SOH @ 86.7% at second service

[inspectorgadget9999]

Should I be worried?

2nd gen, standard range, 20k mileage.

I rarely fast charge, and don't top up daily.

Looking around here, everyone's seems to be in the low to mid 90s at a similar time/mileage.

 

[Whiskery]

Same model as yours, if I remember correctly, at the second service, 45000 miles, mine was at 88%. I charge almost daily and do often use Tesla chargers out on the road. I'm not sweating it.

 

[Susanna]

I have a standard range - my HV battery SOH was at 93% at second service last November. I have only used a rapid twice, and charge on average once a week at home. Mileage is now approximately 11500 miles.

 

[OriginalBigAl]

Same model as yours, if I remember correctly, at the second service, 45000 miles, mine was at 88%. I charge almost daily and do often use Tesla chargers out on the road. I'm not sweating it.

Interesting, a 12% loss, have you noticed a corresponding loss in total range ( both guessometer and actual ) when charging to 100% as from new?

 

[Coulomb]

Interesting, a 12% loss,

That's if the service report can be trusted. I would think so, but I'd be sorely tempted to check that figure with an OBD-II dongle and app.

It might also be that the BMS is overly pessimistic in winter, and a chunk of that reported loss may disappear in summer.

 

[mj224]

My 4 year old ZS EV, 1st gen, is down to 90% after 38,000 miles. Dealer says to balance the battery using the granny charger??

Latest Gom indicates about a 130 mile range at these winter temperatures, so I guess that's good enough for me.

I will have to see what the summer brings..

 

[hmadsen]

As far as i have read, the battery degradation is biggest in the first part of the battery's life.

So in the beginning it will lose more % than later on, this unfortunately makes it seem like the battery is getting worse a lot, but it should taper off.

I also read that some manufacturers reserve a bit of capacity to combat this.

Most cars have a nominal and a usable figure, this is to ensure the battery is not really ever charged to 100% when the GOM reads 100% and not at 0% when the GOM says 0%, but if they reserve a bit "extra", say 1kWh, they might be able to "release" this as the battery degrades. This is done to "mask" the degradation as it is, more in the beginning.

So i would guess, since the ZS EV reports a SoH that is lower than expected for a vehicle of that age and miles driven that the figure you get is either

1. Because you get real degradation, without the extra energy having been factored in.
2. The ZS EV does not have any built in "spare" energy to release.

That being said, 90% after 4 years does not seem THAT far off of what one could reasonably expect.

But at the end of the day, the degradation is the sum of how the battery was "treated":

1. How often was it charged to 100%
2. How often was it driven to near 0%
3. How often was it charged at a DC fast charger
4. How is the car driven, lead foot makes current drawn larger.
5. Often pulling something heavy on the trailer hitch (Not really relevant here though)

 

[Whiskery]

Interesting, a 12% loss, have you noticed a corresponding loss in total range ( both guessometer and actual ) when charging to 100% as from new?

Yes however it is marginal and nothing that would make my jaw drop. I was quite surprised though when I saw the report after the service.
What can I put it down to? Not sure but I do charge at home at least 5 times a week and always to 100% (but that's OK for the SR model apparently).
At least twice a week the remaining charge is around 18% but rarely lower than that.
DC fast chargers - I usually use Tesla chargers on the road but not more than once a week.
I do have a rather heavy right foot which doesn't help the range and I do also use the heater unreservedly.

 

[OriginalBigAl]

The reliability of measuring SOH is one that's going to confound us all ( all EVs ) for a long while to come. It appears to have a variability week to week if not day to day and so depends on which day it was performed and also on the accuracy and variability of the different measuring devices. To find a long range average would need weekly checks on the same equipment , not many , if any of us are going to do that. Touch wood I have not heard of anyone testing MGs 70% rule and guarantee, as of yet, (early days ) I think they are pretty safe on that one as a generality , unless something goes wrong with individual modules or cells which are repairable and measured by different parameters.
I still think there may be a mathematical way of guessing SOH by battery capacity , amount of charge taken in , range achieved by normal driving all averaged out over a year on year basis even allowing for the initial degradation. I'm certainly not going to do a daily check and spreadsheet although some might be tempted, but more of , I'll bear that in mind and try to remember ( subject to failure ) and general gut feeling ( likewise ) . Proving the concept might be the problem.