Tuning the Battery Aging Model

[Stoaty]

Tom,

You now have:

Predicted Loss - 21.52%
Actual Loss - 22.11%

Actual minus predicted = 0.60%

When you reported 5 weeks ago, actual minus predicted was -0.07%. It is concerning that you and I have both continued to lose capacity at a significant rate even as the weather here has moderated significantly.

 

[TomT]

Yeah... So much for degradation leveling out over time! I'm now fairly certain I'll hit the 4BL warranty threshold well before my four year lease is up...

Perhaps the fact that I am still driving the same daily mileage as when the battery was new is partially responsible since it is resulting in more and more charge cycles to maintain that mileage capability as the battery capacity falls due to degradation...

When you reported 5 weeks ago, actual minus predicted was -0.07%. It is concerning that you and I have both continued to lose capacity at a significant rate even as the weather here has moderated significantly.

 

[surfingslovak]

Version 1.00 of the Battery Aging Model has been released (minor changes from version 0.99a, if any). Available on the Wiki now:

http://www.mynissanleaf.com/wiki/index.php?title=Battery_Capacity_Loss#Battery_Aging_Model" onclick="window.open(this.href);return false;

Thanks so much for making this available! I used an online converter and an Excel version is available for a limited time via the link below. Unfortunately, there seem to be some minor problems with the converted file and I see several cells with #REF! in the city dropdown. That said, I was able to calculate the loss for Vienna, Austria for someone on the German LEAF forum.

LEAF Battery Aging Model 1.0 (Stoaty)

 

[Stoaty]

Thanks so much for making this available! I used an online converter and an Excel version is available for a limited time via the link below. Unfortunately, there seem to be some minor problems with the converted file and I see several cells with #REF! in the city dropdown. That said, I was able to calculate the loss for Vienna, Austria for someone on the German LEAF forum.

LEAF Battery Aging Model 1.0 (Stoaty)

I downloaded the conversion, but don't have excel to see where the problem lies. Another option would be to save as an excel file from OpenOffice and have someone familiar manually try to fix the bugs. Any takers?

 

[TomT]

For what it is worth, the Open Document version seemingly works fine in Excel 2013 (version 15), and converts without errors (at least as best as I can tell). If there is interest, I could save it as a standard Excel file and upload it somewhere...

I downloaded the conversion, but don't have excel to see where the problem lies. Another option would be to save as an excel file from OpenOffice and have someone familiar manually try to fix the bugs. Any takers?

 

[Stoaty]

For what it is worth, the Open Document version seemingly works fine in Excel 2013 (version 15), and converts without errors (at least as best as I can tell). If there is interest, I could save it as a standard Excel file and upload it somewhere...

I would be interested in getting that version. PM me for my email address.

 

[thimel]

Lost my first capacity bar today. Also nearly six weeks since my P3227 update.

Manufactured - 05/11
Delivered - 6/11/11
P3227 updte - 9/14/13
Location - Sunnyvale, CA (near San Jose)
Miles/kwh - 4.2
Odometer - 23981
Capacity - 55.02
Date - 10/21/13
Parked in sun - 5 days/week in Palo Alto

 

[Stoaty]

thimel,

You are on the high side of capacity loss. A bit surprising for San Jose area:

Predicted - 15.20%
Actual - 16.95%

Actual minus predicted loss = 1.75%
Actual loss percent of predicted loss = 111.52%

 

[DaveEV]

You are on the high side of capacity loss. A bit surprising for San Jose area:

Yeah, especially considering that Sunnyvale and Palo Alto is typically a few degrees cooler than San Jose.

Parked at night in a warm garage in the summer, perhaps?

 

[Stoaty]

Even in the cooler weather, my Leaf is currently losing capacity at an estimated 6% per year, which is concerning. Perhaps it will slow to a crawl once the weather gets more on the cold side. Even though I am slightly ahead of the Battery Aging Model, in order to track the battery aging model, I can only lose 2.47% of capacity in the next 8 months. Seems like that is not gonna happen. At the current rate, I expect to lose my first capacity bar in 4-6 weeks. Battery Aging Model may need to be revised again in 6-12 months with more data.

 

[walterbays]

Manufactured - 04/11
Delivered - 5/26/11
P3227 update - 9/27/13
Home Location - San Diego, CA (coastal)
Work Location - San Diego, CA (coastal)
Miles/kwh - 3.9 [#1]
Odometer - 20911
Capacity - 55.78
Date - 10/25/13
Parked in sun - ~3 days/week [#2]

Notes:

1 - Guess at lifetime average. It was about 4.0 until 02/04/2013 when I replaced my balding Bridgestone Ecopia tires with Michelin Primacy MXV4, since when it has averaged about 3.8.

2 - Parked outside 5 days/week, in shade when I can

3 - Garaged overnight

4 - Since the first few weeks I've never let it sit long at 100% SOC. I charge overnight to 80% finishing at 5am. About 10% of the time I finish charging 80% to 100% in the morning.

5 - 10 QC's

6 - If I read your spreadsheet right, I have 0.66% greater loss than the model predicts. However I've always been suspicious of the amount of capacity my battery had when new, though lacking at the time the Leaf Spy Pro app and any decent instrumentation from Nissan I can't be sure.

7 - In summer 2012 I began getting 80% charges to only 9 bars, making me fear I would soon lose a capacity bar. But in fall 2012 it went back to 10 bar 80% charges and kept all 12 capacity bars. In summer 2013 it went back to 9 bar 80% charges. At the end of August 2013 I lost a capacity bar and it went to 10 bar 80% charges for a couple of weeks, then returned to 9 bar 80% charges again. Capacity bars today: 11.

 

[jjohncm]

Manufactured - 2/1/11
Delivered - 3/4/11
P3227 update - 8/21/13
Location - Los Altos, CA
Miles/kwh - ~4.0
Odometer - 23,199 mi
Capacity - 56.50
Date - 10/26/13
Parked in sun - 4 days a week for 2-3 hours

Garage - Unventilated & uninsulated, facing South
Capacity bars indicated - 12
DC Charge Count - 13
AC Charge Count - 1,893

 

[Stoaty]

The Wiki now contains links to Excel versions of the battery aging model, one (XLS) for Microsoft Excel 2007 and earlier, one (XLSX) for Microsoft Excel 2010 and later. Both are courtesy of TomT. All earlier versions of the model should be discarded.

http://www.mynissanleaf.com/wiki/index.php?title=Battery_Capacity_Loss#Battery_Aging_Model" onclick="window.open(this.href);return false;

For those who have submitted new reports, I will probably add them to the calibration section when I get time/energy. We still need more reports from Arizona, Texas and other hot climates.

 

[surfingslovak]

The Wiki now contains links to Excel versions of the battery aging model, one (XLS) for Microsoft Excel 2007 and earlier, one (XLSX) for Microsoft Excel 2010 and later.

Excellent news, thank you Stoaty and TomT! I just downloaded it and it looks a lot better than the previous conversion I had access to.

 

[bjherbison]

--Date of Manufacture (month and year): November 2011
--Date of Delivery (month, day and year): February 2012
--Date of P3227 update, if needed (should be at least 3 weeks prior to reading data) : Never
--Geographic location - Bolton, MA; work 4-5 days/week in Burlington, MA
--Average miles/kwh for the life of your Leaf: 4.35 (from CarWings data)
--Current odometer reading: 20,390
--Current AH capacity reading from LeafDD or Leaf Battery App: 65.77
Exact date you took current odometer reading and current AH capacity: 27 October 2013
Days per week parked in the sun: 4.5

 

[Stoaty]

The XSLX spreadsheet on the Wiki has now been updated so that the dropdown for cities works. Many thanks to RegGuheert!!!

 

[RegGuheert]

The XSLX spreadsheet on the Wiki has now been updated so that the dropdown for cities works. Many thanks to RegGuheert!!!

You are welcome! Thanks for making this available!

I will add that this new XLSX file has also been made fully compatible with Google Drive. This might be useful for anyone who does not have either OpenOffice or Excel or who simply would prefer to use Google Drive. You can simply download the XLSX file and upload it to your Google Drive. It imports as a fully functional spreadsheet with all of the features found in OpenOffice or Excel. That is true if you view it from a browser, at least. When you view it from the iPad Google Drive App, it works, but some of the spreadsheet features are limited.

I have also created a live version of Stoaty's spreadsheet that anyone can use simply by clicking this link. This version is also full-featured, but it is slightly different from the other spreadsheets in that it has an additional tab labeled Input. This new tab is the ONLY part of the spreadsheet which you can modify (I hope!). This was done to protect the spreadsheet from any accidental damage by those with access to it. The inputs all now have error checking and hints to help users know what to input. The prediction tab is identical to the one found in the other spreadsheets except that the input fields are no longer live, but rather only display the values that are currently found on the input tab. This is helpful to prevent you from having to flip back and forth to see what you have entered, but it should also warn you if someone else is changing the inputs as you are trying to view your predictions!

Please give it a try and let me know if you find any problems.

Thanks again to Stoaty for putting this together!

P.S. You do NOT have to sign into your Google Account in order to use the link. If Google asks you to sign in or you are already signed in, you can simply sign out and then access the link again.

 

[Stoaty]

I have also created a live version of Stoaty's spreadsheet that anyone can use simply by clicking this link. This version is also full-featured, but it is slightly different from the other spreadsheets in that it has an additional tab labeled Input. This new tab is the ONLY part of the spreadsheet which you can modify (I hope!). This was done to protect the spreadsheet from any accidental damage by those with access to it. The inputs all now have error checking and hints to help users know what to input.

Fantastic work, thanks for helping make the model more easily available! I noticed one part that is missing from the Input tab--the actual % Gids at 80% charge and % Gids at 100% charge (yellow fields on Prediction tab of original spreadsheet. These allow you compare to predicted vs actual Gids at each of these charge levels.

 

[RegGuheert]

Fantastic work, thanks for helping make the model more easily available! I noticed one part that is missing from the Input tab--the actual % Gids at 80% charge and % Gids at 100% charge (yellow fields on Prediction tab of original spreadsheet. These allow you compare to predicted vs actual Gids at each of these charge levels.

You're welcome and thanks for checking! Sorry about that! That should be fixed now. Please have a look!

 

[Stoaty]

RegGuheert noticed a small cosmetic bug. The OpenOffice Version of the spreadsheet has a label on the prediction tab that says it is version 0.99b, when it is actually version 1.00. Happened because version 0.99b (perhaps with a couple of very small changes, not sure) was saved as 1.00 for the official release.