Use CW report from range test to determine battery capacity

Ever since TickTock fist suggested the topic of gid variability, the implications of his observations have been setting in.

TickTock

1 gid *mostly* equals 80Wh

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http://www.mynissanleaf.com/viewtopic.php?f=44&t=9689" onclick="window.open(this.href);return false;

If “gids” do reflect a variable amount of Wh, and they are the values used by the LEAF to calculate kWh use, then the capacity bar displays, dash and nav screen displays of m/kWh, as well as the Carwings calculations based on these same “gid” values, might be expected to be incorrect as well.

I now believe that this quite possibly could be be the case.

I have been noticing an unexplained increase in my dash, nav Screen, and Carwings m/kWh results for a few months now, not only on this test trip, but on other trips, and my long term m/kWh averages.

Before I questioned the accuracies both of the screens and of Carwings, I thought the likely explanations for increased efficiency results, were increased efficiency, in either the driver or vehicle.

I am skeptical of any significant increase in my own driving efficiency, other than that resulting from driving more slowly.

I considered the possibility of increasing vehicle efficiency, and I would not be surprised if drivetrain friction is reduced a bit due to “break-in” of the drivetrain.

But if either of these efficiency factors were improving, I would expect them both to be relatively minor, and self limiting.

This does not seem to be what I am seeing.

I think that my range tests may indicate that whatever method my LEAF uses to calculate kWh, is variable, and has been significantly understating the recent amounts of kWh use, and has probably increasingly inflated all my m/kWh reports, from the dash, nav screen, and CW.

And of course, this could reflect with Tick Tocks observations of variable “gid” Wh values. Gids with higher Wh content could lower the calculated kWh numbers, and raise all the m/kWh results.

Maybe this is what I am seeing, from yesterdays range test. I tried to replicate as accurately as possible, my earliest range test,of almost a year, and almost 10,000 miles ago, to test this hypothesis.

I chose a day with very close to the original temperature condition, and drove the exact same route over the first 87 miles of the trip, using the same mode (eco) and used my original trip logs to closely replicate the same elapsed times for each of the three (same distance) legs of the trip.

The results from 8/30/12 were:

97.3 miles to VLB, 98.9 miles in total, by the odometer.

CW: 96.5 (~2.5% under-report) total miles, at 5.7 m/kWh, 16.8 kWh used from 100% to about the same capacity level, slightly past VLBW.

Compare this test with my first test on 9/7/11:

91.5 miles to VLB, 93.4 in total, by the odometer

CW: 91.1 (~2.5% under-report) total miles, at 4.9 m/kWh, 18.7 kWh used from 100% to about the same capacity level, slightly past VLBW.

I do not believe that the slight increase in range over the last year reflects any increase in battery capacity. On the contrary, I expect that my total capacity ( though maybe not the amount of kWh that the BMS is allowing me to access) has declined by an undetermined amount, but it cannot be detected due to the “noise” of uncontrolled variables in a range test.

But I think the decrease of over 10% of reported kWh use, is simply too great to be consistent.

And for those who doubt CW accuracy or consistency, in calculating that total, I’d point out each of the replicated legs of this trip, and of half a dozen other trips I’ve monitored this month, match the m/kWh dash reports precisely.

Both are probably incorrect, BTW, but by about the same 2.5% odometer error rate. So if you can’t or won’t use CW, I think the nav screen m/kWh is probably using the correct “miles driven”, and will probably be reasonably accurate as long as you have factory tires with most of their tread.

Neither the dash or Nav screen results will tell you much though, IMO, unless you can pin down what they are using for a “kWh” value. and if you are using a gid count to calculate kWh, I’d suggest again, that you check to see whether TickTock’s findings of gid variability are correct.

I could write pages of details on these tests, and will answer any specific questions about my methodology.

However, I think that the real key to understanding what is going on, is to have multiple reports of range tests, comparing initial and “reduced capacity” batteries, rather than extrapolations based on m/kWh reports, gid counts, or GOM readings.

An alternate, and perhaps an even better way of calculating actual kWh use is by taking “from the wall” measurements. Though you will always have a variable in charge efficiency, you should be able to be able to get a pretty good estimate by either a meter or charge time.

I don’t have a meter, but I do do have my recharge time from 9/7/11 logged, at ~ 4 hours and 25 minutes to “80%”.

Unfortunately, I did not get a charge completed Email this AM (poor cell reception?) so I cant compare the two times. Next time I get to VLB, I will be sure to finish charging while I am awake, and watch for the results.

CW: 96.5 (~2.5% under-report) total miles, at 5.7 m/kWh, 16.8 kWh used from 100% to about the same capacity level, slightly past VLBW.

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5.7 m/kwh is a pretty good number. What was your average speed during this test ?

Looking at the data in this thread and as a newbie with no instruments available to collect data other than the info I get from the instrument panel on my Leaf, I am wondering if this would be a way to at least guesstimate my battery degredation.

On September 8, 2011 I made a 40 mile trip and repeated the same trip today. Both days were the same temp and I checked tire pressure before driving. Drove Eco mode the whole way. The only difference is that I have 10 bars on the capacity scale now. The charge state bars remaining in both cases after my 40 mile drive had just dropped to the next level and were esentially full bars. Charged to 100% both times.

Leaf dash on 9/8/11
5.8 miles/kwh 41.2 miles driven 6 bars remain 48 miles left on the GOM

Leaf dash on 8/31/12
6.6 miles/kwh 41.3 miles driven 5 bars remain 39 miles left on the GOM



This is my guess on how I can obtain a CRUDE estimate of capacity loss based on this info. Please provide any thoughts on this. Just to restate, I am not an engineer or even trying to be one. I am trying come up with a crude formula that us non-techies can use.


I want to use the data provided by the Leaf console to determine the total amount of kwh available to me in the battery pack on each day. I will use this number to determine percentage lost in the battery pack over the period of the last year.


2011 trip

41.2 miles driven divided by 6 bars depleted = 6.86 miles/bar
if I could continue that average for all 12 bars, I could roughly obtain a total of (6.86 miles/bar * 12 bars) 82.4 miles on this charge
82.4 miles divided by the Leaf's reported 5.8 miles/kwh average = 14.28kwh available to use on this charge


2012 trip

41.3 miles driven divided by 7 bars depleted = 5.9 miles/bar
if I could continue that average for all 12 bars, I could roughly obtain a total (5.9 miles/bar * 12 bars) 70.8 miles on this charge
70.8 miles divided by The Leaf's reported 6.6 miles/kwh average = 10.73kwh available to use on this charge

Now to compare the total available charge (capacity) from 2011 and 2012.

10.73kwh divided by 14.28kwh x 100 = 75%


Since I have lost 2 capacity bars up to this point, 75% capacity remaining would fall in line with the manual (with expectation that I will be losing my 3rd bar relatively soon). :evil:

Comments/thoughts please.

KJD said:

CW: 96.5 (~2.5% under-report) total miles, at 5.7 m/kWh, 16.8 kWh used from 100% to about the same capacity level, slightly past VLBW.

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5.7 m/kwh is a pretty good number. What was your average speed during this test ?

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Yes, it is a "pretty good number" Too good, IMO.

Please read my comment again. My main point is that the m/kWh from my dash, Nav screen, and CW, are (quite possibly) currently significantly inflated.

Both trips took about 145 minutes to the 87 mile point, excluding the time spent at the same two locations I parked, on both trips.

However, I don't think very useful to calculate an "average" speed on this route, since speeds vary from under 10 to over 50 mph, and there are several stop lights, and always other road conditions, requiring multiple additional full stops, of varying lengths of time.

On both trips, I "Averaged" about 45 mph for the ~45 miles of highway, and under 30 mph, for the ~42 miles of lower-speed roads, including ~8 miles of unpaved roads. After the ~87 mile round trip, it's all low speed, to get to VLBW point.

Take a look at the map and profiles on the first page of the thread, for more details.

spooka said:

Comments/thoughts please.

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Thanks for providing this data and analysis!

The problem with extrapolating from bars is that the charge bars appear to be nonlinear in weight AND there is a fixed offset of a certain amount of kWh below the bottom bar. As a reasult of the offset and nonlinearity you cannot perform an accurate extrapolation of the type you are doing. Also, the bars have about 2 kWh of ambiguity (thickness) to them. Generally, the best data we can get comes between full and one of LBW, VLBW or turtle.

Still, it is interesting to consider your data. Every bit we can collect helps us learn more. Thanks!

Here is some data contrary to that provided by Ed. When I am looking for 100% to LBW or VLBW data I generally head over to Dave's 100-mile thread.

N1ghtrider from the Miami area is the king of 100-mile runs, having done it about 14 times. drees has been kind enough to compile the data from his many runs. I have copied that table below:

drees said:

Code:

12/31/11 111.0 mi 5.9 mi/kWh LBW 102 mi  no VLBW                 18.8 kWh used
 1/05/12 103.1 mi 5.4 mi/kWh LBW 93.3 mi  VLBW?                   19.1 kWh used
 1/13/12 125.4 mi 6.1 mi/kWh LBW 103 mi   VLBW 114 mi             20.5 kWh used
 1/22/12 130.1 mi 6.4 mi/kWh LBW 105.8 mi VLBW 121 mi             20.4 kWh used
 2/17/12 126.1 mi 6.1 mi/kWh LBW 98.1 mi  VLBW 114.3 mi TTL 126.0 20.7 kWh used
 2/26/12 102.0 mi 5.8 mi/kWh LBW 92.3 mi  no VLBW                 17.6 kWh used
 3/03/12 105.1 mi 5.7 mi/kWh LBW ? GOM 6  no VLBW                 18.5 kWh used
 3/10/12 101.3 mi 5.8 mi/kWH LBW ? GOM 8  no VLBW                 17.5 kWh used
 3/24/12 106.3 mi 5.7 mi/kWH LBW 93.2     no VLBW                 18.7 kWh used
 3/29/12 106.2 mi 5.8 mi/kWh LBW 91.3     VLBW 105.7              18.3 kWh used
 4/06/12 111.3 mi 5.8 mi/kWh LBW 91.8     VLBW 108.9              19.2 kWh used
 4/11/12 107.3 mi 6.0 mi/kWh LBW 96.0     no VLBW                 17.9 kWh used
 7/21/12 100.0 mi 5.8 mi/kWh LBW 84.4     no VLBW                 17.2 kWh used

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As you can see, N1ghtrider's efficiency has not gone up (or down) much over time, but the number of miles he drives from full to LBW has gone down.

This seems to be a contrarian case to Ed's recent run. Sigh.

Thoughts?

RegGuheert said:

Here is some data contrary to that provided by Ed. When I am looking for 100% to LBW or VLBW data I generally head over to Dave's 100-mile thread.

N1ghtrider from the Miami area is the king of 100-mile runs, having done it about 14 times. drees has been kind enough to compile the data from his many runs. I have copied that table below:

drees said:

Code:

12/31/11 111.0 mi 5.9 mi/kWh LBW 102 mi  no VLBW                 18.8 kWh used
 1/05/12 103.1 mi 5.4 mi/kWh LBW 93.3 mi  VLBW?                   19.1 kWh used
 1/13/12 125.4 mi 6.1 mi/kWh LBW 103 mi   VLBW 114 mi             20.5 kWh used
 1/22/12 130.1 mi 6.4 mi/kWh LBW 105.8 mi VLBW 121 mi             20.4 kWh used
 2/17/12 126.1 mi 6.1 mi/kWh LBW 98.1 mi  VLBW 114.3 mi TTL 126.0 20.7 kWh used
 2/26/12 102.0 mi 5.8 mi/kWh LBW 92.3 mi  no VLBW                 17.6 kWh used
 3/03/12 105.1 mi 5.7 mi/kWh LBW ? GOM 6  no VLBW                 18.5 kWh used
 3/10/12 101.3 mi 5.8 mi/kWH LBW ? GOM 8  no VLBW                 17.5 kWh used
 3/24/12 106.3 mi 5.7 mi/kWH LBW 93.2     no VLBW                 18.7 kWh used
 3/29/12 106.2 mi 5.8 mi/kWh LBW 91.3     VLBW 105.7              18.3 kWh used
 4/06/12 111.3 mi 5.8 mi/kWh LBW 91.8     VLBW 108.9              19.2 kWh used
 4/11/12 107.3 mi 6.0 mi/kWh LBW 96.0     no VLBW                 17.9 kWh used
 7/21/12 100.0 mi 5.8 mi/kWh LBW 84.4     no VLBW                 17.2 kWh used

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As you can see, N1ghtrider's efficiency has not gone up (or down) much over time, but the number of miles he drives from full to LBW has gone down.

This seems to be a contrarian case to Ed's recent run. Sigh.

Thoughts?

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Well, I think that you would expect to see results like this if his actual m/kwh were declining, due, (for example) to a seasonal increase in AC use which does, in my experience, does cause quite significant reductions in m/kwh during slow-speed trips.

Again, without eliminating variables like speed and climate control use, you really can't conclude anything from the range numbers, IMO.

Note our exchange from "I Beat EPA's 2.9 Miles/KWh : Report Your Monthly Mileage" thread:

N1ghtrider wrote:
Dec/2011 Platinum 574 5.2 miles/kWh
Jan/2012 Platinum 750 5.2 miles/kWh
Feb/2012 Platinum 848 5.2 miles/kWh
Mar/2012 Platinum 769 5.4 miles/kWh
Apr/2012 Platinum 1179 5.3 miles/kWh
May/2012 Gold 2716 4.8 miles/kWh
.

A/C usage and more interstate driving cut my m/kWh to below 5 for the first time.

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Edatoakrun

And I got over 5 m/kWh on my CW monthly report for the first time.
My 540 mile drive (on an L2 trip, the slower you drive, the faster you'll get there) to the San Francisco bay area and back, helped to raise the average.

I also had my greatest miles per single charge on 5/31, 105.8 miles (with about a mile each, of ascent and descent!) by my odometer, reported by CW as 103.2 miles at 5.9 m/kWh.

CW continues to under-report miles driven by about 2.5%, so I believe all the m/kWh numbers below should be adjusted upward by the same 2.5%, for greatest accuracy.

Month and Year Grade Rank Energy Economy
*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 Silver 3457 4.5 miles/kWh
Oct/2011 Silver 3640 4.2 miles/kWh
Nov/2011 Gold 2792 4.2 miles/kWh
Dec/2011 Gold 2827 4.0 miles/kWh
Jan/2012 Gold 2547 4.2 miles/kWh
Feb/2012 Gold 2354 4.4 miles/kWh
Mar/2012 Gold 2975 4.3 miles/kWh
Apr/2012 Gold 3018 4.5 miles/kWh
May/2012 Gold 1978 5.1 miles/kWh

*Prior to CW update. Disregard, as correction factor unknown...

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http://www.mynissanleaf.com/viewtopic.php?f=31&t=3207&start=220" onclick="window.open(this.href);return false;

edatoakrun said:

Again, without eliminating variables like speed and climate control use, you really can't conclude anything from the range numbers, IMO.

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This certainly is a tough nut to crack!

It seems clear that Nissan may have gone a little too cheap on instrumentation, possibly making an issue with battery life appear even more severe than it already is.

Here is a paper from Analog Devices about various techniques for making current measurements for energy metering. I believe Phil has said that the LEAF uses Hall Effect sensors. Perhaps Nissan needs to look into using the Rogowski Coil technique discussed in this paper.

RegGuheert said:

It seems clear that Nissan may have gone a little too cheap on instrumentation, possibly making an issue with battery life appear even more severe than it already is.

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We have been talking about this for years.. can you trust the Nissan instrumentation?.. you dont know until you measure the energy used directly at the battery cables.. everything else has always been circular reasoning chasing its tail. Everyone in Phoenix is now hoping the the battery capacity meter is faking it somehow and lost capacity will return in winter.

edatoakrun said:

An alternate, and perhaps an even better way of calculating actual kWh use is by taking “from the wall” measurements. Though you will always have a variable in charge efficiency, you should be able to be able to get a pretty good estimate by either a meter or charge time.

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IMO - an accurate wall-meter (need at least 0.1 kWh resolution) will easily confirm any drift in the dash's mi/kWh gauge.

edatoakrun said:

I don’t have a meter, but I do do have my recharge time from 9/7/11 logged, at ~ 4 hours and 45 minutes to “80%”.

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Unfortunately, unless you can confirm that wall-voltage was the same, this may not help.

Come to think of it - even measuring from the wall will have some inaccuracy depending on when the BMS decides to stop charging. We all know there can be some significant variation when charging to 100% - and it appears that there is some variation when charging to 80% as well.

At a minimum, you'd have to average the data over multiple runs to be sure.

drees said:

edatoakrun said:

An alternate, and perhaps an even better way of calculating actual kWh use is by taking “from the wall” measurements. Though you will always have a variable in charge efficiency, you should be able to be able to get a pretty good estimate by either a meter or charge time.

Click to expand...

IMO - an accurate wall-meter (need at least 0.1 kWh resolution) will easily confirm any drift in the dash's mi/kWh gauge.

edatoakrun said:

I don’t have a meter, but I do do have my recharge time from 9/7/11 logged, at ~ 4 hours and 45 minutes to “80%”.

Click to expand...

Unfortunately, unless you can confirm that wall-voltage was the same, this may not help.

Come to think of it - even measuring from the wall will have some inaccuracy depending on when the BMS decides to stop charging. We all know there can be some significant variation when charging to 100% - and it appears that there is some variation when charging to 80% as well.

At a minimum, you'd have to average the data over multiple runs to be sure.

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Yes, a meter would be superior. Though when I have checked my wall voltage, it has been fairly constant.

But even with a meter, there will probably be some variation in charging efficiency, especially with large battery temperature variations.

It probably would be much easier the control the recharge measurement variables, than the variables in a range test, IMO.

I think measuring the charge to "80%" might give more accurate results, If Phil's contention that this is more constant indication of total battery capacity than "100%" is correct.

If you have a meter, I'd suggest monitoring both timed charge levels.

Repost below from this AM on the Early Capacity Losses-Was(Lost a bar...down to 11) thread,

http://www.mynissanleaf.com/viewtopic.php?f=30&t=8802&start=3480" onclick="window.open(this.href);return false;

where it is already buried under several pages of...

I have records of 240v 16a charge time to "80%" that I need to look at.

Phil (see link) reports Total Charge Efficiency: 90.9%.

Does anyone have observations of charge efficiency up to an "80%" charge level that differ significantly from Phil's?

If so, what was your methodology?

IIRC, many have reported efficiency in the 85%-90% range, but these often included the lower efficiency charge, from the "80% to "100%" charge level.

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Ingineer

...These measurements are all using our Rev2 Upgraded EVSE:

120v: (112.6v recorded at EVSE input)
Standby Power: 1.7w
Charge Power in: 1.436kW
Power to Leaf Battery: 1.125kW
Total Power Lost: 311w
Total Charge Efficiency: 78.3%

240v: (239.8v recorded at EVSE input)
Standby Power: 3.4w
Charge Power in: 3.756kW
Power to Leaf Battery: 3.414kW
Total Power Lost: 342w
Total Charge Efficiency: 90.9%

All these measurements were with the Leaf pack at around 62 degrees F and ~65% SoC. Readings were allowed to stabilize before recording. The power to the Leaf battery was calculated by recording amperage at the cell interconnect level using a high-accuracy kelvin-connected current shunt, so the losses are a sum of all EVSE/Charger/Leaf systems. Charger input power was similarly recorded using lab-grade calibrated true RMS equipment, not a Kill-A-Watt.

These efficiency calculations do not take into account the coulombic loss in the Leaf's battery, and other Leaf systems during discharge, so this is only charging efficiency up to the battery pack itself but not including the pack, of which also has notable loss...

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http://www.mynissanleaf.com/viewtopic.php?f=31&t=8583" onclick="window.open(this.href);return false;

after 16 months and 16000 miles, I still make my 50-mile. roundtrip to work on 8 bars.
i live in a moderate climate area, near the SoCal coast.
The car has never experienced 100-degree temperatures.
Ninety degrees would be rare for our travel locus, as well.

Another range test, with recharge times compared, to give another view of the possible error in my LEAF's kWh use reports.

On 9/8/12 I made another "100%" to VLBW range test, repeating the same route I drove on 8/18/12, with close to 6,000 ft each of ascent and descent, with very slight variations in the final miles prior to VLBW, and got these results:

107.4 miles to VLBW, and 109.4 miles in total by odometer.

As reported by CW, 106.8 total miles (~2.5% under report), at 6.4 m/kWh, using 16.7 kWh.

Below is a screenshot of my CW "Electric Rate Simulation" including this trip:



As you can see, the results are quite similar to those I got on 8/18, for my "100%" capacity range test on this same route. Trips two and three on 8/18, BTW, correspond to the single trip two above.

8/18/12 capacity test results:

107.1 miles to VLBW, 108.0 miles in total, by the odometer.

CW reports 105.4 miles (~2.5% under-report) total miles, at 6.2 m/kWh, 17.0 kWh used from 100% to about the same capacity level, slightly past VLBW.

Below is a screenshot of my CW "Electric Rate Simulation" including this trip on 8/18/12.



Below are the trip profile and map route, for both tests, excluding the first and last ~0.3 miles and ~200 ft of descent and ascent on my driveway, that is not mapped by google.





Trips two and three above correspond to the drive to Burney Falls, the second vertical red line (point C on the map image), and the end of the profile, and two red line correspond to the return trip distances. The extra miles to initiate the VLBW, came from repeating ~ mile 1 to ~ mile 4 on the profile, several times.

The slightly lower kWh use, 16.7 as compared to 17.0 in the earlier trip could be the result of a 5-10 F cooler battery while charging prior to the 9/8 trip, the greater Regen opportunity past the VLBW (received at ~100 ft. higher altitude) or it could be due to the dash, nav screen, and CW m/kWh "drifting" even further from accuracy, over the last few weeks.

I did not meter my charge a year ago, but I did record the charge time, and also got an accurate 16 amp 240v recharge time on 9/8/12. It took 4 hours and 16 minutes to reach 80% (and another one hour and 11 minutes to reach “100%”) following this trip.

Assuming a 3.75 kWh/h draw from my 16 a modified Panasonic charger, and the 16.7 total capacity from VLBW to 100% charge, I believe that this would indicate a charging efficiency from ~VLBW to the “80%” level of ~96%, which is implausible, in light of all reports of charging efficiency by others.

This compares to a recharge time of ~4 hours 25 minutes to reach “80%” following my first range test, on 9/7/11, with a reported 18.7 kWh used from 100% to about the same capacity level, ~VLBW.

This would seem to indicate a charging efficiency of from ~VLBW to 80%” a year ago of ~89%. but remember, this was recorded after my LEAF had seen most a of a Summer of use, so my LEAF’s m/kWh use reports might have already started to “drift,”meaning this percentage may already have been somewhat inflated, and the kWh use similarly understated.

The ~ 9% (erroneous, I believe) increase in reported charge efficiency is fairly close to the ~11% (also erroneous, I believe) decrease in reported kWh use over my ~one-year-apart-near-identical-driving-condition range test a few weeks ago (from page two of this thread):

The results from 8/30/12 were:

97.3 miles to VLB, 98.9 miles in total, by the odometer.

CW: 96.5 (~2.5% under-report) total miles, at 5.7 m/kWh, 16.8 kWh used from 100% to about the same capacity level, slightly past VLBW.

Compare this test with my first test on 9/7/11:

91.5 miles to VLB, 93.4 in total, by the odometer

CW: 91.1 (~2.5% under-report) total miles, at 4.9 m/kWh, 18.7 kWh used from 100% to about the same capacity level, slightly past VLBW.

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It seems very likely to me that both are reflecting the same underlying error in my LEAF’s dash, nav screen and CW kWh use reports, as also effected by other variables which I cannot eliminate from my observations.

So, I believe that the recharge time results are compatible with my range tests, which indicate no observed reduction in range, both probably indicating that my LEAF has no observable loss of available battery capacity (though some amount has almost certainly occurred) over the last 12 months.

I think it is also very likely that many other LEAFs have similar errors in kWh reports, quite possibly due to the gid Wh variability TickTock observed last year, and that capacity bar displays might be similarly effected. Not having lost a bar (yet) or ever having monitored my gid count, I can’t observe those results.

I do think that anyone seeing capacity bar losses or dropping gid counts should try both range and charge capacity tests, to try to more accurately determine their LEAF’s actual loss of battery capacity.

Something's going on like this with my SOC reporting. The other day I drove 46.8 miles from 80% nominal charge to 1 bar (8% per owners portal). I recharged to 80% again, which was reported as 83% SOC on the portal. (I didn't get a specific percentage the day prior, but had started with 10 bars.) So that would be 72-75% of capacity to travel only 47 miles. It was almost ideal weather, nothing unusual. So that doesn't seem like very good range (extrapolates to ~64 miles). The recharge power consumption from wall per my Blink, though, reported 12.kWh (including losses), so that's 11.6kWh into battery @ 91% efficiency.

So while my consumption economy is OK and I can still get all bars of SOC, I used less than half the pack capacity while SOC reported using 3/4 of it. At the least it seems that either the gauging is off at the bottom or top of the SOC range. It's probably more complicated than that, but I don't think this is just capacity that's intentionally hidden.

aleph5 said:

Something's going on like this with my SOC reporting. The other day I drove 46.8 miles from 80% nominal charge to 1 bar (8% per owners portal). I recharged to 80% again, which was reported as 83% SOC on the portal. (I didn't get a specific percentage the day prior, but had started with 10 bars.) So that would be 72-75% of capacity to travel only 47 miles. It was almost ideal weather, nothing unusual. So that doesn't seem like very good range (extrapolates to ~64 miles). The recharge power consumption from wall per my Blink, though, reported 12.kWh (including losses), so that's 11.6kWh into battery @ 91% efficiency.

So while my consumption economy is OK and I can still get all bars of SOC, I used less than half the pack capacity while SOC reported using 3/4 of it. At the least it seems that either the gauging is off at the bottom or top of the SOC range. It's probably more complicated than that, but I don't think this is just capacity that's intentionally hidden.

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Well, I understand what you are saying, but I don't think you can see this with much precision in only the bar reports.

In fact, My bar capacity reports still seem to be relatively consistent and accurate, despite my m/kWh (I think) having become far less consistent and accurate.

I have records of both time and miles of when each of the capacity bars disappeared over a year's worth of trips now, and I found them to be surprisingly consistent. Each bar is not equal, but each of the individual bars seems to hold a consistent amount of kWh (or at least a consistent percentage of my total capacity, if I am wrong, and my battery capacity has actually declined by ~11% over the last year, as my LEAF reports).

How far did that 12 or 11.6 kWh (at your assumed efficiency) actually get you? 46.8 miles right?

How many m/kWh did your dash, nav screen or CW report say that your car used?

If those numbers are correct, both should have reported very close to 4 m/kWh, close to 46.8 divided by 11.6.

There are still some minor corrections (to account for CW and dash odometer variations, no more than ~2-3% required, as long as you have stock tires) to use any of these as I have mentioned previously.

Do you know what your car reported?

If you did not reset and record either the dash or nav screen m/kWh at the time, your CW report, if you both "accepted" all screen prompts and have got CW working correctly (requiring the necessary update, if you have an "older" LEAF) the CW report should have recorded the same dash m/kWh number, for both individual trips (as shown in the screen shot I posted in my previous comment above) and also total kWh use over each day, as it always has for me.

I didn't reset the car's economy, but CW says 4.5mi/kWh for the day while we calculated 4.03, as you state. (Sorry I can't easily post a screen shot right now.)

My CW should be up to date from last Spring's FW updates, if I understand that correctly. To be honest, I've never really used CW because it's slow and a little hard to access, and because there didn't seem to be much utility to it. The driving records is interesting, though. Never found that before.

I agree we're not seeing the same issue, but what I'm learning it that there are further mysteries relating to SOC and the accuracy of any (or all) of the means we have to assess it.

Another ~annual range/capacity report to add to the previous two on this thread.

For all three tests below, I chose days with very close to the identical temperatures, used the same tire pressure (~43 PSI @~70 F) and drove the same route over the first ~85.7 miles and last ~1.7 miles of the trip, using the same mode (eco). I used my trip logs from the first test to match times for the three (same distance) legs of the trip, and the less-precise time/miles for each charge bar loss. The variable additional miles after ~85.7 and before the VLBW were driven in short loops at ~25 mph and over 7m/kWh, which means the percentage increases in total miles, m/kWh, and drive time, are all somewhat over-represented by the numbers in the results. Since the VLBs all occurred on a slow descending grade ~200 ft. in elevation above the start and end of the route, the SOC variations between the VLBs and end of tests are negligible.

My first test on 9/7/11, ~3,300 miles on the odometer reported on page one of this thread:

91.5 miles to VLB, 93.4 in total, by the odometer, ~177 minutes drive time.

CarWings: 91.1 (~2.5% under-report) total miles, at 4.9 m/kWh, 18.7 kWh used from 100% to about the same capacity level, ~VLB.

The results from the second test on 8/30/12, ~12,100 miles on odometer, reported on page three of this thread:

97.3 miles to VLB, 98.9 miles in total, by the odometer, ~190 minutes drive time.

CarWings: 96.5 (~2.5% under-report) total miles, at 5.7 m/kWh, 16.8 kWh used from 100% to about the same capacity level, ~VLBW.

The results from the third test on 8/04/13, ~20,200 miles on odometer, were:

100.3 miles to VLB, 101.9 miles in total, by the odometer, ~193 minutes drive time.

CarWings: 99.4 (~2.5% under-report) total miles, at 6.3 (dash/CarWings) m/kWh, 15.8 kWh used from 100% to about the same capacity level, ~VLB.

These results are fairly representative of the other ~30 other range test I have done on this same route, as varying with different ambient/battery temperatures, different speeds, and different tire pressures, as well as what I've seen on my regular commute, and on longer trips.

I have experienced no noticeable loss of range.

Whatever loss of available battery capacity my leaf has experienced over the last two years has evidently been offset (and slightly exceeded by) efficiency gains, by both the driver and/or vehicle.

I probably did improve my efficiency in the year between the first and second test, and, IMO, the CarWings regen reports tend to support this.

Other driver efficiency factors that does not all show up in the regen numbers, are that I have learned that making large variations in speed to avoid regen is not efficient, and I may have also reduced the losses to friction braking by a bit, which are significant on this route, with ~6,000 ft. of total ascent, and the same descent.

But I doubt my own driving efficiency has improved significantly since the second test, over the last year.

Vehicle efficiency has improved, and of course the stock tires, now pretty near to replacement, are the prime suspects. But I don't discount the possibility that there have been other efficiency gains due to the other components of the drivetrain's breaking in and reducing frictional losses.

But I doubt both these factors add up to explain the very large increases in reported efficiency, from 4.9 to 6.3 in m/kWh, that I have seen.

So I am very skeptical of the App reported stats, 55.79 AHr and 84.21% at the start of my 8/4/13 test, and the very similar Dash/ CarWings and Nav screen report (15.8/18.7= ~84.5%) of capacity loss from ~VLBW to “100%. I think they are probably both reporting the same “pessimistic gauge” error (as Nissan has called it) an inability of the LBC to accurately monitor battery capacity over time.

I believe that it is more probable that My LEAF’s battery has lost a significantly lower percentage capacity over the last ~2 years, perhaps about the percentage that my recharge time results seem to indicate:

http://www.mynissanleaf.com/viewtopic.php?f=31&t=6876&start=210" onclick="window.open(this.href);return false;

That said, at least until I replace my tires and see what sort of efficiency loss results, and also continue to watch my range, and the App/capacity bar reports for some time longer, I don’t think I can say the App and”gauge” reports of loss of capacity are definitely incorrect.

At this point, I plan on keeping the car a long time, and I plan to continue to test and report the results.

I have also established a slower-speed test standard on the same route that I can use for year-round tests (which produced those ~110-113 mile summer range results I have posted on this thread and the the 100 mile thread) and my LEAF should be able to complete the basic ~87 mile route at that speed for many more years, even after my battery experiences much larger losses of available capacity than it has to date-whatever they are.

I am presently satisfied that, in my own real world use, and now with only 11 capacity bars (I lost the first on 8/22/13, during a 730 mile trip to the Bay Area) my LEAF still goes ~ the same distance as it did ~2 years ago, on a “100%” charge.