SOH and reduced GOM reading

[Jester27]

Morning all.
Just wanted to ask about battery SOH.
I picked up my car in April with 7100 miles on the clock and after using the Torque app to check everything I was happily running 100% SOH, 449 V and 163 miles after a charge and resetting the GOM.
Fast forward to today
10986 miles and just completed a full charge and balance.

I have been checking this regularly and have noticed the SOH is dropping quite a bit now since purchase.

I am still showing 449V after the charge but the GOM is now reading 158 miles after a reset.

The SOH in the torque app is also now 96.92%

This seems rather excessive in less than 4000 miles since purchase.

My charging regime is nothing excessive twice a week at home or work (7kw) and it always gets a balance.

Checking my cells also shows bank 4 has the greatest inconsistency across its cells when compared to all the other 8.

I am concerned that at this rate I am dropping nearly 1% every 12-1300 miles.

Is this normal and acceptable ?

If the battery is guaranteed for 80k miles.
By the time I get there it will have lost around 60% of its charge capacity
Which would induce a warranty claim as they quote less than 70% for repair/replacement.

It may be just one of those it hasn't moved much initially for the first 8000 miles or so and now will even out.

What is everyone else's experience.

Thanks

 

[Cocijo]

I’ve never achieved more than 455v and 160 predicted miles since new. I understand that battery degradation is not linear. Most packs will take a hit during the first 12 Months depending on the number of times cycled. What this should be I’m not sure anyone really knows at the moment. I think there’s loads to compare against with members on here which is probably the best measure.

 

[Electrifried]

What does SOH mean, I have heard of the acronym SOC (state of charge) but SOH is a new one to me?

 

[JodyS21]

That does sound rather concerning to be honest with you.
A lot of people on here have higher milage that you but not lost any SOH (or certainly not as much as you).
When was the car registered?
We don't know how the SOH is calculated, but age could be a factor, could it be yours is one of the very first cars produced/oldest around?

I did find and post something on here before I found out about SOH degradation curve, it was not linear - higher to start with and then much less, so it could be that it will calm down a lot and not appear to be so bad.

Maybe it is that particular cell that you mention that has a slight problem, all you can do is keep an eye on it really.
I can't imagine that you will get anything out of taking it into dealer to look at, they won't be interested!

 

[Cocijo]

What does SOH mean, I have heard of the acronym SOC (state of charge) but SOH is a new one to me?

State Of Health ? too many acronyms

 

[Cocijo]

This may be a silly question. If the fully charged voltage remains the same how can the state of health be reducing? ?

 

[JodyS21]

This may be a silly question. If the fully charged voltage remains the same how can the state of health be reducing? ?

It is a good thought, I had it myself when I first looked into SOH.
I don't think the battery capacity works like that though. It'll still have the same voltage range I believe but effectively the voltage will drop quicker as the capacity is less.

 

[MickH]

My understanding would be that state of charge is indeed the voltage and state of health the ability of the battery to deliver it’s full power.

 

[Cocijo]

Hmmmm. It’s an interesting topic. I think delivering full power and being able to maintain the capacity to deliver range are different. I think that packs that are obviously degraded can still deliver full power but their capacity to provide range is considerably reduced?

 

[MickH]

You’re right, it is interesting. My comment was based on my experience with the standard 12v car battery. When diagnosing non-start or slow cranking issues checking just voltage with a multimeter was pretty pointless as you could measure 12v but when applying a load test the battery would fail miserable. It would be nice to have a better understanding of the technology of these HV batteries and how the battery management all works. I don’t know if there are any MG technical sites available to Joe public.

 

[Cocijo]

Yes it would. I’m always sceptical when a reading says 100% health after a reasonable length of time. From day one every time batteries are cycled they degrade a little so there must be some degradation. I also think that smaller packs like the ZS are more prone to degradation as they generally have to work harder and get fully charged more frequently than larger packs. My iPhone battery health check shows 100% - I’ve no idea how that’s calculated either!

 

[Jester27]

My car was registered Jan 2020
But that doesn't reallyeam anything for actual age.
It could have been sat somewhere
The concern I have is that it was 100% SOH at 7100 miles when I picked it up but 4000 miles later it's dropped.
My range doesn't se to be affected and can easily get decent miles from a charge.

It could be one of those too much knowledge and worrying for nothing.
Though it was more apparent lately with the GOM resetting to 158 after a charge

 

[Cocijo]

If you can stick with it this is very informative…

 

[MickH]

Thanks for that Cocijo, some nice light reading for bedtime?

 

[Cocijo]

Yes. Defo get you off to nod asap

 

[MickH]

Yes. Defo get you off to nod asap

Well that certainly opened the eyes, but does nothing to aid the EV anxiety! The only thing that came out of this is that maybe I’ve gone electric too early? The video was very informative, but the summary of how to slow the degradation process was a little daunting. It seems that all you have to do is never run bellow 15%, never charge above 80%, don’t use rapid charging and the best one, always park in the shade. It’s a pity there was no context offered therefore there was no worst case or best case timescales, but it certainly makes you think. I collect my MG5 on Wednesday and I just hope MG (SAIC) - who in collaboration with CATL boast some interesting battery technology - consider offering some sort of battery referb or repair service, as replacement on a 5-10 year old car will be economically questionable. As someone approaching 70, I had hoped this car would see me out but it seems the battery definitely won’t ? The next question should I go ahead and collect my car??

 

[Kithmo]

Well that certainly opened the eyes, but does nothing to aid the EV anxiety! The only thing that came out of this is that maybe I’ve gone electric too early? The video was very informative, but the summary of how to slow the degradation process was a little daunting. It seems that all you have to do is never run bellow 15%, never charge above 80%, don’t use rapid charging and the best one, always park in the shade. It’s a pity there was no context offered therefore there was no worst case or best case timescales, but it certainly makes you think. I collect my MG5 on Wednesday and I just hope MG (SAIC) - who in collaboration with CATL boast some interesting battery technology - consider offering some sort of battery referb or repair service, as replacement on a 5-10 year old car will be economically questionable. As someone approaching 70, I had hoped this car would see me out but it seems the battery definitely won’t ? The next question should I go ahead and collect my car??

Remember the battery is not going to suddenly die, it'll have less range between charges as it gets older, for quite some time before it becomes unusable. The warranty covers 7 years down to 70% health so 70% of WLTP 163 miles, I'd expect 115 miles, decreasing as it gets older.

 

[Cocijo]

Well that certainly opened the eyes, but does nothing to aid the EV anxiety! The only thing that came out of this is that maybe I’ve gone electric too early? The video was very informative, but the summary of how to slow the degradation process was a little daunting. It seems that all you have to do is never run bellow 15%, never charge above 80%, don’t use rapid charging and the best one, always park in the shade. It’s a pity there was no context offered therefore there was no worst case or best case timescales, but it certainly makes you think. I collect my MG5 on Wednesday and I just hope MG (SAIC) - who in collaboration with CATL boast some interesting battery technology - consider offering some sort of battery referb or repair service, as replacement on a 5-10 year old car will be economically questionable. As someone approaching 70, I had hoped this car would see me out but it seems the battery definitely won’t ? The next question should I go ahead and collect my car??

I wouldn’t worry too much. Most EV battery packs in service throughout the world have far exceeded expectations on longevity. You can read too much into the maintenance side of things. I think just common sense and the battery will last a long time.

 

[Lovemyev]

What does SOH mean, I have heard of the acronym SOC (state of charge) but SOH is a new one to me?

SOH - Refers to the State Of Health of the HV Pack ?.

 

[Lovemyev]

Battery degradation is usually higher at the very start of a lithium ion life span, then it decreases after that first initial hit.
It is very easy to become totally paranoid about the SOH of your pack, it can become an obsession that will destroy the enjoyment of the car.
I guess this condition will concern you more, if when your bought the car, your usage case meant you intended to stretch the range of the car on a very regular basis over many years.
So after a few years, due to the decline in the range of the battery, you are struggling to make the same trips as you did when you first purchased the car.
If on the other hand, 95% of your usage pattern leaves the car with plenty of range remaining, then the degradation ( even if small ) is not going to be a issue.
If you are very dependent on achieving the max range of the car from the pack when new and do not intend to charge on the move, then I guess factoring in some degradation prior to purchasing the car is worth considering ?.
The HV battery has a 7 year warranty, if the charging infrastructure has not improved in that time, then all EV owners are likely to be in big trouble ?!.
It know it has been said many many times before, but it is not range anxiety we suffer from, it is charger anxiety ( the lack of ) that is the real issue here.
Larger HV packs size will not be a big deal, when the charging infrastructure is up to the job.
Lugging around large / heavy and expensive 100 kw packs around will become the exception to the rule I think.
Most people will feel comfortable with a car that can achieve a real world range of around 200+ miles and with the back up of a good / reliable charging infrastructure.