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

Battery degradation, range loss (if you have any post amount, age, miles and testing

38K views 105 replies 49 participants last post by  Norm51 
#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
 
#8 ·
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.
 
#3 · (Edited)
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.
 
#7 ·
I wanted to make sure no "haters" voted/posted and then did not explain their testing..
 
#5 ·
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.)
 
#9 ·
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.
 
#6 · (Edited)
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%
 
#13 ·
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.....
 
#15 ·
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.
 
#17 ·
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.
 
#18 ·
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.
 
#19 ·
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.
 
#22 · (Edited)
I only have 1 vote for two volts...

I bet driving style has more effect than any discernable battery range changes. I try very hard to get 5 miles a kilowatt on the Volt I drive and get really close. My grandson doesnt care at all about that and he is usually under 4, down as low as 3.5. (summer numbers).


Reading some of these posts, I think most are just noticing variances in measurement devices and battery packs. Digital instrumentation conotates an unrealized amount of prescision. I think some are pretty close and some are off. A 2 % signal accuracy is probably pretty acceptable. And then battery packs probably have a build tolerance as well. Who knows what that is but 2% would seem fairly tight. After a year, I am sure some batteries seem to get better, some worse. Now get a car where all these factors are stacked against you, you get a low one and others get a high one. I still think driving style has a bigger effect and the true measure is miles per kilowatt, taking into account terrain.
 
#23 ·
I don't track my 2011 (VIN #541, 38K mi) that closely, and I still drive it like my prior BMW; but, the range sure seems to be improving. I saw an all-time-high range estimate this morning: 42 miles. I know, that's really crappy relative to some newer Volts (and different driving styles). But it's all good by me!
 
#26 ·
This poll is hard to answer because of all the variables.

This summer has been MUCH hotter than last summer, so I am running the A/C quite a bit more. But I still get about 39-40 miles on a charge. Last summer I was easily getting 43-44 miles.

In the winter the heater really uses a lot of power. My range drops to under 30 miles when the heater is running. The lowest electric range I ever had was 26 miles.

I almost always use the ECO settings, unless it is REALLY hot or cold. Then I run comfort mode for about five minutes or so, and then switch back to ECO. In the spring and fall I use fan only. That is when I get the best AER. I have been to 49.5 miles AER. Basically, I don't sacrifice comfort for the sake of range. That is why we have the ICE.

Then there are driving style and terrain issues. I can discount those as I am the only driver and my driving patters are just about constant week to week.

My 2012 Volt over almost two years always switches over to the ICE at 9.9 or 10.0 KWh used on the display. The only exception to that was a trip where I went down a large hill and there was quite a bit of regen. My mileage went up and the switchover did not occur until 10.4 KWh.

My driving requires me to make a lot of short trips to my customer sites. I have found that the AER will drop sometimes when I stop at a site and then come back out after 3-5 minutes and power up the car. The AER will have dropped 1-2 miles, especially when the remaining AER is under 10 miles.

Those are my observations.....

C-5277
 
#27 ·
The poll probably will not tell us much about true battery degradation issues. Seems to me the only way to accurately determine Volt battery true SOC is either be via the detailed internal battery charge data that Walter's collecting via a Dashdaq or with one of those meters measuring battery GIDs like the Nissan Leaf people use.

Because GM built so much cushion in the operating window, they could also have set up the battery-charge software to adjust the high and low points of that window to compensate for degradation. We'd never see kWh degradation on our energy displays until there was no more "wiggle room", which probably will be right at 8 years/100,000 miles (or 10 years/150,000 miles for CA Volts:)
 
#29 ·
Just passed 28 months and 32,000 miles in my 2011 and yesterday I had my best range ever. 52.3 miles and 1 mile remaining on the range estimator. Woke up this morning with a 49 mile range estimate. So no perceived degradation at all but then again I didn't go over the speed limit coming home yesterday since I couldn't charge up at work yesterday and I knew there was a slight chance that I could make it home without using any gas.
 
#30 ·
Like saghost, I've been wondering about the window situation as well. When fairly new, I got on the highway, put the cruise at 70mph, and went 34.9 miles. I thought that was awesome. A few weeks ago, at 2.5 years/27000 miles (21000 EV), I repeated the experiment in similar weather, (except for 1.5 miles @ 50ish to switch roads) and saw 37.5 miles total. I was so impressed, I had intended to post about it at the time. :)

I know it was hardly a scientific test but still... I just can't detect any loss of range at all. The battery should have degraded some measurable amount by now but I don't see it. Day to day, if I drive conservatively, I'm knocking on 50 miles just as when the car was new. With only 40 minutes of mid-day L1 charging I did 52 with 2 left a few days ago.

I should just get another melt-a-watt, I mean kill-a-watt, and check the next time I get to CS mode. I have some data to compare from when the car was new.
 
#35 ·
That is indeed the one definitive source for the changing charge window idea that Don found for me last year. Frank doesn't quite agree with the interviewer's suggestion of changing charge levels, but he doesn't disagree either.
 
#36 ·
#40 ·
It's all rather difficult to measure any degradation based on Volt EV, especially for an '11 or '12 that caps off measuring at 50. At 1 year and 3 months, I have 25k miles/24k EV miles, and this morning I drove to breakfast 8 miles, and STILL had 50 miles range indicated. So it's only *perhaps* years down the road when folks like me can't get 50 AER estimated any more that degradation would be apparrant, assuming no other factors (TTT) changed.

What would be more interesting is to get this guy's battery hooked up to the diagnostics mentioned earlier in the thread.
 
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