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

Peter WA

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but I think you right the drop happens even if car doesn't move.

Yes, and drops of 0.01% are well below what it could reliably measure. For the Mk1 ZS EV, once it started dropping at all after almost 1 year, the smallest I've seen was 0.12%.
 

lusitano

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So I just had a look at the document that came with my car, "Complete vehicles certificate of conformity" date or manufacturer of the vehicle is 10/30/21.

And I just checked battery today and it is 96.53%
 

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N2STY

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Wow it makes it look like LFP really suck my MNC with 5300 miles (8529km) is still 100%
 

Peter WA

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Wow it makes it look like LFP really suck my MNC with 5300 miles (8529km) is still 100%
"Make it look" are the operational words, when if fact it is the opposite. Your software lies to you when it still gives 100%, ours lies to us when it shows SOH drop every day.

I guess we need to bring this issue to MG's attention, so they can fix their software. Any chance you could have a word with them @Miles Roberts CG ?

@lusitano Your car doesn't have a sticker like this on the door frame?

October sounds like very long before you got it. Is that really the date your car rolled off the assembly line, or could that be the date the type was approved?
 

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lusitano

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@lusitano Your car doesn't have a sticker like this on the door frame?

October sounds like very long before you got it. Is that really the date your car rolled off the assembly line, or could that be the date the type was approved?
Mine is not like yours, I've removed my vin and identifier.
 

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BadGolf

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Only just saw your attachment. The measured values line up perfectly with my prediction: 22/12/23 to 15/1/23 are 24 days. Calculated decline in SOH: 24 * 0.0104% = 0.25%. Actual decline in SOH: 96.82% - 96.57% = 0.25%.

I assume you set the day you go the car to 100%, but didn't actually check SOH back then?

My calculation would go: 96.57% is a loss of 3.43%, equal to 330 days of linear decline. I'd put the production day of you battery pack at 19/02/2022.

Do you have a sticker on the driver's side door of your car, with year and month on it? That's when it rolled out of the factory. Battery pack would have been made some days or weeks or even months before that.

@MoDolph Edited - took a little to understand that chart. So that's looking at decline in capacity for a battery stored at a given SOC. Great data, certainly supports my argument that even LFP should not be routinely charged to 100%. Surprised to see how well it supposedly worked being stored at very low SOCs, that's contrary to data I had seen before that saw quite some damage caused by SOC below 20%.

I agree, this will be interesting, hoping that a few people have data. @lusitano posted some data, and it seems to align very well with my predictions, despite taking place at a very different SOH, their car is already below 96%, while my analysis was around 99%.
Assuming I have my ZS much longer, being in Aus, what OBD / Software combo are you using?
 

Peter WA

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Assuming I have my ZS much longer, being in Aus, what OBD / Software combo are you using?
If you have had yours longer it would be the Mk1, previous model with NMC battery. This discussion thread would not apply.

You can still read out information the same way.
For occasional use: ELM327 OBDII dongle that connects via Bluetooth with the eZS Android app
For constant monitoring: OVMS

Dongles are cheap on eBay, i.e.: Bluetooth OBD2 ELM327 Car Scanner IOS & Android Diagnostic Auto Scan Tool OBDII | eBay
Same at car stores, or from Jaycar will cost multiple times the price.

This is todays update, so far.
View attachment 14727

Like clockwork it ticks down in a straight line. 0.0104% a day. 3.8% a year.
 
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BadGolf

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If you have had yours longer it would be the Mk1, previous model with NMC battery. This discussion thread would not apply.

You can still read out information the same way.
For occasional use: ELM327 OBDII dongle that connects via Bluetooth with the eZS Android app
For constant monitoring: OVMS

Dongles are cheap on eBay, i.e.: Bluetooth OBD2 ELM327 Car Scanner IOS & Android Diagnostic Auto Scan Tool OBDII | eBay
Same at car stores, or from Jaycar will cost multiple times the price.
Hi, what I meant is if I kept the ZS much longer - if you look through the menagerie of issues plaguing the ZS I picked up at the beginning of this year, it is looking like the car may become a reject. The car itself was manufactured September 22.
 
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