Stoaty
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Re: Early Capacity Losses-Was(Lost a bar...down to 11)

Sat Aug 18, 2012 9:27 am

I have updated a portion of the Real World Battery Capacity Loss section of the wiki. The section with changes is reproduced below:

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

"When the battery pack loses capacity, bars begin to disappear from the "capacity gauge" (thin 12-segment gauge to the immediate right of the 12-segment state of charge gauge). The first known Nissan LEAF to have its battery pack replaced was reported in November, 2011 when an owner in the Phoenix area reported a missing battery capacity bar on the dash instrument and reduced range. In April 2012 another Phoenix area LEAF driver reported the same issue. All LEAFs reported to have battery capacity loss have been in hotter climates (mainly Arizona and Texas). Note that per the Nissan Leaf Service Manual, the first capacity bar loss represents a 15% loss, while each subsequent bar represents only a 6.25% loss. While exposure to high ambient temperatures over time is thought to be the predominant factor in capacity bar loss, an analysis by Stoaty of the 26 reported cases in the Phoenix metro area showed that there was a moderate correlation between miles driven per month and the rate of battery capacity loss. The correlation coefficient was 0.51 and linear regression suggested that those who drove 1800 miles per month had a 2% per month capacity loss compared to 1% per month for those who drove 900 miles per month. [Remember that this only applies to Phoenix owners who have lost a capacity bar, not the general population of Leafs.] The analysis suggests that something related to charging and discharging the battery (leaving Leaf at high state of charge, high depth of discharge, number of battery charge cycles,etc.) is an additional factor affecting battery capacity loss. An analysis of the available data for all Leafs that had lost a second bar showed that the mean time between losing bars one and two was 52.7 days. The average rate of capacity loss between bars one and two was 3.7% per month (but note that most of these losses were during a hot summer, so do not extrapolate these loss rates to other areas of the country or other times of year). There was no correlation between mileage and rate of capacity loss between bars one and two."

Feel free to suggest additions, corrections or revisions, either on this thread, in a PM, or make the changes yourself on the Wiki. :D
2011 Leaf with 62,000 miles given to Nephew
2013 Tesla Model S85 with 251 miles rated range at full charge
Leaf Spy Manual
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JimSouCal
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Re: Early Capacity Losses-Was(Lost a bar...down to 11)

Sat Aug 18, 2012 10:15 am

OrientExpress wrote:
The next time OrientExpress gives us the next LEAF revelation, just consider these previous revelations about the battery:
Looks like someone is off their meds again.
I don't usually get involved in something like this, but WOW, You are really going to throw out a personal slur in light of events and evidence? Is that really going to help a position that claims rational thought and evidence?

edatoakrun
Posts: 5222
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Delivery Date: 15 May 2011
Leaf Number: 2184
Location: Shasta County, North California

Re: Early Capacity Losses-Was(Lost a bar...down to 11)

Sat Aug 18, 2012 10:19 am

Stoaty wrote:I have updated a portion of the Real World Battery Capacity Loss section of the wiki. The section with changes is reproduced below:

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

"When the battery pack loses capacity, bars begin to disappear from the "capacity gauge" (thin 12-segment gauge to the immediate right of the 12-segment state of charge gauge). The first known Nissan LEAF to have its battery pack replaced was reported in November, 2011 when an owner in the Phoenix area reported a missing battery capacity bar on the dash instrument and reduced range. In April 2012 another Phoenix area LEAF driver reported the same issue. All LEAFs reported to have battery capacity loss have been in hotter climates (mainly Arizona and Texas). Note that per the Nissan Leaf Service Manual, the first capacity bar loss represents a 15% loss, while each subsequent bar represents only a 6.25% loss. While exposure to high ambient temperatures over time is thought to be the predominant factor in capacity bar loss, an analysis by Stoaty of the 26 reported cases in the Phoenix metro area showed that there was a moderate correlation between miles driven per month and the rate of battery capacity loss. The correlation coefficient was 0.51 and linear regression suggested that those who drove 1800 miles per month had a 2% per month capacity loss compared to 1% per month for those who drove 900 miles per month. [Remember that this only applies to Phoenix owners who have lost a capacity bar, not the general population of Leafs.] The analysis suggests that something related to charging and discharging the battery (leaving Leaf at high state of charge, high depth of discharge, number of battery charge cycles,etc.) is an additional factor affecting battery capacity loss. An analysis of the available data for all Leafs that had lost a second bar showed that the mean time between losing bars one and two was 52.7 days. The average rate of capacity loss between bars one and two was 3.7% per month (but note that most of these losses were during a hot summer, so do not extrapolate these loss rates to other areas of the country or other times of year). There was no correlation between mileage and rate of capacity loss between bars one and two."

Feel free to suggest additions, corrections or revisions, either on this thread, in a PM, or make the changes yourself on the Wiki. :D
...Note that per the Nissan Leaf Service Manual, the first capacity bar loss represents a 15% loss, while each subsequent bar represents only a 6.25% loss....
I've asked several times, of those that have access to this source, that they please post this entire table (?) and any associated text.

IMO, if you choose to rely on Nissan for this information, you should at least try to discern exactly what Nissan is stating. The terms "Capacity" and "15% loss", for example, have multiple possible interpretations.

Most importantly, perhaps, is whether Nissan is saying that these percentage losses are of total battery capacity, or rather of that percentage (possibly variable) of the capacity that the BMS allows us to use between a "100% charge" and the low state of charge warnings, and/or shut down.

Please add this info to the Wiki, when it is available.
no condition is permanent

shrink
Posts: 360
Joined: Sun Aug 07, 2011 11:21 pm
Delivery Date: 26 Jun 2012
Leaf Number: 21842
Location: Phoenix, AZ

Re: Early Capacity Losses-Was(Lost a bar...down to 11)

Sat Aug 18, 2012 10:37 am

Stoaty wrote:
Slope = -1,274
Intercept = 29,095
Correlation coefficient = 0.51

Edit: mean annual mileage = 13,894 and standard deviation of annual mileage = 3,967 for Phoenix area.

Interpretation: There is a moderate correlation between annual mileage and number of months to first capacity bar loss. This data suggests that some of the capacity loss may indeed be due to cycling losses rather than calendar losses.
Stoaty, thanks for taking the time to do all the analysis. I have a question about the above conclusion. It appears your phrase, "capacity loss may indeed be due to cycling losses," implies causality. However, a correlation is not causality. Correlation only says if there is or is not a relationship, but strictly speaking, nothing can be said about causality.

Am I reading your interpretation correctly?
2011 LEAF (Sold) | 2012 Volt (Sold) | 2012 LEAF (Lease Ended) | 2010 Tesla Roadster #501 | 2013 Tesla Model S #9001 | 6.827 kW SunPower PV System

Stoaty
Posts: 4490
Joined: Fri Jun 18, 2010 9:50 pm
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Leaf Number: 3871
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Re: Early Capacity Losses-Was(Lost a bar...down to 11)

Sat Aug 18, 2012 11:27 am

shrink wrote:Stoaty, thanks for taking the time to do all the analysis. I have a question about the above conclusion. It appears your phrase, "capacity loss may indeed be due to cycling losses," implies causality. However, a correlation is not causality. Correlation only says if there is or is not a relationship, but strictly speaking, nothing can be said about causality.

Am I reading your interpretation correctly?
"This data suggests that some of the capacity loss may indeed be due to cycling losses"

I thought I included enough weasel words, but perhaps this would be better? :o No, correlation is not causation, but it is a reasonable inference, given what we know about what factors affect battery capacity over time (high SOC, higher depth of discharge, more cycling). Other hypotheses are welcome, because we are all guessing. I was just trying to see if there was any support for the idea that monthly mileage might be related to rate of capacity loss. An alternate interpretation of the data is that those who realize they are losing capacity more rapidly are quickly putting on more miles before their Leaf becomes a lead (correction: lithium) paper weight. :lol: I suppose we could query the affected owners to see if that theory has any merit. ;)
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

palmermd
Posts: 2628
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Leaf Number: 1100011011
Location: Hermosa Beach, CA

Re: Early Capacity Losses-Was(Lost a bar...down to 11)

Sat Aug 18, 2012 11:49 am

edatoakrun wrote: I've asked several times, of those that have access to this source, that they please post this entire table (?) and any associated text.

Please add this info to the Wiki, when it is available.
Everyone has access... http://www.mynissanleaf.com/viewtopic.php?f=30&t=7570" onclick="window.open(this.href);return false; but it is a $20 subscription. Worth every penny if you want to know about the vehicle. I suggest you get a copy for yourself.

The info is in the wiki... http://www.mynissanleaf.com/wiki/index. ... y_Behavior" onclick="window.open(this.href);return false;
Michael

Leaf from 31 March 2011 - Traded 18 April 2019 for Tesla Model 3 Unicorn
Driving electric since 1996


Leaf Bar Loss

dsh
Posts: 183
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Leaf Number: 001069

Re: Early Capacity Losses-Was(Lost a bar...down to 11)

Sat Aug 18, 2012 12:26 pm

One thing I failed to mention, was when speaking to the technician who checked out my LEAF, he mentioned Air conditioning takes it's power directly from the Li-Ion Pack Battery...Does anybody think there is a correlation between battery degredation and LEAF owners who who use the air conditioning every day in the Summer in addition to the the hot air surrounding the battery pack. Sounds like the more strain you put on the Battery pack i.e. A/C and other environmental conditions will cause the battery to get weaker faster...just a thought.
dsh wrote:Avondale Nissan checked out LEAF today. As assumed, “Battery tested good at this time, but is not an indication of future failure.” All computer diagnostics checked out OK. Was informed there’s no ‘cooling fan’ for the batteries, but I do have the battery heater in this vehicle.
Received update on Casa Grande testing…Nissan looking at specific cells measuring highest charge cells vs. lowest charge cells to determine reason for variation. Also, they ARE able to replace out individual modules. In addition, Nissan was able to say LEAFs have approximately 5% more capacity, than what is listed via Li-ion battery capacity level gauge… Good to know.
They did state this is one of the lowest mileage LEAFs they encountered with the battery degradation problem…other owners had at least 20-30k on their vehicles.
Nissan will keep me posted with their conclusions, but nothing as of yet…as expected.
Lastly, received contact back from Executive Relations spokesman for Mark Perry and he said as assumed, no information yet, but Nissan diligently testing. I suggested Nissan offer good faith replacements for these batteries and when /if they have updated versions in 2013 to replace again. Some owners use this vehicle for work, and if they can’t get the range need, it will impact them negatively.
Will keep forum posted…
SL-e

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planet4ever
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Leaf Number: 1537
Location: Morgan Hill, CA, south of San Jose

Re: Early Capacity Losses-Was(Lost a bar...down to 11)

Sat Aug 18, 2012 12:47 pm

Note: Following quote is edited and severely trimmed.
Weatherman wrote:My suggestion, for those concerned about the life of their LEAF's battery, is to think of it this way:
  1. If you almost always see five bars or less on the battery temperature gage, and it only gets up to six bars a handful of times each summer...
    Don't worry about it.
  2. If you see five bars or less during the winter half of the year and, fairly often, see six bars during the summer half...
    You, probably, are going to see the quoted loss (20% loss at 5 and 30% loss at 10).
  3. If seeing six bars is common for a large part of the year and an, occasional, seventh bar pops up during the summer months...
    Don't consider buying.
  4. If you spend a large part of the summer with seven temperature bars, or more, showing...
    It's, probably, best to stay away completely
Well put, Weatherman. I fall in your group 2, I love my car, and I expect that it will continue to satisfy my needs for a number of years.

Ray
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.

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planet4ever
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Re: Early Capacity Losses-Was(Lost a bar...down to 11)

Sat Aug 18, 2012 1:07 pm

LEAFfan wrote:Since the battery warranty DOES cover any capacity loss that isn't "gradual", any intelligent person knows that a 15% or higher loss in about a year isn't gradual.
I'm sorry, LEAFfan, but that is flat wrong. Intelligent English-speaking people should know that "gradual" is not a synonym for "slow". Nissan's lawyers, and any judge hearing a case, will certainly know that. What is covered is sudden capacity loss, not gradual loss. Gradual means a little bit at a time. If you lose a bit of capacity each week, that's gradual, even if that is 0.3% per week. And, yes 0.3%/week adds up to more than 15%/year.

Look, I'm not trying to be nasty here, or to put down those of you who are having battery problems. I do indeed feel for you. But I don't think your complaints will get very far in the court system. I urge you to listen to people like this:
stanley wrote:The only people that do well in this type of litigation are the lawyers not the individual or Class they represent. Most litigation is settled. When matters are settled the lawyers get paid for every hour they put in. While the individual plaintiff or Class receives very little. Usually no more and often less than a reputable Company being sued would have worked out informally without a lawsuit. Nissan is a reputable Company and will ultimately do the right thing. The problem is, as with most large Companys,there are so many bureaucratic layers that it takes a while for them to come up with a plan to do what is right.I am confident Nissan will not let their (Billions) in EV investment be diminished by inaction. Hang in there as Tony suggests.
Ray
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.

DaveinOlyWA
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Contact: Website

Re: Early Capacity Losses-Was(Lost a bar...down to 11)

Sat Aug 18, 2012 1:14 pm

dsh wrote:One thing I failed to mention, was when speaking to the technician who checked out my LEAF, he mentioned Air conditioning takes it's power directly from the Li-Ion Pack Battery...Does anybody think there is a correlation between battery degredation and LEAF owners who who use the air conditioning every day in the Summer in addition to the the hot air surrounding the battery pack. Sounds like the more strain you put on the Battery pack i.e. A/C and other environmental conditions will cause the battery to get weaker faster...just a thought.
dsh wrote:Avondale Nissan checked out LEAF today. As assumed, “Battery tested good at this time, but is not an indication of future failure.” All computer diagnostics checked out OK. Was informed there’s no ‘cooling fan’ for the batteries, but I do have the battery heater in this vehicle.
Received update on Casa Grande testing…Nissan looking at specific cells measuring highest charge cells vs. lowest charge cells to determine reason for variation. Also, they ARE able to replace out individual modules. In addition, Nissan was able to say LEAFs have approximately 5% more capacity, than what is listed via Li-ion battery capacity level gauge… Good to know.
They did state this is one of the lowest mileage LEAFs they encountered with the battery degradation problem…other owners had at least 20-30k on their vehicles.
Nissan will keep me posted with their conclusions, but nothing as of yet…as expected.
Lastly, received contact back from Executive Relations spokesman for Mark Perry and he said as assumed, no information yet, but Nissan diligently testing. I suggested Nissan offer good faith replacements for these batteries and when /if they have updated versions in 2013 to replace again. Some owners use this vehicle for work, and if they can’t get the range need, it will impact them negatively.
Will keep forum posted…

umm not a serious question i hope... because ANYTHING that uses electricity is basically invisible miles on the odometer

maybe the key piece of info we should be looking at and adding to the Wiki is how many Kwh has been pumped thru the pack....

**edit** i checked and once again ANOTHER metric i wished i would have tracked and that is how much freebie juice i have collected but i can say i have pumped just 5,000 Kwh from my house to the LEAF. have to go back thru my diary log to get an estimate on the public charging but guessing it to be in the 300-600 kWh range maybe??
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 13,705 mi, 93.41% SOH
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