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Battery Degradation/Range Loss (and if you have any post age, miles, testing process)

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Discussion Starter #1
This is a poll to help out a gm-volt member/owner (not me) that is doing an article on the Volt, with a largely financial bent. The goal is to collect as large a sample as possible to improve the article.

Note if you have any loss please post amount, age, miles and how tested, or we may delete it from the poll.

Also helpful if people answer these poll's which will be used in the article as well.


kWh/100 miles.
http://gm-volt.com/forum/showthread.php?23449-KWH-100-Miles-Poll

Price per kWh
http://gm-volt.com/forum/showthread.php?32889-What-do-you-pay-for-electricity
 

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At over 33k miles, my battery range estimate actually increased and hit 50 for the first time. Of course, driving style helps.
 

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Actually, some lower mileage cars (like mine) have increased. As your driving style matures and the car gets lapped in.

I also changed my commute route based on Nav. That cut 3 miles which put me within range to do full EV. I also drive on street routes more at each end. Slower steady speed gets me there quicker in most cases.

Today I did 45mi all EV. Started with 38 new.
 

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I haven't posted about it, because I know weather changes the car's choices in charging (charges to a higher reported %SoC in warmer conditions,) but I believe I am seeing the computer progressively opening the charge window - exactly what I argued didn't make sense when a bunch of senior forum folks told me the car was programmed to do it last year (or the year before?) I was waiting for the winter cold again to see where the charging stopped then.

If I'm right, and it isn't just a weather change, then the change in my car so far is on the order of 300Wh (~3%) that it has opened the top of the window to compensate for degradation; like everyone else I haven't seen a decrease in usable range - the energy screen generally reports about 9.8 kWh at switchover on the rare occasions that I get there. So far, it appears that the bottom of the window is unaffected, still switching to engine at 3.5kWh theoretically remaining (22% absolute SoC.)
 

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For the first year of ownership, as I was conducting my 367 days of "testing" I hardly ever ran the AC and heater... Maybe 3 times in a year because I wanted to see what this puppy could do without wasting electrons on creature comforts.

This year (now that I am an old man, unlike last year) I'm riding with the AC blasting and see no difference in range or battery degradation. And I think "what an idiot, going a whole summer last year without the AC in a black Volt."

I'm still able to do 50 miles on a charge, but I do tend to drive a tad slow. And I bet I could repeat my idiocy from last July when I drove really slow and did 71.1 miles (with a couple left) on a single charge... My regular daily commute of 44 miles one way, I typically use about 9 kilowatts, if memory serves me right.

No degradation on my part, just a wider smile on the face.

EV %: 98.4% #31 / 98.2%
MPG: 2375.32 #13 / 99.3%
MPGe: 90.91 #6 / 99.7%
MPGCS: 38.39 #158 / 90.6%
 

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Discussion Starter #7
tboult, just curious, why did you make the poll public?
I wanted to make sure no "haters" voted/posted and then did not explain their testing..
 

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At over 33k miles, my battery range estimate actually increased and hit 50 for the first time. Of course, driving style helps.
At over 30k miles since Feb 2011 (2.5 yrs) and my estimates have been 47-48 lately. Some of the highest I recall. In our hot weather high 80s/low 90s, I'm using the vent setting, 3 vents, 75F, ECO, fan speed of 2. It is stunning. There certainly must be degradation. I wonder when it is going to show for real.
 

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Discussion Starter #9
I haven't posted about it, because I know weather changes the car's choices in charging (charges to a higher reported %SoC in warmer conditions,) but I believe I am seeing the computer progressively opening the charge window - exactly what I argued didn't make sense when a bunch of senior forum folks told me the car was programmed to do it last year (or the year before?) I was waiting for the winter cold again to see where the charging stopped then.

If I'm right, and it isn't just a weather change, then the change in my car so far is on the order of 300Wh (~3%) that it has opened the top of the window to compensate for degradation; like everyone else I haven't seen a decrease in usable range - the energy screen generally reports about 9.8 kWh at switchover on the rare occasions that I get there. So far, it appears that the bottom of the window is unaffected, still switching to engine at 3.5kWh theoretically remaining (22% absolute SoC.)

Interesting. How are you determining that SOC window? 9.8kWh seems low for a switchover, though many other here report similar so maybe its just a scaling issue. Any chance your car is facing the SOC drift that was discussed in http://gm-volt.com/2013/02/26/a-tale-of-two-volts-the-summary/

If you are rarely getting low SOC, maybe the cars SOC estimation is drifting in its measurements.
 

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Dramatic increase, from 26 miles to 44 average. Eight thousand miles. Still playing with the AC to see how it affects range. Only had the car two seasons, so more joy to come.
 

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Actually, some lower mileage cars (like mine) have increased. As your driving style matures and the car gets lapped in.

I also changed my commute route based on Nav. That cut 3 miles which put me within range to do full EV. I also drive on street routes more at each end. Slower steady speed gets me there quicker in most cases.

Today I did 45mi all EV. Started with 38 new.
The range on my 2011 has actually gone up about 10% from the same period over the last two years.
 

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When I got my car, and for at least the first full year, a full discharge gave me 10.4kwh. Now, after 22 months of ownership and 25,000 miles I'm "empty" at 9.7 kwh. So my battery is now 9.7/10.4 = 93.3% of what it started as. In other words, I've had 6.7% of degradation in only 25,000 miles. Good thing it's a 45,000 mile lease.....
 

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I think it has been repeatedly stated that the discharge gauge is not an indicator of battery capacity. I have a 2012, and 9.7 is what I routinely get. My work commute is 35 miles each way, so battery degradation is going to be very obvious. Nothing at 32k miles at 97% electric.
 

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Depending on how Chevy implemented, any battery capacity loss could be masked by how there is only about 10.5 / 16.5 kWh that is actually made available for use. If the battery were to lose 2 kWh of capacity, would the control systems allow 8.5 / 14.5 kWh? 10.5 / 14.5 kWh? Would it be percentage based, and end up somewhere around 9.3 / 14.5? I don't think anyone ever uncovered the details behind how Chevy does it.
 

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Interesting. How are you determining that SOC window? 9.8kWh seems low for a switchover, though many other here report similar so maybe its just a scaling issue. Any chance your car is facing the SOC drift that was discussed in http://gm-volt.com/2013/02/26/a-tale-of-two-volts-the-summary/

If you are rarely getting low SOC, maybe the cars SOC estimation is drifting in its measurements.
I'm using DashDAQ and a number I made up, of course. :)

One of the more interesting things about the DashDAQ is that in addition to displaying OBDII signals, it can multiply them by constants or other signals, add or subtract constants or other signals, and then display that instead.

Clearly, the most important single number in an electric car is the state of charge, but the percentage didn't seem particularly helpful to me. So I have a field displayed I called battery left. Basically, it takes the state of charge (labeled high voltage battery state of charge (VICM) in the DashDAQ list,) and multiplies it by the nominal 16 kWh capacity, then subtracts off 22% (3.52 kWh). This should be the number of kWh remaining before the engine turns on, and mostly works pretty well.

So what I'm seeing is that lately the car is showing a little over 10.6 in the morning. My vague recollection was that last summer it was showing 10.4, and I know that most of this winter it showed 10.180. I know it changes with the weather, so I was waiting until it got cold again to be sure, but I think it is charging to a SoC that's 2-300 Wh higher than it used to (possibly as much as 2% on the raw Absolute SoC.)
 

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13K+ total miles with 12K+ electric miles and depending on regen I still get over 10 kW from my battery on my 2012. I've noticed ZERO loss of range or battery performance.
 

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I think it matters also to collect where those with discernable decreases live and if they are new to the Volt and not understanding how climate controls, ambient air temps and other factors affect range like whether 120V or 240V EVSEs are typically used (shouldn't really matter due to 240V still being "slow" by Li-Ion standards).

My 2011 sat in the Florida sun for about 8 months before I bought it, then I've had it over a year and 20K miles. Today, I should get 48 miles AER on my highway drive over to Trenton NJ from well west of Philadelphia. No discernable decrease in optimal weather conditions without climate controls enabled.
 

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I bought in winter so my increasing range is probably more due to that than anything going on with the battery. I have 12K on her in 8 months and currently go 42 - 48 miles in mixed urban and highway conditions. No turtle mode driving and use the climate control for what it's intended.
 
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