Battery Degradation and Performance Patterns

My car was the subject of Tony Williams' Soul EV range test posted on InsideEVs.com in October 2014. http://insideevs.com/kia-soul-ev-range-autonomy-demonstration-nets-100-miles/

From that date forward I have kept a running Google Sheets spreadsheet tracking how my battery performs. I'm not at all consistent with the variables here (tire pressure, HVAC use, ambient temps, average speeds, etc); I'm simply extrapolating what the car tells me on the dash and contrasting it against a known, carefully-controlled test when the car was new. I do this whenever I know I'll have a long-ish day of driving ahead with no charging interruptions to throw off the data.

https://docs.google.com/spreadsheets/d/1kfyB1q3LMKcM1OzCnLp-CJxcLANAaIMZHRgBmgQgxGw/edit?usp=sharing
Most of the time I just charge to 80%, drive the car around like any other car, HVAC set to "Auto 74," radio blasting, and don't give a thought to range. The car just has plenty of range for me and I've never had any sort of anxiety about it.

As it's been about a year and 16,000 miles now, I'm planning to replicate the original range test as closely as possible to get a feel for degradation. I'll be out of the country for a few weeks but will do this when I return. In the meantime I did a little experiment yesterday because the weather was mild, I knew I wouldn't need any HVAC, and I had a lot of driving to do.

I've never seen the 240V charges do any sort of cell balancing at the end of a 100% charge, it just goes from 32A to 0A in about a second. Generally I'm watching 100% charges like a hawk because they're infrequent and I tend to depart immediately after 100% charging completes; I'd notice if it was dribbling along for an extended period. So yesterday I pulled the 240V at 75% and let the car charge to 100% overnight on the 120V charge cable thinking that may give the car some cell balancing opportunity. I have no data to back it up, but it sure seems to have worked as I achieved my highest-ever capacity remaining estimate yesterday aside from the tightly-controlled Tony Williams test. If it's even remotely accurate I've lost less than 5% pack capacity in more than 16,000 miles. Color me impressed.

In looking at the spreadsheet I'm seeing a pattern with temperature. And I've also noticed, now that it's cooling down, that the Soul's performance follows temperature. The car is noticeably quicker now that it's cooler, so the BMS must be doing something to taper performance to keep the pack cool during warm weather.

I'll post again when I recreate the original 62 MPH all highway, no HVAC test.

Very interesting. I also enjoyed the range test with Tony.

The best way to check the battery degradation, is to take your car to the dealership, and ask them to check "min/max deterioration". This is recorded by the BMS. This way, you will have the correct degradation.

Birkeland said:

Very interesting. I also enjoyed the range test with Tony.

The best way to check the battery degradation, is to take your car to the dealership, and ask them to check "min/max deterioration". This is recorded by the BMS. This way, you will have the correct degradation.

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I have a service appointment (over) due so I'll ask them to do just that!

Aside from a rattle that the dealer can't seem to excise the car has been a real treat over the last year. I love almost everything about it.

mtndrew1 said:

Aside from a rattle that the dealer can't seem to excise the car has been a real treat over the last year. I love almost everything about it.

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I think I may have something similar... We thought it was the trunk cover bumping up and down, but removed it and could still hear it. We think it may be the rear license plate, but keep forgetting to try and wedge something in between to see if that stops the noise.

Is your rattling coming from the rear of the vehicle as well?

mtndrew1: that is interesting data. Thanks for sharing.
I had read that to get a full 100% charge you need to trickle charge L1 after completing the L2 charge here http://rjandeviestay80.blogspot.com.
But I do not have an L1 cable so have never tried this.
I assumed both L2 and L3 charging slowed down at the end to balance the cells, but I have never tested this. I'll add this to my list of things to check once Soul Spy is working.
I too am getting much better performance now the weather is cooling. Daytime temps of 24, nighttime 18 seem to suit the car. Although perhaps the big difference is that I am no longer using the aircon.
My battery degradation as measured using an ELM327 is less than 2% in 6 months. I drive about half as many miles as you per month. If the decay is linear then I will not reach 30% in 7 years and not qualify for the warranty. Your car however may qualify sometime in the sixth year. Do people leasing their cars care what happens after the third year? There is a discussion about measuring battery data on the Soul Spy thread.

DarthNick said:

mtndrew1 said:

Aside from a rattle that the dealer can't seem to excise the car has been a real treat over the last year. I love almost everything about it.

Click to expand...

I think I may have something similar... We thought it was the trunk cover bumping up and down, but removed it and could still hear it. We think it may be the rear license plate, but keep forgetting to try and wedge something in between to see if that stops the noise.

Is your rattling coming from the rear of the vehicle as well?

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I believe I have a solution for your rattle! There are small plastic clips alongside the rear seats which are meant to hold the rear seatbelts taut when they're not in use. Ensure that the seatbelts are secured in these clips and verify that the little nylon loop behind the seatbelt buckles face the impact points where they would bang into the car.

It took me a while to figure out what the hell that noise was and it has been completely remedied since securing the belts after every use.

My rattle is in the A-pillar on the passenger side. The dealer fixed it once but it's back; I'll have them address it at my next service visit.

JejuSoul said:

But I do not have an L1 cable so have never tried this.
I assumed both L2 and L3 charging slowed down at the end to balance the cells, but I have never tested this. I'll add this to my list of things to check once Soul Spy is working.

Click to expand...

If you have access to an EVSE with adjustable amperage, setting it to 240V @ 6A would be equivalent to what the stock US 120V EVSE outputs. Maybe try that and see if you get some cell balancing?

The user manual states that a 6.6kWh charger is the "normal" charger for the car, and the trickle charger should only be used when a normal (6.6kWh) charger is not available. Therefor I think JejuSoul is right in assuming that charging slows down in the end to balance out the cells (this is perfectly normal in expensive LiPo chargers to RC-cars atleast). But I am really curious about your findings JejuSoul

I have driven my car 5.600 miles (9.000km), and still have no degradation according to my dealer ship ( I don't know if they are talking the truth). I have a 6.6kWh charger, since this is recommended by the user manual. The trickle charger makes the battery degrade faster, because the battery is in a state of chemical reactions much longer with a trickle-charger, than the normal-charger.
I always keep my car at 36-40% SOH when parked, and only charge about 10% - 40% at a time due to my driving pattern. I have only recharged the car to 100% four times since I got my car in april 2015, so hopefully my battery will last a long time.

JejuSoul: Regarding better performance in the temperatures you mention. I suspect the battery thrives the best at 22 degrees Celcius. That will explain why you get so good performance with nighttime temperatures at 18 degrees- and daytime at 24 degrees celcius.

I am living in Norway, and I am looking forward to see how the car is coping with the cold temperature and how it behaves in the snow. I will keep you posted if interested.

Other than that, I want to thank You for your good work on "Soul Spy".

Birkeland: My car is similar to yours. 6 months old, driven 7000km. I also avoid charging to 100% but tend to charge to 80% and then run it down to 25% or so before charging again. In the first few months I used both L2 and L3 chargers but tend to stick with L2 now.
I am not the author of Soul Spy I am just one of the people contributing ideas on the Soul Spy thread.

mtndrew1 said:

DarthNick said:

mtndrew1 said:

Aside from a rattle that the dealer can't seem to excise the car has been a real treat over the last year. I love almost everything about it.

Click to expand...

I think I may have something similar... We thought it was the trunk cover bumping up and down, but removed it and could still hear it. We think it may be the rear license plate, but keep forgetting to try and wedge something in between to see if that stops the noise.

Is your rattling coming from the rear of the vehicle as well?

Click to expand...

I believe I have a solution for your rattle! There are small plastic clips alongside the rear seats which are meant to hold the rear seatbelts taut when they're not in use. Ensure that the seatbelts are secured in these clips and verify that the little nylon loop behind the seatbelt buckles face the impact points where they would bang into the car.

It took me a while to figure out what the hell that noise was and it has been completely remedied since securing the belts after every use.

Click to expand...

Oh sweet! Will try that as soon as I get into the car!

mtndrew1 said:

From that date forward I have kept a running Google Sheets spreadsheet tracking how my battery performs. I'm not at all consistent with the variables here (tire pressure, HVAC use, ambient temps, average speeds, etc); I'm simply extrapolating what the car tells me on the dash and contrasting it against a known, carefully-controlled test when the car was new.
https://docs.google.com/spreadsheets/d/1kfyB1q3LMKcM1OzCnLp-CJxcLANAaIMZHRgBmgQgxGw/edit?usp=sharing
Most of the time I just charge to 80%, drive the car around like any other car, HVAC set to "Auto 74," radio blasting, and don't give a thought to range. The car just has plenty of range for me and I've never had any sort of anxiety about it.

Click to expand...

Interesting to see that you are still adding data to that spreadsheet. Looking at the recent data it seems that your car is suffering range loss in the last few months. Yet from your Torque Pro data - posted here Re: Battery Ageing Model we know that you have very little deterioration. Why do you think there is a discrepancy?