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Re: Battery Aging Model

Posted: Wed Oct 17, 2012 7:47 am
by DaveinOlyWA
Sloaty; the row requirement for Excel "used" to be in the neighborhood of 255 columns and 65,000 rows or so, but both those parameters were increased for Excel XP i believe so i doubt that changing the rows will alleviate the issue. i use open office also because its free and works just as well as MS Office.

i have also had random issues trying to convert but others were still able to open the document in Excel anyway. there would always be a popup starting "possible" formatting errors but all the data was still ok.

Re: Battery Aging Model

Posted: Wed Oct 17, 2012 8:50 am
by ENIAC
JPWhite wrote:
ENIAC wrote: They measured temperatures in June of 149 deg F (figure 2a).
That's certainly enough to cook a battery. The body repair manual states that 140F is the max temp in a paint booth for any period of time. 149 is enough to do damage for sure.
I did some more poking around and found this article where Mark Perry was interviewed. He describes "120F-140F" as the temperature range to be concerned over. Clearly 149F is well above the "concerned" range! Also, for a large part of the year parking lot temperatures in Phoenix (and likely many other areas) will exceed 120F. This, in my opinion, feels like the "smoking gun" for the issues we're seeing in the southwest.

So with regard to EVs and hybrids that have battery pack temperature management systems. If the vehicle is turned off and parked on extremely hot asphalt, is the temperature management system still operational? I assume so and then have to wonder how much energy would be used to keep the pack cooled.

Re: Battery Aging Model

Posted: Wed Oct 17, 2012 3:32 pm
by JPWhite
City Temp Profile spreadsheet http://bit.ly/citytemprofiles does not agree with the graphic at http://bit.ly/QI714Y

Should I update my spreadsheet to utilize the numbers from the city temp profiles sheet, or adjust those numbers by another factor?

Re: Battery Aging Model

Posted: Wed Oct 17, 2012 3:46 pm
by surfingslovak
JPWhite wrote:City Temp Profile spreadsheet http://bit.ly/citytemprofiles does not agree with the graphic at http://bit.ly/QI714Y

Should I update my spreadsheet to utilize the numbers from the city temp profiles sheet, or adjust those numbers by another factor?
JP, the graphic is based on older, less accurate data. The Google spreadsheet should have new information, which is now reflected on the Wiki as well. I did not have the time to enter all the new locations into the spreadsheet, and that data is only available offline from Stoaty for the time being. Sorry for the inconvenience. Image

Re: Battery Aging Model

Posted: Wed Oct 17, 2012 4:03 pm
by Stoaty
JPWhite wrote:City Temp Profile spreadsheet http://bit.ly/citytemprofiles does not agree with the graphic at http://bit.ly/QI714Y

Should I update my spreadsheet to utilize the numbers from the city temp profiles sheet, or adjust those numbers by another factor?
As Surfingslovak stated, numbers have been updated with more accurate readings from the Weatherspark data (and generally confirmed with hourly data from Weatherman). Those numbers are listed in the Wiki near the end of this section:

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

However, those numbers could not be made to work in my battery aging model, so I searched for the numbers that would work for Phoenix, "Normal" and Boston. Once I arrived at those numbers and got a very close fit, I went back and scaled the Weatherspark numbers so that they were on the same scale as the numbers I arrived at in the spreadsheet. That is to say, I interpolated between Phoenix and LA Civic Center, and between LA Civic Center and Boston. For cities with lower aging factors than Boston, I extrapolated (best I could do). I plan to use the numbers on the new scale for my prediction model (TM) coming shortly. If you want a copy of the current spreadsheet to look at or play with, just PM me. When I feel it is ready I hope to get some help from Surfingslovak to put it on googledocs (which I know nothing about) so that anyone can access it from a link in the Wiki.

Re: Battery Aging Model

Posted: Wed Oct 17, 2012 5:16 pm
by JPWhite
surfingslovak wrote:
JPWhite wrote:City Temp Profile spreadsheet http://bit.ly/citytemprofiles does not agree with the graphic at http://bit.ly/QI714Y

Should I update my spreadsheet to utilize the numbers from the city temp profiles sheet, or adjust those numbers by another factor?
JP, the graphic is based on older, less accurate data. The Google spreadsheet should have new information, which is now reflected on the Wiki as well. I did not have the time to enter all the new locations into the spreadsheet, and that data is only available offline from Stoaty for the time being. Sorry for the inconvenience. Image
No inconvenience. If I get time I'll update the google docs with the right factors. I have an excel version I've extended to 30 years :-) Norway is good for 30 years if the model is accurate at the extremes. Once complete ill share the excel spreadsheet.

Re: Battery Aging Model

Posted: Wed Oct 17, 2012 5:57 pm
by Stoaty
JPWhite wrote:No inconvenience. If I get time I'll update the google docs with the right factors. I have an excel version I've extended to 30 years :-) Norway is good for 30 years if the model is accurate at the extremes. Once complete ill share the excel spreadsheet.
While I haven't plugged any numbers in yet, I would strongly doubt that the battery will be good for 30 years until EOL, unless perhaps the Leaf is kept in a location that has freezing temperatures most of the year and is never driven. Certainly the battery will fare a lot better in Norway, I just don't think 30 years is possible.

Re: Battery Aging Model

Posted: Wed Oct 17, 2012 6:11 pm
by DaveinOlyWA
TaylorSF has over 54,000 miles and has lost around 10-13% by his reckoning so its looking like he will hit EOL around 120-150,000 miles. a bit less than i had expected. i was thinking under better circumstances something near 200,000 miles might be possible. so that might get you half that 30 years

Re: Battery Aging Model

Posted: Wed Oct 17, 2012 6:47 pm
by JPWhite
Stoaty wrote:
JPWhite wrote:No inconvenience. If I get time I'll update the google docs with the right factors. I have an excel version I've extended to 30 years :-) Norway is good for 30 years if the model is accurate at the extremes. Once complete ill share the excel spreadsheet.
While I haven't plugged any numbers in yet, I would strongly doubt that the battery will be good for 30 years until EOL, unless perhaps the Leaf is kept in a location that has freezing temperatures most of the year and is never driven. Certainly the battery will fare a lot better in Norway, I just don't think 30 years is possible.
Granted.

I updated the sheet on Google Docs using weather spark data points. A second set of eyes to make sure I didn't munge anything up?

I did put the locations in alphabetical order. Just an OCD thing :-)

Put an Excel spreadsheet here
http://dl.dropbox.com/u/2881567/Degrada ... 20Pub.xlsx

Re: Battery Aging Model

Posted: Wed Oct 17, 2012 7:12 pm
by LEAFfan
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.