My carwings energy numbers - CORRECT post NTB11-041 update

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edatoakrun

Well-known member
Joined
Nov 11, 2010
Messages
5,222
Location
Shasta County, North California
As I posted earlier, Since I had the Carwings update done on 8/3, my Dash and Carwings miles/kWh numbers seem to match.

Even more interestingly, the daily Driving Records/electricity consumption now seem to accurately reflect the kWh delivered from my Modified L2, as best as I can calculate by recharge time.

Has anyone tried a 100% charge to Turtle discharge drive since having the update?

What total electricity consumption (kWh) did carwings report-and do you believe it to accurately reflect total battery capacity?

If you have a meter at the wall, what L2 charging efficiency percentage did it show for your recharge, using the Carwings energy consumption report?
 
I thought this thread would be of more interest.

I took the "?" out of the thread title, as I'm convinced my carwings numbers are correct-at least in that they now replicate my dash numbers.

It's knocked the hell out of my Carwings rank, as posted below:

Your rank for the past 12 months

Month and Year Grade Rank Energy Economy

May/2011 Gold 492 5.4 miles/kWh
Jun/2011 Gold 695 5.7 miles/kWh
Jul/2011 Gold 1651 5.3 miles/kWh
Aug/2011 Bronze 3622 4.2 miles/kWh
Sep/2011 Bronze 2850 4.3 miles/kWh


Sure looks like most LEAFs are still running on pre-update carwings.

What's going on? Have most of you NOT had the update?

Those who have, check your carwings numbers since. Are you seeing the same results that I am?

It seems to me that a one-day turtle run from 100% could now give confirmation of the available battery capacity estimates from other threads.

And if you compare the carwings consumption report to a metered 100% re-charge, an accurate charge efficiency rate.

Am I missing something?
 
Thanks for the post. My Carwings has not worked since the day I took delivery. I didn't bother addressing this because I figured there's no point in looking at bad data. But if they've fixed the accuracy issues, perhaps it would be worth my while to have the dealer do the update and get my Carwings working.
 
I may have the update done as a matter of course when I bring in my Leaf for something else, likely the 12 month battery check. Since I never use any of the Carwings ranking or other related features, and have had no telematics problems, it is not a priority to me and not worth my while to bring it in just for that...

edatoakrun said:
I thought this thread would be of more interest.
Sure looks like most LEAFs are still running on pre-update carwings.
What's going on? Have most of you NOT had the update?
 
abasile said:
Thanks for the post. My Carwings has not worked since the day I took delivery. I didn't bother addressing this because I figured there's no point in looking at bad data. But if they've fixed the accuracy issues, perhaps it would be worth my while to have the dealer do the update and get my Carwings working.

I found carwings useful before the update in that it overstated m/kWh and understated energy consumption consistently, so CW results from different driving styles and speeds on identical routes did give some useful info.

Much better now that the numbers are correct...as well as consistent.

For example, on a recent post-update round-trip drive, 85.6 miles (correction: 87.6 miles) by odometer (85.5 by CW) with between 5,000 and 5,500 ft. of total ascent and descent, carwings reports 16.8 kw kWh consumed and 5.1 m/kWh.

16.8 X 5.1=85.68

I returned home with most of one bar, having driven 3.1 relatively level miles averaging about 30 mpg after the "low battery " warning occurred.

From other reports of remaining battery capacity at this level, I expect updated CW would report about 21 kWh from 100% to turtle. Right?

Sorry I won't be doing it, but I live on a steep unpaved one lane road, in an area without consistent cell phone coverage, and expect my "turtle test" might not have a happy ending.

The update did not seem to change when bars 12 to 2 disappear, so I believe battery capacity in the last bar and “reserve” are probably not changed by the update, if any one else wants to try it.
 
edatoakrun said:
For example, on a recent post-update round-trip drive, 85.6 miles by odometer (85.5 by CW) with between 5,000 and 5,500 ft. of total ascent and descent, carwings reports 16.8 kw kWh consumed and 5.1 m/kWh.

16.8 X 5.1=85.68
Beautiful, I might do the update just for that, time permitting. I absolutely hate the messy record keeping CW provides and I still cannot believe that Nissan didn't get something as basic as this right. Generally, manufacturers and OEMs struggle with embedded software, perhaps because it's not their core expertise, but the the delta in data reported by CW was so glaring that you have to wonder if they simply ran out of time when launching the Leaf.

Yes, there is strong consensus for the multiplier you mentioned, and your kWh is coming close to that. We can only estimate what was left in the pack after your trip, but it should be pretty close to the model. The only thing that puzzles me a bit is the elevation difference. Did you mention 5,000 feet? I believe that Tony Williams estimates 1 bar for each 1,000 feet. We don't know how effective regen is, but assuming 50% efficiency, I'm guessing that the change in elevation would account for about 2 to 3 bars lost, which roughly translates to something between 3 to 4.5 kWh. It would be interesting to see if we could refine the model to work with every topography, right now it assumes flat ground and ignores any elevation difference.
 
surfingslovak said:
edatoakrun said:
For example, on a recent post-update round-trip drive, 85.6 miles by odometer (85.5 by CW) with between 5,000 and 5,500 ft. of total ascent and descent, carwings reports 16.8 kw kWh consumed and 5.1 m/kWh.

16.8 X 5.1=85.68
Beautiful, I might do the update just for that, time permitting. I absolutely hate the messy record keeping CW provides and I still cannot believe that they didn't get something as basic as this right. Generally, manufacturers and OEMs struggle with embedded software, perhaps because it's not their core expertise, but the delta in data reported by CW was so glaring that you have to wonder if they simply ran out of time when launching the Leaf.

Yes, there is strong consensus for the multiplier you mentioned, and your kWh is coming close to that. We can only estimate what was left in the pack after your trip, but it should be pretty close to the model. The only thing that puzzles me a bit is the elevation difference. Did you mention 5,000 feet? I believe that Tony Williams estimates 1 bar for each 1,000 feet. We don't know how effective regen is, but assuming 50% efficiency, I'm guessing that the elevation difference would account for about 2 to 3 bars lost, which roughly translates to something between 3 to 4.5 kWh.

I have no idea what regen efficiency is. I have observed that I "gain" about one bar for each 1,000 ft. of descent, and "use" one bar for each 800 ft. of ascent.

So on this trip I used a bit over 1 bar more than I would have on a level drive at the same speed-about 40 mph average.

Remember, most of the energy of ascent is recovered WITHOUT the use of regen, by simply using low throttle on descent to maintain desired speed.

The less regen you use, the further you get.
 
edatoakrun said:
I have no idea what regen efficiency is. I have observed that I "gain" about one bar for each 1,000 ft. of descent, and "use" one bar for each 800 ft. of ascent.

So on this trip I used a bit over 1 bar more than I would have on a level drive at the same speed-about 40 mph average.

Remember, most of the energy of ascent is recovered WITHOUT the use of regen, by simply using low throttle on descent to maintain desired speed.

The less regen you use, the further you get.
Yes, that would make sense. However, I think I misspoke and I blame it on the lack of sleep. The MPK number and the total energy expended should cover losses due to changes in elevation. The only thing that would not work, is the estimated range and the implied MPK based on your speed.

The model says that the reserve is about 3 kWh, and by the looks of it, you barely dipped into that. It might be realistic to assume that about 2.5 kWh of available energy was left at the end of the trip. These are fairly rough numbers, but if we put it all together, it correlates with the model, but there is still some delta:

16.8 + 2.5 = 19.3 kWh
 
surfingslovak said:
edatoakrun said:
I have no idea what regen efficiency is. I have observed that I "gain" about one bar for each 1,000 ft. of descent, and "use" one bar for each 800 ft. of ascent.

So on this trip I used a bit over 1 bar more than I would have on a level drive at the same speed-about 40 mph average.

Remember, most of the energy of ascent is recovered WITHOUT the use of regen, by simply using low throttle on descent to maintain desired speed.

The less regen you use, the further you get.
Yes, that would make sense. However, I think I misspoke and I blame it on the lack of sleep. The MPK number and the total energy expended should cover losses due to changes in elevation. The only thing that would not work, is the estimated range and the implied MPK based on your speed.

The model says that the reserve is about 3 kWh, and by the looks of it, you barely dipped into that. It might be realistic to assume that about 2.5 kWh of available energy was left at the end of the trip. These are fairly rough numbers, but if we put it all together, it correlates with the model, but there is still some delta:

16.8 + 2.5 = 19.3 kWh

As I read the chart here:

http://www.mynissanleaf.com/viewtopic.php?f=31&t=4295&start=190" onclick="window.open(this.href);return false;

I believe I pretty much exactly matched predicted range, less correction for net elevation, with 80% recovery of ascent energy.

As to total kwh as "charted", I would say the total is more like 16.8+3=19.8, as the last 3.1 miles after LBW were at about 25 mph average, and just a few hundred feet of descent (hard to determine my precise altitude at the LBW) would net that out with regen.

There does appear to be a problem with the bottom of the chart, as I always get the "low battery warning" long before losing the first bar.

Yesterday, I drove the same route again at slightly higher speed with more (still not much) AC use. When I reached my driveway, at 85 miles (correction: 87 miles) I still had (less than) one bar, so I drove until I got the "very low battery" warning and simultaneously lost the last bar, at 91.5 miles. I got home with 93.4 miles, and between 5,500 and 6,000 ft. of ascent and descent, at an average speed of about 40 mph (those last 8.4 (6.4) miles were up and down a hill at low speed). Since the last 1.9 miles after the "very low battery” warning were at about 20 mph and required about 150 ft. net descent with regen, I was probably still very close to the VLBW point capacity, when I parked.

I will edit with the CW energy use report for this drive, after it shows up.

9/11 edit-According to CW, I used 18.7 kWh to drive 91.1 miles at average energy economy of 4.9 m/kWh.
 
edatoakrun said:
There does appear to be a problem with the bottom of the chart, as I always get the "low battery warning" long before losing the first bar.
Tony explained to me, in another thread, that the way he intended the chart to be read was that the line between 1 bar and Low Battery is supposed to represent the top of the Low Battery region, but not the bottom of the one bar region. That's what the two stars and their footnote are trying to tell us. He also said that once you get Low Battery you should ignore the bars. Curiously, it seems to me there is a bit of a flip-flop at that point. The last bar becomes unreliable, and the "guessometer" becomes much more reliable, though pessimistic.

Ray
 
planet4ever said:
edatoakrun said:
There does appear to be a problem with the bottom of the chart, as I always get the "low battery warning" long before losing the first bar.
Tony explained to me, in another thread, that the way he intended the chart to be read was that the line between 1 bar and Low Battery is supposed to represent the top of the Low Battery region, but not the bottom of the one bar region. That's what the two stars and their footnote are trying to tell us. He also said that once you get Low Battery you should ignore the bars. Curiously, it seems to me there is a bit of a flip-flop at that point. The last bar becomes unreliable, and the "guessometer" becomes much more reliable, though pessimistic.

Ray

This more closely reflects my experience.

I noticed a math error in my comments above, which I will correct with edit now.
 
On 9/7 I drove the same route from my home to Burney Falls State Park again at slightly higher speed with more (still not much) AC use. When I reached my driveway, at 87 miles, I still had (less than) one bar, so I drove until I got the "very low battery" warning and simultaneously lost the last bar, at 91.5 miles. I got home with 93.4 miles, and between 5,500 and 6,000 ft. of ascent and descent, at an average speed of about 40 mph (those last 6.4 miles were up and down a hill at low speed). Since the last 1.9 miles after the "very low battery” warning were at about 20 mph and required about 150 ft. net descent with regen, I was probably still very close to the VLBW point capacity, when I parked.

According to CW, on this drive I used 18.7 kWh to drive 91.1 miles at average energy economy of 4.9 m/kWh.

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...
 
edatoakrun,
Do you have a low serial number VIN (without the April 2011 "A/C" firmware upgrade)?

In Old-Bars, LBW occurs near the high side of the 2nd bar, and VLBW occurs near the botton side of the 1st Bar ... much like you are describing.

The Bars on Tony's chart only applies to New-Bars, where the LBW occurs near the bottom side of the FIRST bar, and the VLBW occurs down in the invisible "reserve", well AFTER all the bars are gone.

On both old and new-Bar cars, the LBW occurs at SOC raw = 50 (or 49), about 17.8% (or 17.5%) of 281.
 
garygid said:
edatoakrun,
Do you have a low serial number VIN (without the April 2011 "A/C" firmware upgrade)?

In Old-Bars, LBW occurs near the high side of the 2nd bar, and VLBW occurs near the botton side of the 1st Bar ... much like you are describing.

The Bars on Tony's chart only applies to New-Bars, where the LBW occurs near the bottom side of the FIRST bar, and the VLBW occurs down in the invisible "reserve", well AFTER all the bars are gone.

On both old and new-Bar cars, the LBW occurs at SOC raw = 50 (or 49), about 17.5% (of 281).

At what % does the VLBW occur?

My LEAF is # ...2184, delivered on 5/18, supposedly with the "AC" firmware update done.

BTW, the card that came in my glove box, "2011 Leaf OM kit w/o OM", is time stamped, auspiciously, "Mar 11, 2011 15:32"...
 
edatoakrun said:
As I posted earlier, Since I had the Carwings update done on 8/3, my Dash and Carwings miles/kWh numbers seem to match.

Even more interestingly, the daily Driving Records/electricity consumption now seem to accurately reflect the kWh delivered from my Modified L2, as best as I can calculate by recharge time.
Does the Carwings number energy use represent KWh from the wall or from the battery?
 
Stoaty said:
edatoakrun said:
As I posted earlier, Since I had the Carwings update done on 8/3, my Dash and Carwings miles/kWh numbers seem to match.

Even more interestingly, the daily Driving Records/electricity consumption now seem to accurately reflect the kWh delivered from my Modified L2, as best as I can calculate by recharge time.
Does the Carwings number energy use represent KWh from the wall or from the battery?

CW reports "electricity consumption" per day.

I don't see how it could be reporting from the "wall", since some of that electricity is used to heat up my (modified) stock EVSE, before the car can see it.

CW just posted yesterdays "miles driven" as 52.3, again 2.5% less than my odometer and Google maps, which agree on 53.6 miles.
 
Regarding the initial post, I haven't looked at Carwings in months, since it didn't seem connected to reality. So I probably wouldn't take the time to look again until I see others' reports that it has been fixed. Now I'm curious if it really was a firmware update that changed things, or a change to the website. The latter would imply that the car reports good numbers and the website had merely mishandled them.

edatoakrun said:
I have no idea what regen efficiency is. [...]
The less regen you use, the further you get.
Most regen calculations or observations I've seen come out to about 25%. I'd say, barring any technological breakthroughs, it's as good a number as any to start out with.
That second statement is too generalized and may mislead folks. It assumes you aren't substituting friction brakes in place of regen. Also, wind resistance is, in effect, friction braking, so whatever you are doing, if you're doing it at 70+ MPH, you are not getting the efficiency that you could.
 
It is my opinion that the energy consumption reported by Carwings is (or was):

1. something more like motor consumption, ignoring all charging, inverter, and extraction-from-battery losses,

2. Minus the full motor (re)generation, again ignoring the losses in storing and recovery of that energy, and possibly the inverter losses in, and out again.

Basically, I suspect, that something like this is done to make it look like you got 5.9 miles per kWh instead of the 4.2 that the car said you got, or the 3.9 that you actually got.
 
garygid said:
It is my opinion that the energy consumption reported by Carwings is (or was):

1. something more like motor consumption, ignoring all charging, inverter, and extraction-from-battery losses,

2. Minus the full motor (re)generation, again ignoring the losses in storing and recovery of that energy, and possibly the inverter losses in, and out again.

Basically, I suspect, that something like this is done to make it look like you got 5.9 miles per kWh instead of the 4.2 that the car said you got, or the 3.9 that you actually got.

When I looked at individual "day" CW reports, prior to the update, it never seemed to correlate well to any variable such as regen or AC use.

CW always just seemed to be too high in m/kWh, by a constant, somewhere between 20% and 25%.

Anyway, the reason I suggest CW is useful (now) is that it appears to me to be (likely) reporting accurate energy usage.

But so far, no one else has said they're seeing what I am.
 
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