Checking main battery health?

You'll need access to the OBD data listed as CEC, CED, CCC, CDC and SoC (displayed), each to one decimal point resolution.

1. Charge to 100% (or close) and record them all.

2. Drive the car down to 15% (or as low you're comfortable with) and record them all again. It doesn't really matter how you drive or how long it takes, but you'd not want to do this mid-winter.

3. Take the change in each of the five values and remove the charge numbers (added by regen) from the discharge numbers to get the net values. Divide that by the change in SoC as a fraction (e.g. 100% to 15% is 0.85). The 0.98 factor is an estimate of battery cycle efficiency and applies only to the energy calculation.

[ΔCED - (0.98 x ΔCEC)] / ΔSoC(disp)
and
[ΔCDC - ΔCCC] / ΔSoC(disp)

Compare those to the as-new rated capacity of 64 kWh and 180 Ah. I obtained values (in red boxes) close to those in my test below. (Mine are factored by 1/100 because I forgot about expressing the SoC change as a fraction.)

I actually log those values every 5 seconds while driving to check the linearity but that's not required for a simple capacity check.

 

Reports of SoH are rare on the forums and FB but there have been a few at around 95%. The latest from FB is here:

What interested me about this is that the charging data was obtained from the Car Scanner app, data I wasn't aware was available and isn't included in the Torque Pro setup I normally use. It gives you the number of AC and DC charge events plus the kWh added in total by each method.

I suspect the poster's low SoH for the miles could be due to both (a) the 64% of charges being DC and (b) the high probability that a demo EV would have been kept fully charged.

 

No, I've always owned this one.

 

Depending on how much you want to spend this might work for you https://evobd2.com/

 

Tacking onto this, I finally added a SOH query to my OBD "dashboard". [7E4, 220105, "z" and "aa" form a
16-bit value, div 10 for percentage]. The car has about 25K miles on it by now. SOH reports as 100%.
How likely is it to be lying? Anyone been monitoring SOH over the long term?

_H*

 

The latest (and lowest) reported SoH I've seen of of 92.7% was for a 2021 with 17k miles, location not mentioned. Usage was stated as "Never used a DC charger. Only charge on my level 2 at home. Usually charge to 80% once a week or so." Which I guess is the modern equivalent of saying "only driven to church on Sundays".

Torque Pro has always specified that same PID for SoH and my original battery from Sept 2018 read 100% right up until it was replaced 4 years later. I DC charged perhaps a dozen times but mostly kept it under 70% over 22,000 km. I had extrapolated the capacity at the three year point using the cumulative registers between SoC 15-90% and found it matched the as-sold values of 180 Ah and 64 kWh.

Even if the early examples did not properly calculate SoH it seems likely that later examples do and reports will roll in over time on FaceBook and Reddit. The pattern I see is that owners panic about losing some GoM range and learn how to access the SoH reading, made much easier these days with smartphone apps, especially CarScanner which also details DC charging events.

 

Interesting. Esp. if you're using the same PID and response offsets that I am. It's right from the Jeju files.
Unless I've got my math wrong. I have ((Z*256)+AA)/10 in "obdlink-ese", because their app can't parse
"<8" type bit-shifting, but that works fine for several other 16-bit values I read.

_H*

 

Re posting the screen shot from my Car Scanner app at about 30,000kms. Still at 100% and reporting perfect balance. Interestingly it reports only 5 DC charges where as we have counted 12 by looking at invoices. Have to admit some of those were just top ups.(?)

 

Finally got myself set up for data logging with my 2020 SEL, Taking my first look at things on my commute to work and back.

SoH is at 92.5% and "Minimum Deterioration" at 11.6%? It's only 32 months old with ~15K miles. I do expect most of the degradation to happen early but I'm not sure if this is a bit too much. Lease is up in October so I'll be doing some tests to see if it's aging more poorly than expected...

 

Hello Ferenc, please can you tell me what device you are using with the Car Scanner app to get this information? Based on my guessometer I've lost about 50 to 75 miles of range since the battery replacement. Thanks for any thoughts you may have.

 

iPhone 6 and LE link obd 2 reader. I have the 2022 model Kona.

 

When my battery was replaced in march 2021, Minimum Deterioration was at 0.7% while SoH was still at 100%. After battery replacement, Minimum Deterioration was not resetted and still showing 0.7%. It slowly increated to 1.3% over the last two years while SoH remained at 100%. Three weeks ago, the SoH has started to decrease to a rate of 0.8% a week. With each SoH decrease, the Minimum Deterioration number increase by a factor close to 2. SoH is now at 97.5% and minimum deterioration is now showing 5.8%. I put 90000Km on the old battery and about 50000km on the new one. I charge to 80% in summer time and 90% in winter. I charge to 100% once to week. According to Car scanner, I made 26 DC charges. I made a lot more DC charges on the old battery.

I am using a microcontroller to read and record CEC,CED,CDC,CCC, power and other pids numbers for over 3 years now. I drove the car down to 4% last week and I still register over 64kWh of net discharge energy as it has been for the last 3 years. I use same formula as KiwiMe but without 0.98% cycle efficiency. Since the Minimum Deterioration was not resetted after the battery replacement, I don't know what to think about these 2 values.

 

After reviewing my data, the Minimum Deterioration number is actually increasing by the same amount as the SoH decreases. So in fact, the SoH started decreasing after the Minimum Deterioration reached 3.3%. Like if some buffer is reached, the SoH starts decreasing. Although, at 100% SoC display, I still get 96.5% BMS SoC.

But again, with the new battery, the Minimum Deterioration number started with the number accumulated from the old battery...