Yanquetino
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Re: Phoenix Range Test Results, September 15, 2012

Fri Sep 21, 2012 6:58 pm

DaveinOlyWA wrote:very nice story but...

you state you did not see any car losing capacity at 3X the rate of others but you are only looking at AZ cars. look at mine. 21,800 miles, estimated degradation of 2%.

you also dispute the value of the capacity bars then go on to show how the LEAFs are going farther than they should based on the capacity bars missing but you are assigning a value of 8% to each when the first one is 15%. so ya, your chart will appear that the LEAFs are going farther than expected because you have not assigned the correct value to the missing bars.
Um... I must be miscalculating...? According to Nissan's projections in the table, 22,000 miles would render a 93% capacity, i.e., a 7% degradation --not 2%. It's too bad your Leaf wasn't in the test; it would be informative to know how far it would actually go with that mileage on the odometer!

Again, please note: increasing the difference in the capacity bar percentage from 8.34% to 15% would make the difference between "capacity" and "achieved range" even larger --not smaller. My proportional percentage is actually favoring the AZ owners' claims more than the 15% would. The latter would lower the capacity prediction; the former raises it. The actual ranges achieved on the test, however, are unaffected by those bar percentages: the Leafs went... as far as they went.

Weatherman
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Re: Phoenix Range Test Results, September 15, 2012

Fri Sep 21, 2012 7:02 pm

It was the first thing that struck me when I saw the results. Maybe the assumption we have been making that the first bar loss represents a 15% loss in capacity is no longer true and that they really are linear.

On the other hand, to be fair, I would have chosen the middle of the range of mileage-to-empty for 4 miles/kWh, rather than the bottom of the range, as the reference point for any discussion. In other words, 80 miles rather than 76 miles.
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Yanquetino
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Re: Phoenix Range Test Results, September 15, 2012

Fri Sep 21, 2012 7:18 pm

Weatherman wrote:On the other hand, to be fair, I would have chosen the middle of the range of mileage-to-empty for 4 miles/kWh, rather than the bottom of the range, as the reference point for any discussion. In other words, 80 miles rather than 76 miles.
Yes, I can see the argument for using the average number. In fact, I had considered doing just that. But ultimately it occurred to me that Nissan could legitimately claim that the ranges were still "normal" if they were close to the lower end of their scale, so... I figured it would be prudent to just settle for the minimal number to which they have to be held officially accountable. And, in fact, the temperatures were slightly higher than in Nissan's bulletin, so the adage that YMMV seems to favor the lower estimate.

LEAFfan
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Re: Phoenix Range Test Results, September 15, 2012

Fri Sep 21, 2012 7:24 pm

Weatherman wrote:It was the first thing that struck me when I saw the results. Maybe the assumption we have been making that the first bar loss represents a 15% loss in capacity is no longer true and that they really are linear.
On the other hand, to be fair, I would have chosen the middle of the range of mileage-to-empty for 4 miles/kWh, rather than the bottom of the range, as the reference point for any discussion. In other words, 80 miles rather than 76 miles.
It's really simple. If you have full battery capacity (new pack), that's around 21 kW h usable. If you show and keep 4.0m/kW h on your dash (like during the test) , you will be able to drive at least 84 miles. Anyone that doesn't realize this is just ignoring the facts.
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surfingslovak
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Re: Phoenix Range Test Results, September 15, 2012

Fri Sep 21, 2012 7:31 pm

Yanquetino wrote:
klapauzius wrote:Also note that the capacity bars (like many other things in the LEAFs displays) are apparently NOT linear, so the first bar is NOT 8.3% but 15%. I think this non-linearity (also for the temperature) is a BIG mistake on Nissans side, since people generally cannot cope with non-linearity well (unless its asymptotic).
Yes, I have heard that, but please note: if the first bars are not proportional, but represent even higher percentages at the upper levels, then the differences between what the lost bars were predicting and what the actual range was in the test are even greater.

For example, if White626's 11 bars indicated 85% (instead of 92.7%), then the capacity range would predict only 64.6 miles (instead of 69.7 miles), i.e., 8.9 miles lower (instead of 3.8 lower) than the actual 73.5 miles it achieved in the test.
I have finally read your treatise, Mark, it was a bit tough getting through the first portion. It was little too much pontificating for my taste. That said let me sum up what you did:

- take the lowest estimate from NTB11-076a as range expectation for a new Leaf
- assume linear battery capacity degradation dependent on mileage only
- assume linear distribution of battery capacity bars

Let's assume for the moment that the average range in the Phoenix fleet (2011 vehicles only) is down 15%. This is roughly in line with the results Nissan verbally communicated to some owners that had their Leafs examined in Casa Grande. Let's also assume that the usable battery capacity in a new Leaf was in fact 21 kWh, which should be verifiable.

If this was the case, you are virtually erasing 10% from 15% average degradation in the Phoenix fleet by assuming 76 miles of range in a new vehicle. You then proceed to formulate a degradation model based on cycling losses only to fit this artificiality low estimate, and then proclaim that everything is fine. Well done. Did I miss anything?

If you wanted to risk a look at a better effort at analyzing the results, here is a graph from a recent article on thetruthaboutcars.com. This is similar to a plot Stoaty did earlier. Note that the car at 95% and 16,000 miles had in reality a shorter range. Tony misread the results sheet, and it should be at about 90% (Blue534).

Image

LEAFfan wrote:It's really simple. If you have full battery capacity (new pack), that's around 21 kW h usable. If you show and keep 4.0m/kW h on your dash (like during the test) , you will be able to drive at least 84 miles. Anyone that doesn't realize this is just ignoring the facts.
Indeed. The pattern I'm seeing here are a few EV enthusiasts pitting themselves against affected owners thinking that they don't get it. While I applaud what these folks have done for EVs, nothing could be farther from the truth. This is the wrong fight.
Last edited by surfingslovak on Sat Sep 22, 2012 2:06 am, edited 4 times in total.

Yanquetino
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Re: Phoenix Range Test Results, September 15, 2012

Fri Sep 21, 2012 7:41 pm

LEAFfan wrote:It's really simple. If you have full battery capacity (new pack), that's around 21 kW h usable. If you show and keep 4.0m/kW h on your dash (like during the test), you will be able to drive at least 84 miles. Anyone that doesn't realize this is just ignoring the facts.
Yup! That's the way the abacus adds it up! The caveat is the "around" adverb. I suppose that what Nissan is saying with the 76-to-84 range estimate in its Technical Bulletin NTB11-076a is that a fully charged new Leaf could have around 19-to-21 kWh "usable."

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surfingslovak
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Re: Phoenix Range Test Results, September 15, 2012

Fri Sep 21, 2012 7:42 pm

Yanquetino wrote:Yup! That's the way the abacus adds it up! The caveat is the "around" adverb. I suppose that what Nissan is saying with the 76-to-84 range estimate in its Technical Bulletin NTB11-076a is that a fully charged new Leaf could have around 19-to-21 kWh "usable."
Yes, and if they give a range, we must assume the lowest number. But only after accusing others of using the highest number. How about the middle ground then? Would that be agreeable to you?

Stoaty
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Re: Phoenix Range Test Results, September 15, 2012

Fri Sep 21, 2012 7:49 pm

Yanquetino wrote:Sigh.... Given what I have experienced in these forum discussions, I hesitate to state this, but... I draw very different conclusions: AZ Leaf Capacity Kerfuffle
Nissan's own tests don't agree with your conclusions. One of the affected owners was told that of the 7 cars tested at Casa Grande, the best one had lost 14% of capacity from new. That doesn't sound like they are on track to lose 20% in five years.
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klapauzius
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Re: Phoenix Range Test Results, September 15, 2012

Fri Sep 21, 2012 8:09 pm

Yanquetino wrote: Um... I must be miscalculating...? According to Nissan's projections in the table, 22,000 miles would render a 93% capacity, i.e., a 7% degradation --not 2%. It's too bad your Leaf wasn't in the test; it would be informative to know how far it would actually go with that mileage on the odometer!
Yes, that would have helped a lot to interpret the data beyond the obvious result, i.e. reduced range.
If we knew by how much the range was actually reduced, compared to a new ( or like new) car, that would bring more clarity. Unfortunately this particular test can only be done on the same route, if we want to use the numbers from the AZ test.

I think neither 76 or 84 miles is a reliable number, it would be more important how far a new Leaf on that test route in Phoenix would go. Also, if some of the cars involved in the test could repeat the test, we could learn something about the variability in individual ranges

Yanquetino
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Re: Phoenix Range Test Results, September 15, 2012

Fri Sep 21, 2012 8:09 pm

Stoaty wrote:Nissan's own tests don't agree with your conclusions. One of the affected owners was told that of the 7 cars tested at Casa Grande, the best one had lost 14% of capacity from new. That doesn't sound like they are on track to lose 20% in five years.
Huh. The best one has lost 14%? Was that "best" car in the test? Which one was it? I wonder who the Nissan rep was who told the owner that...? And I wonder how many miles that Leaf had on its odometer...? Sure sounds like Nissan's left hand (whoever said that) doesn't know what its right hand (Palmer) is saying.

If that quote is indeed accurate, I'll be very curious to see what Nissan says, when it says it. "In the near term." "Very soon." ;)

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