Weatherman
Posts: 916
Joined: Tue Aug 30, 2011 12:03 pm
Delivery Date: 08 Jul 2012
Leaf Number: 20922
Location: Weston, Florida

Re: Battery Aging Model

Wed Oct 17, 2012 7:34 pm

JPWhite wrote:Put an Excel spreadsheet here
http://dl.dropbox.com/u/2881567/Degrada ... 20Pub.xlsx
Let's see...

Ft. Lauderdale...
10,000 miles a year...

10% loss the first year. First capacity bar falls a little after year 2. 20% down by the time I turn the car in at the end of year 3.

Looks accurate.

Should be interesting if maintaining a relatively low, average SOC allows me to beat the odds.
2013 Crystal Red Volt
2012 SV Glacier Pearl LEAF; turned in 5/12/2015:18.6K Miles:50.13 AHr:10 bars, 24% gone

Stoaty
Posts: 4488
Joined: Fri Jun 18, 2010 9:50 pm
Delivery Date: 12 Jun 2011
Leaf Number: 3871
Location: West Los Angeles

Re: Battery Aging Model

Wed Oct 17, 2012 9:02 pm

Weatherman wrote:Let's see...

Ft. Lauderdale...
10,000 miles a year...

10% loss the first year. First capacity bar falls a little after year 2. 20% down by the time I turn the car in at the end of year 3.

Looks accurate.

Should be interesting if maintaining a relatively low, average SOC allows me to beat the odds.
OK, I have implemented a rough version of the prediction portion based on the model:

Fort Lauderdale
10,000 miles per year
Average efficiency 4 miles/kwh from dash

Predicted Cumulative Losses:

Year 1 - 11.09%
Year 2 - 16.00%
Year 3 - 20.11%

Looks like a pretty good match with the other spreadsheet (which I haven't looked at). Still need to clean things up, automate lookups of aging factors by City, add average speed to calculate miles/kwh, and then try for the harder stuff like high or low SOC, solar loading, etc.

PS I now need some data to compare with my model from the range test or Casa Grande to see how it is coming so far.
2011 Leaf with 62,000 miles given to Nephew
2013 Tesla Model S85 with 251 miles rated range at full charge
Leaf Spy Manual
Battery Aging Model Spreadsheet

Stoaty
Posts: 4488
Joined: Fri Jun 18, 2010 9:50 pm
Delivery Date: 12 Jun 2011
Leaf Number: 3871
Location: West Los Angeles

Re: Battery Aging Model

Thu Oct 18, 2012 7:01 am

OK, the Prediction Model (TM) gives the following numbers for Phoenix at 12500 miles per year (so far, more factors need to be added):

Miles per kwh = 4, cumulative loss:

Year 1 - 12.11
Year 2 - 17.79
Year 5 - 31.11
Year 10 - 49.43

EOL - 4.7 years

Miles per kwh = 3.5, cumulative loss:

Year 1 - 12.45
Year 2 - 18.46
Year 5 - 32.8
Year 10 - 52.81

EOL - 4.3 years

Model does not yet account for solar loading, percent of time at high SOC, etc.
2011 Leaf with 62,000 miles given to Nephew
2013 Tesla Model S85 with 251 miles rated range at full charge
Leaf Spy Manual
Battery Aging Model Spreadsheet

ENIAC
Posts: 647
Joined: Thu Jan 06, 2011 9:05 pm
Delivery Date: 13 Jan 2011
Leaf Number: 224
Location: Sun Diego, CA USA

Re: Battery Aging Model

Thu Oct 18, 2012 8:10 am

LEAFfan wrote:
ENIAC wrote:I found this study which looked at parking lot temperatures in Phoenix at various times of the year. They measured temperatures in June of 149 deg F (figure 2a). BTW, measurements are taken at 8 feet above the surface.
Remember, a lot of us almost always park in shaded parking spots so those temps are only valid for those that usually park in unshaded ones.
True, however I suspect many owners aren't aware of the issue and don't park in the shade. Also, often shaded parking is simply unavailable. Do Nissan dealerships in Phoenix park their LEAFs in the shade? At 149F, how many hours before permanent battery damage occurs? I was just reading another study which said that parking lot temperatures in Atlanta GA in the summer are nearly 50F higher than the ambient temperature. With that sort of temperature variability, feels to me like an owners parking habits should be one of the dominate variables in the battery aging model.
Myths And Facts About Electric Cars

"The ice doesn't care"
-- WetEV

DaveinOlyWA
Posts: 14207
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

Re: Battery Aging Model

Thu Oct 18, 2012 8:37 am

LEAFfan wrote:
ENIAC wrote:I found this study which looked at parking lot temperatures in Phoenix at various times of the year. They measured temperatures in June of 149 deg F (figure 2a). BTW, measurements are taken at 8 feet above the surface.
Remember, a lot of us almost always park in shaded parking spots so those temps are only valid for those that usually park in unshaded ones.
at 147º i am gonna have to guess that unshaded parking is pretty rare. those temps are more than enough to cause 3rd degree burns
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 412 mi, 99.72% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

ENIAC
Posts: 647
Joined: Thu Jan 06, 2011 9:05 pm
Delivery Date: 13 Jan 2011
Leaf Number: 224
Location: Sun Diego, CA USA

Re: Battery Aging Model

Thu Oct 18, 2012 9:23 am

DaveinOlyWA wrote:
LEAFfan wrote:
ENIAC wrote:I found this study which looked at parking lot temperatures in Phoenix at various times of the year. They measured temperatures in June of 149 deg F (figure 2a). BTW, measurements are taken at 8 feet above the surface.
Remember, a lot of us almost always park in shaded parking spots so those temps are only valid for those that usually park in unshaded ones.
at 147º i am gonna have to guess that unshaded parking is pretty rare. those temps are more than enough to cause 3rd degree burns
140F+ water would cause a 3rd degree burning in a matter of seconds, we're talking air temp here. Also, in my experience, the Phoenix valley has a lot of unshaded parking.
Myths And Facts About Electric Cars

"The ice doesn't care"
-- WetEV

DaveinOlyWA
Posts: 14207
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

Re: Battery Aging Model

Thu Oct 18, 2012 9:31 am

ENIAC wrote: 140F+ water would cause a 3rd degree burning in a matter of seconds, we're talking air temp here. Also, in my experience, the Phoenix valley has a lot of unshaded parking.
ooooh we can play that game!!

step one
bake a car at 147º for 2 hours in the middle of the day

step two; toss the hot pads

step three; open door and grab steering wheel tightly with both hands for 60 seconds...
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 412 mi, 99.72% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

ENIAC
Posts: 647
Joined: Thu Jan 06, 2011 9:05 pm
Delivery Date: 13 Jan 2011
Leaf Number: 224
Location: Sun Diego, CA USA

Re: Battery Aging Model

Thu Oct 18, 2012 9:59 am

DaveinOlyWA wrote:
ENIAC wrote: 140F+ water would cause a 3rd degree burning in a matter of seconds, we're talking air temp here. Also, in my experience, the Phoenix valley has a lot of unshaded parking.
ooooh we can play that game!!

step one
bake a car at 147º for 2 hours in the middle of the day

step two; toss the hot pads

step three; open door and grab steering wheel tightly with both hands for 60 seconds...
Again, we're talking air temperature at 8 feet above the surface of a parking lot. Are you disputing the parking lot temperature readings in the Phoenix study? I'm grasping to understand your point.
Myths And Facts About Electric Cars

"The ice doesn't care"
-- WetEV

Stoaty
Posts: 4488
Joined: Fri Jun 18, 2010 9:50 pm
Delivery Date: 12 Jun 2011
Leaf Number: 3871
Location: West Los Angeles

Re: Battery Aging Model

Thu Oct 18, 2012 2:10 pm

surfingslovak wrote:I left my Leaf out in the sun on a hot day once. The sheet metal on the roof was at about 130 F. The battery container was a few degrees warmer compared to what I would see when the Leaf was parked in a shade. Additionally, the battery was about two degrees warmer on side facing the sun.
How many degrees? How hot was it? What time of year? The number is important in deciding how to account for solar loading, and another data point would be very valuable.

Remember that the study of the Prius found the average annual battery temperature to be 1.3-3.1 degrees C. higher (depending on geographic location) with solar loading (parked every day in the sun vs in the shade) than without. That isn't a huge amount, but adds 10-24% to battery aging for the year (24% was for the Phoenix location) based on doubling of degradation for every 10 degrees C. increase in temperature. Presumably I should add that factor in to both the calendar loss and cycling loss. I might scale the numbers back a bit to account for the fact that the aging factors we calculated at for the hottest climates (e.g., Phoenix) were about 20% higher than the empirically derived values in the model.

Other thoughts welcome. Those super high numbers measured in Phoenix parking lots do make me wonder if some batteries may actually be damaged rather than just suffering extreme heat degradation.
2011 Leaf with 62,000 miles given to Nephew
2013 Tesla Model S85 with 251 miles rated range at full charge
Leaf Spy Manual
Battery Aging Model Spreadsheet

Stoaty
Posts: 4488
Joined: Fri Jun 18, 2010 9:50 pm
Delivery Date: 12 Jun 2011
Leaf Number: 3871
Location: West Los Angeles

Re: Battery Aging Model

Thu Oct 18, 2012 8:56 pm

I found this resource to help estimate solar loading by geographic location:

http://rredc.nrel.gov/solar/old_data/ns ... ook/atlas/" onclick="window.open(this.href);return false;

I selected average and annual, but couldn't decide which of the 14 instrument orientations would be the best proxy. Anyone have thoughts about this?
2011 Leaf with 62,000 miles given to Nephew
2013 Tesla Model S85 with 251 miles rated range at full charge
Leaf Spy Manual
Battery Aging Model Spreadsheet

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