Tuning the Battery Aging Model

klapauzius said:

But since the Leaf-AHs are temperature dependent in exactly the opposite way a real world battery would behave, I am curious how real "AH" compare to "LEAF-AH" for a given temperature.

Click to expand...

The same effect has been observed with GIDs. The only difference is that Ah values were not available last year, and we don't know as much about this value and its idiosyncrasies as we do about GIDs. It's more convenient to measure, that's for sure. Also, GIDs depends on cell balancing, not just the current pack capacity, which introduces another variable.

Yes, both Ah figures and GIDs are dependent on the BMS and other software and instruments in the car. That's a given. We have not seen many LEAF owners, who would be willing to take raw measurements of the pack and the cells. There were several similar debates last year, where the accuracy and the veracity of these values was questioned. You are obviously correct and right to raise this point, but unfortunately it's all that is available.

Anything from the CAN bus, including pack voltage, could be of interpretative and of synthetic nature. So far, GIDs have aligned well with range predictions, and the observations collected last year. This led to the correct conclusion that the packs were in fact degrading in hot locales, and owners there did not observe primarily software and gauge errors. The likelihood that Ah is a legitimate proxy to GIDs measured on a full charge is good or very good.

Manufactured - 03/11
Delivered - 5/02/11
P3227 updte - 7/11/13
Location - La Mirada, CA; Leaf spends 5 days a week in Irvine, CA
Miles/kwh - 5.1
Odometer - 30437
Capacity - 48.28
Date - 10/06/13
Parked in sun - 5 days/week

Almost a month later and significantly colder. 1000 miles driven, 0.55 Ah lost, according to Leaf Spy.


Date of Manufacture (month and year): 11/2010

Date of Delivery (month, day and year): 01, 23,2011

Date of P3227 update, if needed (should be at least 3 weeks prior to reading data): July 2013

Geographic location - be specific, must include city and state, otherwise data of no use (also include work location city and state and days Leaf spends at work if climate significantly different than home): Seattle, Wa.

Average miles/kwh for the life of your Leaf: ~ 4 m/kWh

Current odometer reading (i.e. total miles your Leaf has been driven): 23,759 mi

Current AH capacity reading from LeafDD or Leaf Battery App: 60.00

Exact date you took current odometer reading and current AH capacity : 10/9/2013

Days per week parked in the sun: 0

sksingh,
happen to have the Ahr readings when you lost your 2nd bar? i think most 2011s in S. Cal are reporting near 51 Ahr.

sksingh said:

Manufactured - 03/11
Delivered - 5/02/11
P3227 updte - 7/11/13
Location - La Mirada, CA; Leaf spends 5 days a week in Irvine, CA
Miles/kwh - 5.1
Odometer - 30437
Capacity - 48.28
Date - 10/06/13
Parked in sun - 5 days/week

Click to expand...

klapauzius said:

Almost a month later and significantly colder. 1000 miles driven, 0.55 Ah lost, according to Leaf Spy.


Date of Manufacture (month and year): 11/2010

Date of Delivery (month, day and year): 01, 23,2011

Date of P3227 update, if needed (should be at least 3 weeks prior to reading data): July 2013

Geographic location - be specific, must include city and state, otherwise data of no use (also include work location city and state and days Leaf spends at work if climate significantly different than home): Seattle, Wa.

Average miles/kwh for the life of your Leaf: ~ 4 m/kWh

Current odometer reading (i.e. total miles your Leaf has been driven): 23,759 mi

Current AH capacity reading from LeafDD or Leaf Battery App: 60.00

Exact date you took current odometer reading and current AH capacity : 10/9/2013

Days per week parked in the sun: 0

Click to expand...

dleted

Sorry, did not have the Leaf Spy app then.

opencar said:

sksingh,
happen to have the Ahr readings when you lost your 2nd bar? i think most 2011s in S. Cal are reporting near 51 Ahr.

sksingh said:

Manufactured - 03/11
Delivered - 5/02/11
P3227 updte - 7/11/13
Location - La Mirada, CA; Leaf spends 5 days a week in Irvine, CA
Miles/kwh - 5.1
Odometer - 30437
Capacity - 48.28
Date - 10/06/13
Parked in sun - 5 days/week

Click to expand...

Click to expand...

Just got the Leaf Spy app. Here's the data:

Manufactured: ?
Delivered: 4/20/2011
P3327 update: July 2013
Location: Arrowbear Lake, CA. Most workdays spent parked in Redlands, CA or Highland, CA.
Miles/kWh: 4.1
Odometer: 43,421 miles
Capacity: 55.45 Ah
Date: 10/11/2013
Parked in sun: 2 days/week

The Manufactured date in on a black tag on the drivers door post.

abasile said:

Just got the Leaf Spy app. Here's the data:

Manufactured: ?
Delivered: 4/20/2011
P3327 update: July 2013
Location: Arrowbear Lake, CA. Most workdays spent parked in Redlands, CA or Highland, CA.
Miles/kWh: 4.1
Odometer: 43,421 miles
Capacity: 55.45 Ah
Date: 10/11/2013
Parked in sun: 2 days/week

Click to expand...

--Date of Manufacture: 9/11
--Date of Delivery: 11/8/11
--Date of P3227 update: 7/12/13
--Geographic location - Chapel Hill, NC (Research Triangle Park or Raleigh, NC will do)
--Average miles/kwh for the life of your Leaf: totally a guess: 4.9-5.1
--Current odometer reading: 19516 (start of day)
--Current AH capacity reading (from Leaf Battery App): 57.41
--Exact date you took current odometer reading and current AH capacity: 10/15/13
--Days per week parked in the sun (fractional days OK): 7 days mixed sun and shade. estimate 2 days sun and 5 days mostly shade (I have no garage, but shade from house and trees covers the driveway for all but about 2-3 hours).

The 100% charge on 10/15 also showed: 242 GIDs, 86.65% battery, and 19.4kw

I'm guessing it isn't too long before the first capacity bar goes away?

Fortunately, my company (where we have over 40 Leafs by now, maybe over 50) is adding more L2 EVSEs - about to make 4 more dual post models available right near my building. Initially I was the first Leaf owner, and there was a Volt, too. Now we have well over 50 EVs on campus including at least one Tesla. I almost never luck out at the first-come, first-served EVSEs (free charging, four hour limit).

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;

I have also updated the table in the Wiki showing predicted capacity loss for each geographic location assuming:

--4 miles/kwh
--12500 miles per year
--solar loading not included

I still need to:

--update the description in the Wiki to include changes made in the model to calibrate it
--finish the documentation and put it on the Wiki

PS I don't know if/how well the spreadsheet works when converted to Excel. If someone wants to make an Excel version from the OpenOffice version, let me know and I will post it to the Wiki as well.

Update because I lost my first capacity bar last week (10/12/2013)

Manufactured - 5/11
Delivered - 6/16/11
P3227 update - 7/23/13
Location - Van Nuys, CA
Miles/kwh - ~4.4
Odometer - 27,382mi
Capacity - 55.15
Date - 10/18/13
Parked in sun - 5 days/week (75% Burbank, 25% Woodland Hills)

Garage - Unventilated & uninsulated, exposed on South, East, and North sides (faces North)
Capacity bars indicated - 11
DC Charge Count - 19
AC Charge Count - 2,985

Devin,

Those numbers bring you closer to the model predictions:

Actual loss - 16.75%
Predicted loss - 18.21%

Actual minus predicted = -1.45%

Your last reading had actual minus predicted = -2.45%

finally hit 6 wks from my update:

Manufactured - 3/11
Delivered - 6/3/11
P3227 update - 9/6/13
Location - San Diego, CA
Miles/kwh - ~4.2
Odometer - 24,440mi
Capacity - 54.79
Date - 10/18/13
Parked in sun - 5 days/week

Garage - Unventilated & uninsulated
Capacity bars indicated - 11
DC Charge Count - 17
AC Charge Count - 1613

opencar,

here are the results of the model:

Actual loss - 17.3%
Predicted Loss - 16.3%

Actual minus predicted - 1.0%

My first entry:

Manufactured - 4/11
Delivered - 6/15/11
P3227 update ~ 6/20/13
Location - Camas,WA
Miles/kWh - ~4.2
Odometer - 34,061mi
Capacity - 57.16
Date - 10/18/13
Parked in sun - 1 days/week

Garage - Unventilated & insulated
Capacity bars indicated - 12
DC Charge Count - 49
AC Charge Count - 1769

camasleaf,

Using Portland as the closest match for your city, the model shows:

Actual Loss - 13.72%
Predicted Loss - 13.56%

Actual minus predicted = 0.16%

Been about a month since my first report:

Manufactured - 4/11
Delivered - 6/7/11
P3227 update - 6/28/13
Location - Encinitas, CA (~3 mi inland)
Miles/kwh - 4.5
Odometer - 23003
Capacity - 55.12
Date - 10/19/13
Parked in sun - 5 days/week in Vista, CA (~7 mi inland).

drees,

Actual Loss - 16.80%
Predicted Loss - 15.56%

Actual minus predicted = 1.24%

Previous report actual minus predicted = 1.02%

Update on Stoaty's own stats (using Van Nuys, since that is where his Leaf spends most of its time during the day):

Predicted Loss - 15.85%
Actual Loss - 15.55%

Actual minus Predicted = -0.31%

Comment: Stoaty's lead over the Battery Aging Model is evaporating, and almost non-existent now. He is still on track for 6.80 years total to EOL, but that may not hold.

Just an update:

Date of Manufacture: 1/11
Date of Delivery: 3/1/11
Date of P3227 update: 6/3/13
Geographic location: Garaged and weekends: Granada Hills, CA 91344; Work (Mon-Fri 8am-5p) Santa Monica, CA
Average miles/kwh for the life of your Leaf: 4.4
Current odometer reading: 39,400
Current AH capacity reading from LeafDD or Leaf Battery App: 51.60
Exact date you took current odometer reading and current AH capacity: 10/20/13
Days per week parked in the sun (fractional days OK): 5 days for 8 hours each day (see work above)