Stoaty
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Re: Battery Aging Model

Sat Oct 20, 2012 2:07 pm

edatoakrun wrote: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?
No, because I didn't do any tuning based on those numbers. As I said, the model doesn't account for it, and fractional years will consequently be less accurate than a whole number of years. The model is based exclusively on Nissan's data, with the exception of the solar loading factor which is based on the study of the Prius (probably not a great choice, but I don't have anything else to go on; a scaling factor is included so I can easily increase or decrease the effect of solar loading).
Do you not consider variables in Battery care may be very large factors in capacity loss?
If you have been following the thread, you will know that this factor is not included in the model yet, and may or may not be depending on whether I have some kind of data or study to reasonably base it on. That data is certainly not available from Nissan, and wasn't mentioned by Nissan as a significant factor in the Casa Grande cars. Armchair quarterbacking not helpful.
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
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Re: Battery Aging Model

Sat Oct 20, 2012 8:44 pm

I am ready to release version 0.81 of the Battery Aging Model, but I don't have a good place to make it easily available for download from a link in the Wiki. Suggestions?

PS Many thanks to JP White for figuring out how to make a dropdown list including only the cities for which I have an Aging Factor!
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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JPWhite
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Re: Battery Aging Model

Sun Oct 21, 2012 4:16 am

Stoaty wrote:I am ready to release version 0.81 of the Battery Aging Model, but I don't have a good place to make it easily available for download from a link in the Wiki. Suggestions?

PS Many thanks to JP White for figuring out how to make a dropdown list including only the cities for which I have an Aging Factor!
How about using dropbox? A 2GB account is free and the public link is only good for a single file shared in the public folder.
--
JP White
http://jpwhitenissanleaf.com
2011 Blue SL-e, 132,400 Miles.
Lost 5 Capacity bars
7/18/13 (29,206), 8/25/14 (51,728), 7/12/15 (71.108), 5/12/16 (88,362), 10/17/16 (96,532)
New Battery 12/3/16 (98,956)
2018 Model 3 20,000 Miles.

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TickTock
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Leaf Number: 3626
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Re: Battery Aging Model

Sun Oct 21, 2012 5:17 am

Stoaty wrote:I am ready to release version 0.81 of the Battery Aging Model, but I don't have a good place to make it easily available for download from a link in the Wiki. Suggestions?

PS Many thanks to JP White for figuring out how to make a dropdown list including only the cities for which I have an Aging Factor!
I would recommend https://drive.google.com it can import excel, you can share, and a really nice feature is the ability to create forms to collect data such as you requested on the other thread. For example, on my daily log, I created a online form with just the information I need and it automatically adds a row to the spreadsheet with the new information. Any web-attached device can make an entry.
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Stoaty
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Re: Battery Aging Model

Sun Oct 21, 2012 7:11 am

Forgot I already have a dropbox account. Version 0.81 available here now:

https://dl.dropbox.com/u/48149991/Leaf% ... %20081.ods" onclick="window.open(this.href);return false;

There is brief documentation on the "Documentation" tab of the spreadsheet. It is strongly suggested that you read it before asking questions or making suggestions for improvement. Spreadsheet created in OpenOffice, you need that to open and use it. OpenOffice is available here:

http://www.openoffice.org/download/" 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
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Location: West Los Angeles

Re: Battery Aging Model

Sun Oct 21, 2012 3:36 pm

Version 0.82 of Battery Aging Model now available here:

https://dl.dropbox.com/u/48149991/Leaf% ... %20082.ods" onclick="window.open(this.href);return false;

Changes from version 0.81:

--added Sacramento, CA to list of cities the model can predict for
--additional Tab added "End of Life" for brute strength method of End of Life calculation
--added End of Life calculation (number of years to nearest 0.1 year), with user selectable percentage for end of life (default = 70%) - for Fractional Year Prediction section only
--added Miles at End of Life calculation based on calculated annual mileage and predicted End of Life
--minor updates to Documentation
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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Re: Battery Aging Model

Fri Oct 26, 2012 12:27 pm

Version 0.83 of Battery Aging Model now available here:

https://dl.dropbox.com/u/48149991/Leaf% ... %20083.ods" onclick="window.open(this.href);return false;

Changes from 0.82:

--added El Paso, TX
--added corrected aging factors for Dubai and San Juan Puerto Rico so predictions will now work for those cities
--fixed bug that caused international cities to show bogus solar loading effects (solar loading not implemented for international cities, it now correctly shows no effect)
--percentage remaining capacity that is less than end of life shown in red
--Days Per Week in Sun = 0 now shown with white text on black background to remind you it isn't set
--Documentation updated, including to lower zoom percentage if everything doesn't fit on screen
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

Sat Oct 27, 2012 8:34 pm

Version 0.83 of the Battery Aging Model is now available as a Microsoft Excel spreadsheet:

https://dl.dropbox.com/u/48149991/Leaf% ... 20083.xlsx" onclick="window.open(this.href);return false;

Thanks to JPWhite for saving in Microsoft Office 13 and making a couple of small changes for compatibility.
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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Re: Battery Aging Model

Sun Oct 28, 2012 6:13 pm

Links to both spreadsheet versions of the Battery Aging Model added to the wiki:

http://www.mynissanleaf.com/wiki/index. ... acity_Loss" 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

tbleakne
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Re: Battery Aging Model

Tue Oct 30, 2012 2:37 pm

RegGuheert wrote:I'm not sure it is worthwhile trying to fit a model to the curves which Nissan gave to TickTock. Frankly, I don't expect to see any LEAFs in Phoenix with 76% capacity left after five years, regardless of miles driven.
>>>>>
As usual, I hope I am wrong about this. OTOH, Nissan's track record for making predicitions in Phoenix is quite poor to date.
I commend all the detailed work that has been reported on this thread, using solid analysis to apply corrections, but I still agree with this comment posted on pg 1. The curves Nissan gave to TickTock are not data, but rather their model. We should suspect that this model has been massaged to fit with the optimistic projections that Nissan is still standing behind. I am concerned that folks might put more faith in your results than is warranted to the extent that they are based upon their model.

From another thread:
Stoaty wrote:
surfingslovak wrote:It should also not come as a surprise that owners experiencing 15% range loss or more after less than 1 1/2 of ownership feel uneasy about Nissan's projections of 80% original range after five years (76% for Phoenix).
Especially true because the Battery Aging Model built from Nissan's own data predicts 76% remaining capacity for Phoenix owners driving 12500 miles per year at an average 4 miles/kwh efficiency after only 3.3 years. You can only reach 5 years with 76% remaining capacity if you limit your mileage to 7500 miles per year.
One clue that Nissan's curves might not be based upon solid science is that they show no seasonal variation, contrary to what we know will happen from the Arrenhius factor. Published government studies clearly show annual variation, with steeper decline during Summer and a leveling off during Winter, such as this graph from the NREL paper which has been displayed before:

Image

For what it is worth, an update of my data is below, based upon 160 days of monitoring the Gid count whenever I charged to 80% with no End Time specified.

Mileage: 11K per year steady.
DOC: on days not shown on the graph,
Upper Limit: usually 40-50% based upon current Gids, which should be 45-55% of current capacity.
Lower Limit: typically 25%, never more than 2% below LBW.
Charges to 100%: 3 during this period
Charges to 85-90%: 2-3 per month.

A lot of people on this forum do not trust the Gids. I am aware of your opinions, and I have found them not perfect by any means, but more than adequately reliable. Assessing the SOC of a Li-ion battery pack is clearly not an easy problem, but Nissan has done a fairly good first attempt. While we don't know the details, it is clear to me that the Gid calculation uses both voltage and coulomb-counting. The voltage varies substantially as a function of power level, so coulomb-counting must be used for minute-to-minute readings while driving. During stops Open Circuit Voltage can be used to re-calibrate the Gids. At the outer-most, slowest level of the algorithm, the coulomb-counting is used to adjust the SOC vs voltage table as the battery capacity declines. The algorithm has problems estimating the energy stored at the very bottom of the battery, especially if one never goes that low. We can agree to disagree on how relevant are errors below VLBW.

For modeling capacity loss the big problem is trying to get a good measure of the temperature history of the battery pack, with only ambient temperature and the temperature bars to guide us. Given that the thermal time-constant of the battery seems to be somewhere in the range of 4 to 8 hours, my experience is that the battery history over a 24-hr period is quite significant. In my inland Southern California climate, the battery swings between 5 and 6 Tbars, so I have attempted to monitor the fraction of time the battery spends at each level with a scale that runs from 0 to 1, with the following interpretation:

Temperature Value Interpretation
0 100% "deep" within 5 Tbars (24-hr average temperature below 65 F)
.2 "barely" 100% within 5 Tbars,
.5 50% at 5 Tbars, 50% at 6.
.8 "barely" 100% within 6 Tbars
1.0 100% "deep" within 6 Tbars (24-hr average temperature above 80 F)

Image

As the last of the warm 6 Tbar weather draws to a close, we can see about 4 Gids of rebound, but I am still looking at 10% capacity loss for the season, which has been confirmed by several charges to 100%. My graph represents half of one "wiggle" on the research graph. Next May I expect to begin another downward decline. Hopefully it will be shallower, especially since I will have my garage A/C available for a full summer season.
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