TonyWilliams said:
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Is CarWings kW data accurate? We'll see soon with LEAFscan, I predict.
Well, I’ll stick to what we know, or can know now, if we make the effort to look, now.
My CW appears to be entirely accurate, save the data input for “miles “driven” by a constant 2.5% error, as reported by many observers.
I first posted the odometer discrepancy over 7 months ago, and also posted the several questions that remain unanswered today.
I rechecked 2 other recent drives of 85-105 miles and each time CW has erred, under-reporting distance traveled, as compared with both my odometer and Google Maps, by 2.5%, +/- 0.1%.
Has anyone else-before or after the NTB11-041 update-seen this same odometer/CW mileage disparity?
If so, do you suppose this may reflect the similar discrepancy between the dash and screen numbers, as widely reported?
My car shows 4.3 m/kWh on the dash and 4.4 on the screen, as average since delivery.
Extrapolating from the chart, it appears CW may be saying the 1.7 kWh (8.5% from the chart, of 20.4 total kWh-anyone have a better number?) I had left at or near VLBW implies total available battery capacity of about 20.4 kWh.
So, from the limited info I can gather, looks to me that Carwings may now be accurate as to energy use.
Posts from others who can take the charge lower could verify this...
Comments from the SOC meter crowd, and also those who have metered L2 charging and can determine charge efficiency, as a % from Carwings reports, would also be greatly appreciated...
http://www.mynissanleaf.com/viewtopic.php?f=31&t=5423&hilit=carwings&start=10" onclick="window.open(this.href);return false;
I believe from other’s reports, but (since I have never resets either m/kwh readout on my car, and they still read 4.3/4.4) have not observed, that the “behind the wheel“ (BTW), rather than the Nav screen, m/kWh, may also be understated by the same percentage. IMO, more reports of m/kWh from BTW and the CW reports being identical, for the same miles driven, might confirm both the same constant inaccuracy in both these sources of data.
I also pointed out 7 months ago that observations after changing tires, or after tire wear, effecting this 2.5% constant, would answer the question of CWs source for for the odometer understatement. As far as I know, we still don’t know if CW gets it distance data, through an internal calculation (but not from the odometer) or from GPS data.
The problem is, every tire varies slightly in circumference, especially between different manufactures. And even the same tires will show about this percentage in odometer readings, over their life, due to tread wear.
So it is entirely possible CW will become more accurate, and your odometer less so, as your tires wear. This is an easy question to answer by observation, by anyone who has high tire wear, or has replaced their tires. If the 2.5% constant remains, following any change to tire circumference, we should know if both BTW and CW reports, get the same erroneous m/kWh data, presumably from a GPS source error.
Other than this constant underreport of miles driven, my CW has seemed entirely accurate, since my posting above. Unfortunately, the refusal, by many to look at their own CW data, has retarded, not only the explanation of this CW inconsistency, but our more general understanding of LEAF operation, in far more significant ways, as shown ,IMO, by errors in the range chart.
There do seem to be many significant inaccuracies in the range chart, and since it is purported to be based on gig data, either that data is inaccurate, or, much more likely, the interpretation, is in error. The most significant errors seem to be due to misstatement of the actual high and near-constant percentage of ascent energy recovery, and the supposition that the battery warnings, and the bar display, must reflect fixed values of the percentage of underlying battery capacity, in kWh.
Again, more than seven months ago, Both I, and, IIRC, several other LEAF drivers, observed, from simple bar watching, that LEAF ascent energy recovery was at a high and near-constant rate:
...I would not have thought near 80% recovery of ascent energy (by both "coasting" and regen) likely in real-world use on extreme grades, but that's what I'm seeing, and it seems other recent hill climb threads reflect the same experience.
http://www.mynissanleaf.com/viewtopic.php?f=31&t=5022&hilit=+lassen" onclick="window.open(this.href);return false;
The analysis of a single trip, with the “regeneration fraction“ shown as a coefficient of 0.8 shown in this paper, explains my earlier observations, in more detail than I can here:
http://www.roperld.com/science/NissanLEAFRangeCalculation.pdf" onclick="window.open(this.href);return false;
The author also reports Variable battery warnings, based on “driving style”, but does not give his source for this observation.
My experiences, most recently and in the most detail, reported here:
http://www.mynissanleaf.com/viewtopic.php?f=31&t=8420&start=10" onclick="window.open(this.href);return false;
Is highly suggestive that LBW occurs earlier, when following periods of high kW demand, or after a stop/start cycle. It also suggests to me, that either the bars are located incorrectly on the range chart, as representative of underlying battery capacity, or that the bars, also, might in fact be variably representing battery capacity, on our dash displays.
There is also the sleight, IMO, possibility that My battery may have suffered a recent reduction in capacity, which, however unfortunate for me, would be of great interest to all LEAF owners, so I will look for this, and report, ASP
But again, mine is only one report, from one LEAF driver. The problem here, is just as some accepted, as orthodoxy the lack of usefulness of CW, we
may have accepted another orthodoxy, for LBW and VLBW, and bar displays, as fixed battery capacity indications, rather than basing our understanding on data collected by multiple observations, with control for other variables.
Have other seen variable LBW or VLBW, based on CW kWh use reports?
Have those with gig counts checked for battery warning variability, or are basing their conclusions on assumptions, based on limited observations?
