Capacity Loss on 2011-2012 LEAFs

[charge]

Well, they DO say highway speeds affect range due to wind resistance... http://www.nissanusa.com/leaf-electric-car/range?next=ev_micro.section_nav" onclick="window.open(this.href);return false;

Speed
Higher speeds require more energy to overcome air resistance.

Tip: Drive at constant, moderate speeds. Smooth acceleration and deceleration can extend your range.

Yes, they do say that, but never that driving at highway speeds would have an impact on battery capacity.

 

[edatoakrun]

CHLPatent wrote:


...You’ll have to forgive me, but I wonder if these owners have actually looked at their own test data, for the results clearly do not substantiate the sweeping claims they continue to make...

Yes, this has been the essential problem in analyzing the test, ever since Tony misstated the test results on page one of this thread.

A Few day ago, on page eight of this thread, I commented:

Below, in my opinion, is an accurate short summary of the test results, and significant conclusions, based on the partial release of test data:

After selecting LEAFs nationwide, whose drivers believed them to have some of the largest range losses, a recent range test in Phoenix showed less than the range loss as had been expected, by relying on what the test showed were inaccurate capacity bars displays, and "gid" counts.

One outlier on the low side got only 59.3 miles. The unknown conditions experienced by this LEAF during over 29,000 miles of use, make it impossible to determine if any factor or factors of use contributed to this car's relative under-performance.

While the other eleven of the twelve did all have close to the highway range (and many, even more) that Nissan had estimated for new LEAFs in its promotional materials, many, but not all, seemed to show a significant reduction from the higher "new" LEAF range, as estimated by another source, Nissan Technical Bulletin NTB11-076a.

There was large variability between the LEAFs individual ranges, of between 66.1 and 79.6 miles. Inadequate test protocols could only seem to explain a small part of the large range disparities, between all twelve cars.

We can now conclude, in all likelihood, that many or all LEAFs have a a significant flaw or flaws in their energy use reports, that make it difficult to determine with great precision what capacity or range loss has been experienced by any LEAF, either from new, or from an assumed standard range.

Alternate means of testing of the battery capacity, such as by measuring the charge accepted, might allow more accurate battery capacity results, from which standardized ranges at m/kWh use levels, could be calculated.

However, all data indicating accuracy or inaccuracy of all m/kWh reports from the test LEAFs, has so far been withheld, by the promoter of the range test.

Since I wrote that, Tony has admitted even more flaws in his methodology, such as publishing "guesstimates" of range in several LEAFs, rather than actual test results, and an error in one of the cars reported range, so I will have to qualify these conclusions further, depending on how much more factual data on the test dribbles out.

The data on m/kWh variations which Tony was withholding earlier is quite interesting. I still have to give that some analysis.

Hopefully, someone will eventually put the entire data set in one coherent presentation, including the necessary corrections and asterisks, which will make the actual results much easier to understand.

See also: http://www.casteyanqui.com/ev/capacity_kerfuffle/index.html" onclick="window.open(this.href);return false;

AZ Leaf Capacity Kerfuffle:
Much Ado About Nothing?

September 21, 2012

Mark D Larsen

* Extrapolated from Nissan Technical Bulletin NTB11-076a:
Nissan LEAF Range Estimates at 4 Miles-per-kWh



For the last several months, a few early adopters of the Nissan Leaf in Phoenix have been complaining long and loud about losing capacity bars prematurely, supposedly because of the extremely hot temperatures in Arizona. What originally started out as a worrisome concern has now snowballed (fireballed?) into something of a feeding frenzy, with nearly 400 pages of discussion piling up in the “My Nissan Leaf” forum...

You’ll have to forgive me, but I wonder if these owners have actually looked at their own test data, for the results clearly do not substantiate the sweeping claims they continue to make with mere anecdotes. I purport that perhaps apologies to Nissan might be in order for the accusations of being "in complete denial" and committing "outright fraud." As a matter of fact, I think that those apologies should also be given ample air time to the general public, because the news coverage to date has sullied Nissan’s reputation and likely contributed to the recent slow down in Leaf sales...

Of course, to be fair, I also have to decry that Nissan continues to withhold its own results rather than openly communicating with both those owners and the public in general. They would only issue a prepared statement to KPHO for yesterday’s story, which reads:

Nissan has been working hard to understand some LEAF customers’ concerns in the desert southwest. We've tested a number of individual vehicles and will be contacting those owners to discuss their individual results in the near term. We also anticipate having more information to release to the wider Arizona customer base soon. We are taking Phoenix customer concerns seriously and are working hard to ensure their full satisfaction.

As far as I am concerned, that “near term” couldn’t get here soon enough, and should have occurred many months ago to nip this fiasco in the bud before it morphed into such a public relations nightmare. At this point I perceive that they will have to convey some very “tough love” to those whose own test data seem to undermine their complaints.


The Out Campaign: Scarlet Letter of Atheism ©2012 Mark D Larsen
Home Page * Contact Me

Edited for length, per request. 7:52 PM.

 

[TonyWilliams]

CHLPatent wrote:


...You’ll have to forgive me, but I wonder if these owners have actually looked at their own test data, for the results clearly do not substantiate the sweeping claims they continue to make...

Yes, this has been the essential problem in analyzing the test, ever since Tony misstated the test results on page one of this thread....

Since I wrote that, Tony has admitted even more flaws in his methodology, such as publishing "guesstimates" of range in several LEAFs, rather than actual test results, and an error in one of the cars reported range, so I will have to qualify these conclusions further, depending on how much more factual data on the test dribbles out.

The data on m/kWh variations which Tony was withholding earlier is quite interesting. I still have to give that some analysis.

Hopefully, someone will eventually put the entire data set in one coherent presentation, including the necessary corrections and asterisks, which will make the actual results much easier to understand

I thought I already stipulated for you that this test, like my range chart, was just an awful mess, and you are the master. I will say that you're not nearly as factually challenged as Mark with LEAF issues, but I think you could give him a run for the money in the "bedside" department.

 

[ALLWATZ]

Well, they DO say highway speeds affect range due to wind resistance... http://www.nissanusa.com/leaf-electric-car/range?next=ev_micro.section_nav" onclick="window.open(this.href);return false;

Speed
Higher speeds require more energy to overcome air resistance.

Tip: Drive at constant, moderate speeds. Smooth acceleration and deceleration can extend your range.

Back the trolly up! First, what about those of us who have had bar losses and don't travel any freeway miles (my car has been on the freeway about 5 times last year!). My car gets driven about 40 miles every day to and from work with errands all in the optimal stop and go traffic sited. As well as the fact that it is not high mileage at 9500 miles (1 year) when the loss happened.
Second, even in his statement, Mark Perry says "it appears that Leafs in Arizona are "on a glide path" to average battery capacity of 76 percent after five years rather than 80 percent. The seven cars the company inspected in depth are likely to have less capacity than that after the same time". Once again the only common factor is heat.

 

[DesertDenizen]

I called the Leaf hotline to report my loss of a capacity bar. They had me make an appointment with the dealer, and told me to have the technician call them while he is with my Leaf. Not sure what this is about, will find out on Wednesday.

 

[CHLPatent]

Tony: (sorry I tried to quote you but got an error):

Well, wasn't the amateur AZ test a 'range' test at highway speeds?

Also it seems to me that the range estimating in the Leaf on-board system could use some improvement. I read somewhere they use a Hall-effect sensor - these are subject to interference and are not all that precise to begin with. Garbage in, garbage out. Any battery 'capacity' measurement on-the-fly is just a fancy guesstimate anyway, so maybe their software that calculates this number could use some improvements too? And temperature has an effect - is temperature included as a variable in the estimate? I don't know.

Suppose the Hall-effect sensor (or some other device) is subject to heat stress - copper wire resistance increases with temperature and the Hall-effect sensor is presumably measuring the current in a copper conductor somewhere in there - the output would be even less perfect due to heat. You'd think they'd have heat-hardened some of these components, but there are trade-offs with any design. Still, it seems from the test result data that even with the possibility of heat skewing the measurement process within the Leaf's, the inferred from range capacity loss was within Nissan's predictions based on mileage.

Now, don't get me wrong, I'd love it if this exercise in owner-PR mishandling spurs Nissan to vastly improve battery capacities, estimating circuitry, charging circuitry, etc.

But it doesn't seem like this is anything more than the perhaps unrealistically high expectations of some of us Leaf owners, who happen to live in AZ and other hot climates, being let down. I do not yet see anything abnormal with the battery. As they warned/recommended...

Nissan recommends owners the following preventive actions to help maximize the lithium-ion battery’s useful life and its ability to hold a charge:
Avoid exposing a vehicle to ambient temperatures above 120 °F (49 °C) for over 24 hours.
Avoid storing a vehicle in temperatures below -13 °F (-25 °C) for over 7 days.
Avoid exceeding 70% to 80% state of charge when using frequent (more than once per week) fast or quick charging.
Allow the battery charge to go below 80% before charging.
Avoid leaving the vehicle for over 14 days where the Li-ion battery available charge gauge reaches a zero or near zero (state of charge).

How you recharge the pack will affect its life. Nissan has said it expects to Leaf drivers to have around 70 to 80 percent capacity left in the pack after ten years. What will get drivers to the upper or lower end of that range? The amount of fast charging one does. With regular Level 2 charging, drivers should expect 80 percent live left in the battery. With a lot of Level 3 charging – two or three times a day – the pack will only be at the 70 percent level. Level 3 charging is appealing because it can get the battery from zero to 80 percent full in under 30 minutes, but there is a very clear drawback if it becomes a habit.

Nissan has done "hundreds of thousands" of miles of reliability testing on the battery packs, including dunking them in a pool and freezing them.

Even with these limitations, it beat the heck out of infernal combustion vehicles in my book.

ALLWATZ: without knowing the details of your situation, I cannot even guess - how many bars did you loose? What sort of charging do you do, e.g., to 100%? DC/Fast Charging? Do you ever re-charge before down to the 80% mark? Or below the 20% mark? All those things will affect battery life. If it were me, I'd be trying to work it out with Nissan in one of those face-to-face meetings they are apparently going to be holding. Maybe you DO have some component failure - as I have said, I'd be suspicious of the charging and sensing circuitry - if a charger fails (due to heat related issues?) and over-charging results, that could damage the battery.

As for what the common factor is, yes heat, as in ambient temperature, is one, but perhaps there are others, like a particular electronic component on-board? A utility glitch (yes they are supposed to be immune to voltage spikes/surges, over-voltages or brown-outs, but...)? Does the temperature guage (on the left on my instrument panel) in your Leaf ever show a high temperature in the battery? If not, maybe battery temperature is NOT the real problem? Or, maybe the temperature sensor is at issue? A methodical bench testing of the various components is probably the only way to nail it down, and even then... Perhaps ther really isn't any capacity loss, but the Leaf on-board system detects it in error? A faulty Hall-effect sensor could do that (used in calculating range by sensing current to then calculate power consumption = energy used per unit time). I just think we should NOT jump to conclusions, and I've seen a lot of that here, understandable, but no way to efficiently determine what's really going on, imho.

 

[shrink]

The common thread among the seven Leafs from Arizona, Perry said, was that all of them had covered much higher mileage than the 12,500 miles Nissan used to estimate the rate of battery capacity loss over time.
All of them had covered at leas 50 percent more than that--or roughly 19,000 miles a year--and a few were "significantly higher" than that.

I wasn't part of the Case Grande 6 (or 7), but my car certainly wasn't high mileage:

 

[DesertDenizen]

I wasn't part of the Case Grande 6 (or 7), but my car certainly wasn't high mileage:

I lost my bar at 6,771 miles! Two months after getting all 5 stars at the one year annual.

 

[azdre]

Mark Perry has responded, pretty much as expected:

http://www.greencarreports.com/news/1079343_nissan-suggests-leaf-battery-capacity-loss-due-to-high-miles-exclusive" onclick="window.open(this.href);return false;

LIES!!! More LIES! If Nissan can't even divide number of miles by the number of months owned, how on earth can anyone expect them to design a car?!?!?!?!?!?!?!!?!?!?!!?

On July 23rd, when our car was taken to Casa Grande for testing, it had 20,803 miles on the odometer. We purchased our car on March 21, 2011, 16 months prior to the test. This equates to 1300.1875 miles per month or 15,602.25 miles per year.

According to the Federal Highway Administration (http://www.fhwa.dot.gov/ohim/onh00/bar8.htm" onclick="window.open(this.href);return false the average US driver, in our demographic drives 15,291 miles per year.

I have seen the milage and manufacture date for 3 of the other Casa Grande cars, and they are WELL below 19,000 per year.

 

[dsh]

I totally agree, these comments by Mark Perry from Nissan at the below link, are just
'damage control' ...looks like nothing will come of Nissan helping the wider LEAF community with capacity issues...

http://www.greencarreports.com/news...ery-capacity-loss-due-to-high-miles-exclusive

I wasn't part of the Case Grande 6 (or 7), but my car certainly wasn't high mileage:

I lost my bar at 6,771 miles! Two months after getting all 5 stars at the one year annual.

 

[azdre]

I have seen the milage and manufacture date for 3 of the other Casa Grande cars, and they are WELL below 19,000 per year.

I just ran the numbers, 2 of the casa grande 7 average UNDER 12,000 per year.

 

[surfingslovak]

I have seen the milage and manufacture date for 3 of the other Casa Grande cars, and they are WELL below 19,000 per year.

I just ran the numbers, 2 of the casa grande 7 average UNDER 12,000 per year.

Could you post the numbers or would that breach some confidentiality agreement?

 

[dsh]

azdre,

I would Register at http://www.greencarreports.com/ and post a comment to the article, to set this idiot straight.

I have seen the milage and manufacture date for 3 of the other Casa Grande cars, and they are WELL below 19,000 per year.

I just ran the numbers, 2 of the casa grande 7 average UNDER 12,000 per year.

 

[ALLWATZ]

ALLWATZ: without knowing the details of your situation, I cannot even guess - how many bars did you loose? What sort of charging do you do, e.g., to 100%? DC/Fast Charging? Do you ever re-charge before down to the 80% mark? Or below the 20% mark? All those things will affect battery life. If it were me, I'd be trying to work it out with Nissan in one of those face-to-face meetings they are apparently going to be holding. Maybe you DO have some component failure - as I have said, I'd be suspicious of the charging and sensing circuitry - if a charger fails (due to heat related issues?) and over-charging results, that could damage the battery.

I charge to 100% all the time, never to 80%. Up till this year all charging used to be done when the car arrived home at the hottest part of the day. Have left it at full charge many times and used to "top off" everyday regardless of SOC. No turtles and no level 3s. There, get it over and post how it's all my fault. Come on, I know you want to. Oh, but wait, let's look at the posting from DesertDenizen
"DesertDenizen wrote:
I don’t wanna to be in this club!
I lost my first capacity bar today. Only 6,771 miles. Manufactured 6/21/2011, took ownership 7/25/2011. I charge to 80%, never did a QC and charged to 100% exactly three times. The 100% charges were done just before I drove so the car spent no time sitting with a full charge. Never drove below 2 SOC bars. Received all 5 stars at my first annual, which was on 7/25/2012. I only charge every other day or so. I start to charge at 6 in the morning and usually leave around 9 so my Leaf doesn’t even spend much time at 80% charge. My Leaf has spent 90-95% of its time between 3 and 8 SOC bars. My long term average is 5.7 m/kwh and I drive on the frontage roads, not the highway, so I never exceed 45 mph. Exclusively in Eco. It is parked under a carport. I am out in the desert so there is no blacktop or concrete, just dirt. Tucson averages about 6 degrees cooler than Phoenix. Summer temp bars are usually 6, I have driven (but not charged) with 7 temp bars for short durations, but not many times. My case # is 8997717.

So he did everything right and I did it all wrong and we both wound up with the same problem. Our manufacture and ownership dates are the same. Expain please?

 

[dgpcolorado]

Mark Perry has responded, pretty much as expected:

http://www.greencarreports.com/news/1079343_nissan-suggests-leaf-battery-capacity-loss-due-to-high-miles-exclusive" onclick="window.open(this.href);return false;

LIES!!! More LIES!

That was my take also when I read it: there were several outright lies in Mark Perry's statement. He isn't even pretending to present the issue accurately. Definitely not helpful.

 

[mwalsh]

Please see the following thread for an open letter from Nissan regarding this issue:

http://www.mynissanleaf.com/viewtopic.php?f=27&t=10074&p=229382#p229382" onclick="window.open(this.href);return false;

 

[mark1313]

I wish that Nissan had taken my Leaf to Casa Grande..I think my car has spent a total of 10 minutes on the freeway,if I remember correctly I have been on the freeway 3 times because of road construction and I hated taking the Leaf on the freeway because of the huge KW usage..

My main concern with my car was losing 2 capacity bars in 45 days,I thought a 3rd bar loss could be weeks away but I have been working hard at saving the cars battery in everyway possible..

It will be interesting to see how many Leafs owners have 5 battery capacity bars loss after the 2nd year of ownership..I believe the 2nd year will be worst because we now need to charge the Leaf more because of capacity loss..

 

[TomT]

+1

I'm at two now, as of this morning. Just under 19 months and 22,000 miles.

Mark Perry has responded, pretty much as expected:

LIES!!! More LIES!

 

[TonyWilliams]

+1

I'm at two now, as of this morning. Just under 19 months and 22,000 miles.

Mark Perry has responded, pretty much as expected:

LIES!!! More LIES!

Holy crap. All the crap I got with driving my car to turtle, yet it didn't lose any bars with 25,300 miles.

Are you the first coastal 2 bar loser?

 

[dsh]

TickTock,

After your appointment with Nissan to go over the results from Casa Grande, will you please let us know how Nissan attempted to "satisfy" you? I would like to know will they offer you a 2013 battery pack, buy back the car...offer a new LEAF, etc. as Mark Perry did stress that Nissan wanted to satisfy each owner individually..."The company's goal, is to discuss how to satisfy those owners. We want to make sure they're satisfied with their vehicles."

I was called yesterday to set up an appointment to go over what they found during the investigation at Casa Grande. Said they would have some "technical people" there should I have any questions. I would be very surprised if I get to talk to actual engineers (in fact, the probability of that is vanishingly small), but any information is welcome at this point.