Capacity Loss on 2011-2012 LEAFs

[Stoaty]

Has anyone established if there is any scientific validity to using the localized Arizona average of 7500 miles per year rather than the 12,000 miles per year number cited elsewhere?

Not sure what you mean by "scientific validity". You can use any annual mileage you want. In this case, Nissan chose to use the Arizona average because comparing on a level playing field (12500 annual mileage as used for other areas) would have made it obvious that the Phoenix Leafs were wilting a lot faster than those in most other parts of the country. It also allowed them to call Leafs with 14,000 miles a year "high mileage", implying that the hapless owners were somehow to blame for their misfortune.

 

[cwerdna]

cwerdna said:

It IS a problem for those in hot climates like Phoenix, AZ and TX. Others in hot climates (and a few in not so hot climates) have also lost battery capacity.

Heat impacts battery longevity and performance. That impact is worse in places like Phoenix. Nobody denies that, including Nissan. The results of the Leaf owner's tests verified that most were still operating within published limits. At what point his constitutes a "problem" is arbitrary.

It is a problem when folks in hot climates have vehicles that have significantly degraded range vs. when they were new after only a year, sometimes to the point where the car is no longer usable for their daily usage. You'd be singing a different tune if you lived in Phoenix and lost 3 or 4 capacity bars after going thru two summers.

Nissan made all sorts of claims to the effect of 70 to 80% capacity after 10 years. Well, some AZ folks already were down to that capacity level (or lower) after only one year w/MUCH lower mileage than TaylorSFGuy (who lives in a temperate climate).

It was only after lots of complaining and people going to the media did Nissan suddenly pick (and disclose) some 7500 miles on average figure for AZ out of the air and also claimed that based on that, they're on track to hit 76% capacity after 5 years doing only 7500 miles/year average. This is FAR below the 12K to 15K mile/year figure I've heard for cars in the US. NONE of this was disclosed to hot climate area buyers.

Unless something is done, I'm pretty sure we're going to see another wave of battery capacity losers in those hot climates next summer as new cars reach the one year mark and others have theirs age another year. The cycle will repeat... Meanwhile, those in mild climates (e.g. San Francisco, Western WA, Portland, etc.) will see MUCH slower degradation, even w/higher mileage than their AZ/hot climate counterparts.

Battery capacity loss is normal and expected. Higher loss in really hot places is also expected and normal, just as really short range is expected and normal on a -10 degree day. Something is being done. Nissan is responding by buying back cars that fall outside of the published band, and then some.

And, what did it take for them to buy back some cars? It took lots of complaining, media attention, Tony's range test, etc. Even then, Nissan still hasn't given a universal remedy to all owners and lessees in hot climate areas (e.g. buyback, early lease termination, converting purchases to leases, capacity warranty, replacement pack, etc.)

AFAIK, Nissan still continues to sell the Leaf in AZ, TX and other hot climate areas. Nissan should stop selling them there altogether and/or make them lease only in such areas until they add active thermal battery management or provide a capacity warranty. They still haven't provided a price for a replacement battery. They still continue to say "it's normal".

They need to properly disclose to potential AND current buyers/lessees in those areas these new numbers we learned of.

OTOH, these posts sum up things pretty well:
http://www.mynissanleaf.com/viewtopic.php?p=233289#p233289" onclick="window.open(this.href);return false;
http://www.mynissanleaf.com/viewtopic.php?p=233299#p233299" onclick="window.open(this.href);return false;
http://www.mynissanleaf.com/viewtopic.php?p=233418#p233418" onclick="window.open(this.href);return false;

Has anyone established if there is any scientific validity to using the localized Arizona average of 7500 miles per year rather than the 12,000 miles per year number cited elsewhere?

Not sure what you mean by "scientific validity". You can use any annual mileage you want. In this case, Nissan chose to use the Arizona average because comparing on a level playing field (12500 annual mileage as used for other areas) would have made it obvious that the Phoenix Leafs were wilting a lot faster than those in most other parts of the country. It also allowed them to call Leafs with 14,000 miles a year "high mileage", implying that the hapless owners were somehow to blame for their misfortune.

Yep, we only learned of this supposed 7500/mile year AZ figure in an Andy Palmer video along w/the supposed 76% glide path after 5 years based on that low mileage. Nissan sure didn't disclose it to hot climate people who bought or leased. It's hard to say how credible even those claims are given what they stated prior to all these revelations.

 

[jlsoaz]

Has anyone established if there is any scientific validity to using the localized Arizona average of 7500 miles per year rather than the 12,000 miles per year number cited elsewhere?

Not sure what you mean by "scientific validity". You can use any annual mileage you want. In this case, Nissan chose to use the Arizona average because comparing on a level playing field (12500 annual mileage as used for other areas) would have made it obvious that the Phoenix Leafs were wilting a lot faster than those in most other parts of the country. It also allowed them to call Leafs with 14,000 miles a year "high mileage", implying that the hapless owners were somehow to blame for their misfortune.

Hi Stoat, I think I understand your points, but since we've had this lecturing from Biodiversivist, ostensibly from some sort of science or math or engineering standpoint, I just thought I'd ask this question for the second time:

I think it would be useful to have an explanation as to whether it is standard operating procedure in analysis of this type of situation to limit the matter to the localized average miles.

Andy Palmer referenced this 7,500 figure and also in more or less the same breath referenced his background as an engineer. Maybe he thought there was no further explanation needed. I don't have a degree in science, but the shifting of the analysis from 12,000 miles to 7,500 miles sounded more like a red-flag than an easy-to-accept explanation to me. Could I be one of those who are not getting it or missing something? Sure. I think a first step for me would be to understand if (and to what extent or in what circumstances) it is legit for the localized 7,500 figure to be used.

 

[planet4ever]

I don't have a degree in science, but the shifting of the analysis from 12,000 miles to 7,500 miles sounded more like a red-flag than an easy-to-accept explanation to me. Could I be one of those who are not getting it or missing something? Sure. I think a first step for me would be to understand if (and to what extent or in what circumstances) it is legit for the localized 7,500 figure to be used.

I don't have a degree in science either (unless you include a 50-year-old minor in physics) but it sure is a red flag to me. I'm not even ready to accept that it is real. Not that I'm claiming that Nissan is lying, only jumping on an all-too-convenient statistic generated by a very flawed measuring device. I'm willing to bet that is what CarWings is telling them the average mileage is in Phoenix. I'm also willing to bet that a measurable fraction of Phoenix LEAF drivers never say OK, that another fraction only say OK part of the time, and that some Phoenix cars find themselves unable to make a connection at times.

Note that I haven't mentioned the rather obvious effect loss of range would have on the true average distance those cars are driven. That would make the Phoenix average lower than the national average, but it would (at least arguably) be legitimate to use that in qualifying the degradation.

Ray

 

[surfingslovak]

A recent study conducted by six insurance carriers suggests that the average annual mileage driven in AZ was 13,021. I saw a similar number, around 12K miles, from another source. Annual mileage distribution by demographic varies a bit, according to the DOT, but this alone would not suffice as an explanation. However, the battery poll conducted by Plug In America implies a figure around 8,000 miles (note that the average vehicle age is 19.5 months).

 

[RegGuheert]

Simply put, because you used 84 miles as your standard instead of 76, this was not a test to see if these twelve cars performed within published acceptable limits, which would be a reasonable thing to test. It was instead, a test to prove that they would not meet the maximum value in an acceptable range, which is a nonsensical thing to test.

I don't see how anyone could arrive at a conclusion like this. Batteries do not degrade from some arbitrary value in a chart. Batteries degrade from *their* original values, as Nissan properly stated in the LEAF Owner's Manual:

Nissan estimates battery capacity will be approximately 80% of original capacity after five years...

Note that Nissan does not say "...80% of capacity at purchase..." or any such thing. Tony referenced the NTB because it is perhaps the only document which gives a clue of what Nissan thinks the "original capacity" of the LEAF battery might be. And he has now confirmed that the "original range" of at least one LEAF is over 84 miles.

Is there variation in the "original capacity" of LEAF batteries? Of course. Is the range in NTB11-076a intended to cover the "original capacity" of LEAF batteries? That is what is being debated here, but I will say it does not. As I have stated previously, the range of ranges provided in that document are likely intended to cover two things:

1) By the time a customer complains to a dealer about range, the capacity of the battery in the LEAF has already degraded from "original capacity" due to time spent traveling from Japan, sitting in port, sitting on the dealer's lot and then being used by the owner for some time.
2) The range of the LEAF will be reduced in the case of a pack which is not fully balanced.

IMO, reason 2) above accounts for no more than about 1kWh's worth of range in NTB11-076a. The rest of the variation must come from reason 1).

So, what should we use for "original range" for the LEAFs tested in Phoenix? In other words, what is the proper denominator for range degradation calculations? Since reason 1) covers the issue of degradation from "original capacity", it makes no sense to use lower numbers from the NTB-076a ranges as "original capacity". We know that it could be as high as 88 miles for some LEAFs, so I expect that is a good number for at least some of the LEAFs in the test. But we cannot know or assume that all of the battery packs in these cars were fully balanced. Going with the 84 mile number Nissan provided and that Tony adopted seems more than reasonable to me.

 

[TonyWilliams]

But we cannot know or assume that all of the battery packs in these cars were fully balanced. Going with the 84 mile number Nissan provided and that Tony adopted seems more than reasonable to me.

We did record all the cell-pair voltages prior to launch. None exceeded the 50 millivolt threshold, even the car that went 59 miles. All the cars sat long enough after a full charge to allow the automation to balance the cell-pairs prior to their road test.

I originally estimated that the cars would go 86-88 miles when new (in our specified conditions), and as you correctly point out, only used 84 as a baseline since that is the highest on their chart.

The true degradation of RANGE from the highest to lowest performing cars is actually about 33%.

 

[RegGuheert]

We did record all the cell-pair voltages prior to launch.

Wow! I had no idea you had done that or even that you had the capability to do that!

I don't recall seeing this data. Did you publish it?

None exceeded the 50 millivolt threshold, even the car that went 59 miles.

If you made this measurement after the full charge, then I will point out that the 50mV threshold applies to the balance at low SOC, since the pack is top-balanced. I would expect a well-balanced pack to have closer to 5 mV differences at the top of the charge range.

All the cars sat long enough after a full charge to allow the automation to balance the cell-pairs prior to their road test.

Sure, but I think we have previously discussed the fact that it can take a few consecutive days of doing this to get an unalanced pack fully balanced.

 

[TonyWilliams]

We did record all the cell-pair voltages prior to launch.

Wow! I had no idea you had done that or even that you had the capability to do that!

We did not publish that, nor is there any reason to do so. Hey, we're not a one trick pony !!

None exceeded the 50 millivolt threshold, even the car that went 59 miles.

If you made this measurement after the full charge, then I will point out that the 50mV threshold applies to the balance at low SOC, since the pack is top-balanced. I would expect a well-balanced pack to have closer to 5 mV differences at the top of the charge range.

I can only tell you that the Nissan published threshold is 50 mV. All cars met that threshold.

All the cars sat long enough after a full charge to allow the automation to balance the cell-pairs prior to their road test.

Sure, but I think we have previously discussed the fact that it can take a few consecutive days of doing this to get an unbalanced pack fully balanced.

Yes, it can. We didn't experience that on any of the cars.

 

[TonyWilliams]

Your "Phoenix sick LEAFs" test for example used what you thought were ten damaged cars, not a statistically significant number of randomly chosen cars in the Phoenix area, yet you still got results that disproved your claim ...and didn't even realize it until it was pointed out to you by Mark's simple plots of your results, which I concur with:

First, let me suggest for the sake of clarity that neither you, nor Mark, "pointed out" anything to me or those of us directly involved in these findings. As stated to both of you many times by many people in comments on your blog, we don't agree with either of YOUR interpretations.

Simply put, because you used 84 miles as your standard instead of 76, this was not a test to see if these twelve cars performed within published acceptable limits, which would be a reasonable thing to test. It was instead, a test to prove that they would not meet the maximum value in an acceptable range, which is a nonsensical thing to test.

No, not what we were testing. I have discussed many times why I even referenced the Nissan data, and won't rehash that. I agree with the "nonsensical" part, just not its application.

Once it was pointed out that most of this skewed sampling still met specs, you shifted gears and are now trying to convince people that the published specification boundaries are some kind of ruse or conspiracy theory.

Listen, this falls into the "OrientExpress" nuttiness category. I suggest that if you wish to make a point, that this probably isn't the best way to accomplish it.

It is utterly irrelevant should somebody demonstrate that the performance band of cars coming out of a factory door is different than the published spec telling owners what to expect in the real world. Once again, because your latest car failed to hit 84, your test results are belying your own claims

Gosh, I really don't know what to tell you. I suspect you are smarter than your posts indicate. You_did_actually_read_the_data? It drove to 83.x miles because that's where it was convenient to end the test. It then drove under it's own power for several more miles, without refueling, and still had sizable measured energy left to have driven an estimated 88.x miles.

Honestly, this type of post doesn't enhance your argument.

For sure, and I'm one of those engineers, which highlights why your insinuation that they all agree with you is misleading..... Riiight ...the truth. Everyone thinks they have the truth, which is why it is irrelevant that we do.... I'd rephrase that to say you are doing harm with your pseudoscience and lack of engineering knowledge to a budding and critically important new technology.... I'm also glad you are the first to broach the subject of motivation. I'm hard pressed to understand what motivated you to drive a leased Leaf into the ground (29.000 miles in a single year) other than as a notoriety seeking antic. You repeatedly leap-frogged from charger to charger, a Leaf, designed for urban city driving of less than 100 miles on a charge, from Mexico to Canada. I’m trying to think of a better way to stifle the sales/development of the first generation of mass produced electric vehicles than by highlighting their inherent engineering limitations by taking them on missions they were never designed to do.

Woo Hoo !!! Now, a rant like this is my kind of entertainment !!!! Who knew that the Mexico to Canada trip was "bad" for EV's ??? You, apparently. By the way, we're going to_do_it_again_next_year, so fire up the hate machine, 'cuz you've got some preaching to do!

Honestly, I don't know much about you, or your engineering skills, but when I read in your blog how your wife's Prius had mileage "all over the place", and that our test couldn't possibly be valid based on that (ya, I'm loosely paraphrasing), that kind of sets up my expectations from you.

FACT CHECK DEPARTMENT: I didn't drive 29,000 miles in a leased LEAF. You are confusing that, perhaps, with the LEAF that went 29,000 miles, and drove 59 miles in our Sept 15, 2012 test. My leased LEAF went 10,700 miles before I traded it in. I did own a purchased LEAF that I drove 25,300 miles. I'm hard pressed to find the "notoriety" in that, as we have one LEAF driving with over DOUBLE that mileage.

Anyway, the 84 mile range autonomy is repeatable.... over and over and over.
A) It is irrelevant what the performance band is at the factory door.

I'm going to have to say that Nissan probably doesn't agree with you. Or any other major auto manufacturing, anywhere in the world.

For the tenth time, nobody, including Nissan has ever claimed that extreme temperatures won't affect battery performance. You signed a waiver acknowledging that performance will be a function of things like temperature, not once, but twice, assuming you leased two Leafs.

If this quote is for me, I purchased and leased. Here's some things Nissan didn't include in those documents:

1. Heat in Phoenix can provide a battery End Of Life of about 4 years for average 12,000 miles/year drivers
2. Driving on freeways is bad for the car
3. Anything over 7500 miles/year is "high mileage"
4. The degradation forecasts are based on 7500 miles/year
5. The chemistry battery is one of the most adversely affected by heat of the many current Li automotive grade technologies used today
6. The car will likely take a 10% degradation in performance in one year, even in moderate climates

Listen, like Mark, I'm sure you're well meaning. I think your motivation is much like Mark's; to "protect the box" as I learned in the advocacy business many years ago. The box for you is this "budding and critically important new technology" that you think we're attacking by pointing out the failings of Nissan (both in performance and disclosures to customers).

Good for you. I respect that. It doesn't change the facts, however.

 

[Stoaty]

A recent study conducted by six insurance carriers suggests that the average annual mileage driven in AZ was 13,021.

Yes, but you have to remember that is for cars with basically unlimited remaining range... unlike some of the Phoenix Leafs. Perhaps they drove just 7500 miles because that's all they could get from their degraded battery packs.

 

[leafkabob]

I don't have a degree in science, but the shifting of the analysis from 12,000 miles to 7,500 miles sounded more like a red-flag than an easy-to-accept explanation to me. Could I be one of those who are not getting it or missing something? Sure. I think a first step for me would be to understand if (and to what extent or in what circumstances) it is legit for the localized 7,500 figure to be used.

I don't have a degree in science either (unless you include a 50-year-old minor in physics) but it sure is a red flag to me. I'm not even ready to accept that it is real. Not that I'm claiming that Nissan is lying, only jumping on an all-too-convenient statistic generated by a very flawed measuring device. I'm willing to bet that is what CarWings is telling them the average mileage is in Phoenix. I'm also willing to bet that a measurable fraction of Phoenix LEAF drivers never say OK, that another fraction only say OK part of the time, and that some Phoenix cars find themselves unable to make a connection at times.

Note that I haven't mentioned the rather obvious effect loss of range would have on the true average distance those cars are driven. That would make the Phoenix average lower than the national average, but it would (at least arguably) be legitimate to use that in qualifying the degradation.

Ray

You are absolutely right Ray. Although I religiously hit "OK," Carwings shows that I drove approx. 4500 miles in 2011 and 0 miles in 2012, even though I have 13,600 mile on my Arizona leaf since May, 2011.

 

[DaveinOlyWA]

I don't have a degree in science, but the shifting of the analysis from 12,000 miles to 7,500 miles sounded more like a red-flag than an easy-to-accept explanation to me. Could I be one of those who are not getting it or missing something? Sure. I think a first step for me would be to understand if (and to what extent or in what circumstances) it is legit for the localized 7,500 figure to be used.

I don't have a degree in science either (unless you include a 50-year-old minor in physics) but it sure is a red flag to me. I'm not even ready to accept that it is real. Not that I'm claiming that Nissan is lying, only jumping on an all-too-convenient statistic generated by a very flawed measuring device. I'm willing to bet that is what CarWings is telling them the average mileage is in Phoenix. I'm also willing to bet that a measurable fraction of Phoenix LEAF drivers never say OK, that another fraction only say OK part of the time, and that some Phoenix cars find themselves unable to make a connection at times.

Note that I haven't mentioned the rather obvious effect loss of range would have on the true average distance those cars are driven. That would make the Phoenix average lower than the national average, but it would (at least arguably) be legitimate to use that in qualifying the degradation.

Ray

You are absolutely right Ray. Although I religiously hit "OK," Carwings shows that I drove approx. 4500 miles in 2011 and 0 miles in 2012, even though I have 13,600 mile on my Arizona leaf since May, 2011.

which makes the pluginamerica.org survey important to fill out. we need data and AZ seems to be one of the areas we are not getting a lot of participation in!

 

[TomT]

It might be worthwhile listing the link to the survey. I, for one, did not even know that they currently had one underway...

which makes the pluginamerica.org survey important to fill out. we need data and AZ seems to be one of the areas we are not getting a lot of participation in!

 

[KJD]

It might be worthwhile listing the link to the survey. I, for one, did not even know that they currently had one underway...

which makes the pluginamerica.org survey important to fill out. we need data and AZ seems to be one of the areas we are not getting a lot of participation in!

http://www.mynissanleaf.com/viewtopic.php?f=27&t=10494" onclick="window.open(this.href);return false;

 

[Yanquetino]

A recent study conducted by six insurance carriers suggests that the average annual mileage driven in AZ was 13,021.

Yes, but you have to remember that is for cars with basically unlimited remaining range... unlike some of the Phoenix Leafs. Perhaps they drove just 7500 miles because that's all they could get from their degraded battery packs.

Spooka once wrote to me about the 7,500 mileage issue, and since it keeps coming up in this thread, here is a variation of my reply.

For whatever it's worth, I don't think that Andy Palmer was changing the capacity benchmarks in his video interview with Chelsea. I got the impression that he was merely observing that the average driver in AZ is putting about 7,500 miles per year on the car. Period.

You see, I have always understood that automakers issue years/miles projections with an industry-wide disclaimer: "whichever comes first." That is what the warranty for every car I have ever owned states, including the Leaf:

The Lithium-Ion coverage period is 96 months or 100,000 miles, whichever comes first.

In other words, if I have driven 100,000 miles in only 4 years (instead of 8), the warranty expires. Similarly, if after 8 years I have driven only 20,000 miles (instead of 100,000), the warranty expires.

Whichever comes first.

This especially makes sense to me with batteries, because they also deteriorate with age --not just miles.

Ergo... my interpretation of what Andy Palmer was actually stating is that, so far, the 400 AZ Leafs are putting an average of 7,500 miles per year on their cars, BUT... Nissan expects their capacity will still drop to approximately 80% (= 76% in AZ heat, apparently) after 5 years of aging.

To interpret him otherwise would imply a change to the battery warranty, and I have a hard time believing he was stating that --only in AZ-- the warranty would now be 8 years/60,000 miles instead of the published 8 years/100,000 miles. I think the original warranty still applies, but according to the data gathered so far, it looks like AZ owners will simply hit the age threshhold before they hit the mileage threshhold in Nissan's capacity benchmarks.

And I think that is the way LEAF owners should keep a watchful eye on their capacity, perhaps using my 6 scenario capacity chart based on the polynomial curve.

For example, let's say someone has owned a Leaf for 24 months, but only driven 6,000 miles. To estimate its remaining capacity, the owner should look down the first column, because age trumps mileage:

• Its remaining capacity should thus be approximately 91% (age) --NOT about 98% (mileage).

Conversely, someone who has driven 24,000 miles, but in only 6 months, should look down the second column, because mileage trumps age:

• Its remaining capacity should thus be approximately 91% (mileage) --NOT about 98% (age).

Whichever comes first.

I get the impression that some AZ owners are now mistakenly focusing solely on mileage (7,500 x 5 = 37,500) because of Any Palmer's statement, and forgetting about the age threshhold (5 years).

What I find most ironic is that the original complaints were stressing just the opposite: owners were focusing on their Leafs' age ("after only one year"), rather than mileage (29,000 miles). They were thus expecting the capacity to still be about 95% (age), when "normal" projections would estimate approximately 89% (mileage). And let's remember --once again-- that such projections do not take into account other factors stated in Nissan's disclaimer that "may hasten the rate of capacity loss": driving habits, vehicle usage, charging habits, etc.

In short, I have a hard time believing we can have it both ways. Perhaps I am mistaken, but I've never known an automaker to state "whichever comes last"...?

My 2¢ worth, anyway. For the penny bowl.

 

[surfingslovak]

Please keep in mind that battery capacity is not covered under the warranty, and all these thoughtful (and verbose) considerations will matter little in that context. We have seen higher correlation between vehicle mileage and range loss in Phoenix than elsewhere, which led some to believe that the pack won't last 100K miles there, even if a Leaf drove perfect 12.5K miles annually. Stoaty's aging model captures all of this, and more, including climatic influences and the effects of solar loading, which your charts do not consider. There batteries won't age the same way in Phoenix, Seville or in Ivins, as they would in Seattle.

 

[Yanquetino]

There batteries won't age the same way in Phoenix, Seville or in Ivins, as they would in Seattle.

No doubt about that! Nor will the increasing mileage affect capacity "the same way in Phoenix, Seville, or in Ivins, as they would in Seattle." Perhaps it is just wishful thinking, but I would like to think that Nissan's pre-production testing and projected parameters would cover such variables within a reasonable margin of error --although it is clearly evident that some here are adamantly convinced that such was not the case.

Again, my chart is simply applying the polynomial curve of Nissan's published benchmarks to the automaker's range scenarios to estimate a "normal" capacity loss under those 6 particular conditions. True: unlike Stoaty's model, it does not include additional variables from other, external sources unspecified in those scenarios such weather influences, solar loading, etc. Nor does it include differences in driving style, charging frequency, 80% vs. 100% charging, 120v vs. 240v. vs. QuickCharging, weight in the vehicle, road and traffic conditions, wind resistance, elevation changes, etc. --or other types of factors that may or may not affect the health of the battery pack.

The chart simply lists the bare bones, "default" capacity degradation drivers might expect in those scenarios with (as Nissan's disclaimer states) "normal operation and recommended care." If such is the case, yet they find that their capacity nonetheless is falling significantly below a reasonable margin-of-error for those estimates --according to age or mileage (whichever comes first) -- then they have a legitimate reason to complain to Nissan. I think that is useful and helpful.

 

[LEAFfan]

For whatever it's worth, I don't think that Andy Palmer was changing the capacity benchmarks in his video interview with Chelsea. I got the impression that he was merely observing that the average driver in AZ is putting about 7,500 miles per year on the car. Period.

I don't believe his remarks were worth much and herein lies the problem: Andy wasn't observing AZ drivers, but most likely using CarWings which is as much as a joke as the GOM. He has received so much erroneous info from CarWings which makes his 'observation of AZ drivers' useless and non-factual. The figure of 12K average for AZ drivers from the insurance companies is much more accurate and realistic.

 

[Stoaty]

And I think that is the way LEAF owners should keep a watchful eye on their capacity, perhaps using my 6 scenario capacity chart based on the polynomial curve.

For example, let's say someone has owned a Leaf for 24 months, but only driven 6,000 miles. To estimate its remaining capacity, the owner should look down the first column, because age trumps mileage:

The problem with this simplistic chart is that it doesn't even take average ambient temperature--the main factor slowing or speeding battery capacity loss--into account. My model closely predicts loss in many cases, with some outliers, virtually all of which have lower capacity than predicted. It correctly predicts loss in Phoenix (much faster degradation even with low mileage) and in Seattle (much slower degradation even with high mileage). If an owner wants to estimate his/her likely remaining capacity at a given point in time, the Battery Aging Model is the most accurate predictor we currently have.