JejuSoul
Posts: 1379
Joined: Wed Jul 08, 2015 6:47 am
Location: Jeju
Contact: Website

Re: Battery Ageing Model

Sun Feb 18, 2018 7:14 pm

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Here's a comment to explain what State of Health SOH is, and how it is measured by us on the Soul EV.

The SOH is an indication of the point which has been reached in the life cycle of the battery and a measure of its condition relative to a fresh battery. A new battery has 100% SOH. This goes down as the battery ages.

The Soul EV OBD provides degradation data for the loss from the total capacity of the battery. However what we call SOH and refer to is the percentage of usable capacity remaining.

For cars prior to 2017 with an original BMS we know that there is a 10% buffer of battery capacity that is lost before any loss of usable capacity occurs. We see this when comparing our own data with the GDS reading for SOH taken by the Kia service tech. Hence on Torque you start with 110% SOH.

We do not know if the BMS algorithm for calculating SOH has changed in later cars. We do not know if the way the BMS handles the buffer has changed. For example the new 30kWh Soul EV may work the same as our cars. Hence on Torque you can start with 110% SOH. But we won't know for sure until someone compares our readout with the GDS reading for SOH taken by the Kia service tech. And that can only be done once the usable capacity has gone below 100%. We need to wait for 2 years!

An example of someone not understanding the SOH reading is here. Official Kia Soul EV thread
mtndrew1 who used to post his data on this thread states in his signature - "2015 Kia Soul EV+ Lease returned 10/14/17 45,000 miles w/ 13.8% degradation."
But we can see his data posted here, he actually only has a 3.8% loss from usable capacity.
The codes for using Torque Pro can be found by clicking the link in the website icon under my user name on the left.

Kish
Posts: 75
Joined: Mon Jan 29, 2018 11:56 pm
Location: SoCal, CA

Re: Battery Ageing Model

Tue Feb 20, 2018 5:54 pm

Out of curiosity, I checked the SoH values on the Soul EV again today, and to my surprise they were up to 91.7% (up from 79.1% last month)! Hoping that it was just the BMS being un-calibrated again, I ended up doing another range/drain test:

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To 1% yielded only 47.9 miles!

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After a full recharge, the Soul EV pulled 18.52 kWh from the wall and still shows 90.2% SoH! This should be 68.59% of SoH, what's going on here? Likewise, the 23.1 max kWh available shown in Torque should be < 18 kWh.

I have not yet taken the car in to the dealer yet.
2015 Soul EV+ | 47k miles
2017 Bolt EV Premier | 52k miles

JejuSoul
Posts: 1379
Joined: Wed Jul 08, 2015 6:47 am
Location: Jeju
Contact: Website

Re: Battery Ageing Model

Thu Feb 22, 2018 9:43 pm

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Yet another car driven far and fast that seems to be suffering battery degradation. - Getting only 73 miles in the winter

The other main cause of battery problems is extreme heat - Arizona SOUL EV Heat testing

All these 'bad' cars seem to be 3 year rentals. This thread is going to be most of use for the owners who buy these second hand cars at auction, and want to know how to get the replacement battery. An example is here - 2015 Soul EV: My Battery Replacement Story

And a reminder - none of the cars being tracked on this thread have serious degradation. My car which is average for these 'good' cars still has 100% SOH after 3 years and 44,000km. Some comments and an example from Spain here - KIA EV Soul battery decay
The codes for using Torque Pro can be found by clicking the link in the website icon under my user name on the left.

JejuSoul
Posts: 1379
Joined: Wed Jul 08, 2015 6:47 am
Location: Jeju
Contact: Website

Re: Battery Ageing Model

Tue Mar 20, 2018 7:39 pm

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I was inspired to start this thread by the great work being done to analyse the battery degradation on the Nissan Leaf Forum.
In particular - Battery Aging Model and Battery Capacity Loss
It turns out that understanding the real world long term losses in battery health is much harder than originally thought.

The latest study to look at this is by the group Flip the Fleet in New Zealand. - Benchmark your Leaf before buying!

They have collected data from second hand Nissan Leafs in New Zealand purchased from both Japan and the UK.
...we present a scatter graph of the SoH versus odometer of the EVs of different year and model. You can see the wide scatter in the graph – obviously lots of other things than just age of the EV and odometer affect battery health. Flip the Fleet needs more data to test ideas about what causes this variation and to see how best to minimise battery SoH loss.

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Their full study is here - Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf

There's a comment by pushevs about this result - Nissan Leaf battery degradation data: 24 vs 30 kWh batteries
pushevs wrote:It’s not surprising that the 30 kWh versions suffer more from charge/discharge cycles, since they are more often charged to 100 %. Remember that the option to limit the charge to 80 % was present in the 24 kWh version, but was removed when the 30 kWh battery was introduced (to game EPA range ratings…).

Kia played the same game as Nissan. The option to limit the charge to 80 % was removed for the 30kWh. Should we expect the same result? My own opinion is that the NZ sample size is too small, and the number of factors too great for us to make any conclusions based on this Leaf data.

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One effect however we can now state confidently. EVs without a liquid-cooled TMS fail in very hot climates. All the Kia Soul EV have failed in Phoenix Arizona. see - Arizona SOUL EV Heat testing

Here's the latest data for my car compared with 4 cars at the AVTA Intertek facilty in Phoenix Arizona.

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Last edited by JejuSoul on Fri Mar 23, 2018 5:51 pm, edited 1 time in total.
The codes for using Torque Pro can be found by clicking the link in the website icon under my user name on the left.

edzee3
Posts: 82
Joined: Mon Jan 19, 2015 2:56 pm
Location: Long Beach, CA

Re: Battery Ageing Model

Thu Mar 22, 2018 9:50 pm

Thx for the charts of Batt Deterioration vs. distance and time. I assume the time scale is for days; correct ?
And you are now out to about 3 years.
Ed
'15 Soul EV+, '10 Prius

JejuSoul
Posts: 1379
Joined: Wed Jul 08, 2015 6:47 am
Location: Jeju
Contact: Website

Re: Battery Ageing Model

Fri Mar 23, 2018 7:15 am

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Yes. my car is now 3 years old, and has driven 45,000km.
I measure the battery data on my car every 250km. The blue data is all from my car.

The x-axis scales used in the charts above are days for the time chart, and km for the distance.
The y-axis shows the SOH of usable capacity. A 10% buffer is lost from the battery before any usable loss hence this axis starts at 110%.

The warranty line assumes a 7 year, 160,000km limit to 70% SOH.
I think this is the norm for most countries.
The exception is the United States where the warranty is 10 years 100,000 miles.

I am trying to make these charts as simple as possible because there is so much confusion about this topic.
And to reiterate none of the 20+ drivers who are posting their battery data on this thread are likely to get a replacement battery under warranty if the current linear trend continues.
The codes for using Torque Pro can be found by clicking the link in the website icon under my user name on the left.

Elmil
Posts: 142
Joined: Mon Oct 26, 2015 9:46 am
Location: Sweden

Re: Battery Ageing Model

Sat Mar 24, 2018 4:27 am

JejuSoul wrote:-
The warranty line assumes a 7 year, 160,000km limit to 70% SOH.
I think this is the norm for most countries.
The exception is the United States where the warranty is 10 years 100,000 miles.

In most European countries the limit is 150,000km, so the warranty of my car will end sometimes late next year...

We have had an unusual winter with longer periods of cold weather and lots of snow in my area. My deterioration numbers have not changed during november to march, and I think it is because of the constantly low temperatures we had (not as bad as Canada though). The day temperatures are starting to reach above 0°C lately, and so I got updates.

Current data: Odometer= 91500km Max det= 12.5% Min det= 10.0%

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Kia Soul EV 2015 / 115,543 km Sold
Kia Soul EV 2019

JejuSoul
Posts: 1379
Joined: Wed Jul 08, 2015 6:47 am
Location: Jeju
Contact: Website

Re: Battery Ageing Model

Sat Mar 24, 2018 8:00 pm

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Elmil - thanks for the info. Your stats are amazing. 3 years, 90,000km and you still have near 100% SOH. I am still wondering though whether the BMS reset changed the algorithm used to determine the deterioration values. It seems your values are much lower than they would have been if you had not had the BMS reset. This may also explain why some people continue to argue that they get more range after a BMS reset.
I don't get that BMS update because it is for cold weather countries only. My stats have continued a linear decline ( once I average out the spikes).

Would be nice to see more data from people who have had the BMS reset.
The codes for using Torque Pro can be found by clicking the link in the website icon under my user name on the left.

JejuSoul
Posts: 1379
Joined: Wed Jul 08, 2015 6:47 am
Location: Jeju
Contact: Website

Re: Battery Ageing Model

Tue Apr 17, 2018 8:04 pm

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Firstly a correction to my earlier statement about the battery warranty.

The Korean warranty is 10 years, 160,000km to 70% SOH.
The United States is 10 years, 100,000 miles to 70% SOH.
Europe is 7 years, 150,000km to 70% SOH.

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And some new data from my car

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There was a spike up in my readings a month ago. It occurred immediately after driving fast 100km/h over a mountain.
The Min and Max reading initially reversed. This is the second time I have seen this in 3 years.
Both times were driving fast over the mountain.
It is something I rarely do, so I doubt this is coincidental.

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A month later and my car is back down to a level with no loss in usable capacity.

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My conclusion is that driving very fast, or just fast up a steep hill causes high battery stress which can degrade the battery much faster than normal. Perhaps this is not a problem if you only do it occasionally, but if your daily commute is 55 miles at 75 mph then it seems the battery will degrade to 70% in less than 3 years.
The codes for using Torque Pro can be found by clicking the link in the website icon under my user name on the left.

JejuSoul
Posts: 1379
Joined: Wed Jul 08, 2015 6:47 am
Location: Jeju
Contact: Website

Re: Battery Ageing Model

Fri Apr 20, 2018 5:16 pm

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Here's a car in the area Seattle : see - https://www.facebook.com/groups/SoulEV/ ... 449725528/
Brian Henderson wrote:...my Soul EV has 35,000 miles and had 99.2% SOH (State of Health, ie: 99.2% of usable capacity vs new from factory) ...

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And one in Korea at 93.9% -

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Another in Germany - 95% at 75,000km
https://www.goingelectric.de/forum/kia-soul-ev/akku-laesst-anscheinend-stark-nach-t31139-30.html#p736505
The codes for using Torque Pro can be found by clicking the link in the website icon under my user name on the left.

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