Phoenix Range Test Results, September 15, 2012

[klapauzius]

Here's the list:

LEAF --- CapBars- miles-M/kWh-Volts ---GOM
Red429 --- 10 --- 71.8 - 4.3 - ----------74
Blue494 ---- 8 --- 59.3 - 3.7 - ----------56
Blue534 --- 10 --- 75.7* - --- - 315.5----74 (ECO=84) (*Data edit 75.7 for typo)
White530 -- 10 --- 69.7 - 4.0 - ----------73
White272 -- 10 --- 66.1 - 4.4 - ----------68
Red500 ---- 9 ----73.3*- 4.4 - -342.5*---66 (*No turtle; 2 miles >VLB: Added 4 miles)
White626 --12 ----73.5 - 4.3 - -317.5----73 (CapBars were 10, reset 12, now 11)
Blue842 ---12 ----79.6 - 4.1 - --------- 76
Silver679-- 10 ----71.8 - 4.2 - -303.5--- 75 (18.2 miles after LBW)
Blue917--- 10 ----72.5 - 4.1 - -310.5 ---67
Black782-- 12 ----76.6 - 3.9 - -295.0 ---88ECO (Out4.0/In3.8; LBW 6.9, VLB 6.5)
Blue744 ---9 -----72.3*- 4.4 - -352.0*-- 63 (*No Turtle; 1 mile after VLB; added 5 miles)

Notably the 8 bar car also had the lowest M/kWH, any idea why that is? If we extrapolate to e.g. 4.2 M/kWh, which is the mean for the other cars, it would have gone 67.3 miles, which makes it less of an outlier in terms of range as it appears. This would also lower the overall correlation of observed range with e.g. capacity bars or gids.

Given the variation in (reported) efficiency, one should actually consider the quotient of actual range (lets assume that these values are comparable, i.e. every car was indeed driven to turtle) of range measured divided by efficiency.

The you would get the following list
[Car] [Apparent capacity (=range/efficiency)] [normalized capacity = (apparent cp- <apparent cp>)/std(apparent cp)
Red429 16.7 -0.43
Blue494 16.0 -0.94
Blue534 18.0 0.57
White530 17.4 0.12
White272 15.0 -1.70
Red500 16.7 -0.46
White626 17.0 -0.13
Blue842 19.4 1.63
Silver679 17.1 -0.13
Blue917 17.7 0.31
Black782 19.6 1.8
Blue744 16.4 -0.63
-----------------
mean 17.3 std 1.3

So all tested cars (with this small sample size), fall within 2 standard deviations of the sample mean, so technically, no outliers there. If we now had results for supposedly healthy new batteries (e.g (e.g. for at least 12 (ideally 30 or so) brand new leafs) under the same conditions, we could actually tell which of the tested cars had significant degradation. If we assume that 19.6 apparent capacity (Black782) is representative of the mean for a healthy battery, and we have the same variation as in our sample of 11 bad cars then we have


Red429 -2.59
Blue494 -3.18
Blue534 -1.42
White530 -1.95
White272 -4.07
Red500 -2.63
White626 -2.24
Blue842 -0.20
Silver679 -2.24
Blue917 -1.72
Blue744 -2.83

Which shows that 7 out of these 11 are below 2 std, i.e. are significantly degraded with respect to Black782.
Right now it actually appears that white272 is the worst case (despite a mere 2 bar loss).

Still, since we compute a quotient of two very noisy variables, the error on these values is actually going to be quite high. Also, the sample size is really small....What we really need are ~ 30 new cars tested on the same track.

[surfingslovak]

Tony... school me here... on the surface it seems like the GOM did a fairly good job? What is the take-away from your view.

Level terrain, constant speed... yes, the GOM handles that well, as we already know. I'm surprised at how well in this controlled demonstration.

But, if we had cars that had been operated up hills, or driving fast, when we took that first GOM reading, it would not be so good.

So, one win for GOM.

Yes, it's interesting, thank you for pointing it out! I drove Blue744 last Saturday. The GOM indicated 63, and the Leaf went 66.3 miles to the low battery warning, which means that it still had some life left in it. Not a huge aberration, but it's significant nonetheless.

The GOM was showing 47 miles on a full charge the next day (lifted from Randy's blog). It's still pretty inconsistent, but perhaps less so in the degraded cars we have seen? I've noticed that the GOM overestimates the range by about 20 to 30% on a full charge, but this was before the software update (NTB12-015).

[TonyWilliams]

If you were basing your earlier comments of 60 volt difference between cars at turtle by including these cars, then that's completely misleading since voltage of the pack starts dropping rapidly after VLBW is reached.

Yes, of course. From the voltage knee at VLB and 350v-ish, it power dives to 300-ish volts. I didn't make the 60 volt statement while knowing that those cars didn't reach turtle. So, part of the reason I preferred to get all the data organized before spewing it. So, I take the 60 volt spread comment back!!!!

Those two cars that didn't hit turtle can be dropped from consideration, but it's not necessary. We know how far some of the cars went from VLB to turtle (Black782 went 6.5 miles, Blue494 6.7 miles) and for the purpose of a demonstration, the adjustments I made are reasonable.

Plus, they are annotated. The extremes, which was what I was most concerned with, went 59 and 79 miles. I now have access to a new dealer car, and I think it will go 84.

[TonyWilliams]

Tony... school me here... on the surface it seems like the GOM did a fairly good job? What is the take-away from your view.

Level terrain, constant speed... yes, the GOM handles that well, as we already know. I'm surprised at how well in this controlled demonstration.

But, if we had cars that had been operated up hills, or driving fast, when we took that first GOM reading, it would not be so good.

So, one win for GOM.

Yes, it's interesting, thank you for pointing it out! I drove Blue744 last Saturday. The GOM indicated 63, and the Leaf went 66.3 miles to the low battery warning, which means that it still had some life left in it. Not a huge aberration, but it's significant nonetheless.

The GOM was showing 47 miles on a full charge the next day (lifted from Randy's blog). It's still pretty inconsistent, but perhaps less so in the degraded cars we have seen? I've noticed that the GOM overestimates the range by about 20 to 30% padding on a full charge, but this was before the software update (NTB12-015).

Another note is that any of the GOM data taken in ECO mode are still WAY off. The GOM is expecting savings from limiting the climate control, and we turned it off. So, GOM does OK with a softball pitch in ideal conditions, but can't even figure out ECO considerations (it should adjust for climate control on or off).

[TonyWilliams]

+1 incomplete data should be clearly marked or kept in a separate table. I'm not a big fan of any of this extra data from instrumentation not in the car from the factory. Charge it until it stop by itself, and then drive it until it stops by itself. How far did it go and how did it do compared to the instrumentation we have in the car.

It's marked now with *, and with notes. We did exactly what you suggested, otherwise. Charged car, drove to loss of power (turtle), with two marked exceptions. We measured the distance.

You don't have to look at other data!

[palmermd]

+1 incomplete data should be clearly marked or kept in a separate table. I'm not a big fan of any of this extra data from instrumentation not in the car from the factory. Charge it until it stop by itself, and then drive it until it stops by itself. How far did it go and how did it do compared to the instrumentation we have in the car.

It's marked now with *, and with notes. We did exactly what you suggested, otherwise. Charged car, drove to loss of power (turtle), with two marked exceptions. We measured the distance.

You don't have to look at other data!

I did not, and I suggest others don't as well for the purpose of the test. The extra data gathering is great for other reasons, and I'm glad you were able to gather it. Thank you so much for all your effort in this Tony.

[EatsShootsandLeafs]

I kept looking at the other thread for three days waiting for results, too stupid to check this forum.

Great job Tony AND everybody else who put time in. I know a few people put in serious effort in addition to Tony.

These results confirm what most of us suspected: A real loss of range, prematurely. The only saving grace of these particular cars is if the loss of capacity now stops and I cannot imagine any of us expect that. Clearly these batteries have lost capacity much faster than Nissan indicated they would, or that they should have, thus making these particular cars not usable long term.

[Yanquetino]

These results confirm what most of us suspected: A real loss of range, prematurely. The only saving grace of these particular cars is if the loss of capacity now stops and I cannot imagine any of us expect that. Clearly these batteries have lost capacity much faster than Nissan indicated they would, or that they should have, thus making these particular cars not usable long term.

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



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

[palmermd]

These results confirm what most of us suspected: A real loss of range, prematurely. The only saving grace of these particular cars is if the loss of capacity now stops and I cannot imagine any of us expect that. Clearly these batteries have lost capacity much faster than Nissan indicated they would, or that they should have, thus making these particular cars not usable long term.

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



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

VERY thoughtful review. Thank you for posting this.

[klapauzius]

These results confirm what most of us suspected: A real loss of range, prematurely. The only saving grace of these particular cars is if the loss of capacity now stops and I cannot imagine any of us expect that. Clearly these batteries have lost capacity much faster than Nissan indicated they would, or that they should have, thus making these particular cars not usable long term.

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



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

Yes, that is an interesting perspective. However it should be noted that there Leafs in colder climates, who have NOT experienced similar degradation, despite having similar mileage or more. It all depends what you consider the baseline performance, but I guess Nissan spelled that out in their manual.

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).