Maintaining battery life

[Zoomit]

Correct--I see no seasonal variation in the capacity estimate.

 

[MrDRMorgan]

I am not treating my battery with any specific "kindness". I charge to 100% nightly and discharge to 10-15% about 3-4 days a week, plus other shorter trips.

There is no noticable difference in the battery capacity estimate between summer and winter. The battery definitely performs worse in cold weather but that just means the kWh used goes up, per unit range, but the capacity seems constant. I'm getting close to a full year, when I will have theoretically nulled out all the seasonal variation and will summarize my findings.

The thing is though, I can't yet point to any decreasing capacity trend over my first 11,000mi. This is a geat conclusion for long term ownership of the 2015/16 cars, but it is obviously different than Kevin's results with his 2014 car, which has a different battery.

Very interesting. This is important to me because it will be a major determining factor for keeping my 2015 Spark EV at the end of the lease in 2018 or not. I have 2 more years to figure it out. Moreover, I have to believe, if a large number of 2015 & 2016 Spark EV owners see and make it known that a significant degradation in battery capacity is occurring in GM EVs built with the LG battery technology, GM may have a real problem getting people to buy the BOLT due out at the end of this year.

 

[elpwr]

I haven't kept detailed records, but I haven't seen 10% degradation in my '14 battery over 9000 miles so far. In fact, the computed re-charge capacity has only changed minimally from the 19 kWh I saw initially. Maybe down a fraction of a kWh.

I haven't "babied" my battery. But I have, where possible, used some well documented techniques for extending life - some of which we've discussed in this thread. But if I need a full charge, or to use a DCFC, (both of which are harder on the battery), I don't hesitate to do it.

Looking across the literature and in the EV forums, on average most of the lithium batteries degrade around 4-5% in the first year and then 1-2% each year thereafter when used in BEV applications. Seems like most of the reports here are close to that.

 

[SparkevBlogspot]

I'm not sure if comparing to other EV is apples-to-apples. For example, Leaf and eGolf lack thermal management (worse in Leaf), so they're more likely to degrade than SparkEV's excellent thermal management (probably best in industry, even better than Tesla IMO). But even SparkEV's 2014 vs 2015 thermal management is different, though probably minor in effect.

There's also the cycling; not all EV cycle to the same level. For example, Volt (also excellent thermal management) cycle far less of the full capacity than SparkEV, even with same sized battery (18.4 kWh).

Then there's the difference in chemistry. Even SparkEV 2014 vs 2015 chemistry is different.

As such, drawing conclusions based on other EV is probably not good. But given such excellent design, I suspect SparkEV ranks among the top in terms of degradation subject to similar usage. The key word here is similar usage, and that differs from person to person.

For reasonable care, one can look to best in business (Tesla); Tesla forums has some nice plots. For extreme use, one can look to warranty period of 8 years for 35% degradation. Best, of course, is to plot it oneself like Kevin did.

 

[MrDRMorgan]

I haven't kept detailed records, but I haven't seen 10% degradation in my '14 battery over 9000 miles so far. In fact, the computed re-charge capacity has only changed minimally from the 19 kWh I saw initially. Maybe down a fraction of a kWh.

I haven't "babied" my battery. But I have, where possible, used some well documented techniques for extending life - some of which we've discussed in this thread. But if I need a full charge, or to use a DCFC, (both of which are harder on the battery), I don't hesitate to do it.

Looking across the literature and in the EV forums, on average most of the lithium batteries degrade around 4-5% in the first year and then 1-2% each year thereafter when used in BEV applications. Seems like most of the reports here are close to that.

Thanks for that info. The limited warranty manual that came with my 2015 Spark EV says "Depending on use, the battery may degrade as little as 10% to as much as 35% of capacity(kWh storage) over the warranty period." The warranty period is 8 years or 100,000 miles.

 

[elpwr]

I think drawing conclusions from this and other BEV's, with similar thermal management, similar chemistry and similar capacity usage is reasonably useful.

I'm not obsessive enough to keep charts and worry that much about battery degradation. It is what it is. I think most of the better designed BEV will have similar degradation over time. It's just important to realize and accept that battery degradation is inevitable. And take some reasonable precautions to minimize it.

 

[MrDRMorgan]

I think drawing conclusions from this and other BEV's, with similar similar thermal management, similar chemistry and similar capacity usage is reasonably useful.

I'm not obsessive enough to keep charts and worry that much about battery degradation. It is what it is. I think most of the better designed BEV will have similar degradation over time. It's just important to realize and accept that battery degradation is inevitable. And take some reasonable precautions to minimize it.

To use some of your words with modification and a bit of tongue in cheek - I am obsessive enough to keep charts and wonder about battery degradation and characteristics. But, I can't change the battery's design nor how the battery is going to perform over time - It is what it is and I can live with 35% battery capacity degradation at the end of 8 years and still love driving this car. My purpose for purchasing / leasing the Spark EVs was to break away from "Big Oil". 90% of the driving my wife and I do is within 20 miles of our home and amounts to no more than 50 miles per day. On occasion we may venture to the Bay Area or the Sacramento / Roseville areas and that is when the Quick Charge option in the 2015 Spark EV is needed. Quick charge stations are already sited every 40 to 50 miles along all of my longer distance routes so battery degradation and its affect on my driving range is not a problem.

 

[elpwr]

- It is what it is and I can live with 35% battery capacity degradation at the end of 8 years and still love driving this car.[/quote]

And that's all that really matters!

 

[SparkevBlogspot]

Meanwhile, next gen EV battery could last a lifetime.

http://www.computerworld.com/article/3060005/mobile-wireless/scientists-can-now-make-lithium-ion-batteries-last-a-lifetime.html

 

[MrDRMorgan]

Meanwhile, next gen EV battery could last a lifetime.

http://www.computerworld.com/article/3060005/mobile-wireless/scientists-can-now-make-lithium-ion-batteries-last-a-lifetime.html

Alright!!! Long may Sparkie live!

 

[elpwr]

I just did two 100% charge to about 30% charge cycles. I recorded several data points during both discharges and computed the capacity from the energy usage screen. Got 18.8 kWh and 18.95 kWh.

These figures are very close to the 19 KWh I saw 9 months and 9000 miles ago when the car only had a couple hundred miles on it. It's a '14 MY car with a build date of Dec '13 so the battery is actually over 2 years old. This isn't a large enough sample to say for sure, but it appears that I have negligible battery degradation in the first 9000 miles and 2 years of usage.

I charge to 100% only when necessary, maybe two or three times a month. Most days I charge to about 80- 90% and end the day with 35-40%. I also avoid leaving the car for more than a couple of hours at 100% charge. Most of my driving is on country roads at 50–55 mph with some small-town traffic mixed in. I usually see around 5.2–5.5 m/kWh and about 100 to 102 mile indicated range at full charge.

 

[MrDRMorgan]

I just did two 100% charge to about 30% charge cycles. I recorded several data points during both discharges and computed the capacity from the energy usage screen. Got 18.8 kWh and 18.95 kWh.

These figures are very close to the 19 KWh I saw 9 months and 9000 miles ago when the car only had a couple hundred miles on it. It's a '14 MY car with a build date of Dec '13 so the battery is actually over 2 years old. This isn't a large enough sample to say for sure, but it appears that I have negligible battery degradation in the first 9000 miles and 2 years of usage.

I charge to 100% only when necessary, maybe two or three times a month. Most days I charge to about 80- 90% and end the day with 35-40%. I also avoid leaving the car for more than a couple of hours at 100% charge. Most of my driving is on country roads at 50–55 mph with some small-town traffic mixed in. I usually see around 5.2–5.5 m/kWh and about 100 to 102 mile indicated range at full charge.

Good information. Thanks. I am seeing similar numbers but I only have 5000 miles on my 2014 Spark EV. The average for the last 11 full charge sessions is 18.82 kWh. I guess it is possible that it takes a number of charging cycles to "normalize" the battery. My 2015 Spark EV has 10,000 miles on it and, after 20 recent full charge cycles covering 1000 miles, I am averaging 17.58 kWh with a flat trend line.

 

[elpwr]

Nobody likes to see battery degradation but it's normal and inevitable. Best we can do is try to minimize it by using some of the well-known techniques to preserve the battery.

An important thing to remember: lithium batteries degrade with time and usage but seldom completely fail. Several years from now with 25% less capacity, the battery should still be able to power the car effectively and reliably, but just with some reduced range and very slightly less power output.

 

[MrDRMorgan]

Nobody likes to see battery degradation but it's normal and inevitable. Best we can do is try to minimize it by using some of the well-known techniques to preserve the battery.

An important thing to remember: lithium batteries degrade with time and usage but seldom completely fail. Several years from now with 25% less capacity, the battery should still be able to power the car effectively and reliably, but just with some reduced range and very slightly less power output.

6-8 years from now, if not sooner, I hope someone will have figured out how to provide inexpensive replacement / rebuilt battery packs for EVs. My concern for the Spark EV is the small number of cars that will have been sold by the time it is discontinued at the end of 2016.