Capacity Loss on 2011-2012 LEAFs

[Stoaty]

I have lost 2 bars, living in Phoenix:

Car has always been stored in garage. Sits in a parking lot for 8 hours during the day 3 days a week on average.

Bar 1 On or around Aug 1, 2012. Took possession of the car July 15th, 2011. (1 yr) 12,500 miles. 1 QC, all others L2 charging to 100%. VIN 004917.
Bar 2 August 26, 2012 (today!). (1yr, 1mo) 13,365 miles. 1 more QC. Only 1 month and 865 miles between bar loss

Not reported to Nissan. Will report this week.

Manufacturer date 05/11

Added to Wiki. Sorry to hear about your loss. I believe you may have set a record, with only 26 days elapsed between first and second bar loss. Let us know case number and date reported to Nissan.

 

[Jimmydreams]

LBW very rarely. I can't remember the last time I hit VLB. I drive very conservatively: 65mph max, A/C on (low fan). I'll go as slow as 55mph if I think I need to save the electrons. CC always on the highway, ECO mode on side streets It's about 61.5 miles round-trip and I usually arrive with at least 1 or 2 bars left, no LBW.

How long does your Leaf typically sit at 100% charge at night before you start your commute in the AM? Do you keep the Leaf charged to 100% on weekends and sitting at high SOC for significant periods of time?

It varies. It's usually charged to 100% by 4-5am. 2-3 days a week, I get in and drive it between 5-6am, so it doesn't sit long at all at 100%. 2-3 days a week it doesn't get driven until 11am-ish. And on my weekends, it sometimes doesn't get driven until noon-3pm, and USUALLY my weekend driving only uses 1-3 bars. Hindsight being 20/20 (and if the car wasn't a lease), I probably should have charged to 80% or even less on the weekends.

But IMHO, you could take great pains to baby the batteries and all you'd be doing is delaying the inevitable, and even then maybe not by much. This is EXACTLY the reason that I leased instead of purchased.....I had no idea of the reliability and longevity of the batteries.

 

[Jimmydreams]

Jimmy, how deeply do you discharge the battery on your commute each day? Do you routinely get the "low battery" warning or the "very low battery" warning?

LBW very rarely. I can't remember the last time I hit VLB. I drive very conservatively: 65mph max, A/C on (low fan). I'll go as slow as 55mph if I think I need to save the electrons. CC always on the highway, ECO mode on side streets It's about 61.5 miles round-trip and I usually arrive with at least 1 or 2 bars left, no LBW.

I didn't expect to see a battery bar lost already, but I'm still happy with the range. Let's see if I feel the same way when it starts getting cooler!!!!

How much range do you feel that you've lost compared to last year at this time? Have you had all the software/firmware updates?

I'd guess about 10-15% reduction. I stopped keeping paper records of distance/charging/etc. after the first couple months.

As for software updates, I had the first one done (that changed the way the battery bars report) but did not have the second one done yet.

 

[DaveEV]

How much range do you feel that you've lost compared to last year at this time? Have you had all the software/firmware updates?

I'd guess about 10-15% reduction. I stopped keeping paper records of distance/charging/etc. after the first couple months.

As for software updates, I had the first one done (that changed the way the battery bars report) but did not have the second one done yet.

Thanks Jimmy - what's your typical mi/kWh for your 60 mile commute?

IMO, getting back home w/1-2 bars remaining after driving 60 miles at 65 mph is not much different than a new car. Certainly less than the 15% the loss of a capacity bar might indicate...

 

[Jimmydreams]

Thanks Jimmy - what's your typical mi/kWh for your 60 mile commute?

IMO, getting back home w/1-2 bars remaining after driving 60 miles at 65 mph is not much different than a new car. Certainly less than the 15% the loss of a capacity bar might indicate...

I quit figuring my mi/kWh long ago, sorry!! I no longer look at the wall-to-wheel numbers or anything....I charge to 100%, I know the range/my driving habits. I drive the car. Lather. Rinse. Repeat.

 

[spooka]

I just received this from Nissan. To view the PDF version, click here


An open letter to Nissan LEAF owners from Carla Bailo, senior vice
president, Research and Development, Nissan Americas:

At Nissan, we consider ourselves fortunate to have such passionate
and engaged customers—especially within our LEAF family. Recently,
we learned from the Nissan LEAF community—and specifically from
some Phoenix-area LEAF owners—of a growing concern about battery
capacity loss with their electric vehicles. In fact, the MyNissanLEAF
online owners' forum—a resource that allows owners to share their
experiences and discuss EVs— helped bring the concern to our
attention for which we’re appreciative.

The forum's discussion around battery capacity loss has reached a
point where I feel it important to personally address what is being
debated, to provide Nissan's viewpoint and, most importantly, to
explain the actions we are taking to work with owners.

First, it is important to stress that while battery capacity loss incidents represent only a
handful of cases, we are taking them—as well as the concerns of the larger LEAF family—
very seriously. Battery capacity loss of the levels reported may be considered normal
depending on the method and frequency of charging, the operating environment, the
amount of electricity consumed during daily usage and a vehicle's mileage and age. But the
only way to know for sure is to examine customer vehicles, perform a thorough diagnostic
on the vehicle and battery, and better understand the real-world driving and charging
history of the owners. We are now reaching out to individual owners to start this process to
ensure that we fully understand these events and all potential causes, and pledge to provide
an update as soon as possible.

Battery data collected from Nissan LEAFs to date currently indicates that less than 0.3
percent of Nissan LEAFs in the U.S. (including vehicles in service dating back to December,
2010) have experienced a loss of any battery capacity bars. Overall, this universe of
vehicles represents a very small fraction of the more than 13,000 Nissan LEAFs on U.S.
roads. Also, data received globally from other LEAF vehicles shows that this condition
typically occurs to high-mileage cars or those in unique operating situations.

Second, I want to explain battery capacity, how it is affected by the operating environment
and usage patterns and what is considered normal battery health. All lithium-ion batteries
lose capacity with use and age. This is normal and expected. In general, lithium-ion
batteries exhibit a higher loss of capacity early in life, with the rate of loss decreasing over
time. Nissan has projected that LEAF batteries will generally have 80 percent of their
capacity under normal use after 5 years, and 70 percent after 10 years.

Are there factors that could negatively affect this performance curve? Yes. A customer's
method and frequency of charging, operating environment, the amount of electricity
consumed during daily usage and a vehicle's mileage and age can all affect the rate of
battery capacity loss. Until we know more about each customer's unique situation, it would
be premature to declare what is happening with the Nissan LEAFs in Phoenix, and whether
their performance is within the range of expectations or not. Working closely with our
owners to get to the bottom of these concerns is exactly what we’re committed to do.

Nissan engineers from our Arizona Testing Center and around the world will study each
customer case, work to discover the root cause and will determine next steps to satisfy our
customers. While we do this, we pledge to provide an update to our customers as soon as
possible.

Together, we are confident that by collaborating with our LEAF community—including the
more than 400 owners in Arizona—we will ensure that owners experience many years of
enjoyable driving as EV pioneers.

Thank you for your passion for the Nissan LEAF and the electrical vehicle movement. It is
only through your dedication and willingness to innovate that we are able to bring zeroemission
mobility to the mass market.

Kind regards,
Carla Bailo
Senior Vice President, Research & Development
Nissan Americas

I am using the underlined/highlighted sections of the above statement to support the following comments:

You can make statistics support just about any position and although I appreciate the above response from Nissan, stating that only 0.3% of Leaf's nationwide present with this problem is misleading. Looking at the 42 Leafs (as reported in the wiki) of the approx. 400 vehicles sold/leased in the Phoenix area (as reported in the above statement from Nissan) shows this issue affects at a minimum, 10% of the cars in Phoenix. Nationwide 1 in 300 (0.3%) cars sold have presented with this issue. In Phoenix, 1 in 10 have this issue and that is only based on known wiki reports. This stat alone demonstrates that this is not a "method and frequency of charging issue, amount of electricity consumed during daily usage issue or a vehicle's mileage or age issue". If any of these reasons were the case, you wouldn't be seeing a 30 fold increase of Leafs in the Phoenix area experiencing this issue vs the national rate. This is a statistical impossibility. How many more drivers have experienced reduced capacity in Phoenix but either haven't noticed or reported it yet? I also wonder how many of these 400 cars are still less than a year old and will be added to the growing list over the next year? If only 100 of the 400 Phoenix Leafs are a year old, for example, then it would be 40% rate (2 out of every 5 cars)!!! I didn't even know about this issue until I bumped into an Ecotality technician who was servicing a level 3 charger last week. He stated to me that this was a Phoenix issue. I'm going with his take on this.

 

[Stoaty]

Looking at the 42 Leafs (as reported in the wiki) of the approx. 400 vehicles sold/leased in the Phoenix area (as reported in the above statement from Nissan) shows this issue affects at a minimum, 10% of the cars in Phoenix. Nationwide 1 in 300 (0.3%) cars sold have presented with this issue. In Phoenix, 1 in 10 have this issue and that is only based on known wiki reports.

I added the (accurate) statistic that at least 10% of Leafs in Arizona have lost a capacity bar to the Wiki:

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

 

[TomT]

So, pretty much your standard corporate letter of non-committal...

I just received this from Nissan. To view the PDF version, click here
An open letter to Nissan LEAF owners from Carla Bailo, senior vice
president, Research and Development, Nissan Americas:

 

[surfingslovak]

So, pretty much your standard corporate letter of non-committal...

Yup, Nissan has behaved like every other large corporation I ever dealt with so far. As much as I want their EV program to succeed, there are some question marks now, at least in my mind. I hope they will address the battery degradation issue adequately before it's too late. Talk is cheap.

 

[DaveinOlyWA]

So, pretty much your standard corporate letter of non-committal...

Yup, Nissan has behaved like every other large corporation I ever dealt with so far. As much as I want their EV program to succeed, there are some question marks now, at least in my mind. I hope they will address the battery degradation issue adequately before it's too late. Talk is cheap.

unfortunately it does not matter which corporation it is or the services they provide. their response still comes from the same little pool of corporate lawyers who tend to bounce from one company to another without learning much or changing their corporate strategies

 

[TonyWilliams]

Note that for the two bar losers, the rate of capacity loss increased from about 1.3% per month (over time to loss of first bar) to 3.7% per month (over time between first and second bar 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."

It must be stated that the first capacity bar is over double the capacity of subsequent bar segments.

 

[DaveinOlyWA]

10%? that is only because the rest of the LEAFs in AZ are simply too new most likely with less than 10,000 miles and ON THEIR FIRST SUMMER in the AZ heat

lets look at LEAFs delivered say by August of 2011...no, make that Sept...no wait. when does it cool off there (or does it ever?) but anyway, lets look at AZ LEAFs on round two of summer heat and i bet the percentage is more like 50%

 

[Stoaty]

It must be stated that the first capacity bar is over double the capacity of subsequent bar segments.

It is all there in the Wiki. However, I just bolded the portion that states this so it won't easily be missed:

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

Edit: I also added the percentage capacity loss in parentheses for each number of bar losses to make it obvious to the casual observer.

 

[ecoobsessive]

Do we have any data or evidence, even anecdotal that the "leveling off" will not occur soon? What do the curves look like - steep at first? More steep and deep for high temp cars, but those may still level off. Is it unreasonable to think that even though I appear to have lost 15% , I may only lose 2-3% more in the next year - what are the chances of that? Does anyone have a graph of capacity loss over time that could help to predict future capacity?

See Wiki:

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

Note that for the two bar losers, the rate of capacity loss increased from about 1.3% per month (over time to loss of first bar) to 3.7% per month (over time between first and second bar 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. The mean time to lose one capacity bar was 11.9 months, with a range of 7-16 months. [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. A similar analysis of Texas Leafs that had lost one capacity bar did not show any correlation between monthly mileage and rate of capacity loss, but the sample was much smaller (12 Leafs) and the climatic variation between different areas may have dominated. Phoenix Leafs that had lost a bar showed a mean rate of capacity loss of 1.3% per month; for Texas Leafs the value was 1.2% per month.

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."

I very much appreciate this analysis and find it interesting, but still I believe it assumes a linear curve - even for the 2 and 3 bar losses, the curve may be just more steep and deep, like I said before because of the heat. I want to know more about the idea that the curve is not linear and that it will level off. If Nissan did say it would level off (I don't know if they said that) do you think we have evidence that it is not going to level off? This is the main reason I have not reported to agencies other than Nissan, because I'm hoping to see a "leveling off"

 

[Stoaty]

I very much appreciate this analysis and find it interesting, but still I believe it assumes a linear curve - even for the 2 and 3 bar losses, the curve may be just more steep and deep, like I said before because of the heat. I want to know more about the idea that the curve is not linear and that it will level off. If Nissan did say it would level off (I don't know if they said that) do you think we have evidence that it is not going to level off? This is the main reason I have not reported to agencies other than Nissan, because I'm hoping to see a "leveling off"

Yes, it assumes that the curve is relatively linear in this (? early) portion. The data that we have so far suggests that the rate of loss may stay the same or accelerate. However, this could be due to the fact the 2nd bar loss is occurring during the very hot summer. Nissan didn't necessarily suggest the curve would level off, but that the rate of capacity loss would slow significantly. We don't have any evidence against that claim. However, for those that have already lost 3 bars (27.5%), they are very close to "end of life" by industry standards, assuming the capacity loss is permanent.

 

[DaveinOlyWA]

I very much appreciate this analysis and find it interesting, but still I believe it assumes a linear curve - even for the 2 and 3 bar losses, the curve may be just more steep and deep, like I said before because of the heat. I want to know more about the idea that the curve is not linear and that it will level off. If Nissan did say it would level off (I don't know if they said that) do you think we have evidence that it is not going to level off? This is the main reason I have not reported to agencies other than Nissan, because I'm hoping to see a "leveling off"

Yes, it assumes that the curve is relatively linear in this (? early) portion. The data that we have so far suggests that the rate of loss may stay the same or accelerate. However, this could be due to the fact the 2nd bar loss is occurring during the very hot summer. Nissan didn't necessarily suggest the curve would level off, but that the rate of capacity loss would slow significantly. We don't have any evidence against that claim. However, for those that have already lost 3 bars (27.5%), they are very close to "end of life" by industry standards, assuming the capacity loss is permanent.

i think you have it. right now people getting 2nd and 3rd lost bars are due in part to the heat and is temporary. so the curve which looks likes its accelerating is actually two events compounding the curve.

i ran experiment detailed in blog (TTID) that suggests that as much as 5% was a temperature adjustment and that is temps to near 100º so guessing AZ adjustment to be greater due to much higher temps... maybe. problem is that parts of AZ never gets to the temp (about 70) you need to be to get full capacity. one thing i observed is that i lost initially capacity immediately upon adding heat, but it took several days of cool charging to get it back suggesting the pack controls has to see a certain temp for a few days before it readjusts to add capacity back

 

[TonyWilliams]

right now people getting 2nd and 3rd lost bars are due in part to the heat and is temporary. so the curve which looks likes its accelerating is actually two events compounding the curve.

i ran experiment detailed in blog (TTID) that suggests that as much as 5% was a temperature adjustment and that is temps to near 100º so guessing AZ adjustment to be greater due to much higher temps... maybe.

I've had the battery at over 130F... hotter than any battery temp that I've ever read in any post. The Gid count worked for the expected 75 wattHours usable per Gid (80 wattHour stored).

I posted the video from this occasion during BC2BC 2012:


[youtube]http://www.youtube.com/watch?v=mqd9qbvBoME[/youtube]

 

[Roughneck]

Lost my first capacity bar Friday 8/24/2012. Purchased car new 8/11/2011. Mileage 16,670. I charge once per day, starting at 10 pm. Five days a week to 80% and two days per week to 100%. All charges have been level 2, no quick charges.

No discernable loss of range to date. Every weekend I make a trip from Spring, Tx to Bernardo, Tx a distance of 71 miles one way. The first trip in Aug 2011, I arrived with 7 miles of range left. This weekend's trip I arrived with 6 miles of range left. Daily work commute is 43 miles round trip.

 

[Stoaty]

Lost my first capacity bar Friday 8/24/2012. Purchased car new 8/11/2011. Mileage 16,670. I charge once per day, starting at 10 pm. Five days a week to 80% and two days per week to 100%. All charges have been level 2, no quick charges.

No discernable loss of range to date. Every weekend I make a trip from Spring, Tx to Bernardo, Tx a distance of 71 miles one way. The first trip in Aug 2011, I arrived with 7 miles of range left. This weekend's trip I arrived with 6 miles of range left. Daily work commute is 43 miles round trip.

Sorry to hear about the capacity bar loss. Added to Wiki. To complete your Wiki entry we need case number of report to Nissan, date of report, and date of manufacture. Thanks.

 

[DaveinOlyWA]

Lost my first capacity bar Friday 8/24/2012. Purchased car new 8/11/2011. Mileage 16,670. I charge once per day, starting at 10 pm. Five days a week to 80% and two days per week to 100%. All charges have been level 2, no quick charges.

No discernable loss of range to date. Every weekend I make a trip from Spring, Tx to Bernardo, Tx a distance of 71 miles one way. The first trip in Aug 2011, I arrived with 7 miles of range left. This weekend's trip I arrived with 6 miles of range left. Daily work commute is 43 miles round trip.

so your losing a bar says you now only have at most 85% of your battery to use and still making a 71 mile trip? nice!

one thing i can say for warm weather, it may hurt the battery but the LEAF sure likes it. i have a errand i run for my son on a regular basis. i am only able to hit 6+ miles/kw if the temp is more than 80º otherwise, in Summer (normal temps in low 70's) i average 5.4-5.8 miles per k.