LEAFfan
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Leaf Number: 1855
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Re: Discuss data obtained from the LEAF Battery app

Sun May 19, 2013 10:43 am

JPWhite wrote:I noticed I had lost quite a bit of battery capacity in short order. I found it was Thursday (May 16th) and did an analysis of what was going on to cause the 0.3 reduction in Ah in a single day.

As one might predict based on what happened (and is happening) in Arizona, high battery temp is the culprit.

Here's a graph of battery temp and Ah of the battery on Thursday this week. My battery got to 90F. :o

Left axis an orange line is battery temp
Right Axis and blue line is Ah of the battery.

Image

Battery Ah never recovered overnight after cooling.

Daily degradation appears to be .02 or .03 Ah. So once battery temp gets above 86 or so, the degradation accelerates by one order of magnitude !!

This is just one day, but it does look like single incidences can impact overall battery health.
Yep, a lot of research shows battery degradation begins at 87F. The App should stay yellow (up to 86F) until the BT reaches 87F.
2013 LEAF SV Del. 2/28/13
2013 LEAF World Record for Most Miles Driven On One Charge-188 miles/8.8 m/kW h
4.8 kW DC PV ($ .91/W fully installed)/ Dec., 2010

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JPWhite
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Re: Discuss data obtained from the LEAF Battery app

Sun May 19, 2013 12:18 pm

Stoaty wrote:
JPWhite wrote:I noticed I had lost quite a bit of battery capacity in short order. I found it was Thursday (May 16th) and did an analysis of what was going on to cause the 0.3 reduction in Ah in a single day.

As one might predict based on what happened (and is happening) in Arizona, high battery temp is the culprit.

Here's a graph of battery temp and Ah of the battery on Thursday this week. My battery got to 90F. :o

Battery Ah never recovered overnight after cooling.

Daily degradation appears to be .02 or .03 Ah. So once battery temp gets above 86 or so, the degradation accelerates by one order of magnitude !!
I would want longer follow-up when the battery had cooled to 5 bars to be certain the loss is permanent. However, doesn't look too good. How did you get your battery to 90 degrees? QC? Parking on hot blacktop? What was the ambient temp?
It was in the 80's that day and I charged at an L2 in a state park late afternoon for 2 hours. Hot temps and charging sends the internal temps up. Good to have this tool, now we know what's gong on indie the battery and when to be wary about plugging in.
--
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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turbo2ltr
Posts: 1376
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Delivery Date: 04 Feb 2011
Leaf Number: 185
Location: Phoenix, AZ

Re: Discuss data obtained from the LEAF Battery app

Sun May 19, 2013 3:51 pm

Heres my data.

Image

Image
Silver SL-e
Ford F450 Crew Cab Hybrid Conversion

FairwoodRed
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Joined: Wed May 18, 2011 10:25 am
Location: Fairwood, WA

Re: Discuss data obtained from the LEAF Battery app

Mon May 20, 2013 10:44 am

I also saw a 0.24 drop in AH’s in one day during a range test and following QC. Overall, I’ve seen my AH’s vary between 56.86 and 62.33 in the screenshots and more screenshots I’ve taken since LeafBatt became available.

I kept a log of my drive and following QC and I’d sure like some help analyzing it because I haven’t done a lot of data analysis. Could someone point me to a free site to upload files or instructions on how to upload it directly to the board?

sorphin
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Delivery Date: 18 Apr 2013
Leaf Number: 403273

Re: Discuss data obtained from the LEAF Battery app

Wed May 22, 2013 11:08 am

Another 100% charge (from 48%), another 23.6kWh. Battery temp (in the garage (mostly because someone else left their garage door open)) as seen below:

Image
Image


So far, the 23.xkWh seems to be consistant for me on my 13.

Stoaty
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Leaf Number: 3871
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Re: Discuss data obtained from the LEAF Battery app

Wed May 22, 2013 9:30 pm

I noticed something interesting about my Leaf looking at the cell pair voltages. Usually I charge to around 75% and run the Leaf down to about 35% SOC. So far, I have seen balancing going on pretty much all time on some of the cell pairs--perhaps 6-10 would be balancing at any one time. This morning I charged to 80% and left the Leaf plugged in to balance for an extra 30 minutes after I figured the charging would stop. Today I saw very few shunts come on, usually maximum of 4 at a time and often no shunts would be on for several minutes. Also, the maximum voltage difference was a little lower than usual (20 mv today) and didn't vary much at all (generally 19-21 mv difference). First time I have seen this behavior with the Leaf app.

Conclusion: all SOC are equal at balancing effectiveness, but some are more equal than others. ;) It does appear that the 80% (and undoubtedly 100%) charge is an optimal balancing point.
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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JeremyW
Posts: 1541
Joined: Sun Nov 13, 2011 12:53 am
Delivery Date: 23 Jun 2012
Leaf Number: 19136
Location: San Gabriel, CA

Re: Discuss data obtained from the LEAF Battery app

Thu May 23, 2013 6:26 pm

I've dropped over 1 Ah over a weekend of high heat and 4 quick charges (and 8 TB's to match! 48c max temp recorded), with ~0.2 Ah recovery after the heat wave passed. I was at 61.7427 Ah
on May 11th, I'm at about 60.2 Ah now. :cry:

Honestly I don't see summer this going well... I need to be able to do multiple qc's in a day to get to where I need to be as this is my only car, but losing an Ah every spirited weekend is going to be an issue. At the end of my lease they are getting back a car with one very trashed pack. :roll:
Former 2012 SL leasee 6/23/12 - 9/23/15
Former Fit EV leasee.
Now driving Spark EV and Model 3.

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DaveEV
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Joined: Fri Apr 23, 2010 3:51 pm
Location: San Diego

Re: Discuss data obtained from the LEAF Battery app

Thu May 23, 2013 7:47 pm

It's obvious that the Ah reading like GIDs are affected by battery pack temperature - but that doesn't necessarily correlate to an actual change in capacity.

So you should only be comparing those readings under similar temperature conditions.

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JeremyW
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Re: Discuss data obtained from the LEAF Battery app

Sat May 25, 2013 1:44 am

These past two days have been cooler, pack temps been around 20-25c. My capacity has "grown" to 60.6 Ah. So I've gained back some, but I'm still down overall. Full gid count was 252 last night, doing another 100% charge tonight.

Looks like capacity needs several days or maybe a week to recover, but how much I "get back" is anyone's guess. Quick charging so often and multiple times in a day is catching up with me. My car was manufactured in February of 2012, over a year after JPwhite. I also only have a bit less than 13,000 miles on mine while JPWhite has 24k, almost double.

Heat is bad. Really, really bad. ;)
Former 2012 SL leasee 6/23/12 - 9/23/15
Former Fit EV leasee.
Now driving Spark EV and Model 3.

toasty
Posts: 241
Joined: Sun Feb 26, 2012 3:53 am
Location: Atlanta, GA

Re: Discuss data obtained from the LEAF Battery app

Sat May 25, 2013 7:21 am

Image

how is this for a 2011 w 18k miles?

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