Maintaining battery life

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Anonymous

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Hello all.
New owner here.
I read the energy tip on the car and it says keep plugin even if the battery is fully charged to condition the battery for the next ride. However, some websites say never charge the battery full to extend battery life. http://www.lacarguy.com/green/article/eight-tips-to-extend-battery-life-of-your-electric-car , http://www.teslarati.com/top-5-tips-to-maintaining-ev-battery/ . I guess GM knows their batteries and give the right tips, but other websites made solid points too. Which way is better?
 
Go with GM's recommendations. Note that there are special considerations for long term storage, and plugging in during extreme weather is specified. I've had a Spark EV for 26 months and over 24000 miles and the battery seems to be as good as ever. Certainly, it's not degrading nearly as much as a friend's Leaf has.
 
The articles seem more geared to the Leaf and the Tesla. The Spark EV uses a different thermal management design from the others. The Leaf doesn't even have active liquid cooling.

The recommendation from GM is to leave the car plugged in. On a hot day, the car will activate the cooling loop for the battery. On a cold day, the heater will turn on. All of that fo course can drain the battery. Another recommendation I've seen is to start the car while it's plugged in, if it's a hot or cold day. This will heat up or cool down the interior without drawing as much power from the battery.

The Spark EV has three separate cooling systems -- one for the electric motor, one for the heater, and the other for the battery.
 
I would respectfully disagree. There is plenty of evidence, including technical data, to indicate that lithium ion batteries kept at 100% SOC degrade much faster. Tesla recommends only charging to 80–90% unless you absolutely need the full range. The same applies for extreme discharging. Try to avoid going down to under 10 miles.

Unfortunately, lithium ion batteries are fussy: They don't like to be fully charged, don't like to be fully discharged, don't like to be too hot, and don't like to be too cold. Obviously, these extremes cannot be fully avoided in normal use. But you can extend battery life by minimizing them.
 
elpwr said:
I would respectfully disagree. There is plenty of evidence, including technical data, to indicate that lithium ion batteries kept at 100% SOC degrade much faster. Tesla recommends only charging to 80–90% unless you absolutely need the full range. The same applies for extreme discharging. Try to avoid going down to under 10 miles.

Unfortunately, lithium ion batteries are fussy: They don't like to be fully charged, don't like to be fully discharged, don't like to be too hot, and don't like to be too cold. Obviously, these extremes cannot be fully avoided in normal use. But you can extend battery life by minimizing them.
The question I have is this - Did the engineers protect the battery by limiting a "full" charge to something less than 100% of maximum capacity and a full discharge to something greater than 0% full discharge? The manual states the vehicle should be left plugged in during extremely hot or cold conditions.
 
MrDRMorgan said:
elpwr said:
I would respectfully disagree. There is plenty of evidence, including technical data, to indicate that lithium ion batteries kept at 100% SOC degrade much faster. Tesla recommends only charging to 80–90% unless you absolutely need the full range. The same applies for extreme discharging. Try to avoid going down to under 10 miles.

Unfortunately, lithium ion batteries are fussy: They don't like to be fully charged, don't like to be fully discharged, don't like to be too hot, and don't like to be too cold. Obviously, these extremes cannot be fully avoided in normal use. But you can extend battery life by minimizing them.
The question I have is this - Did the engineers protect the battery by limiting a "full" charge to something less than 100% of maximum capacity and a full discharge to something greater than 0% full discharge? The manual states the vehicle should be left plugged in during extremely hot or cold conditions.


I've had the same question: does the Spark actually reach 100% charge, or is it limited to something less than that? I don't think comparing the Spark to a Tesla is necessarily valid.
 
The Spark, the Tesla, and almost all EV's block a certain amount of battery capacity at both the top and bottom of the range to extend battery life. Many hybrids use only 60% or so of battery capacity to extend life. But most pure EV's push their batteries much harder often using 90% of capacity.

My '14 Spark will show almost 19kwh/hrs used on a full charge/discharge cycle. This on the A123 battery rated for 21.4 kWh/hrs. That's using nearly 90% of capacity, similar to what Tesla owners are seeing.

You can find several technical papers showing that lithium batteries will frequently only have a few hundred cycles of full 100% charge/discharge before significant degradation sets in. The same studies will show that the life can be extended to many thousands of cycles if the SOC extremes are avoided.
 
I can understand, and agree with, the rationale of keeping the Spark plugged in during temperature extremes. Over 90° and less than 32°. When plugged in, battery conditioning will occur in these extreme conditions, providing better initial cold weather capacity and cooling the battery if temps exceed about 90°.
 
elpwr said:
...My '14 Spark will show almost 19kwh/hrs used on a full charge/discharge cycle. This on the A123 battery rated for 21.4 kWh/hrs. That's using nearly 90% of capacity, similar to what Tesla owners are seeing. ..

^^^This is the answer.

And also the part about letting the pack sit in storage with 100% SOC, especially if you are not keeping it plugged in for the Thermal Management System (TMS) to keep the battery from getting too hot, like at an airport for weeks in the summer heat. (For some reason on the Spark EV they call TMS 'battery conditioning'.)

I charge mine once a day at work. It sits for ~4 hrs at 100% SOC, then I commute home and it sits over night at ~60% SOC. So it's only spending 4hrs a day of its life at 100%.
In the coldest weather I'll plug in at home also.

That's my routine. Who knows if it will help in the long run?
 
Could you use your delayed charging to arrive at 100% right before you depart work? That would really minimize your 100% SOC time.

I typically only use about 50% of a full charge per day. So I charge to about 80-85% in the morning by setting my departure time about 1 1/2 hours later than my actual departure and unplugging early.
 
elpwr said:
Could you use your delayed charging to arrive at 100% right before you depart work? That would really minimize your 100% SOC time.

I typically only use about 50% of a full charge per day. So I charge to about 80-85% in the morning by setting my departure time about 1 1/2 hours later than my actual departure and unplugging early.
Excellent idea !! Thanks for the suggestion !

I really don't use 50% in a one way direction. In fact, I can make 3 one way trips now that 'heat season' is gone.
I don't feel like fiddling with what time to start the charge and good EV etiquette keep me from hogging a charge spot all day.
(But really it's only me and a friend in a Volt. We both work across from the company that is providing the spots and the electrons.....but the network is free to the public, the EV Public !)

I think what I'll start doing is park at work in the AM and then take it to the charge station at a time that will give me the ~80-90% SOC by quitting time.
If I get the Bat Signal to head out on the town when I get home, I can always stop at one of 14 DCFC units around town,, as needed.
 
nikwax said:
I've had the same question: does the Spark actually reach 100% charge, or is it limited to something less than that?
For 2014 with 21kWh A123 battery, Tony Williams found the range to be 98 miles at 62 MPH as 5 mi/kWh. Then the usable battery capacity is

98/5 = 19.6 kWh, or about 93%

For 2015 with 19 kWh (actually 18.4) LG battery, Tony found the range to be 88 miles at 62 MPH as 5 mi/kWh.

88/5 = 17.6 kWh, or about 93%

Both are rough numbers. Since they're not likely to drain the battery down to 0%, we can assume some margin, maybe half the reserve on top and bottom. Then I suspect the peak would be very close to 100%, maybe 96%. Whether 96% is significantly better than 100%, I don't know, but I doubt it.
 
SparkevBlogspot said:
nikwax said:
I've had the same question: does the Spark actually reach 100% charge, or is it limited to something less than that?
For 2014 with 21kWh A123 battery, Tony Williams found the range to be 98 miles at 62 MPH as 5 mi/kWh. Then the usable battery capacity is

98/5 = 19.6 kWh, or about 93%

For 2015 with 19 kWh (actually 18.4) LG battery, Tony found the range to be 88 miles at 62 MPH as 5 mi/kWh.

88/5 = 17.6 kWh, or about 93%

Both are rough numbers. Since they're not likely to drain the battery down to 0%, we can assume some margin, maybe half the reserve on top and bottom. Then I suspect the peak would be very close to 100%, maybe 96%. Whether 96% is significantly better than 100%, I don't know, but I doubt it.
I think it is quite important to have a way to calculate any degradation in the battery's capacity. Last year I started collecting the energy information data available on the display. I allow the car to use about 50% and then I calculate the battery's capacity by dividing the kWh used by the percent of the battery that was used. Then I fully recharge the battery so the energy info values reset to zero. for my 2014 Spark EV, I had 8 values in 2015 that averaged 20.04 kWh and I have 11 values to date in 2016 that average 18.86 kWh. For my 2015 Spark EV, I had 15 values in 2015 that averaged 18.48 kWh and I have 23 values so far in 2016 that average 17.62 kWh. I think it would be useful to see what other Spark EV drivers are getting. Any serious degradation in battery capacity would reflect negatively on the new Chevy Bolt due out at the end of this year. I believe GM has to be using OnStar to gather useful data from the Spark EVs on the road to get a good feel for the answer to this question.
 
MrDRMorgan said:
SparkevBlogspot said:
nikwax said:
I've had the same question: does the Spark actually reach 100% charge, or is it limited to something less than that?
For 2014 with 21kWh A123 battery, Tony Williams found the range to be 98 miles at 62 MPH as 5 mi/kWh. Then the usable battery capacity is

98/5 = 19.6 kWh, or about 93%

For 2015 with 19 kWh (actually 18.4) LG battery, Tony found the range to be 88 miles at 62 MPH as 5 mi/kWh.

88/5 = 17.6 kWh, or about 93%

Both are rough numbers. Since they're not likely to drain the battery down to 0%, we can assume some margin, maybe half the reserve on top and bottom. Then I suspect the peak would be very close to 100%, maybe 96%. Whether 96% is significantly better than 100%, I don't know, but I doubt it.
I think it is quite important to have a way to calculate any degradation in the battery's capacity. Last year I started collecting the energy information data available on the display. I allow the car to use about 50% and then I calculate the battery's capacity by dividing the kWh used by the percent of the battery that was used. Then I fully recharge the battery so the energy info values reset to zero. for my 2014 Spark EV, I had 8 values in 2015 that averaged 20.04 kWh and I have 11 values to date in 2016 that average 18.86 kWh. For my 2015 Spark EV, I had 15 values in 2015 that averaged 18.48 kWh and I have 23 values so far in 2016 that average 17.62 kWh. I think it would be useful to see what other Spark EV drivers are getting. Any serious degradation in battery capacity would reflect negatively on the new Chevy Bolt due out at the end of this year. I believe GM has to be using OnStar to gather useful data from the Spark EVs on the road to get a good feel for the answer to this question.

This is the capacity of my 2014 Spark EV using the same technique from September 2013 to now (~2.5 years). I usually charge at night so the car is sitting at 100% (or whatever the full SOC is) for many hours. Whether that is significant I don't know.

kevin
SparkBattery.png
 
Wait, what? This graph says you lost 10% in 13,000mi. That's horrendous.

In my 2015 (completely different battery), I'm showing no appreciable degradation over 11,000 mi using 240+ datapoints.
 
Zoomit said:
Wait, what? This graph says you lost 10% in 13,000mi. That's horrendous.

In my 2015 (completely different battery), I'm showing no appreciable degradation over 11,000 mi using 240+ datapoints.
Perhaps you have found the "correct way" to treat your battery. What is your secret? Also, how are you calculating your capacity values? Here is my info: I purchased my used 2014 Spark EV in August of 2015 and the car had only 1500 miles on the ODO. I took 8 measurements from Aug 17 through Sep 9 and the ODO went from 1661 to 2014 miles. The average calculated battery capacity is 20.04 kWh. This year, 2016, from Mar 7 through Apr 18, I collected 11 more readings and the ODO has gone from 4483 to 4990. These 11 readings have averaged 18.86 kWh. The calculated drop in average battery capacity is 5.6%. I leased my 2015 Spark EV at the end of May in 2015. In 2015, I took 15 readings from Jul 1 through Aug 29. The average of the 15 battery capacity calculations was 18.48 kWh and the ending ODO was 2450 miles. This year, 2016, I have collected 23 readings from Mar 3 through Apr 19 and the ODO started at 8410 and ended at 9406 miles. The average of the 23 battery capacity readings is 17.56 kWh. The calculated drop in average battery capacity is 5%.
 
MrDRMorgan said:
Perhaps you have found the "correct way" to treat your battery. What is your secret? Also, how are you calculating your capacity values? Here is my info: I purchased my used 2014 Spark EV in August of 2015 and the car had only 1500 miles on the ODO. I took 8 measurements from Aug 17 through Sep 9 and the ODO went from 1661 to 2014 miles. The average calculated battery capacity is 20.04 kWh. This year, 2016, from Mar 7 through Apr 18, I collected 11 more readings and the ODO has gone from 4483 to 4990. These 11 readings have averaged 18.86 kWh. The calculated drop in average battery capacity is 5.6%. I leased my 2015 Spark EV at the end of May in 2015. In 2015, I took 15 readings from Jul 1 through Aug 29. The average of the 11 battery capacity calculations was 18.48 kWh and the ending ODO was 2450 miles. This year, 2016, I have collected 23 readings from Mar 3 through Apr 19 and the ODO started at 8410 and ended at 9406 miles. The average of the 23 battery capacity readings is 17.56 kWh. The calculated drop in average battery capacity is 5%.

Just wondering, for both cars you took the "good" reading during the summer and the "bad" readings in winter/spring. I know temperature affects battery performance, couldn't that be skewing your data?

On a side note, I have a 2014 Spark EV and can drive from San Diego to Disneyland (about 100 miles) and still have about 20+ miles left on the guessometer during the summer with an efficiency of 6.7m/kWh, I could not make the same trip during the winter.
 
Zoomit said:
Wait, what? This graph says you lost 10% in 13,000mi. That's horrendous.

In my 2015 (completely different battery), I'm showing no appreciable degradation over 11,000 mi using 240+ datapoints.

I agree it is very disappointing - I had hoped for better from LiFePO4.

Surprisingly the fully charged range hasn't dropped quite as much as the battery capacity as the efficiency has increased from 5.7mi/kWh to ~5.9mi/kWh - probably because the front tires are wearing out.

I have updated my post with more recent data and the capacity seems to be leveling out at ~17kWh.

kevin
 
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.
 
saintyohann said:
MrDRMorgan said:
Perhaps you have found the "correct way" to treat your battery. What is your secret? Also, how are you calculating your capacity values? Here is my info: I purchased my used 2014 Spark EV in August of 2015 and the car had only 1500 miles on the ODO. I took 8 measurements from Aug 17 through Sep 9 and the ODO went from 1661 to 2014 miles. The average calculated battery capacity is 20.04 kWh. This year, 2016, from Mar 7 through Apr 18, I collected 11 more readings and the ODO has gone from 4483 to 4990. These 11 readings have averaged 18.86 kWh. The calculated drop in average battery capacity is 5.6%. I leased my 2015 Spark EV at the end of May in 2015. In 2015, I took 15 readings from Jul 1 through Aug 29. The average of the 11 battery capacity calculations was 18.48 kWh and the ending ODO was 2450 miles. This year, 2016, I have collected 23 readings from Mar 3 through Apr 19 and the ODO started at 8410 and ended at 9406 miles. The average of the 23 battery capacity readings is 17.56 kWh. The calculated drop in average battery capacity is 5%.

Just wondering, for both cars you took the "good" reading during the summer and the "bad" readings in winter/spring. I know temperature affects battery performance, couldn't that be skewing your data?

On a side note, I have a 2014 Spark EV and can drive from San Diego to Disneyland (about 100 miles) and still have about 20+ miles left on the guessometer during the summer with an efficiency of 6.7m/kWh, I could not make the same trip during the winter.
Yes, it is very possible the air temperature is skewing the numbers. I will be taking readings for the next year or so with emphasis on taking readings at the same time as I did in 2015. July, August and September 2015 were quite hot here in the Central Valley of California. But I am just not sure air temperature affects the capacity calculation using % of Battery Used and the number of kWh used. I know air temperature affects my mi / kWh numbers.
 
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