DaveinOlyWA
Posts: 14384
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 9:21 pm

149° is hot enough to burn you.
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; 2640.9 mi, 99.37% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

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surfingslovak
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Re: Battery Aging Model

Fri Oct 19, 2012 12:53 am

Here are couple of photos taken in Phoenix around 3 pm on September 15. One was taken in a covered parking lot, and the other when stopped at a traffic light. Infer from it what you will, hope it helps with the discussion.


ImageImageImage
Stoaty wrote:
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.
It was a hot day. Ambient temps were between 80 and 90 in the afternoon. Battery enclosure temperature was about 80, and 82 F on the side facing the sun. If I parked the car in the shade in similar conditions, the pack would not heat up as much during the day, and the container wall temperature would not exceed 76 F. The sheet metal on the roof of the car reached 130 degrees. I saw a report somewhere, which estimated the effect of solar loading at about 3-4%, but I forget which locales they were considering. I will try to find it.

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TickTock
Posts: 1701
Joined: Sat Jun 04, 2011 10:30 pm
Delivery Date: 31 May 2011
Leaf Number: 3626
Location: Queen Creek, Arizona
Contact: Website

Re: Battery Aging Model

Fri Oct 19, 2012 6:35 am

FWIW, I totally believe the study. You can literally fry eggs on your hood during the summer. Locals learn very fast to run from shade to shade like Van Diesel on Crematoria (Chronicles of Riddick) :).

Stoaty
Posts: 4490
Joined: Fri Jun 18, 2010 9:50 pm
Delivery Date: 12 Jun 2011
Leaf Number: 3871
Location: West Los Angeles

Re: Battery Aging Model

Fri Oct 19, 2012 6:51 am

I settled on this graphic as the best proxy to estimate average annual solar radiation, since it "represents the maximum solar radiation at a site available to a collector". As expected, Arizona, New Mexico, and parts of Texas, California, Nevada and Colorado are really getting cooked!
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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: 4490
Joined: Fri Jun 18, 2010 9:50 pm
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Leaf Number: 3871
Location: West Los Angeles

Re: Battery Aging Model

Fri Oct 19, 2012 8:43 am

I added the solar loading (kwh/square meter) for each city to the spreadsheet, and also added it to the table of battery aging factors on the Wiki:

http://www.mynissanleaf.com/wiki/index. ... acity_Loss" onclick="window.open(this.href);return false;

Solar loading varies between 4.5 and 9 kwh/square meter depending on geographic location, although it may well be somewhat higher in places like Phoenix. The data I can see on the map isn't granular enough to make finer distinctions; perhaps I can find the data for individual cities from which the colored map is drawn.

I haven't figured out yet how many degrees C. increase in battery temperature on an annual basis to expect for various degrees of solar loading (besides the Prius model), but these solar loading numbers should allow appropriate scaling for each city. I will probably start with the Prius numbers, include an adjustment factor if I want to change it later, and put in number of days per week parked in the sun as input for the prediction model.

Further thoughts welcome.
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: 4490
Joined: Fri Jun 18, 2010 9:50 pm
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Location: West Los Angeles

Re: Battery Aging Model

Fri Oct 19, 2012 11:38 am

Solar loading has been added to the Battery Prediction Model, but I need more data to tune the numbers. Currently the model uses 3.0 degrees C. increase in average annual battery temperature for Arizona and related areas, and 1.5 degrees C. for areas like Northwestern Washington state. This is for parking the Leaf in the sun every day for a year. For fewer days parked in the sun (e.g., only 5 days a week at work, or only 2 days a week at home), the numbers are scaled accordingly. See this thread to add a data point:

http://www.mynissanleaf.com/viewtopic.php?f=27&t=10397" onclick="window.open(this.href);return false;
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: 4490
Joined: Fri Jun 18, 2010 9:50 pm
Delivery Date: 12 Jun 2011
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Location: West Los Angeles

Re: Battery Aging Model

Fri Oct 19, 2012 1:09 pm

The solar loading factor certainly looks reasonable (but that doesn't mean it is correct, of course). I tested my predicted remaining capacity with and without solar loading:

16 months
11500 miles
Battery aging factor adjusted for model - 0.9
Solar loading factor 1.19
Days/week parked in the sun - 4 (no covered parking where I work!!! :twisted: )
Miles/kwh - 5.7

Without solar loading - 8.64% predicted capacity loss
With solar loading - 9.57% predicted capacity loss

I don't have a good handle on my actual capacity loss, except that an incomplete range test to just past LBW gave an extrapolated 106 miles, and theoretically I should get 119.7 miles with a new pack assuming 21 kwh usable, which calculates to a 11.4% loss, for a difference of 1.83%. However, I never tested my Leaf when new so don't have a good baseline.

An additional factor that my model doesn't take account of is the extra heat of 1.6 summers in 16 months, and 1.6 summers worth of solar loading (I have been leaving the Leaf at home this past summer when predicted high is greater than 95 degrees). As with ambient temperature, solar loading is not easy to model for fractional years.

For 5 years, the numbers predicted are 18.27% (no loading) and 20.26% (solar loading)

For 10 years, the numbers predicted are 27.58% (no loading) and 30.57% (solar loading)
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: 4490
Joined: Fri Jun 18, 2010 9:50 pm
Delivery Date: 12 Jun 2011
Leaf Number: 3871
Location: West Los Angeles

Re: Battery Aging Model

Fri Oct 19, 2012 4:48 pm

I took the data on Azdre/Opossum and plugged it into my model:

Phoenix, AZ
21,834 miles at 17.25 months
Assumed 4 miles/kwh
Assumed no parking in the sun
Assumed no significant time spent at 100% charge (but haven't incorporated that into the model yet anyway)
Scaled mileage to 16.25 months

Model predicts 85.12% capacity at time of Casa Grande test

Bench test at Casa Grande (after 16.25 months of ownership) showed capacity of 85%

I re-tested TickTock's data and got 86.94% predicted capacity remaining at the time of Casa Grande test (mileage and time weren't properly scaled before; I used 13.5 months at time of Casa Grande testing and scaled mileage to 16536 at time of Casa Grande testing). Casa Grande testing showed 87% per the Wiki, but 85% per TickTock's own graph. Not sure which is correct. :D
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: 4490
Joined: Fri Jun 18, 2010 9:50 pm
Delivery Date: 12 Jun 2011
Leaf Number: 3871
Location: West Los Angeles

Re: Battery Aging Model

Fri Oct 19, 2012 9:22 pm

Validation page added to Battery Aging Model spreadsheet. I am collecting all of the data in one place so I can see how well it fits the model, and whether the match gets better or worse if I make changes to the model. Model version number added, currently at version 0.81. As soon as I improve the model a bit more I am going to upload it to the Wiki so others can play with it. Just requires OpenOffice installed on your computer.
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

edatoakrun
Posts: 5222
Joined: Thu Nov 11, 2010 9:33 am
Delivery Date: 15 May 2011
Leaf Number: 2184
Location: Shasta County, North California

Re: Battery Aging Model

Sat Oct 20, 2012 7:47 am

Didn't both TickTock's and Azdre/Opossum's LEAFs actually suffer two, rather than 1.6, Phoenix "Summers", the ~3 months with the highest ambient temperatures?

So aren't you actual "tuning" your model to match an incorrect value, a world where Phoenix has two summers in only ~16 months?
Stoaty wrote:
...An additional factor that my model doesn't take account of is the extra heat of 1.6 Summers in 16 months, and 1.6 summers worth of solar loading...

I took the data on Azdre/Opossum and plugged it into my model:

Phoenix, AZ
21,834 miles at 17.25 months
Assumed 4 miles/kwh
Assumed no parking in the sun
Assumed no significant time spent at 100% charge (but haven't incorporated that into the model yet anyway)
Scaled mileage to 16.25 months

Model predicts 85.12% capacity at time of Casa Grande test

Bench test at Casa Grande (after 16.25 months of ownership) showed capacity of 85%...
Do you not consider variables in Battery care may be very large factors in capacity loss?
azdre
* We always charge to 100% (we drive it a lot, 17,000 miles in 14 months of driving).
* We do 'top it off' a lot. That's the one item we got 4/5 stars on the battery check in March 2012.
* The car sat at 100% for a month in May, 2011, not plugged in...
http://www.mynissanleaf.com/viewtopic.p ... 2&start=20" onclick="window.open(this.href);return false;
no condition is permanent

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