Battery degredation

[SparkE]

Steves Chevrolet Buick in Oakdale has a 25kW charger (Bosch, not the crappy ChargePoint 24 kW unit).

There are two ChargePoint 50 kW (125A) units going in on N Third Ave in Oakdale - work started, unit there, just not turned on yet.

 

[MrDRMorgan]

Steves Chevrolet Buick in Oakdale has a 25kW charger (Bosch, not the crappy ChargePoint 24 kW unit).

There are two ChargePoint 50 kW (125A) units going in on N Third Ave in Oakdale - work started, unit there, just not turned on yet.

Thanks. for the info. I am aware of both but I rarely venture to Oakdale and I have never tried Steves Chevrolet. I may have to try it.

 

[RSC]

Steves Chevrolet Buick in Oakdale has a 25kW charger (Bosch, not the crappy ChargePoint 24 kW unit).

There are two ChargePoint 50 kW (125A) units going in on N Third Ave in Oakdale - work started, unit there, just not turned on yet.

Thanks. This would make Modesto an easy reasonable trip for me.

 

[ChaosMageX]

So, who has put the most mileage on their owned Chevy Spark EV by now? Is there a point where degradation at least starts to plateau off, or will the battery just keep gradually melting away with every mile, down to 14 kWh, 13 kWh, 12 kWh...until you can't even get 40 miles out of the car on a single charge, even in city commuting without running the HVAC?

Again, please tell me otherwise. Please tell me I don't have sweat bullets with looking at 2016 models on Carvana with more than 30,000 miles or more than 40,000 miles or even more than 50,000 miles.

 

[MrDRMorgan]

So, who has put the most mileage on their owned Chevy Spark EV by now? Is there a point where degradation at least starts to plateau off, or will the battery just keep gradually melting away with every mile, down to 14 kWh, 13 kWh, 12 kWh...until you can't even get 40 miles out of the car on a single charge, even in city commuting without running the HVAC?

Again, please tell me otherwise. Please tell me I don't have sweat bullets with looking at 2016 models on Carvana with more than 30,000 miles or more than 40,000 miles or even more than 50,000 miles.

This is a good question and, from my experience so far, I can only say that it looks like battery degradation is a continuous process. The real question is what is causing it.

I have a 2014 Spark EV 2LT w/o DCFC and it only has 18054 miles on the ODO. The battery capacity, as measured by TorquePro, has dropped from 17.2 kWh to 16.2 kWh over the last 3910 miles. This car is mainly charged using an L1 EVSE set to 12 amps.

I also have a 2016 Spark EV 2LT with DCFC and it only has 18351 miles on the ODO. The battery capacity, as measured by TorquePro, has dropped from 16.6 kWh to 15.5 kWh over the last 8067 miles. This car is mainly charge using an L2 EVSE and, much less often, at EVgo DCFC stations.

Right now I am only charging to 80-85% SoC and discharging to an SoC no lower than 25% to see if charging to 100% is the culprit. I will be running this test for the next 6 months or more to see if there is also a seasonal variation due to air temperatures.

 

[NORTON]

...
Again, please tell me otherwise. Please tell me I don't have sweat bullets with looking at 2016 models on Carvana with more than 30,000 miles or more than 40,000 miles or even more than 50,000 miles.

There is one Spark EV that has over 100k miles. The owner posts here.

My '14 at +65k miles still shows mid to upper 70's miles of range on the GOM , now that spring has sprung!
But I still use a little heat and defrost and I always flog the little beasty in the left lane in rush hour traffic. 70-80 mph, but with some slow bumper to bumper in the evenings, sometimes.

If I drove the slower country way to and from work I'm certain it would be displaying in the 80's again!
I don't know how this is explained. It got better after the SW update when it was in the shop for a long repair/dispute over what is covered by the 8yr/100k mile power train warranty.

I haven't calculated kWh capacity in a while. I'll start logging that again soon.

 

[MrDRMorgan]

...
Again, please tell me otherwise. Please tell me I don't have sweat bullets with looking at 2016 models on Carvana with more than 30,000 miles or more than 40,000 miles or even more than 50,000 miles.

There is one Spark EV that has over 100k miles. The owner posts here.

My '14 at +64k miles still shows mid to upper 70's miles of range on the GOM , now that spring has sprung!
But I still use a little heat and defrost and I always flog the little beasty in the left lane in rush hour traffic. 70-80 mph, but with some slow bumper to bumper in the evenings, sometimes.

If I drove the slower country way to and from work I'm certain it would be displaying in the 80's again!
I don't know how this is explained. It got better after the SW update when it was in the shop for a long repair/dispute over what is covered by the 8yr/100k mile power train warranty.

I haven't calculated kWh capacity in a while. I'll start logging that again soon.

If I charge either of my cars to 80 to 85% SoC and divide the final GOM number by the SoC number (as measured by TorquePro), I get a very good estimate of my full-charge range. My 2014 is currently at 95-96 miles and my 2016 is at 102-103 miles. Most of my driving is around town so I expect higher GOM numbers and I am currently seeing is my mi/kWh values in the 6s and 7s. This seems to always be the case as the air temperature gets back into the 70's and 80's and before I start using the AC.

This morning I disconnected my 2014 at 8 am as scheduled. I used TorquePro and measured my battery SoC number. It was 78.0%. The GOM read 74 miles. 74 miles / 78% = 100 miles of range at 100% full charge.

If I jump onto the freeway and drive at 65 mph for a long period, my mi/kWh drops to around 5.0 to 5.3. Kick on the AC and I drop to 4.5 - 5.0 mi/kWh.

 

[ChaosMageX]

...
Again, please tell me otherwise. Please tell me I don't have sweat bullets with looking at 2016 models on Carvana with more than 30,000 miles or more than 40,000 miles or even more than 50,000 miles.

There is one Spark EV that has over 100k miles. The owner posts here.

My '14 at +65k miles still shows mid to upper 70's miles of range on the GOM , now that spring has sprung!
But I still use a little heat and defrost and I always flog the little beasty in the left lane in rush hour traffic. 70-80 mph, but with some slow bumper to bumper in the evenings, sometimes.

If I drove the slower country way to and from work I'm certain it would be displaying in the 80's again!
I don't know how this is explained. It got better after the SW update when it was in the shop for a long repair/dispute over what is covered by the 8yr/100k mile power train warranty.

I haven't calculated kWh capacity in a while. I'll start logging that again soon.

Well, it's good to know that GOM still displays high range on a high mileage Spark EV, but unfortunately yours and probably the 100k one use A123 batteries, and comparing those to the LG Chem batteries in the newer models is probably like comparing apples to oranges. Things will get even more confusing if GM decides to switch to another supplier further down the line, such as CATL or SKI, since I heard LG Chem is being rather mean to its clients.

Like I said, as I look at the selection on Carvana right now, the average mileage of the 2016 Chevy Spark EVs available is around 30k to 40k, so it would be helpful to know how much the 19 kWh LG Chem battery has decayed by that mileage. That kind of mileage makes sense, because that's about how much you'd rack up from an average length work commute over the course of 3 years, so hopefully someone will have data soon. Fortunately, all of them seem to have fast charging provisions, so they'll be compatible with EVgo, Electrify America, and other DCFC stations. If MrDRMorgan's post is any indication, the battery seems to decay twice as slowly when using DCFC, probably because of what others have said about DCFC helping to balance charge between all of the cells in the traction battery. It seems that DCFC might be the way to go, even if it's more expensive than slow charging at home. Though recently, I've heard it's possible to put a 100 amp 220 volt circuit in your home, so it may be possible to get DCFC at home. Are there any good reliable 22 kW SAE CCS home DCFC chargers that can balance the cells?

 

[NORTON]

It is my understanding that the balancing routine takes place after the pack is at 100% SOC on L1 or L2, only.
After all there are some of these cars without the $750 optional DCFC provisions. How would they ever have balanced cells if it was only on DCFC?

I've seen it happening sometimes on a public L2 where I can see on the app that the car continued to use ~600W for a while, ~20 mins, after it stopped charging at 3.3kW. It was a nice day and I sure it wasn't TMS using the power.

I thought I read it does not happen on a DCFC. And I personally have never charged to 100% SOC on a DCFC. It's usually a 10-15 minute chit&git.

 

[MrDRMorgan]

Here is what I have seen over the last four years:

1. My 2014 Spark EV without DCFC is charged almost every night to 100% using my L1 EVSE set to 12 amps. The HV battery capacity in my 2014 Spark EV w/o DCFC has degraded from 19.81 kWh at 2k miles to 16.2 kWh at 18k miles

2. My 2015 Spark EV with DCFC (leased and now returned) was charged almost every night to 100% using my L2 EVSE. When I drove out of town, I use EVgo DCFC stations and charge to 90-95%. The HV battery capacity in my 2015 Spark EV degraded from 18.8 kWh at 1400 miles on the ODO to 15.49 kWh with 26508 miles on the ODO.

3. My 2016 Spark EV with DCFC is charged almost every night to 100% using my L2 EVSE. When I drive out of town I use EVgo DCFC stations and charge to 90 -95%. The HV battery capacity in my 2016 Spark EV with DCFC has degraded from 17.4 kWh at 8k miles to 15.5 kWh at 18k miles.

A friend of mine, who had a 2015 Spark EV with about 33k miles on the ODO, charged to 100% every night using his L1 EVSE. I used to TorquePro to check his battery capacity at 33k miles. It read 14.8 kWh!

The HV battery does degrade. How fast and why are questions for which I am still trying to find answers. I have just started limiting my at-home charging to 85% of full charge to see if the HV battery degradation can be slowed down by not stressing the battery with a 100% full charge. I also limit DCFC charging of my 2016 Spark EV to 90%. An occasional 100% full charge will be required to keep the cells balanced.

 

[user 1908]

My recently purchased 2016 Spark was a Certified Pre Owned. I also purchased an OBD2 port to monitor my car’s diagnostics. From the day I got it, it has shown a total capacity of 15.9 kWh. It seems others are showing much higher capacity, more in the 18-19kWh range.

At what point does the battery capacity degradation become a warranty issue? And is it different for a CPO?

 

[MrDRMorgan]

My recently purchased 2016 Spark was a Certified Pre Owned. I also purchased an OBD2 port to monitor my car’s diagnostics. From the day I got it, it has shown a total capacity of 15.9 kWh. It seems others are showing much higher capacity, more in the 18-19kWh range.

At what point does the battery capacity degradation become a warranty issue? And is it different for a CPO?

You can find the information you need in the Chevrolet Limited Warranty and Owner Assistance Information booklet. Here is the link-

https://my.chevrolet.com/content/dam/gmownercenter/gmna/dynamic/manuals/2016/Chevrolet/Multi-Model%20PDFs/2k16chevylimitedwty3rdPrint.pdf. Refer to page 14.

8 years or 100K miles or >40% battery degradation in that period of time or mileage; which ever comes first.

My 2016 Spark EV 2LT only has 18.5K miles on the ODO and the TorquePro measured battery capacity is already 15.5 kWh. Assuming a new battery had 19 kWh, my battery needs to degrade below 11.4 kWh to become a warranty issue AND as long as it occurs within the specified time or mileage limits.

 

[RSC]

I have a 2014 Spark EV 2LT w/o DCFC and it only has 18054 miles on the ODO. The battery capacity, as measured by TorquePro, has dropped from 17.2 kWh to 16.2 kWh over the last 3910 miles. This car is mainly charged using an L1 EVSE set to 12 amps.

I also have a 2016 Spark EV 2LT with DCFC and it only has 18351 miles on the ODO. The battery capacity, as measured by TorquePro, has dropped from 16.6 kWh to 15.5 kWh over the last 8067 miles. This car is mainly charge using an L2 EVSE and, much less often, at EVgo DCFC stations.

Right now I am only charging to 80-85% SoC and discharging to an SoC no lower than 25% to see if charging to 100% is the culprit. I will be running this test for the next 6 months or more to see if there is also a seasonal variation due to air temperatures.

Sounds like you could use a control. My car might be appropriate. I have a 2015 purchased off-lease as a CPO. Currently it has 18590 miles and I'm getting 16.x kWh according to the energy display. I recently got an OBD2 adapter but haven't yet set up Torque Pro. I might try to get to it this week and might have to ask questions if I run into difficulties. I've recently being doing the delayed departure (9 am) and disconnecting at 7 am, but am thinking about going back to my usual charging routine. This way my car could be compared to yours over the next 6 months. I'm using the stock L1 EVSE set to 8 amps.

 

[MrDRMorgan]

I have a 2014 Spark EV 2LT w/o DCFC and it only has 18054 miles on the ODO. The battery capacity, as measured by TorquePro, has dropped from 17.2 kWh to 16.2 kWh over the last 3910 miles. This car is mainly charged using an L1 EVSE set to 12 amps.

I also have a 2016 Spark EV 2LT with DCFC and it only has 18351 miles on the ODO. The battery capacity, as measured by TorquePro, has dropped from 16.6 kWh to 15.5 kWh over the last 8067 miles. This car is mainly charge using an L2 EVSE and, much less often, at EVgo DCFC stations.

Right now I am only charging to 80-85% SoC and discharging to an SoC no lower than 25% to see if charging to 100% is the culprit. I will be running this test for the next 6 months or more to see if there is also a seasonal variation due to air temperatures.

Sounds like you could use a control. My car might be appropriate. I have a 2015 purchased off-lease as a CPO. Currently it has 18590 miles and I'm getting 16.x kWh according to the energy display. I recently got an OBD2 adapter but haven't yet set up Torque Pro. I might try to get to it this week and might have to ask questions if I run into difficulties. I've recently being doing the delayed departure (9 am) and disconnecting at 7 am, but am thinking about going back to my usual charging routine. This way my car could be compared to yours over the next 6 months. I'm using the stock L1 EVSE set to 8 amps.

I found the following HV battery capacity information from Chevrolet Product Information documents for each model year:

2014 Spark EV - 21.0 kWh
2015 Spark EV - 18.4 kWh
2016 Spark EV - 19.0 kWh

 

[RSC]

I found the following HV battery capacity information from Chevrolet Product Information documents for each model year:

2014 Spark EV - 21.0 kWh
2015 Spark EV - 18.4 kWh
2016 Spark EV - 19.0 kWh

That's interesting. I had assumed that 2015 and 2016 were the same.

 

[MrDRMorgan]

I found the following HV battery capacity information from Chevrolet Product Information documents for each model year:

2014 Spark EV - 21.0 kWh
2015 Spark EV - 18.4 kWh
2016 Spark EV - 19.0 kWh

That's interesting. I had assumed that 2015 and 2016 were the same.

Using data from the energy information screen in my leased 2015 Spark EV, my "calculated" battery capacity from 1000 miles to 8000 miles ranged between 18.09 kWh to 18.98 kWh. Between 8000 miles to 25000 miles it ranged between 17kWh an 18 kWh. At about 26000 miles, the Check Engine light came on and my calculated battery capacity dropped to right around 16 kWh and never improved even after the defective electrical component was replaced by the dealer. When I turned in the car at about 30k miles, the calculated battery capacity had dropped further to about 15.3 kWh.

 

[RSC]

I found the following HV battery capacity information from Chevrolet Product Information documents for each model year:

2014 Spark EV - 21.0 kWh
2015 Spark EV - 18.4 kWh
2016 Spark EV - 19.0 kWh

That's interesting. I had assumed that 2015 and 2016 were the same.

Using data from the energy information screen in my leased 2015 Spark EV, my "calculated" battery capacity from 1000 miles to 8000 miles ranged between 18.09 kWh to 18.98 kWh. Between 8000 miles to 25000 miles it ranged between 17kWh an 18 kWh. At about 26000 miles, the Check Engine light came on and my calculated battery capacity dropped to right around 16 kWh and never improved even after the defective electrical component was replaced by the dealer. When I turned in the car at about 30k miles, the calculated battery capacity had dropped further to about 15.3 kWh.

I got started today on setting up Torque Pro. I used the Bolt PIDs from Sean Graham (chevybolt.org). So far I've only set up one, the "Battery Capacity Guess", displayed as "Bat Cap Est" in Torque Pro. The displayed value is 16.1 kWh at 18601 miles. Is this the value we mean when we are talking about battery capacities as displayed by Torque Pro?

I guess this means 12.5% degradation. I'll log this over the next few months.

P.S.
I did this on a Chromebook because I thought that it would be easier to work with files and spreadsheets, and also a larger display.

 

[MrDRMorgan]

That's interesting. I had assumed that 2015 and 2016 were the same.

Using data from the energy information screen in my leased 2015 Spark EV, my "calculated" battery capacity from 1000 miles to 8000 miles ranged between 18.09 kWh to 18.98 kWh. Between 8000 miles to 25000 miles it ranged between 17kWh an 18 kWh. At about 26000 miles, the Check Engine light came on and my calculated battery capacity dropped to right around 16 kWh and never improved even after the defective electrical component was replaced by the dealer. When I turned in the car at about 30k miles, the calculated battery capacity had dropped further to about 15.3 kWh.

I got started today on setting up Torque Pro. I used the Bolt PIDs from Sean Graham (chevybolt.org). So far I've only set up one, the "Battery Capacity Guess", displayed as "Bat Cap Est" in Torque Pro. The displayed value is 16.1 kWh at 18601 miles. Is this the value we mean when we are talking about battery capacities as displayed by Torque Pro?

I guess this means 12.5% degradation. I'll log this over the next few months.

P.S.
I did this on a Chromebook because I thought that it would be easier to work with files and spreadsheets, and also a larger display.

I now use TorquePro instead of the "calculated" capacity value derived from information taken from the Energy Information screen in the car. I am using the PIDS provided by Sean Graham and I use the PID !Battery Capacity as the measurement I use to monitor the battery capacity degradation in my 2014 and 2016 Spark EVs. So far, it has been very useful over time in showing the rate of HV battery degradation in both cars. I also monitor the SoC and all cell voltages plus the average cell voltage.

I believe the 16.1 kWh value you mentioned IS the battery capacity for your car. You can use this number as a starting reference. Over time - many charging cycles and weeks of operation - you will begin to see the degradation curve develop. I am currently monitoring the number of miles between points where the measured battery capacity drops by 0.1 kWh.

 

[scrambler]

I now use TorquePro instead of the "calculated" capacity value derived from information taken from the Energy Information screen in the car.

Have you found a consistent above or below difference in the derived capacity value between using the energy information screen of the car (being careful to note values when all numbers change almost at the same time as to minimize rounding errors) and TorquePro?

 

[MrDRMorgan]

I now use TorquePro instead of the "calculated" capacity value derived from information taken from the Energy Information screen in the car.

Have you found a consistent above or below difference in the derived capacity value between using the energy information screen of the car (being careful to note values when all numbers change almost at the same time as to minimize rounding errors) and TorquePro?

I went back and looked at the Energy Information data I took for the first three years I had for my 2015 Spark EV. Many times the calculated value swung as much as +/- 1.0 kWh from the previous value. I find that the data taken using TorquePro is much, much, more stable and is easier to graph. But... if you collect enough data using the Energy Screen information over a long period of time and plot a linear trendline, you will still see an average degradation plot that should be reasonably accurate.

The TorquePro data for my 2014 spark EV shows a degradation rate of about 0.24 kWh per 1000 miles.

The Energy Information trendline for my 2015 Spark EV shows a degradation rate of about 0.11 kWh per 1000 miles.

The TorquePro data for my 2016 Spark EV shows a degradation rate of about 0.17 kWh per 1000 miles.