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Re: Battery Ageing Model

Posted: Sat Oct 12, 2019 7:24 am
by JejuSoul
Omar wrote:...Now my SOH dropped to 64.7%. I do not know if the warranty covers my KIA, the car is imported from USA-California, I do not think that KIA middle east will accept a warranty claim. ...

Hi Omar,
No, I do not think Kia Jordan will cover the battery warranty for a car privately imported from the USA.
I have seen another query like yours from a Soul EV imported from Korea.
Kia will not cover battery failure in these cases.

I do know of a repair facility in Amman that has 'fixed' Soul EV batteries in the past. - مركز انفيرتر : الألكتروني: Electronic Inverter Center
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Re: Battery Ageing Model

Posted: Wed Oct 16, 2019 8:10 pm
by JejuSoul
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The SOH on my 2nd car has now dipped below 70%. Less than 3 months ago I bought this car with 85%. It's now 69.5%.
Really sudden degradation. In the same 3 month period my original car has not degraded at all.
The rate of deterioration seems to be accelerating in the last week, even though the weather is cooler and I'm driving slower.
But I do need to charge more often.
I took it in to the local Kia today. Official reading 69.5%.
Battery replacement is done at the main center. I have to book an appointment because there is a waiting list.

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Re: Battery Ageing Model

Posted: Thu Oct 17, 2019 12:35 am
by JeroenE
JejuSoul wrote:-
Really sudden degradation. In the same 3 month period my original car has not degraded at all.
The rate of deterioration seems to be accelerating in the last week, even though the weather is cooler and I'm driving slower.
But I do need to charge more often.
I hope you get your replacement soon!

I find it disconcerting that the battery deterioration seems to go very fast all of a sudden with 'lots' of cars. I hope this doesn't mean there is something wrong with the battery design.

Does it look like there are one or two cells that are getting really bad in your car too?

Re: Battery Ageing Model

Posted: Thu Oct 17, 2019 2:06 am
by Omar
First to update you on my car. The battery seems like recovering some range gradually!, now its consumption is back at around 39% per my daily commute (last year it was 37%, 2 weeks ago it was 43 - 45%).
But max deterioration, min deterioration and SOH still read the same. (4.4%, 43.8%, 64.7% respectively).

About the quick drop in the battery performance, it is in fact a kind of normal if 1 cell or more performs worse than the others. This is because of the battery way of connection and the battery chemistry.
Once a cell deteriorates, its voltage jumps while charging. The car BMS avoids overcharging the cell, so it stops the charging once it is over a certain limit. This is to protect the cell from more damage. So, other good cells will not reach their full charge. All the good cells lose a portion of their capacity. This means that the capacity loss will be amplified 96 times!, the same happens at the low charge level as well!.
another observation supports this claim!, when I start driving from home, the car loses the first 2% very quickly! while the total estimated range stays the same!, because the percentage of charge shown on the car screen is dependent directly on the max cell voltage. Once I drive some distance, the voltage jump disappears. and the percentage of charge drops more logically with distance
This is still a theory, I am doing more reading and learning about the battery technology, that would be in line with my plans to study sustainable energy systems in the future !

I monitored my car, on time the jump of the bad cell was higher, so other cells were charged up to 4.10V, another time the jump was a little less, so half of the cells reached 4.12V.

Re: Battery Ageing Model

Posted: Thu Oct 17, 2019 2:15 am
by Omar
Why does the BMS suddenly notices the battery performance change?

1. It can happen if some kind of resetting happens to your BMS. It happened with me after I disconnected the 12 volts battery for 8 hours in order to fix an issue with the clock!
2. If your battery charge is regularly in the middle range like between 30 or 40% - 80%, your BMS is less likely to detect a bad cell, the bad cell normally behaves bad at the top and the bottom of the charging range!. So if you stay in the middle, then for a day or two you charge your car to 100% then discharge it to a low level, the BMS will realize the problem.

Re: Battery Ageing Model

Posted: Thu Oct 17, 2019 2:26 am
by JeroenE
Omar wrote:Once a cell deteriorates, its voltage jumps while charging. The car BMS avoids overcharging the cell, so it stops the charging once it is over a certain limit. This is to protect the cell from more damage.
I understand that 1 cell can make an entire battery-pack useless.

But what I don't understand is that the cell keeps deteriorating, even if the BMS is doing it's best to protect it.

Note that in my car the first 15% with my bad battery were almost identical to driving with a good battery. Only when the charge was below 84% the percentages were dropping much faster than they should with regards the distance travelled.

Re: Battery Ageing Model

Posted: Thu Oct 17, 2019 11:04 am
by ksoul2084
Omar wrote:First to update you on my car. The battery seems like recovering some range gradually!, now its consumption is back at around 39% per my daily commute (last year it was 37%, 2 weeks ago it was 43 - 45%).
But max deterioration, min deterioration and SOH still read the same. (4.4%, 43.8%, 64.7% respectively).

About the quick drop in the battery performance, it is in fact a kind of normal if 1 cell or more performs worse than the others. This is because of the battery way of connection and the battery chemistry.
Once a cell deteriorates, its voltage jumps while charging. The car BMS avoids overcharging the cell, so it stops the charging once it is over a certain limit. This is to protect the cell from more damage. So, other good cells will not reach their full charge. All the good cells lose a portion of their capacity. This means that the capacity loss will be amplified 96 times!, the same happens at the low charge level as well!.
another observation supports this claim!, when I start driving from home, the car loses the first 2% very quickly! while the total estimated range stays the same!, because the percentage of charge shown on the car screen is dependent directly on the max cell voltage. Once I drive some distance, the voltage jump disappears. and the percentage of charge drops more logically with distance
This is still a theory, I am doing more reading and learning about the battery technology, that would be in line with my plans to study sustainable energy systems in the future !

I monitored my car, on time the jump of the bad cell was higher, so other cells were charged up to 4.10V, another time the jump was a little less, so half of the cells reached 4.12V.


This matches my own observations well.

Re: Battery Ageing Model

Posted: Sat Oct 19, 2019 9:36 pm
by Omar
This morning, I checked my battery cell map before I started driving. It was surprising to me that most of the cells charged up to 4.06V only. The bad cell was at 4.18V. (the car shows 100% charge). in a new battery they must reach 4.14/4.16 V. Recently they were reaching 4.10V.
So what was different today?
First, the battery was at lower level than usual when I started charging (22% compared to usual 40%).
Second, I charged the car in one shot. Normally when I charge the battery to 100%, I do it in 2 stages, using 2 timers, with a "rest" of about 2 hours in the middle.
Third, the weather was colder by around 6 C.

Re: Battery Ageing Model

Posted: Wed Oct 23, 2019 6:37 am
by JejuSoul
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Spoke to Kia about my replacement battery.
Good news is that it is a 3 hour fix. I get to keep driving the car beforehand.
But there is only 1 service center on the island that can do it.
And the bad news is that there is a 2 month waiting list. ( 50 cars perhaps. 3% of the older Soul EVs here) .

This is unusual. Previously I would hear about 1 car every few months needing a replacement.
Perhaps this spike in failures happened because of sudden deterioration during the summer.

I am certain that we get new packs, not refurbished.
The old packs are taken to a recycling center and the cells taken out and put into ESS storage units.
I don't know yet, how many cells are in the new packs.

Re: Battery Ageing Model

Posted: Tue Nov 05, 2019 3:24 am
by JejuSoul
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Am still waiting to hear from Kia about when I can take my car in to get the battery replaced.
I am still driving the car as normal.
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In the Torque codes we use to measure the SOH I have two different calculations for measuring the SOH.
The original version uses the average of MIN and MAX deterioration values.
This works well when the battery is in good health. ( But only slightly better than the other version.)
But fails completely when the battery goes 'bad'.

The 'new' version ignores the MIN deterioration values.
This version works well in all cases.
I suggest users prefer this version at all times.
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Here's the MIN and MAX deterioration values graphed over the last 4 months for my car that is waiting to get the battery replaced.
The MIN deterioration value is chaotic and trending down. It cannot be used in any calculation that makes sense.

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For various reasons I am no longer going to collect and publish the data from cars other than my own on this thread.
The 20 cars I had monitored were all doing well, and it seemed like the batteries would last a long time.
But it has become obvious that a very substantial number of other cars are requiring replacement batteries under warranty.
The subset of drivers that measured their battery data from the start is clearly unusual.

I believe Kia recognized the fact that many batteries were failing and would soon need replacement years ago.
It helps understand why Kia stopped selling EVs in the American market and focused almost entirely on Norway.
Norway - the one place where climate and driving conditions mean a substantial number of battery packs will survive.
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