Battery Ageing Model

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There does seem to be a seasonal effect; yes. It happened to your car last year too. A sudden jump down on the 4th April 2016.

A couple of new cars here in Jeju that I have data for:

1. 38,135km - max 9.8% min 7.6% - measured using Torque.

2. 60,000km - SOH 92% - measured using GDS

These 2 new values are much the same as all the others. If the deterioration continues in a linear way they will get to about 180,000km before needing a replacement battery. I am still assuming that deterioration will follow a curve, and that the actual distance will be greater than this. We must wait and see.
JejuSoul said:
I am still assuming that deterioration will follow a curve, and that the actual distance will be greater than this.

I agree : free graphics of NMC components.





My dealership changed my 12V battery and I asked them to take a new readout of SOH. My SOH is no longer at 100%, but has been reduced to 99.4%.

New numbers:
Min det: 9.8%
Max det: 11.3%
SOH: 99.4%
Odometer: 43.500km
On the Facebook forum -

Car in Slovenia -
2016 Kia Soul EV 37,718km after 13 months and SOH 100% using GDS.
In Torque Pro there is min. and max. deterioration 5.5% and 8.9%

Update from previous values:

My numbers did improve again (old -> new):

Date 2017-02-20 -> 2017-04-06
Min 12.6% -> 11.7%
Max 14.2% -> 13.3%
Avg 13.4% -> 12.5%
CEC 9065 -> 9583
CED 8852 -> 9342
Odometer 47103 km -> 49992 km


Actually, I am back to the values measured one of the first readouts, more than 1 year ago and with 30.000 km less driven:
Date 2016-01-28
Min 11.1%
Max 13.4%
Avg 12.3%
Odometer 19493 km
Just checked mine today (nice spring day).

Mileage: 2010 mi
000_Minimum Deterioration(%): 0%
000_Maximum Deterioration(%): 1%
004_CALC Lost of SOH(kWh): 2.57
004_CALC MaxMin DET: 1
004_CALC SOH Battery in 100 ratio(%): 109.5
004_CALC SOH Battery in kWh(kWh): 29.57
004_CALC Average Battery Module Temperature(°F): 57.88
000_Cumulative Energy Charged(kWh): 799.8
000_Cumulative Energy Discharged(kWh): 781.5

I don't drive it much... usually charge 100% on the weekends, and 80% during the week. I usually do on average ~30 miles during the week, and ~90+ miles on the weekend.
add GDS reading. :mrgreen:


Charged energy (from 1,1kW EVSE or 43kW Chademo) = 2740 kWh.
This measure is made by a personal wattmeter (1,1kW) and from the reading of the Chademo Panel (Nissan).
I'm a little concerned about my stats.

I generally baby the battery too.. charge to 80% or short bump up charges from 40 - 60 or so between drives... almost no L3 charges to date (maybe a half dozen).

Yet, I've got around 22,500 km on the meter with this:

CEC 5656 kw
CED 5472 kw
Max det: 13%, cell #42
Min det: 10.4%, cell #72

Seems kind of high, given the vehicle (2016 purchased in October 2015), and the low kms... high energy usage is attributable to cold climate heating needs, and the use of snow tires in the winter.

Perhaps I need to use an L1 charger to top up slowly to full, and see what happens?
2016Electric said:
I'm a little concerned about my stats. ..
Yes, that recent reading is bad. But, this data is often extremely varied. We need an average of multiple readings over a few seasons to make a more reliable judgement.

Something else you could try is a calibration check. Here's one I did a year ago. --- Old post from Tue Apr 05, 2016 4:17 am
JejuSoul said:
... To calibrate your battery pack you need to charge to 100% then drive the pack down to nearly empty and then charge to 100% again. It is on this 2nd 100% charge that calibration occurs.
Results for my calibration test:- charged to 100%, drove 200km, charged to 100%
I stopped driving and started charging at 9% SOC.
GOM before 174km, GOM after 178km. My highest so far this Spring.
Deterioration values did reset. min det reduced from 6.8% to 5.5% at just above 4.08V (some cells were showing 4.10V) It was at 92% SOC, Battery pack =393V
max det reduced from 9.0% to 8.5% at 100% after I turned the car off to unplug the c harger.
I have seen much greater movement in these numbers recently that was not associated with charging to 100%.

Energy charged = 25.0 kWh for 91% (based on the BMS data) => Full pack 25/0.91 = 27.47kWh
Energy discharged = 23.9 kWh for 91% (based on the BMS data) => Full pack 23.9/0.91 = 26.3kWh

The energy charged figure is simple; it is the difference in cumulative energy charged before and after charging.
The energy discharged is the difference in cumulative energy discharged during driving minus the regenerative energy put back into the battery.
I replicated this calibration check over the last 5 days. It is just my normal driving, no special trips or hypermiling involved.

Results for my calibration test:- charged to 100%, drove 210km, charged to 100%
I stopped driving and started charging at 9% SOC.
GOM before 182km, GOM after 187km.
At 92% SOC deterioration values did not reset, but the cell numbers for the min and max did. (from 83, 29 to 1, 2)
max det reduced from 11.5% to 10.5% at 100%.
min det increased from 7.1% to 7.4% at 100%.

Energy charged = 24.5 kWh for 91% (based on the BMS data) => Full pack 24.5/0.91 = 26.92kWh
Energy discharged = 23.6 kWh for 91% (based on the BMS data) => Full pack 23.6/0.91 = 25.9kWh
Regenerated Energy on the trip was 14.5kWh.
C harger efficiency was 24.5 / 26.48 = 92.5%

From this data, even though my car is two years old it still has the same usable capacity.

About a year ago Elmil stated that the Ah data is more accurate than the kWh for doing these comparisons. Also the SOC reading is based on the Ah. I started collecting the Ah data in May 2016, so I don't have my original range test Ah data. But here is the same calculations for my recent trip, but done in Ah. Also instead of just using the displayed SOC, I will graph the SOC over the charging period and calculate a more exact starting SOC with one decimal place.

Results for my calibration test:- charged to 100%, drove 210km, charged to 100%
I stopped driving and started charging at 9.5% SOC.

Ah charged = 66.9 Ah for 90.5% (based on the BMS data) => Full pack 66.9/0.905 = 73.9Ah
Ah discharged = 65.4 Ah for 90.5% (based on the BMS data) => Full pack 65.4/0.905 = 72.2Ah
Regenerated Ah on the trip was 42.7Ah.

The rated usable capacity for our battery is 75Ah; if I used this figure it appears my battery has lost 1 or 2 percent. However I would rather use a figure generated by my own car for that comparison.


Update: I have been looking more carefully at the data for this charging session in the torque logs. The number 9% I gave for the SOC was that displayed on the dash before I turned off the car, so that I could plug it in. But in the logged data the SOC starts at 11% once torque starts up again after he car has started charging.


I performed a 'calibration' of sorts as described by Jeju. I charged to 100%, then used the car over the next couple days until I had the battery down to about 4%, and the Turtle light came on. Immediately thereafter I charged the car to 100% (last night) at a rate of 208-212v/30A (~6 kw).

I checked the battery stats this morning and they have changed. I'm now at around 23000km or so with:
CEC 5765
Ced 5567
Min Det 6%
Max Det 11.5%

Also, I checked the trip log for total distance travelled since the full charge, and it was about 147.5km, with the 4% battery remaining. About 1/3 of that was highway at 100 km/hr, the rest was stop and go traffic in 50-60 km/hr zones. I think one of the highway trips required some heat use as it was night time and cold.

Thats better.. But quite the spread between cells in terms of deterioration.
Soul EV 27kWh all new (2017) with 700km and 1 time at Chademo 43kW and only others 1,9kW EVSE Kia Official Charge cable.


Deviation Min-MaxDET with Chademo = less than 10%
Deviation with 1kW = less than 1%
Deviation with 6,6kW = less than 5%
I just did a second range test, immediately after the first.

Results for my calibration test:- charged to 100%, drove 195km, charged to 100% (Heavy rain reduced range on one of the 4 days.)
I stopped driving and started charging at 12% SOC.

Deterioration numbers for the last week.
max det reduced from 11.5% to 10.5% to 10.0%.
min det increased from 7.1% to 7.4% then decreased to 1.4%

I charge at 32A , that's about 6kWh. It does seem the difference between min and max is greater at higher currents. The average and trend however are the same.

We have seen brand 'new' cars with terrible stats before. Often they adjust back to normal after a few months. 'New' cars that have been sitting on the dealer lot for a long time, or ex-demo cars do not seem to adjust back.
A couple of topics recently have me concerned that the model being developed in this thread to determine the ageing of the battery due to deterioration may no longer be applicable. In particular using the internal BMS data.

1. According to these posts by Elmil - SOH change some cars have had a BMS upgrade. The BMS numbers all get reset during the upgrade, and it seems possible that a different algorithm is used to calculate the deterioration. If so comparing these numbers on different cars no longer makes sense.

2. Up until now almost all of us have had SOH =100% or nearly so. We have no idea on how the BMS data changes once the usable capacity begins to shrink. I have been testing a 2012 Kia Ray EV. The results have me worried that all the BMS data ceases to be reliable after a few years.
Am adding a thread to discuss the Ray EV BMS - Comparing BMS data on the Soul EV with the Ray EV
The CCC/CEC or CCD/CED counters are often counting up a bit just after the car is started. Here's an example:

Normal commute to work, 50km, then parked during the day (no c harger connected), then home 50km.
The graph is computed as ["consumed Ah"] divided by ["consumed SOC%"] = ["Projected capacity at 100% SOC"].


The interesting part here is what happens at 50km when I start the car and drive home. My data shows that the CCC had increased by 0.8Ah and the CEC by 0.3 kWh, that is energy IN to the battery. This is roughly corresponding to 1% SOC, but the SOC is not adjusted, hence the shift in the diagram.

When I check my old logs it seems this is a common behaviour, and the shift can also be in the opposit direction, i.e CCD/CED are counting. I found another case where this leap was 1.5Ah <=> 2% SOC.

Anyone with Torque Pro can easily test this by taking logs just when turning off the car, leave it for an hour or so, and then take logs again when starting up. Check the energy counters before and after.
Another SOH 100% reading from GDS. This one from Quebec.
MY2015 Soul EV 31,000 km see -

Here is some info on a talk by Thierry St-Cyr from Taxelco (Téo Taxi, the EV Taxi company in Montréal — They have L eafs, Soul EVs, and T eslas in their fleet.

They are doing range testing with Téo Taxi and the IVI institute : the put the car on dynamometers and run the car to empty.

They calculate an average degradation of 2.2% every 10,000km driven However, their situation is special because most of the time they charge on DC fast c hargers (77% of the time). This is higher than the degradation we are seeing on most of our cars.


Also from Quebec. Battery stats from a MY2015 Soul EV with 90,000km. Calculated SOH is 94.2%. Far better than the taxis above, and in the same climate zone.

The answer is simple for the taxi : BYD use LifePO4 battery.
LifePO4 battery is for heavy duty usage ... like industry.
And this answer is not new.