edatoakrun
Posts: 5222
Joined: Thu Nov 11, 2010 9:33 am
Delivery Date: 15 May 2011
Leaf Number: 2184
Location: Shasta County, North California

Re: Use CW report from range test to determine battery capac

Sat Sep 01, 2012 8:07 am

drees wrote:
edatoakrun wrote: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.
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 wrote: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%”.
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.
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.
no condition is permanent

edatoakrun
Posts: 5222
Joined: Thu Nov 11, 2010 9:33 am
Delivery Date: 15 May 2011
Leaf Number: 2184
Location: Shasta County, North California

Re: Use CW report from range test to determine battery capac

Fri Sep 07, 2012 11:08 am

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

http://www.mynissanleaf.com/viewtopic.p ... 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.
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...
http://www.mynissanleaf.com/viewtopic.php?f=31&t=8583" onclick="window.open(this.href);return false;
no condition is permanent

thankyouOB
Posts: 3583
Joined: Mon Feb 21, 2011 11:14 am
Delivery Date: 30 Apr 2011
Leaf Number: 1442
Location: Coastal LA

Re: Use CW report from range test to determine battery capac

Fri Sep 07, 2012 11:13 am

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.
may reserve/delivery 4/30/11
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ECOtality/LADWP/ Blink 4/4/11
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Gardena Nissan, msrp -1k
red SL with etec L3
SOLAR POWERED since 2008

edatoakrun
Posts: 5222
Joined: Thu Nov 11, 2010 9:33 am
Delivery Date: 15 May 2011
Leaf Number: 2184
Location: Shasta County, North California

Re: Use CW report from range test to determine battery capac

Mon Sep 10, 2012 5:12 pm

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:

Image

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.

Image

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.

Image

Image

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.
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.
no condition is permanent

aleph5
Posts: 73
Joined: Sun Aug 15, 2010 4:08 pm
Delivery Date: 26 Jun 2015
Location: Knoxville, TN

Re: Use CW report from range test to determine battery capac

Sun Sep 23, 2012 7:03 am

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.

edatoakrun
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Joined: Thu Nov 11, 2010 9:33 am
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Leaf Number: 2184
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Re: Use CW report from range test to determine battery capac

Sun Sep 23, 2012 8:20 am

aleph5 wrote: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.
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.
no condition is permanent

aleph5
Posts: 73
Joined: Sun Aug 15, 2010 4:08 pm
Delivery Date: 26 Jun 2015
Location: Knoxville, TN

Re: Use CW report from range test to determine battery capac

Sun Sep 23, 2012 7:44 pm

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.

edatoakrun
Posts: 5222
Joined: Thu Nov 11, 2010 9:33 am
Delivery Date: 15 May 2011
Leaf Number: 2184
Location: Shasta County, North California

Re: Use CW report from range test to determine battery capac

Fri Aug 30, 2013 6:55 pm

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.p ... &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.
no condition is permanent

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