Battery degredation

[DDMan11]

I've had my 2014 Spark for now a year and 8 months. The car now has 23k on the odometer but my battery life has suffered greatly. I began with 80-100 miles of range (depending on my driving style and weather), but now I'm getting 60-75 miles.

I've used the built in battery usage meter, and today, I had 8.8 KW used at 50% battery life. This indicates I have somewhere around 17.6 KW total battery life. That is a nearly 16% battery life lost. Does anyone else have this type of battery deterioration? Anyone know what Chevy's battery life warranty is, or when they will do something about excessive battery life loss? If I hit the 20% mark, I won't be able to make my daily round trip.

 

[SparkevBlogspot]

I've had my 2014 Spark ... somewhere around 17.6 KW total battery life.

Based on another with 2014, that level seems about right.

http://www.mychevysparkev.com/forum/viewtopic.php?f=9&t=4457&p=14961#p14961

I don't know how diligent people "baby" their batteries or how much better it'd be to follow conventional rules, them being

1. Don't charge to full.
2. Don't drive to empty.
3. Keep it between 20% to 80% while operating.
4. If not operating, keep it at about 50% level.

Of course, above are not realistic for battery EV, better suited to hybrids. For example, if you kept it parked at 50% level, and can only drive to 20%, that's only 30% usable, which is 80*.3 = 24 miles range.

 

[DDMan11]

Realistic? No, not when I have a 60 mile trip I have to take on a daily basis. Thank god this car is a lease!

The car gets charged to full just about every time it's driven more than 10 miles or so. It gets charged to full 5x per week, sometimes more often. I also don't drive nicely (80+ on the freeway, and willingly use the AC/Heater). Again, range isn't so much my concern yet, but it will be. If I can't turn my heater on in the middle of winter or the AC on in the middle of summer and make my round trip... we have a big problem. When I got the car, I made the entire trip with the AC on with 20+ miles of range left.

I just know Leaf drivers had their batteries replaced because if extreme degradation. Curious if that will happen with the Spark.

 

[SparkevBlogspot]

Nissan ... batteries replaced because if extreme degradation. Curious if that will happen with the Spark.

If you have warranty booklet, check page 14. Apparently, there is something about degradation warranty. Nissan will not replace the pack with new, only with similar that exceeds minimum (if they can find one). I suspect Chevy will do the same.

As for range, my latest blog post is about range using some made up data. ;-) It might be of some interest to you. 2014 has bit over 19 kWh usable.

http://sparkev.blogspot.com/2016/03/range-polynomial.html

 

[JoeSchmoe]

I'm at approx 7500 miles and my indicated range is 58 miles give or take. I have much sticker tires, though, and they are slightly larger than stock. I also don't drive slowly and charge to full each day. I think the range indicator is becoming more conservative, though. Meaning that by the time I reach 50% charge I have more than 29 miles of indicated range remaining. I don't pay it too much attention though, since it's well within the range I need it to be even with heater and A/C usage.

Lastly, I agree. I'm also really glad this is a lease.

 

[NORTON]

.... today, I had 8.8 KW used at 50% battery life. This indicates I have somewhere around 17.6 KW total battery life. That is a nearly 16% battery life lost. ...

The 2014 Spark EV has a 21 kWh rated battery, but it does not use the entire capacity. No EV does that for battery life reasons.
DD, what are you using as your starting capacity?


I'm still coming to grips with this method of measuring 'degradation'.
As seen in the other thread on this subject there is a large variation on all data points and it must be plotted over time to see a trend.
My few initial attempts at gathering data shows minimal degradation. But time will tell. I need to start a spread sheet.

 

[NORTON]

I don't know how diligent people "baby" their batteries or how much better it'd be to follow conventional rules, them being
......
Of course, above are not realistic for battery EV, better suited to hybrids. ....

I don't know how you would quantify the results of your diligent "baby" techniques of BEV ownership.

And I can only assume when you discuss all this with potential BEV buyers they are left with their heads spinning with more questions and worries.

What's wrong with just driving it and plugging it in when you get home? And forget about it...

Or for me, it's once a day when I get to a free public L2 across the street from where I work.
Weekends I'll swing into a DCFC, as needed, for 10-15 minutes to get close to the 80% mark (if I'm waiting) or walk away and let it top up to 100%.

It's true, 'conventional' thinking for a hybrid is to only use the pack from 20% to 80%. And the driver has no control over that.
With a BEV it makes sense to use more of the battery capacity. But 'baby' or not, will it be worth it for all the extra care and effort? Only time will tell.

 

[MrDRMorgan]

I've had my 2014 Spark for now a year and 8 months. The car now has 23k on the odometer but my battery life has suffered greatly. I began with 80-100 miles of range (depending on my driving style and weather), but now I'm getting 60-75 miles.

I've used the built in battery usage meter, and today, I had 8.8 KW used at 50% battery life. This indicates I have somewhere around 17.6 KW total battery life. That is a nearly 16% battery life lost. Does anyone else have this type of battery deterioration? Anyone know what Chevy's battery life warranty is, or when they will do something about excessive battery life loss? If I hit the 20% mark, I won't be able to make my daily round trip.

I have just started checking this to see if I can get a baseline reference against which to compare future measurements. My 2015 Spark EV 2LT currently has 8000 miles and 9 months of use. The other day I charged at a DCFC and let the charge continue until the charger turned itself off. I started out at 55%, ended at 100% and used 7.5 kWh. I do not know if the 7.5 kWh is what went into the battery or into the AC to DC converter in the DCFC. Regardless, it calculates too 16.67 kWh battery capacity. I will run this test a few more times to get an average value and then use that number as a reference point for evaluating any battery degradation. Note: the blue-ball guess-o-meter read 102 miles after the full charge. My best full-charge guess-o-meter number for both my 2014 and 2015 Spark EV usually is 101-106 mi in mild to warm weather. This winter I saw these numbers fall into the low 70s which is what I expected to see. If battery degradation is occurring, then I expect to see my maximum blue-ball guess-o-meter value fall year to year everything else being equal.

9 Mar 2016: I just finished my fourth full-charge DCFC session in the last 6 days for my 2015 Spark EV. The battery capacity test data was taken from the display on the same NRG eVgo DCFC station. The results look encouraging as something I can use as a baseline to determine if my battery is degrading or not. The battery capacity results for the four tests ranged from 16.48 kWh to 16.70 kWh with an average of 16.58 kWh. The percent the battery was discharged at the start of the tests ranged from 45% to 77%. The guess-o-meter reading after each full charge ranged from 97 miles to 102 miles (mi/kWh ranged from 5.3 to 5.8).

 

[SparkevBlogspot]

But 'baby' or not, will it be worth it for all the extra care and effort?

My point about "babying" the battery is with regard to people who complain about degradation. I completely agree, just use it as you see fit, not worry about such extremes to save the battery. Even with all that effort, it's dubious how much it'll be saved.

However, few things can be done that may (or may not) extend battery are.
1. Don't charge to 100%.
2. Don't drive too low (5%?) or "turtle" mode.
3. Keep it about 50% if not driving for a while.

I do #1, just because I live on mountain top, and I save extra for regen braking. #2, I think it's obvious unless one's in a pinch. #3 is not so obvious to people unfamiliar with Li batteries.

 

[xylhim]

I think temperature may be a pretty big factor in determining the battery capacity as well- if temps are low, you'll likely under-estimate your capacity. I would suggest a test were you are charging at and running the vehicle at around 25 degrees C: http://batteryuniversity.com/learn/article/discharging_at_high_and_low_temperatures

 

[NORTON]

..I would suggest a test were you are charging at and running the vehicle at around 25 degrees C...

This may be stating the obvious but,,, The Spark has battery pack TMS while plugged in or when powered up.
If you were to unplug the car once it is topped up and let it 'cold soak' or 'hot soak' for (?) 48 hrs the battery might get to outside air temps.
But as soon as the car is powered on the TMS starts to cool or heat the battery pack as required.
This is displayed as "Battery Conditioning" on the 'energy page'. This would mean more power is being used while TMS is working, so mi/kW would be skewed.
If you monitor that 'energy page' you'd be able to tell approximately when the TMS stopped working when the ' % ' display stops increasing.

 

[MrDRMorgan]

I started collecting all kinds of display and charging information when I took delivery of my 2015 Spark EV at the end of May last year and stopped collecting in August. Fortunately, I kept the data. In 2015 I collected the % battery used and kWh used data found on the car's energy info display. This month, as I started collecting DCFC data at a full charge, I continued to also record the % battery used and kWh used data found on the car's energy info display. The car currently has approximately 9000 miles on the odo. The average battery capacity calculation for the 36 readings in 2015 was 19.03 kWh. The 3 readings for March are 17.21, 17.29 and 17.76 kWh. Temperature may be a factor as the 2015 data was collected during June, July and August which were very hot months. The 2016 data was collected while the temperature was in the 60s. I plotted the 2015 June, July and August data and it looked to be almost flat indicating no or little degradation. I will be doing the same throughout 2016.

Comments?

 

[Zoomit]

I'm doing something similar and have over 200 data points since last July. Any possible battery degradation is within what might be seasonal variation, due to temperature or weather effects on battery performance and my usage patterns. So the data won't mean anything until we go all the way around the sun.

The data says about 2% loss over about 10k miles, but again, I don't believe it yet.

 

[Anonymous]

Hi everyone..actually i do not know if the 7.5 kWh is what went into the battery or into the AC to DC converter in the DCFC. Regardless, it calculates too 16.67 kWh battery capacity. I will run this test a few more times to get an average value and then use that number as a reference point for evaluating any battery degradation.

High Density Interconnect PCB

 

[MrDRMorgan]

Hi everyone..actually i do not know if the 7.5 kWh is what went into the battery or into the AC to DC converter in the DCFC. Regardless, it calculates too 16.67 kWh battery capacity. I will run this test a few more times to get an average value and then use that number as a reference point for evaluating any battery degradation.

I would just use the car's Energy Info display and use total kWh used divided by the total % battery used to calculate the battery capacity regardless of DCFC , L2 or L1 power source.

 

[lude219]

Sorry for the OT, but if the car display states that i've used roughly 16.5kwh for 100miles, does that mean that in an emergency that i could eeked out another 1-2kwh (or another 10mi...lets say that i get about 5mi/kwh) or will that 'reserve tank' be off limit and the car will completely shut off?

 

[Zoomit]

There is no reserve tank or equivalent. The usable battery capacity is around 17.6 kWh in the 15s and 16s. As you get close to that, your best gauge is the range estimate on the driver's display.

 

[lude219]

There is no reserve tank or equivalent. The usable battery capacity is around 17.6 kWh in the 15s and 16s. As you get close to that, your best gauge is the range estimate on the driver's display.

I figured as much, thanks. So I'm curious, what's the other 2kwh being used for if they advertised a 19kwh battery?

 

[Zoomit]

The battery capacity is described as 18.4kWh, but GM appears to have taken off about 4% to help battery longevity. Charging to 100% frequently reduces battery life so only giving us ~17.6 helps the long term value. The EPA numbers were created using the same battery limitation.

 

[CSW]

I have a 2014 spark with about 31k miles on it now. I have had it for 2 years. I have had no loss of capacity. I do nothing to baby the battery. I just drive it and plug it in every day to charge up to 100%. Just one of the reasons I call it Super Spark.