Latest E400 BMS update appears to have reduced usable capacity.

[mariano3113]

The pack 37510-E4203R has 96 cells and is for the 2015-2017 models.
The pack 37510- E4302R has 100 cells and is for the 2018-2019 models.

Given that the fire safety recall adds the 2018-2019 BMS hardware and wiring harness to the 2015-2017 cars I'm not sure why they bother keeping the two versions.

Yeah why would they still do 2 different battery variants.

I assumed since the "Battery warranty for US is a replacement battery with >70% battery capacity....then even putting the smaller Refurbished battery in a 2018-2019 would fulfill Warranty promise and save them some "cells" to have move packs available.

 

[JejuSoul]

My assumption would be that giving everybody the same replacement packs would simplify their software maintenance. Having to write a BMS 'fix' is much easier if you only need to test it on one variant.

My guess for the recent BMS 'fix' fiasco is that they did only test it on one variant but applied it to many.

 

[chilibt]

Th summer Before the second update (that is after the first update last winter), my battery cell voltage was 4.18VDC, After the second update it is 4.10. My range is also 16% less that before the two updates. What I do NOT have is the Pre-update Cell voltage , that is prior to the first update in the BMS software.
What cell Voltage history do others have prior to any updates?

 

[JejuSoul]

Th summer Before the second update (that is after the first update last winter), my battery cell voltage was 4.18VDC, After the second update it is 4.10. My range is also 16% less that before the two updates. What I do NOT have is the Pre-update Cell voltage , that is prior to the first update in the BMS software.
What cell Voltage history do others have prior to any updates?

Can you confirm this is a MY2018 30kWh Soul EV. With original pack or a replacement.?
Do you have any readings of the SOH?

Note:
I have two 2015 Soul EV both with replacement packs.
Both have now had the BMS fix. Both now have the 2018-2019 BMS hardware and wiring harness.
My battery packs have 96 E400 cells not 100.
The BMS software and algorithm they use is not the same as MY2018 30kWh Soul EVs.
In particular the standing voltage at full charge for a new battery is 4.14V
This suggests the size and loss over time of the 'early years' buffer for the 2015 cars is different from the 2018 cars. I cannot estimate that difference because I don't have any data.

 

[chilibt]

Yes it is a 2018 , original battery, dealer SOH was 100% prior to second update (September 3). The previous SOH at the dealer 2 or 3 years ago was 100%.

The soul spy SOH in August was 100%. but it has not given a SOH reading from just before the 2nd update (September). It has 96,000 KM and is going in next week for a Transmission Oil change and to see if everything is good prior to the warranty expiring at 100K Km (Canada).

 

[JejuSoul]

About the 'early years' buffer.
The BMS divides the battery pack into three parts.
Usable Capacity, an 'early years' buffer and a 'safety buffer'.
The 'safety buffer' is required to protect a lithium ion cell from severe degradation at the very top and bottom of the voltage range. This buffer is never lost.
The 'early years' buffer was a construct added by the manufacturer to protect resale values in the first 3 years.
This buffer is lost over time by widening the voltage spread as the battery degrades to maintain the usable capacity at the same value as new.

It seems the BMS algorithm has been modified to alter the behavior of the 'early years' buffer during the BMS fire-safety recall. ( At least for the two 2018 cars in this thread. My two 2015 cars don't show this for now. )
We don't know the reason for this.
Maybe it is somehow related to fire-safety.
Maybe the BMS just thinks the car is new again and will reduce the 'early years' buffer over the next 3 years.
Maybe it is just a software bug and they will fix it at some point.
I don't think we are ever going to know. Kia is never going to tell us.

Also maybe this change will be positive overall by increasing longevity.
I doubt they did it for this reason though because all our cars will be out of warranty soon and after that Kia couldn't care less about battery longevity.