balancing is starting at 99,8% and takes only 9 minutes, is this normal?
The milage after charging I can see in the OVMS app, this value is matching with eco-mode with hvac on, normal start.
With this settings, last summer it was 262 km in june with SOH still 100%.
At the moment it is going down, but this is also due to the colder weather.
When you look at this website 97,6% SOH is actually very normal after 16 months.
Nissan Leaf 2017 is about the same as my MG, but Kia Soul 2017 is much better.

Geotab - EV Battery Degradation

Geotab

storage.googleapis.com

A pity this site is not so complete, but after some time it will come.
OK, here some screenshots of my data.

View attachment 5596View attachment 5597
View attachment 5599

60mV imbalance does seem high given you're balancing it regularly.
9 minutes balancing time would mean it's not doing much if any balancing at all, given it takes something like an hour to balance 0.01V.
I'd guess it is to do with your BMS version, maybe you should consider getting it updated.
Complete guess here, but could it be that you have 1 individual cell that has lost a bit of health thus its low voltage & that's why the SOH has gone down a bit?

 

[Johnberg51]

60mV imbalance does seem high given you're balancing it regularly.
9 minutes balancing time would mean it's not doing much if any balancing at all, given it takes something like an hour to balance 0.01V.
I'd guess it is to do with your BMS version, maybe you should consider getting it updated.
Complete guess here, but could it be that you have 1 individual cell that has lost a bit of health thus its low voltage & that's why the SOH has gone down a bit?

Yes, I had the same thoughts, I know sombody who has a BMS update from september last year or so. And his balancing is taking almost four hours, which is extremely long again.
How long does your balancing take?
Which BMS update would be recommanded? The last one which is reducing the HV voltage to 449V. I think the battery would be happy with a lower voltage/SOC. Does this cost range?
When the battery is out of balance, should n’t you get a prompt of this on display in the car?
I don’t hope there is one bad individual cell.
BTW, the garage does not worry at all as long it not exceed 100 mV, I can’t believe this.

 

[JodyS21]

Yes, I had the same thoughts, I know sombody who has a BMS update from september last year or so. And his balancing is taking almost four hours, which is extremely long again.
How long does your balancing take?
Which BMS update would be recommanded? The last one which is reducing the HV voltage to 449V. I think the battery would be happy with a lower voltage/SOC. Does this cost range?
When the battery is out of balance, should n’t you get a prompt of this on display in the car?
I don’t hope there is one bad individual cell.
BTW, the garage does not worry at all as long it not exceed 100 mV, I can’t believe this.

I don't think we've ever ascertained exactly what the criteria is that triggers the car to warn to slow charge (balance).
The very latest BMS has been around for well over 6 months now, so I'd say it is a safe update. The voltage change does not affect the range as it "just" shifts the usable battery range (moves the top and bottom buffers).

Mine varies a lot with balancing time, it can be hours, sometimes it decides not to do any.

I do kinda understand why the garage doesn't worry unless it's over 100mV, it still provides a total battery well within its warranty. Also bear in mind that I doubt any garage have any knowledge/are allowed to take battery packs apart - that will be a specialist job/company and I imagine the car will be off the road for a long time if that ever occurs.

 

[Lovemyev]

And his balancing is taking almost four hours, which is extremely long again.

If this helps in any way at all, my ZS EV is about 22 months old and has covered 16,000 miles.
The car WAS running on the original factory software ( 455 - 456 ) volts until its first service after one year, then it received the latest BMS update ( 448 - 450 ) volts.
On the original software, it would take around about 45 mins to 1 hour to balance the pack.
When the BMS was applied, the first balance process had taken about 8 hours to complete !.
Then after a few charges, the balance time started to reduce each time.
Now a balance process will take roughly about 2 hours.
Is this because the BMS update has created more of a space / buffer at the upper end of the pack and has this increased the balancing time ?.
I have no idea TBH.
It has never returned to the one hour balance time that the original software had original taken.
This longer balancing time after the BMS update, does appear to be a common factor.
My predicted range after a full charge & balance, in normal mode and regen level 3 is now 155 miles.
It started reporting 163 miles of range when the car was first returned after the update.
But the predicted range appears to have reduced and settled down into a closer mileage given the age / mileage on the car.
A common factor here, appears to be that cars that have covered more miles, are reporting a little less predicted range now.
Cars that have covered very low mileages, appear to be reporting a constant predicted range of 163 ( new BMS ) and a 100% SOH.
Just for the record, our car has been charged for about 99.9% of its time, on our home on our 7 kw wall box.
It has only had two very small charges from a rapid unit.
I do not have any equipment to actually measure my true SOH.
But I am fairly sure the SOH is around the 95% mark ??????.

 

[Kithmo]

On may 27 it was 54 mV, october 62 mV

Just keep an eye on it.

 

[Kithmo]

FWIW For some strange reason mine has started taking less time to balance, only 10-30 minutes after full, so I have started unplugging it and plugging it back in now and it then goes on balancing for another 30-60 minutes.

 

[Coulomb]

On may 27 it was 54 mV, october 62 mV

The voltage versus SOC has a higher slope at very high cell voltages, so I think that means that you will generally see higher cell voltage deltas at 455V than at 450V.

But the older firmware seems not to try as hard to balance, or equivalently it seems to give up sooner. I would get the BMS firmware updated. The higher delta is going to cost you some range, and possibly less GOM (predicted range to empty) accuracy at the low end, where it's most important.

However, I don't believe it will have any real effect on battery longevity.

 

[BruceT]

This might be...... hell, no doubt IS a totally stupid question, but where do you get all this information from? I've never seen anything like any of these stats. It says in the handbook you get a warning if your pack needs balancing, but I've never seen it.

 

[Coulomb]

where do you get all this information from?

Most of it we get from apps that read CAN bus data from the car via the OBD2 port.

 

[Johnberg51]

Thank you all very much for the usefull information.
I think I gonna update my BMS now to the latest firmware (449V)
At first for the better balancing, but also because it is better for the longevity of the battery.
The old firmware charges to 455V which means 4,2V per cell.
The battery has 108 serial blocks, so 455 : 108 = 4,21V
4,2V is max charging cutoff voltage for Li-ion cells and not good for battery, at least if you want 80+ SoH after 500 charging cycles.
The new firmware charges to 4,16V per cell as you can see in the post of @rbpasapera here:

Post your battery SOH data please

4,16 x 108 = 449V and is about 95% SOC, much better for battery and increases the amount of charging cycles significantly.
I think this is the main reason why MG changed the voltage to 449V, just better for reaching the 7 years garantee.

 

[BruceT]

Most of it we get from apps that read CAN bus data from the car via the OBD2 port.

ok, SO not something available to everyone then. I thought I was missing something.