Battery Ageing Model

[mtndrew1]

I have new numbers.

35,900 miles (57,775 km)
Min det: 13.5%
Max det: 15.5%
CEC: 12192
CED: 11666

 

[SmoothJ]

Climate: NJ, USA - lots of up/downs temps in this area. Some days it can be a nice 60 degrees in the winter, other days it can be 10 or so degrees. Spring/Summer, is also a mixed bag, but during that time usually never really below 50F...but could go as high as 100F (with it being humid).

Driving style: To be honest, I don't drive that much at the moment, but I try to drive at least 10 miles a day. I mainly take the bus to work, and then go out on the weekend. In the morning, its all city driving (~2-3 miles), but when I come home I drive on the highway for at least 4 miles, and then the rest city just to stretch the legs of the EV. During the weekend, I could drive around more (~50-60 miles).

Charging behavior: Currently using the standard 110v EVSE that came with my car, and my wife's Ford c-max (use both). However I am getting a 50A circuit installed hopefully next week, and I have a 50A OpenEVSE on order (purchased 50A due to us possibly getting another BEV soon). I usually charge to ~80% on the weekdays, and ~100% on the weekends. I keep a semi detailed charge log with percent, miles, charged to what percent, etc. I charged so far 29 times, with never going below 19% charge (only one time so far). The charge for the weekdays usually last me a few days. I don't usually charge the car till about the 40% mark (mainly cause my wife needs to charge too, she drives more, we have single car driveway, and we have a slow EVSE).

Chademo: I have used this only 1 time (from 35% to 83%). Still have only 1000 miles on the car, so its fairly "young" for it being purchased in December of 2016, but built 12/15.

Picked these off of a newly installed Torque install and logging:

004_CALC SOH Battery in kWh(kWh): 29.7
004_CALC Lost of SOH(kWh): 2.7
004_CALC SOH Battery in 100 ratio(%): 110
000_Maximum Deterioration(%): 0
000_Minimum Deterioration(%): 0
000_Cumulative Energy Charged(kWh): 471.9
000_Operating Time(hours): 361.95

 

[SoulEV2016]

 

[JejuSoul]

SoulEV2016: thanks for the data.
Your car is very unusual, compared to the other cars we are tracking.
Some of the differences I understand and 1 I don't.

Your operating time is really high compared to your distance driven.
This is because you charge really slowly.

Your average Energy Consumption is really high. 37.8kWh / 100 km.
Almost all other cars are between 20 and 24.
(Note this includes regen so it is not the same as the value shown on the dash or navi.)
This is because you drive really hard in the mountains.

What I don't understand is why your Cumulative Energy Discharged is higher than your Cumulative Energy Charged.?
Given efficiency losses common sense suggest the reverse must be true. And for all other cars, older than a few weeks, it is.

--------------------------------------------------

A few days ago I posted -

For our Soul EVs, if hypothetically a replacement battery costs $6,000USD and lasts only 1000 cycles (160,000km) then the cost of battery deterioration per kWh throughput is about 45 cents.

That hypothetical $6,000 USD replacement battery cost was taken from the first post in this lengthy thread -
http://www.mynissanleaf.com/viewtopic.php?f=4&t=17168&p=4805073#p480507 - Update on Nissan L EAF Battery Replacement

The very last post in this 99 page thread has a YouTube video with Chelsea Sexton and a Nissan executive.
He talks a lot about battery degradation, and clearly states the batteries will deteriorate more in the first few years, and deterioration will slow down.
Problem is, the fact that this was posted 5 years later as evidence that Nissan was deceptive in its original comments about battery degradation, might suggest this claim about battery degradation be taken with a grain of salt.

https://youtu.be/R1tfX7fRWPI

 

[SoulEV2016]

Perhaps, the others owners use more regenerative brake than me ?
Perhaps, it's like the ACI indicator in Tesla ?
http://teslamotorsemotion.blogspot.fr/2017/01/les-occasions-bien-choisir-sa-tesla.html?m=1

 

[JejuSoul]

Regenerative braking is just another way to charge the battery. The energy added gets recorded in the CEC (Cumulative Energy Charged) and then when you continue driving gets recorded in the CED (Cumulative Energy Discharged). It doesn't matter whether you regen more or less, both aspects always get recorded.

A kWh cycled through the battery using regen and driving is roughly equivalent to a kWh cycled through the battery by charging and driving.
For our Soul EVs, if hypothetically a replacement battery costs $6,000USD and lasts only 1000 cycles (160,000km) then the cost of battery deterioration per kWh throughput is about 45 cents. So the cost of each kWh of regen is actually about 45 cents.

This still makes regen a great deal. For me to drive to the city I have to go over an 1100m mountain pass. Without the regen I would need to charge in the city at 35 cents / kWh. It is not possible to coast on the mountain road, so I would also have to pay for the cost of replacing the brakes every few years in a regular car, and or the fuel cost for engine braking.

 

[JejuSoul]

SoulEV2016: on the French forum Teirhy has posted this - SOH de nos Soul EV dans le temps et les km (à épingler)

Soul EV new on 04/09/2015, 32 000 km

If Torque was working properly here this car would be the best car we have data for. But like your car there seems to be something odd with the CED (Cumulative Energy Discharged data). My car has almost identical mileage 31,250km but I have a CED 6296.6kWh. My car is reading max 8.5% min 1.5%.
Could you ask him for more details about his driving, charging, and if possible the build date.

 

[SmoothJ]

There could be a chance its reading the PID wrong due to possible older/different firmware in the ODB reader.

 

[Elmil]

It would be interesting to see the values of the CAC and CAD counters (Cumulative Amperage) for these abnormal readings. I don't use Torque but I can't find them in the CSV files.

Btw my deterioration numbers changed today:

Odometer: 57595 km

Max det: 12.4%
Min det: 10.9%
CEC: 10117 kWh
CED: 9811 kWh
CAC: 27402 Ah
CAD: 27352 Ah
SOC: 91.5%

Note that the amperage counters are VERY accurate - The Charge counter has 50Ah more on it than the Discharge counter, at 91.5% SOC. So the inaccuracy is less than 30 out of 27400, while the CEC normally should be a little bit ahead of the CED.

 

[SoulEV2016]

Could you ask him for more details about his driving, charging, and if possible the build date.

message sended.

 

[SoulEV2016]

It would be interesting to see the values of the CAC and CAD counters (Cumulative Amperage) for these abnormal readings

 

[teirhy]

hi,
(sorry for my bad english)

my CED has a bug, when it work it's about 5400kWh for ~32 000 km

i use my car normally, in town to go to work, 10 km with many traffic lights, with about one charge per week with kia charger (1.8 kW) (~25% to 85% battery)
it represents ~5000 km / year

Once or twice a month I make a 200 km trip for weekend (2x 100 km whith night recharge at 1.8 kW
it represents ~3000 km / year

Every 1000 km or so I make a full charge of the battery (10%-100%)



and i travel a lot with chademo charge, it represents ~15000 km / year

For example here is my trip for the summer holidays 2016

i try to take care of my battery, but it's not easy, we know nothing...



* car ordered in May and delivered in September 2015

 

[JejuSoul]

Hi teirhy,
Thanks for the info. Your data is so similar to mine that I would like to know more about your car, and driving style.

I am assuming that you live in the South West of France.
I just looked up the weather data.
It is much cooler there in summer, than I expected. With mild winters.
Can you confirm that this is approximately the climate for actual location.

Daily High and Low Temperature for Pau, France. (Charts from weatherspark.com)

I live in a slightly warmer climate than you. But winters are similar.
Daily High and Low Temperature for Jeju,South Korea.

The mild winter driving here means I have no need of winter tyres, I never drive on snow, I have hardly ever used the heater. It means my fuel efficiency in winter is far higher than those in cold climates like Scandinavia and Eastern Canada. I have been getting 7.9km / kWh or 12.6 kWh / 100km.
Note I also drive slower on average than anyone else here. The maximum speed limit on the island is 80km/h. My car has not been off the island since it arrived from the factory. My car was built in early May 2015, and the VIN ends in #04294.

 

[teirhy]

my location was Paris, and now it's Bordeaux, In fact the weather is temperate but this winter, at mountain the battery was -15°C, and last summer i traveled accross France for 700 km with 30°C and 5 chademo recharge.
i think the cooling system is effective.

when i drive, i avoid the maximum recharge power especially when the battery is full and i avoid max power discharge as i can especially when the battery is low

Apart from that, I do nothing special


When I was in Paris my consumption in town was of 11kWh/100, and when i travel it's close to 14kWh/100
I drive near the limit speed except when I have to go 180 km in winters where I do not exceed 80km / h

I do not know when my car was built, the VIN ends by ....06084


i avoid "turtle mode" but with my trips, i have no choice.
0 to 83 % after 171km with 94% at depart

some pictures : http://www.mykiasoulev.com/forum/viewtopic.php?f=4&p=6470#p6470

 

[ZuinigeRijder]

My deterioration values became better after a calibration (12% SOC).
From:
Date km Avg Det
2017-02-08 46158 14.1
Into:
2017-02-20 47103 13.4

Previous change was without calibration and that is a sign the deterioration values are not correct.
Normally the Max. Cell no is 2,3 or 9 when a calibration occurred.

I do not understand the relationship between the cumulative Ah en kWh. Because this would mean approx 375 Volt, whereas the screenshot shows 395 Volt.

Climate: https://weatherspark.com/averages/28807/Gilze-and-Rijen-Noord-Brabant-The-Netherlands

In the work week I drive daily 80 km (2x40km), 2/3 are urban roads, 1/3 is highway. On the highway I drive calm, often about 95 km/h. My average speed is 55 km/h over the last 10.000 km.

I charge on my work (3.7 kWh), because there they have solar panels. At home, when needed, I charge with the mobile L1 charger (2 kWh). Because I mostly charge at work, I did not install a charger at home. In the summer I have an efficiency about 12 kWh/100 km, in the winter about 15 kWh/100 km. I normally do not use a fastcharger (only one month, when I had a free month of Fastned). In the winter I charge till 100% for the extra range (after 80 km about 50% left), in the other periods I charge till 80% (after 80 km about 40% left). I do not have the car long at 100% in the winter, only a few hours before I leave at work. I try to keep above the 30% SOC, but now and then I calibrate (below 19% SOC). But I keep this to the minimum.

 

[SoulEV2016]

Whooaaaaaa ... the final voltage is really altered !

example of a end of with a 9000km battery : http://www.mykiasoulev.com/forum/viewtopic.php?f=14&t=620&p=6264#p6185

400,20v at 2,2kW charge.

 

[JejuSoul]

I do not understand the relationship between the cumulative Ah and kWh. Because this would mean approx 375 Volt, whereas the screenshot shows 395 Volt.

When I divide those numbers I see your average voltage as 357V from the numbers above, not 375V. All the cars are between 350 and 360.
(8851.6 * 1000) / 24784 = 357V

This number should just represent the average SOC that your vehicle has been at. If the average SOC your car was at was 50% then seeing an average voltage of 360V makes sense. If 100% SOC = 400V and 0% = 320V then average is 360V.

--------------------------------------------

I think I have the mildest winter of anyone reporting data here, I don't need to charge to 100% SOC in winter because I haven't lost any range. In fact my summer range is exactly the same as my winter. I have the best range in spring and fall. The last few months my deterioration values have been much the best, which I have assumed is a winter effect. The trade off for those in very cold climates is that you have to use the battery much more. The battery deteriorates less in the cold, but deteriorates more with use. My average deterioration is greater than those cars in cold climates, because any benefit I get in the mild winter is lost during the hot summer.

The above is speculation, you can't make any statistical judgement from just one car. It could just be random. When I saw Teirhy's data I thought it was similar to mine. But it can't be. If his battery can get to minus 15. That is cold. Mine never goes below zero. Also my data jumped today so I am no longer in the front.

My data km 31,500km from max 8.5% min 1.5% to max 8.5% min 5.4%

So in terms of the most recent single data point the ranking is:
Teirhy - 294,253km
Elmil - 197,751km
Birkeland - 186,207km
JejuSoul - 181,318km (was 235,00 until it changed today)
GizmoEV - 179,413km

The ranking based on multiple data collected over a year
Birkeland
Elmil
GizmoEV

Teirhy and mtnDrew1 would both be high up on the second list, but I don't have enough data points from them to get a yearly average.

 

[Elmil]

Found this interesting article about Li-Ion battery ageing by researchers at Journal of Nanomaterials

It contains a nice diagram showing causes for battery ageing at anode and their effects:
https://www.hindawi.com/journals/jnm/2015/631263/fig1/

 

[mtndrew1]

I had my car in for service yesterday and they ran my State of Health (SOH) query.

The odometer reads roughly 37,000 miles / 59,545 km and my SOH is at 94.9%.

I'm assuming this means I've eaten through the 10% "overhead" in the pack capacity and have lost ~5% of actual usable capacity. This would correlate with my Torque Pro capacity loss readings (see above) and what I'm actually experiencing as far as true range capability.

 

[JejuSoul]

It contains a nice diagram showing causes for battery ageing at anode and their effects:

Thanks for the link - that journal article is good. I will comment more about the theory later at the Battery University thread

Here's the image you link. Interesting that it includes low temperature.



-------------------------------------

The odometer reads roughly 37,000 miles / 59,545 km and my SOH is at 94.9%.

Do you have the matching min and max deterioration values for that SOH reading? The average of those should be about 15% if our idea about the buffer being 10% is correct.
Also it would be great to see a range test done on your car before you return it.