MassDeduction
Posts: 118
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EVDee wrote:Biggest factor at play: you need the battery to recalibrate itself vs giving you old & outdated data.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: 267
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: 118
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: 267
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.

MassDeduction
Posts: 118
Joined: Tue Feb 25, 2020 3:24 pm

Re: 20k km and no SOH reading yet

Wed Dec 15, 2021 7:19 pm

IanL wrote: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.

I'm happy to update periodically. So far with one year and over 20k km of use, the numbers I'm getting via SoulEV Spy suggest it doesn't need a balancing charge yet. Despite a year of use, it's never once been charged to 100%. Only on two occasions has it been charged to 90%. A few occasions for 80% (once to 85%), and several occasions to 70%. But the overwhelming number of times, it's charged to only 60%. It has only once ever been DC charged, and that was just about a half hour, and not up to a particularly high charge level. The car is also consistently driven very conservatively, so the battery pack is rarely being drained especially quickly.

TLDR; it's AC charged, usually only to 60% (and never to 100%), and driven conservatively.

After charging to 90%, and then letting it sit for 90 minutes, the display then read 92%. I noticed one other instance of it being charged to 50%, and then after 90+ minutes of settling the display read 55% (it had been unusually low, like 32% or so, before commencing that charge I think). I've seen this on my e-bike as well, and I think it's a natural process of the cells providing a more accurate reading after some settling/cooling down. An effort is made to let the car sit for 90+ minutes before every recharge, to allow for the cells to cool/settle and give more accurate BMS readings before charging starts.

Anyway, after that charge to 90% and letting everything cool/settle, every single cell in the pack had the exact same voltage. 4.06v I think? I didn't write it down, but it was black across the board (the grid is colour-coded with cells that are higher one colour, and cells that are lower another colour, but every single one was black indicating no variation across the board, meaning any variation was so minor that it was effectively hidden by them all rounding off to the same number). So I take that to mean that even a year of conservative charging and driving wasn't enough to require a rebalancing charge.

IanL
Posts: 267
Joined: Tue Feb 18, 2020 12:57 pm
Location: Jersey, English Channel Islands

Re: 20k km and no SOH reading yet

Thu Dec 16, 2021 1:48 am

I've recently checked mine, after several months of not charging above 80% (using the timer, as the 80% cut-off facility was deleted from the 30 kWh models - grrrr), and my experience is the same. All cells at the same value.

MassDeduction
Posts: 118
Joined: Tue Feb 25, 2020 3:24 pm

Re: 20k km and no SOH reading yet

Fri Dec 17, 2021 2:41 pm

IanL wrote:I've recently checked mine, after several months of not charging above 80% (using the timer, as the 80% cut-off facility was deleted from the 30 kWh models - grrrr), and my experience is the same. All cells at the same value.

Are you a lead-footed driver, or do you accelerate relatively conservatively? Because charging gently is valuable, and discharging gently is just as valuable.

To the degree that it's convenient and makes sense for your situation, of course. Ultimately these are tools to be used, not pieces of art to be babied. :)

But these results both strongly suggest that if you're mostly/exclusively AC charging (and especially if you're also driving conservatively) that you likely won't benefit from a monthly conditioning charge. In fact, most people who AC charge and accelerate conservatively may never need to make a point of doing one, as it's likely they'll charge to 100% at least occasionally anyway (such as before a road trip).

If I didn't have the OBDII adaptor and SoulEVspy, I would probably charge to 100% before every long trip. Not knowing how close to needing rebalancing I was, I would take advantage of every time that I needed a high state of charge anyway. But because I do have the adaptor, I will charge to a maximum of 90% even for most long trips. Unless the adaptor says it's been so long that there's a benefit to doing the conditioning charge, of course, but if a year isn't enough to require a conditioning charge then it may never need that at the rate we're going. :)

IanL
Posts: 267
Joined: Tue Feb 18, 2020 12:57 pm
Location: Jersey, English Channel Islands

Re: 20k km and no SOH reading yet

Sat Dec 18, 2021 1:51 am

MassDeduction wrote:Are you a lead-footed driver, or do you accelerate relatively conservatively? Because charging gently is valuable, and discharging gently is just as valuable.


Good point. I accelerate "firmly", but for short duration (the speed limit on this island is nowhere greater than 40 mph) and I drive in B, lifting off early so I hardly use the footbrake . I always use ac charging. Probably near to an ideal usage cycle.

MassDeduction
Posts: 118
Joined: Tue Feb 25, 2020 3:24 pm

Re: 20k km and no SOH reading yet

Sat Dec 18, 2021 4:02 pm

IanL wrote:
MassDeduction wrote:Are you a lead-footed driver, or do you accelerate relatively conservatively? Because charging gently is valuable, and discharging gently is just as valuable.


Good point. I accelerate "firmly", but for short duration (the speed limit on this island is nowhere greater than 40 mph) and I drive in B, lifting off early so I hardly use the footbrake . I always use ac charging. Probably near to an ideal usage cycle.

Some versions of the Soul EV software can average out your recent driving and give you a rolling average of how much of your driving is "Economical" vs. "Normal" vs. "Aggressive". Our 2021 is typically driven around 97% conservative, 3% normal, and 0% aggressive. So that likely contributes to keeping the cells in good balance. Our speed limits go as high as 110 km/h here, but we accelerate our Soul EV very conservatively (unless forced to do otherwise by traffic). When it comes to battery drain, it's less about the top speed and more about how slowly you get the speed up to there.

MassDeduction
Posts: 118
Joined: Tue Feb 25, 2020 3:24 pm

Re: 20k km and no SOH reading yet

Sat Jan 08, 2022 5:42 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. 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]

I suppose I would get an even more accurate guess if I used SoulSpy to see the state of charge down to a decimal too, eh? But then I'd have to go by the full size of the pack, not just the useable portion.

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