MassDeduction
Posts: 92
Joined: Tue Feb 25, 2020 3:24 pm

20k km and no SOH reading yet

Wed Sep 15, 2021 2:34 pm

In another part of this forum, it was stated:

EVDee wrote:Biggest factor at play: you need the battery to recalibrate itself vs giving you old & outdated data.

Basically:
- the temperature outside needs to be above 10C
- the battery needs to be fully charged then discharged to 10-15%
- then the battery needs to be fully charged again without interruption
- the battery recalibration will occur

Otherwise taking a reading will be worthless as its just the value from the last calibration which was likely before it sat and degraded.

Best of luck!


I'm replying here to stay on topic.

So if I read this comment correctly, if the SOC is never brought below 20% it will never give you a SOH reading? I have a Soul EV 2021 with over 20k km on it that has never been charged above 85% since being driven off the lot, or drained any lower than 28%. In Soul EV Spy it just says no info yet for SOH, which makes sense if I'm reading the above comment correctly. Sounds like it'll keep saying that until it's drained below 20% and charged back up to 100%, if so. Can anyone confirm?

IanL
Posts: 219
Joined: Tue Feb 18, 2020 12:57 pm
Location: Jersey, English Channel Islands

Re: 20k km and no SOH reading yet

Thu Sep 16, 2021 6:06 am

If you are in this situation, it is possible to calculate the SOH.

After charging, reset the m/kWh (shows "--" when reset). Note the mileage and the battery %age if not 100%. At the next charge note the mileage and the battery %age before charging commences and note the m/kWh. Divide the difference in mileages by the m/kWh to get the kWh consumed. Divide this by (difference in %ages x 0.01, i.e. a decimal fraction). This gives the kWh capacity at 100% charge. Divide that by 27. 30, 39.2, 64 or other value, depending on the nominal battery size, and multiply by 100 to get SOH.

I have tested the method against Spy, and it gives close agreement.

[Edited to cover larger batteries in Gen2 models]
Last edited by IanL on Wed Oct 13, 2021 11:57 pm, edited 2 times in total.

MassDeduction
Posts: 92
Joined: Tue Feb 25, 2020 3:24 pm

Re: 20k km and no SOH reading yet

Tue Oct 12, 2021 4:16 pm

IanL wrote:If you are in this situation, it is possible to calculate the SOH.

After charging, reset the m/kWh (shows "--" when reset). Note the mileage and the battery %age if not 100%. At the next charge note the mileage and the battery %age before charging commences and note the m/kWh. Divide the difference in mileages by the m/kWh to get the kWh consumed. Divide this by (difference in %ages x 0.01, i.e. a decimal fraction). This gives the kWh capacity at 100% charge. Divide that by 27 or 30, depending on battery size, and multiply by 100 to get SOH.

I have tested the method against Spy, and it gives close agreement.

Thank you for the detailed reply! I note you say divide by 27 or 30, but I posted this in the 2020+ forum and as such we're talking either a 39.2 or a 64 kWh battery pack. Would the same procedure likely be just as valid for the newer Soul EVs?

IanL
Posts: 219
Joined: Tue Feb 18, 2020 12:57 pm
Location: Jersey, English Channel Islands

Re: 20k km and no SOH reading yet

Wed Oct 13, 2021 12:19 am

Yes, it would, as it is just expressing the actual battery capacity as a percentage of the nominal capacity, whatever that is. I have edited the original post to cover that point.

On a separate issue raised by your usage, it is frequently stated that a 100% charge should be occasionally be performed to balance the battery cells. So what does Spy show about the balance (or otherwise) of yours? What is the difference between the highest and lowest cell voltage? It would be valuable to know whether the way you operate your battery is bad for cell balance, or otherwise.

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