Capacity Loss on 2011-2012 LEAFs

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Stoaty said:
OrientExpress said:
As I thought, the mean is 14~15K, so that shows that most are high mileage. Now combine that with the severe duty environment, and it appears that there is correlation.
Actually, assuming a normal distribution 68% of the cars would fall in the range 10,344 - 18,178. Note that 14,100 is also the median, which means there are just as many cars below that value as there are above that value. There isn't any data showing that "most are high mileage". See statistics from DOT:

http://www.fhwa.dot.gov/ohim/onh00/bar8.htm" onclick="window.open(this.href);return false;

Average is 13,476 across all age groups and both sexes... very close to the 14,000 miles per year driven by the average one capacity bar loser.
Nice response, Stoaty!

And what severe duty environment is OrientExpress talking about? Is there anything else other than heat? We've already established that heat is the primary cause of capacity reduction. Calling it any other name to make it appear like owners are abusing their cars is a bunch of BS. If Nissan considers the heat in AZ severe duty to be avoided, then why sell in AZ in the first place?
 
Volusiano said:
Stoaty said:
OrientExpress said:
As I thought, the mean is 14~15K, so that shows that most are high mileage. Now combine that with the severe duty environment, and it appears that there is correlation.
Actually, assuming a normal distribution 68% of the cars would fall in the range 10,344 - 18,178. Note that 14,100 is also the median, which means there are just as many cars below that value as there are above that value.... See statistics from DOT:
Average is 13,476 across all age groups and both sexes... very close to the 14,000 miles per year driven by the average one capacity bar loser.

And what severe duty environment is OrientExpress talking about? Is there anything else other than heat? We've already established that heat is the primary cause of capacity reduction. Calling it any other name to make it appear like owners are abusing their cars is a bunch of BS. If Nissan considers the heat in AZ severe duty to be avoided, then why sell in AZ in the first place?

Honestly, I don't quite understand why what seems so apparent to so many, is so different to some.

12,000 to 15,000 miles is so common and average, those are the two most sold mileages for leases.

I agree that Phoenix is abusive to vehicles; what's different is that every new gasoline vehicle handles it fine (and if it didn't, the warranty would fix it). Even data from several years of Tesla Roadsters seem to be doing fine. Edit: Chevy Volt is doing fine, too.

Plus, if the problem is a software issue, as you notably informed us recently, why would mileage matter?
 
mksE55 said:
It would take alot of force to get it rolling but not as much to keep it going. It still requires energy to maintain the drum at a set speed but probably 80% or real world energy.
Really? Why so much? I assumed at freeway speeds on level ground nearly all of the car's energy would be going to air resistance. Once that drum is spinning it can't slow down at all without transferring energy somewhere, probably to heat. If there is no artificial friction, what is going to be getting hot? Bearings? I would think tires would be the biggest heat generator, and they don't generate that much, do they?

Ray
 
aqn said:
shrink said:
However, it does bring to mind another column for the wiki - model year. I think we all assumed the reports were from 2011's. That's not the case anymore.
What's wrong with going by the VIN? That's more fine grained than model year, no? A LEAF with higher VIN number is younger than one with a lower VIN number (excepting the few (?) that may be in the wrong chronological order due to SNAFUs resulting from the earthquake/tsunami), while "2011 LEAF" encompasses a comparatively much larger time period.

I don't know how Nissan does it, but some manufacturers restart the serial number at 1 each model year. Also, since there are typically technical differences among model years, it's just a quick way to get a sense if what is being tracked, in this case loss of battery capacity, might have something to do with the unique features of a model year.

I think most of us assumed the capacity losses were all 2011's. It's just informative to know the 2012's are being affected as well. You don't get that sense from just looking at a VIN number.
 
TonyWilliams said:
Honestly, I don't quite understand why what seems so apparent to so many, is so different to some[...]

Plus, if the problem is a software issue, as you notably informed us recently, why would mileage matter?

Well said, Tony. The "some" in this case went from declaring "all" the cars were high mileage; to only the mean being high mileage (despite data cited indicating the mileages were indeed average); to saying there was a correlation without actually performing a correlation. Those who actually did the calculation found no correlation.

Previously, this "some" also denied repeatedly any problem existed, then insisted the solution to the non-problem was simply to "charge more," then declared a software error (in software that checked out at the factory and subsequently gave no error messages to Nissan or the user during subsequent battery inspections) was the most rational explanation to the non-problem. Now, it's a non-correlation to mileage.

Back on topic, several in the Casa Grande study were told 85% capacity remained. Although that number seems debatable, assuming it is accurate, is that acceptable after 12-16 months of ownership when 80% after 5 years is what is advertised? I suppose it is, since capacity is not under warranty, but how many cars would have been sold if buyers knew 15% loss after a little over a year would be considered normal?

We just sit and wait for some sort of announcement about the conclusions of the Casa Grande study. I'm expecting corporate spin, but I'm hoping for a real solution. I believe there were some good ideas being discussed in part 2 of this monster thread.
 
The average to me @ 14,000k+ a year is actually low. To me, the best case on how many miles should be on the vehicle (for average use) is the service manual. If follow Nissan's recommened service, it happens every 6 months OR 7,500 miles. The best case scenario is that those two numbers are in sync. This would lead to a yearly mileage of 15,000, so less than that is actuall less wear than normal.

For myself, I know I put more miles than many on mine (I average about 1,700+ per month), but there are many countercases of Washington and Oregon LEAFs with extreme high mileage and almost no capacity loss (only a few percentage points) - those cases have been discussed in this thread...somewhere.

Add to the fact that it appears the second bar was loss from almost all the vehicles at an average of 2 months, and mine was lost one day shy of 2 months really affirms that my high mileage didn't factor in when lower mileage cars were losing their second bar in the same amount of time.
 
planet4ever said:
mksE55 said:
It would take alot of force to get it rolling but not as much to keep it going. It still requires energy to maintain the drum at a set speed but probably 80% or real world energy.
Really? Why so much? I assumed at freeway speeds on level ground nearly all of the car's energy would be going to air resistance. Once that drum is spinning it can't slow down at all without transferring energy somewhere, probably to heat. If there is no artificial friction, what is going to be getting hot? Bearings? I would think tires would be the biggest heat generator, and they don't generate that much, do they?

Ray


I am no physics major but here are some. friction of bearings. air resistance on drum from other side, gravity, tire friction. I dont know the real world percent but when I do this I will get a quick since of it by the number of bubbles it will take to keep it moving at 60mph, and the Kwh rating. If it crazy high like 6-7 I will probably bail on the experiment, but if its in the 4-5 range I may wait it out. Guess thats why they call it an experiment. Many unknowns. ;)
 
mksE55 said:
I dont know the real world percent but when I do this I will get a quick since of it by the number of bubbles it will take to keep it moving at 60mph, and the Kwh rating.
Rather than looking at the number of bubbles, please use the power from the pie chart in the ZeroEmission->Energy Usage display. You should be able to read the power used for propulsion to a resolution of about 500 W.

Thanks for doing this experiment!
 
Here is a scatter graph of Annual Mileage vs. Months Owned to first capacity bar lost including all available data:

Slope - -576
Intercept - 21500
Correlation coefficient - 0.13

Interpretation: while visually from the line drawn it appears there may be some relationship, the very low correlation coefficient says that there is not a correlation from the available data. As a reminder, here is how to interpret correlation coefficient:

correlationcoefficient.jpg


annualmileagevsmonths.jpg
 
RegGuheert said:
mksE55 said:
I dont know the real world percent but when I do this I will get a quick since of it by the number of bubbles it will take to keep it moving at 60mph, and the Kwh rating.
Rather than looking at the number of bubbles, please use the power from the pie chart in the ZeroEmission->Energy Usage display. You should be able to read the power used for propulsion to a resolution of about 500 W.

Thanks for doing this experiment!

Good point, I will get some of that on Video as well, but to me the real issues is will this take 1-2 hrs or like 4-5 hrs, I can quickly guesstimate with the others.
 
To eliminate what is almost certainly the greatest variable in early capacity bar loss, climate, I'd suggest you might try graphing only the one or two-bar loss LEAFs reported from the Phoenix area.

And also, perhaps, graph only the first-hand reports from LEAF drivers, and only those reporting who received delivery, as opposed to orphans, demos, and pre-owned LEAFs, with much less certain use/abuse histories.

If there is still a low correlation, then other factors (amount of time spent a high rate of charge, for example) might prove more significant than time and miles driven.

Manufacture date would also probably be better than delivery date, but I realize you don't have that for most of the reports.

And total kWh use (which no one seems to be reporting) would probably be a better indicator than miles driven. A leaf that has driven a given number of miles at 3 m/kWh, has done about twice the battery cycling as one that has averaged 6 m/kWh.


Stoaty said:
Here is a scatter graph of Annual Mileage vs. Months Owned to first capacity bar lost including all available data:

Slope - -576
Intercept - 21500
Correlation coefficient - 0.13

Interpretation: while visually from the line drawn it appears there may be some relationship, the very low correlation coefficient says that there is not a correlation from the available data. As a reminder, here is how to interpret correlation coefficient:

correlationcoefficient.jpg


annualmileagevsmonths.jpg
 
edatoakrun said:
To eliminate what is almost certainly the greatest variable in early capacity bar loss, climate, I'd suggest you might try graphing only the one or two-bar loss LEAFs reported from the Phoenix area.

And also, perhaps, graph only the first-hand reports from LEAF drivers, and only those reporting who received delivery, as opposed to orphans, demos, and pre-owned LEAFs, with much less certain use/abuse histories.

If there is still a low correlation, then other factors (amount of time spent a high rate of charge, for example) might prove more significant than time and miles driven.

Manufacture date would also probably be better than delivery date, but I realize you don't have that for most of the reports.

And total kWh use (which no one seems to be reporting) would probably be a better indicator than miles driven. A leaf that has driven a given number of miles at 3 m/kWh, has done about twice the battery cycling as one that has averaged 6 m/kWh.
Very good thoughts, but my time and energy (and the data) are limited. Besides, my Leaf is cooling its battery in my 70 degree parking garage where it spends most of its life, so I am not personally affected to any great degree (although the hot San Fernando Valley where the Leaf spends its time during work days is somewhat of a concern).

However, here is the latest data on one bar capacity loss in the Phoenix area. Plot is annual mileage vs. months to first capacity bar loss. There are 26 data points.

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.

Note: when I did the graph previously in another thread, I did not plot against annual mileage,which is the correct figure. I believe the current analysis is the correct one, but comments are welcome re: whether the Y-axis should be total miles (previously plotted) or annual mileage (the current, and probably the correct choice).

phoenixonebarloss.jpg
 
="Stoaty"...Note: when I did the graph previously in another thread, I did not plot against annual mileage,which is the correct figure. I believe the current analysis is the correct one...

I don't understand why you have come to that conclusion, since one axis itself is months since delivery.

I wanted to see what might account for the anomalous 24,000 mile one bar loss report, and only then realized it must be the 10 month/20,000 mile report on the Wiki, right?

Stoaty said:
... here is the latest data on one bar capacity loss in the Phoenix area. Plot is annual mileage vs. months to first capacity bar loss. There are 26 data points.

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

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.

Note: when I did the graph previously in another thread, I did not plot against annual mileage,which is the correct figure. I believe the current analysis is the correct one.

phoenixonebarloss.jpg
 
edatoakrun said:
I don't understand why you have come to that conclusion, since one axis itself is months since delivery.

I wanted to see what might account for the anomalous 24,000 mile one bar loss report, and only then realized it must be the 10 month/20,000 mile report on the Wiki, right?
Right. To be honest, I don't know which is the correct comparison:

One compares the total miles driven to the time it takes to lose a bar - no correlation
The other compares the rate at which miles are accumulated to the time it takes to lose a bar - moderate correlation

The more I think about it, the more confused I have become. I welcome input from others more knowlegeable than I. :oops:
 
taking miles driven is one thing but i think a weighted number is better similar to car evaluations on mileage where they take a set figure (currently 15,000 a year) and then deduct points for miles over that or add points for miles under that.

there are basically 2 #s. the 15,000 used to value used cars and the 12,000 used as standard warranty fair (3 yrs OR 36,000 miles, etc.)

so that is the real metric that we should be looking at since both time and distance play a part along with temps
 
mynameisjim said:
I am growing quite tired of Orient Express' denial of the evidence regarding displayed battery capacity loss.

It is possible that Orient Express is right, since so far there is only anecdotal evidence, not proof. We need a valid representative sample of all Leafs, not just ones with capacity bar losses. So far, I don't know if it is 90% of the Leafs in Phoenix losing capacity, or only 9%. I don't know how that percentage corresponds to the people in Seattle. I don't know if this data has been compiled either, since the focus is ONLY on Leafs with capacity bar losses.

What is more important than mileage, which has shown a low correlation to capacity loss, is the temperature history of each battery, but I don't know if the car tracks that data.
 
mksE55 said:
since of it by the number of bubbles it will take to keep it moving at 60mph, and the Kwh rating. If it crazy high like 6-7 I will probably bail on the experiment, but if its in the 4-5 range I may wait it out. Guess thats why they call it an experiment. Many unknowns. ;)

I'm not sure what you are actually saying, or trying to prove. The LEAF takes about 250 wattHours per mile at 60mph on level, sea level elevation, 70F, no wind, on dry hard surfaced roads. That's 15kW of power (20 horsepower).
 
sub3marathonman said:
mynameisjim said:
I am growing quite tired of Orient Express' denial of the evidence regarding displayed battery capacity loss.

It is possible that Orient Express is right, since so far there is only anecdotal evidence, not proof. We need a valid representative sample of all Leafs, not just ones with capacity bar losses. So far, I don't know if it is 90% of the Leafs in Phoenix losing capacity, or only 9%. I don't know how that percentage corresponds to the people in Seattle. I don't know if this data has been compiled either, since the focus is ONLY on Leafs with capacity bar losses.

What is more important than mileage, which has shown a low correlation to capacity loss, is the temperature history of each battery, but I don't know if the car tracks that data.

there is a lot of hysteria on the board right now and some balance is needed and i dont think that OE's comments are farther out than comments made on the other side. both are rife with speculation and the problem we have is really limited information and no parameters to go by.

so the only thing we can do is continue to gather what information we can, continue to crunch it various ways and see what results.

speculating on how badly Nissan is doing is becoming counterproductive to this forum. i am not saying that the affected should not be unhappy or should not voice their concerns to Nissan but that issue ALONE has made it difficult to sift thru the real value of pertinent information posted here.
 
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