MG ZS EV MK2 - LFP (standard range) - Battery SOH Theory

[fred12345]

Another question I had. The car was advertised with OTA updates, it even has a menu for it . But unfortunately hasn't happened yet. Nor does the garage mention that there are any updates. Seems hard to believe given that I still have to manually reset the maintenance interval every 2months.
Mine Shows entertainment system version SWI17-17-29176-1300R19

Since the car connects to MG iSmart app, it could obviously receive OTA updates if MG sends them - but - if everything works, I would rather not risk update for something that's not really needed.
If you have to reset maintenance interval every 2 months, something is not right. When was your last service? It's supposed to be every year.

 

[Peter WA]

Driven 200km and dropped 0,02%. If its a real measurement probably not informative given battery is at 42% SOC.

Yeah, not a real measurement, it could never be that precise. And nothing to do with distance driven. Just 0.01% every day.

Not sure what might have caused the 'slowdown' you saw. I've got one single 'jump' in the otherwise linear decline. About 1 week after the so far only software update I got at the dealership.

 

[fred12345]

So, SoH on mine, second hand March 2022 reg Mk2 standard range Trophy with 45,000 miles (70,00km) on the clock is this:
19.04.24 92.32%
20.04.24. 92.31%
12.05.24. 92.1%
22.06.24. 91.67%
20.07.24. 91.88%

Measured using Car Scanner app. From April, only charged on granny charger apart from one fast charge top-up of about 30% charge.
If anyone can make any sense of it all, let me know. Hope it helps figuring out how it all works...
So far (? fingers crossed) everything works well...

 

[Peter WA]

19.04.24 92.32%
20.04.24. 92.31%
12.05.24. 92.1%
22.06.24. 91.67%
20.07.24. 91.88%

The first measurements, up to 22.06.24, look spot on with the 0.01% decline every day. Countdown timer, not measured.

Then there's a jump of about 0.4% (should have gone down to 91.49) on 20.07.24.

I'm curious what triggered that. Anything different with the car between June and July? A service maybe?

 

[fred12345]

Anything different with the car between June and July? A service maybe?

nothing at all. driven on mixture of roads and speeds, charged mainly 30% top-ups with one up to 100%, all slow charge (but done that in between other measurements too) so no explanation really ...

will have it serviced in August so we'll see what happens then...

 

[zetro]

Hi There,

I've been following your thread here as I have been looking to purchasing a new ZS EV MKII. Unfortunately they stopped shipping the Excite model into Australia after Sept23. But that aside, I have been asking the dealers for SOH battery reports when the deal has been getting serious, they are very much not forth coming with this data. I walked away from one deal back in Jan24, the vehicle was a Demonstrator Excite and it was 10 months old with a SOH of 96%. Currently we are looking at new Excite we are at the signing stage, as the vehicle has a build date of Mar23 it is New never registered, long term storage and technically 16 months old. They sent us the SOH report pdf from the workshop which came back as 95%. We are using this information to attempt to reduce the price or we will walk again but it is a worry for an unused vehicle.

Just food for thought, trying to be a more informed new EV buyer

 

[Peter WA]

but it is a worry for an unused vehicle.

Just food for thought, trying to be a more informed new EV buyer

I hope you didn't walk away from the deal in January only because of the SOH reading you were given. That would be a shame, knowing what we know now: that the value reported by the car is just a number with little or no meaning.

Regarding the one you're considering now: the only thing you can be pretty sure of is that it would be a big coincidence if the actual SOH was 95%. Just like you looking at a broken clock at the very moment when it shows the correct time.

It could be anything really. If the car has been stored at a state of charge that is intended for storage (from my reading somewhere between 50% and 70% is the safest range), it could still be almost 100% SOH. If it has been stored at 100% SOC that could have done considerably more damage than expressed in the 95% reported SOH.

The good thing, no matter what you decide: you should get the full 7 years new car warranty. And knowing what you know about the reported SOH, if you are very unhappy with how the battery performs, you can ask the right questions to get help and not be fobbed off.

Best of luck!

 

[natasha y]

Just food for thought, trying to be a more informed new EV buyer

fellow perth dweller here. I bought a ‘new’ feb23 manufactured ZS excite in jan 24 for a discounted price. I didn’t have the knowledge to ask for SoH at the time. However this thread piqued my interest so I got myself a dongle and car scanner and tested the SoH today. 95% at 1.4yrs looks very similar to the linear degradation proposed by the OP, albeit a bit ‘better’ (calc 94.6%)

I have only used DC at 50kW once to get to 60%. Most other charging has been <4kW from solar with one 3p 11kW. Generally max charge to 80%- 90%. Balance charged once in 6 mths. 3800km mostly around town.

PS: Love the car for the $$, especially with the govt rebate. V2L is beaut. I have used it to keep the fridges going during a power outage already.

 

[DB Go Rex]

Hi There,

I've been following your thread here as I have been looking to purchasing a new ZS EV MKII. Unfortunately they stopped shipping the Excite model into Australia after Sept23. But that aside, I have been asking the dealers for SOH battery reports when the deal has been getting serious, they are very much not forth coming with this data. I walked away from one deal back in Jan24, the vehicle was a Demonstrator Excite and it was 10 months old with a SOH of 96%. Currently we are looking at new Excite we are at the signing stage, as the vehicle has a build date of Mar23 it is New never registered, long term storage and technically 16 months old. They sent us the SOH report pdf from the workshop which came back as 95%. We are using this information to attempt to reduce the price or we will walk again but it is a worry for an unused vehicle.

Just food for thought, trying to be a more informed new EV buyer

What have we come to when we need to get what is effectively a check you would have done on a used car, on a new car?

 

[natasha y]

I suppose the only real way of testing SoH is to discharge it to zero and then measure how much you can put back in it using a coulomb meter shunt and comparing with the original specified capacity. Perhaps the BMS has an integration tool in it but we can’t access it other than the 100% range estimate.

 

[fred12345]

We are using this information to attempt to reduce the price or we will walk again but it is a worry for an unused vehicle.

Yes I would be worried too, luckily I didn't know anything about SoH when I bought mine... I don't pay much attention now, when it comes down to 80%, I'll trade it in ...

If I were your dealer, I would offer to sell it at 95% of RRP on account of 95% SoH ...? But seriously, yes give it a go ... Good luck!

 

[Bam Bam]

Hi There,

I've been following your thread here as I have been looking to purchasing a new ZS EV MKII. Unfortunately they stopped shipping the Excite model into Australia after Sept23. But that aside, I have been asking the dealers for SOH battery reports when the deal has been getting serious, they are very much not forth coming with this data. I walked away from one deal back in Jan24, the vehicle was a Demonstrator Excite and it was 10 months old with a SOH of 96%. Currently we are looking at new Excite we are at the signing stage, as the vehicle has a build date of Mar23 it is New never registered, long term storage and technically 16 months old. They sent us the SOH report pdf from the workshop which came back as 95%. We are using this information to attempt to reduce the price or we will walk again but it is a worry for an unused vehicle.

Just food for thought, trying to be a more informed new EV buyer

I don't know, 95% or 96% doesn't sound too bad because I think that the steepest drop is in the early days of the battery.

Ours was listed at 94% at the first annual service, which was disappointing at the time, but looking at this thread perhaps is about normal.

 

[zetro]

What have we come to when we need to get what is effectively a check you would have done on a used car, on a new car?

I'd be asking lots of questions if any vehicle I'm purchasing has been sitting for 16 months. Now if the vehicle was fresh 2 months old from the factory or is secondhand used as a daily that is a totally different scenario. Why deal with issues in warranty when due diligence questions should be asked before you hand over your cash.

I suppose the only real way of testing SoH is to discharge it to zero and then measure how much you can put back in it using a coulomb meter shunt and comparing with the original specified capacity. Perhaps the BMS has an integration tool in it but we can’t access it other than the 100% range estimate.

yeah I know that's not what happened in this last situation. As they had no easy/quick way to discharge the battery to force a full charge cycle, but they did provide a full battery report SOH, SOC and voltage levels on every cell pack(min~max). So I know they at least attempted to top end balance the battery from what ever level it was at. But it does go to show that its not just charge cycle but cell pack age that is a factor in SOH.

I just thought I'd share my finding on a aged non used one as a good bench mark for the community.

I'd also love to know what scanning app your having luck with and what EVSE you found appropriate for our weather conditions

 

[natasha y]

yeah I know that's not what happened in this last situation. As they had no easy/quick way to discharge the battery to force a full charge cycle, but they did provide a full battery report SOH, SOC and voltage levels on every cell pack(min~max). So I know they at least attempted to top end balance the battery from what ever level it was at. But it does go to show that its not just charge cycle but cell pack age that is a factor in SOH.

I just thought I'd share my finding on a aged non used one as a good bench mark for the community.

I'd also love to know what scanning app your having luck with and what EVSE you found appropriate for our weather conditions

Hi There,

I've been following your thread here as I have been looking to purchasing a new ZS EV MKII. Unfortunately they stopped shipping the Excite model into Australia after Sept23. But that aside, I have been asking the dealers for SOH battery reports when the deal has been getting serious, they are very much not forth coming with this data. I walked away from one deal back in Jan24, the vehicle was a Demonstrator Excite and it was 10 months old with a SOH of 96%. Currently we are looking at new Excite we are at the signing stage, as the vehicle has a build date of Mar23 it is New never registered, long term storage and technically 16 months old. They sent us the SOH report pdf from the workshop which came back as 95%. We are using this information to attempt to reduce the price or we will walk again but it is a worry for an unused vehicle.

Just food for thought, trying to be a more informed new EV buyer

This is pretty much the same as mine. Feb 23 build.

 

[MeGatron4]

I've had my MG4 Excite for less than 4 months and the range on a full charge has dropped 1km when fully charged.. Am I to lose 3km a year?? Or is this a calculation error?

 

[fred12345]

I've had my MG4 Excite for less than 4 months and the range on a full charge has dropped 1km when fully charged.. Am I to lose 3km a year?? Or is this a calculation error?

range you see goes up and down depending on outside temperature and driving style. What people look at is battery state of health SoH - don't worry about it too much and enjoy the drive ...
search for ODB2 on this forum and you'll see how to check your SoH but again, don't let it take over your life ... ?

 

[Lovemyev]

The next post cast will be covering the subject of charging and battery health condition etc.

MG EVs Podcast Tuesday 20 August 2024 @ 7:30pm BST

Tuesday 20th August 2024 at 7:30pm. In this podcast we discuss the highest voted topic in our poll. https://www.mgevs.com/threads/what-topic-should-we-cover-in-our-next-podcast.17441/ Battery management techniques We plan to cover the following discussion points: Different battery chemistries...

www.mgevs.com

 

[natasha y]

Update 30 days after my initial SOH interrogation:
95.02 to 94.71

Near as dammit to 0.3% drop but still maxing out at 320km range as it was in Jan. 4000km charged by solar AC 99%. Cells balanced once only. DC charged only once. Interesting that the system appears to show the DC charge taper. 77.6kW at 72.1% and 32.6kW at 91.8%

 

[fred12345]

So, SoH on mine, second hand March 2022 reg Mk2 standard range Trophy with 45,000 miles (70,00km) on the clock is this:
19.04.24 92.32%
20.04.24. 92.31%
12.05.24. 92.1%
22.06.24. 91.67%
20.07.24. 91.88%

Measured using Car Scanner app. From April, only charged on granny charger apart from one fast charge top-up of about 30% charge.
If anyone can make any sense of it all, let me know. Hope it helps figuring out how it all works...
So far (? fingers crossed) everything works well...

To add SoH after 45,000 miles service in August + 2 fast charges of about 15 min each:

10.09.24. 91.85%

 

[Peter WA]

To add SoH after 45,000 miles service in August + 2 fast charges of about 15 min each:

10.09.24. 91.85%

Good to see the programmed decline of 0.01% each day has stopped.

A bit surprising to see that it happened before your service already. Did you get a software update at any time?

My 2 year service is in about 6 weeks time. I'll see whether that makes any difference.