Collecting data:Off-the-wall power for turtle to 100% charge

[edatoakrun]

...The dash was only predicting 15.0 hours for a full recharge using L1, which seemed very low to me, so I decided to perform a test. Ambient temperature was about 35F at the end of the charge. Here are the numbers:

Recharging from VLBW to 100%
Wall energy, L1, just before VLBW - 100%: 24.74 kWh
Time, L1, just before VLBW - 100%: 16.0 hours

Odometer reading for this charge: 9038 miles

Shouldn't the 16 hour charge at 12 amp and 120 volt be ~ 23 kWh maximum?

for comparison:

Following 97.4 mile range test on 2/16/13, starting Odometer ~15,450 miles, where I got CW/nav screen report of of 15.8 kWh use from “100” to ~the VLBW, dash indicated “15 hours” recharge time to “80%”. test began with 4 temp bars, and went to 5 ~18 miles into the test, where it stayed to the end.

Recharged overnight (~35 f low temp) on L1 and monitored with kill-a-watt, 120.00 volts, 17.52 kWh and 12 h 25 m to (nine bars) “80%”.

Finished charge from “80%“ to "100%" 3 h 10 m (total charge time 15 h 35 min) 22.01 kWh total, showing 4 temp bars and at ~ 45 f ambient .

So (if I got the math right) I believe that looks like ~72% charge efficiency wall-to-motor (?) (using the "correct” (IMO) CW kWh and 6.2 m/kWh from nav screen) and ~74 % using the 6.0 dash m/kWh report.

Do those percentages sound about right, or a bit low, as my range test results, IMO, seem to indicate?

 

[RegGuheert]

Shouldn't the 16 hour charge at 12 amp and 120 volt be ~ 23 kWh maximum?

Yeah, you would think that wouldn't you? But I measured 1560W during pretty much the entire charge time. And that is with the voltage drooped to 115V. I hope my meter is not off by THAT much!

for comparison:

Following 97.4 mile range test on 2/16/13, starting Odometer ~15,450 miles, where I got CW/nav screen report of of 15.8 kWh use from “100” to ~the VLBW, dash indicated “15 hours” recharge time to “80%”. test began with 4 temp bars, and went to 5 ~18 miles into the test, where it stayed to the end.

Did your range come from the odometer or Carwings?

Recharged overnight (~35 f low temp) on L1 and monitored with kill-a-watt, 120.00 volts, 17.52 kWh and 12 h 25 m to (nine bars) “80%”.

Finished charge from “80%“ to "100%" 3 h 10 m (total charge time 15 h 35 min) 22.01 kWh total, showing 4 temp bars and at ~ 45 f ambient .

Your recharge took about 89% as much energy as mine, assuming our meters are accurate (which is likely not the case). This even though it was colder here at the end of the charge.

So (if I got the math right) I believe that looks like ~72% charge efficiency wall-to-motor (?) (using the "correct” (IMO) CW kWh and 6.2 m/kWh from nav screen) and ~74 % using the 6.0 dash m/kWh report.

Do those percentages sound about right, or a bit low, as my range test results, IMO, seem to indicate?

I have nothing to compare on the driving side since yesterday's trip was a 47-mile trip starting from 8 bars and ending with one.

For reference, NREL got the following efficiency numbers using L2: 25.414kWh from wall and 21.381 from the battery, for an efficiency of 84%. If I "L2-ise" your results by subtracting 10.2 hours * 300 watts =3.06 kWh from your charge, I get (97.4mi/6.2)/18.95 kWh = 82.9% (CW) or (97.4mi/6.0)/18.95 kWh = 85.6%. Those look to be pretty much in the ballpark to me, particularly the Carwings one.

 

[edatoakrun]

="RegGuheert"

Shouldn't the 16 hour charge at 12 amp and 120 volt be ~ 23 kWh maximum?

Yeah, you would think that wouldn't you? But I measured 1560W during pretty much the entire charge time. And that is with the voltage drooped to 115V. I hope my meter is not off by THAT much...

I don't get it.

Doesn't 1560W indicate, either your LEAF's charger is operating incorrectly in L1 mode, or (much more likely, especially in light of your charge time) your kill-a-watt is way off?

 

[RegGuheert]

Doesn't 1560W indicate, either your LEAF's charger is operating incorrectly in L1 mode, or (much more likely, especially in light of your charge time) your kill-a-watt is way off?

Why do you think my charge time (energy) implies an error in my measurement equipment?

There is certainly some measurement error, but there is also certainly error in the current limit controlled by the EVSE (IIRC). Phil also reported the charger drawing more than 12A, measured using calibrated true RMS equipment: 1436W/112.6V=12.75A.

 

[DaveinOlyWA]

Kill a watts have a fairly low tolerance error. Hard to beleive it would be that far off but easy to beleive the LEAF is that far off. Lot of reports here of shorter than predicted charge times and i saw charging better than 1500 watts on mine frequently

 

[edatoakrun]

Doesn't 1560W indicate, either your LEAF's charger is operating incorrectly in L1 mode, or (much more likely, especially in light of your charge time) your kill-a-watt is way off?

Why do you think my charge time (energy) implies an error in my measurement equipment?

There is certainly some measurement error, but there is also certainly error in the current limit controlled by the EVSE (IIRC). Phil also reported the charger drawing more than 12A, measured using calibrated true RMS equipment: 1436W/112.6V=12.75A.

While the amps vary with voltage, IMO, Phil's results show that L1 is constant for kW output at a lower rate than your results seem to show.

...Charging using the original 120v EVSE: (112.5v recorded at EVSE input)

Standby Power: 4.9w
Charge Power in: 1.451kW
Power to Leaf Battery: 1.125kW
Total Power Lost: 326w
Total Charge Efficiency: 77.5%

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%...

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

Your results also show your LEAF to be an outlier on the high side in terms of available battery capacity.

I believe my range test results are fairly typical for a LEAF with the it's use history.

Do you believe your LEAF range exceeds the norm by the ~8%-10% (IMO) that your kill-a-watt charge capacity results would seem to dictate?

https://docs.google.com/spreadsheet/ccc?key=0An7gtcYL2Oy0dG9vbzBiMW8tc1c2UzFKM3RiUG5ORHc#gid=0" onclick="window.open(this.href);return false;

I replied to this point of your varied inquiries on Saturday, hoping it could be resolved before replying to your others, which I will now do in separate posts, to avoid confusion between the several related issues you raised.

 

[edatoakrun]

="RegGuheert"

Edatoakrun:
...Following 97.4 mile range test on 2/16/13, starting Odometer ~15,450 miles, where I got CW/nav screen report of of 15.8 kWh use from “100” to ~the VLBW, dash indicated “15 hours” recharge time to “80%”. test began with 4 temp bars, and went to 5 ~18 miles into the test, where it stayed to the end...

Did your range come from the odometer or Carwings?...

Odometer. I would never report CW miles without noting the constant error rate I mentioned on another thread Saturday:

...All 2011-2 LEAFs, AFAIK, have reported the same Carwings odometer and Dash m/kWh error of consistently under-reporting by ~2.5%.

So if your CW miles driven is ~2.5% lower than your dash odometer miles, and your dash m/kWh is showing ~2.5% less than your nav screen m/kWh (0.1 m/kWh lower below ~6 m/kWh, and 0.2 m/kWh lower when you are getting over ~6 m/kWh) this is "normal" for 2011-2012 LEAFs...

http://www.mynissanleaf.com/viewtopic.php?f=27&t=11769" onclick="window.open(this.href);return false;

Do you not see the same constant error in both CW miles and dash m/kWh in your LEAF?

 

[edatoakrun]

="RegGuheert"

Edatoakrun

...So (if I got the math right) I believe that looks like ~72% charge efficiency wall-to-motor (?) (using the "correct” (IMO) CW kWh and 6.2 m/kWh from nav screen) and ~74 % using the 6.0 dash m/kWh report.

Do those percentages sound about right, or a bit low, as my range test results, IMO, seem to indicate?

I have nothing to compare on the driving side since yesterday's trip was a 47-mile trip starting from 8 bars and ending with one.

For reference, NREL got the following efficiency numbers using L2: 25.414kWh from wall and 21.381 from the battery, for an efficiency of 84%. If I "L2-ise" your results by subtracting 10.2 hours * 300 watts =3.06 kWh from your charge, I get (97.4mi/6.2)/18.95 kWh = 82.9% (CW) or (97.4mi/6.0)/18.95 kWh = 85.6%. Those look to be pretty much in the ballpark to me, particularly the Carwings one.

First, your calculations show, IMO, why you should use neither the erroneous (by ~2.5%) dash m/kWh report, or even the relatively accurate nav screen m/kWh for calculating the kWh charge (or for charge efficiency) and use the kWh use report from CW instead.

Putting aside for the moment your "L2-ise" operation, when you divide the 97.4 odometer miles by the 15.8 kWh use (rounded to the nearest 0.1 kWh) reported, you get 6.16... which the nav screen displays as 6.2 m/kWh.

If you recalculate dividing the odometer miles by using the rounded 6.2, the result is ~15.7 m/kWh. No reason to introduce further inaccuracy into the equation, IMO.

I am not asserting the CW kWh use report is correct. On the contrary, my objective in trying to isolate the charge efficiency error in my LEAF, is so that I can find the error in that CW kWh use report.

This points out why the dash m/kWh report should never be used to calculate battery capacity, as in my LEAF it reflects both the constant error in miles, and (IMO) the unknown error in the CW kWh use report.

 

[DaveinOlyWA]

must be the effect of cold weather but tried 3 times to charge at 120 volts to see power over 1440 watts but max so far has been 1383. it is about 40 º. might have to wait till Summer and try it again

 

[edatoakrun]

...
For reference, NREL got the following efficiency numbers using L2: 25.414kWh from wall and 21.381 from the battery, for an efficiency of 84%. If I "L2-ise" your results by subtracting 10.2 hours * 300 watts =3.06 kWh from your charge, I get (97.4mi/6.2)/18.95 kWh = 82.9% (CW) or (97.4mi/6.0)/18.95 kWh = 85.6%. Those look to be pretty much in the ballpark to me, particularly the Carwings one.

Rather than try to “L2-ise”, my L1 results, lets take a look at my 2/17 recharge session using Phil's L1 efficiency results to the battery, and other sources for the efficiency of the battery charge and discharge itself, to try to estimate “meter to Inverter" efficiency.

Please review my tentative conclusions below, and please comment if you find any (of what I expect are many) possible errors.

Following 97.4 mile range test ton 2/16/13, starting Odometer ~15,450 miles, where I got CW/nav screen report of of 15.8 kWh use from “100” to the VLBW, dash indicated “15 hours” recharge time to “80%”. test began with 4 temp bars, and went to 5 ~18 miles into the test, where it stayed to the end.

Recharged overnight (~35 f low temp) on L1 and monitored with kill-a-watt, ...17.52 kWh and 12 h 25 m to (nine bars) “80%”.

First, my results were 17.52 kWh/12.42h= 1.41 kw charge rate for the VLBW to “80%” charge, very close to the 1.436 Phil reported, and the difference might be explained by the fact that his results were from a charge session done at ~20 f higher temps.

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

I finished my charge from “80%“ to 100’% in 3 h 10 m (total charge time 15 h 35 min) and 22.01 kWh in total, showing 4 temp bars and at ~ 45 f ambient .

15.58h x 311w (Phil's L1 loss figure, =4.845 kWh loss while charging , so 22.01-4.85 = 17.15 kWh to the battery..

The AVTA LEAF Efficiency analysis:

http://www.transportation.anl.gov/D3/data/2012_nissan_leaf/AVTALeaftestinganalysis_Major%20summary101212.pdf" onclick="window.open(this.href);return false;

Reports c to e L2 efficiency =17.957/18.529= .969.

Another source, NREL:

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/veh_sys_sim/vss030_lohsebusch_2012_o.pdf" onclick="window.open(this.href);return false;

reports .97 for this c/e value

969 x 17.15kWh =16.62 kWh. 16.62 kW/22.01= ~75.5% efficiency. I believe there are a few factors I skipped in this analysis, but I think they mostly bias toward a higher result, and are small enough that hey could cause the efficiency to increase only slightly from that 75.5%, so I’ll leave them aside, for now.

In comparison, I got 15.8/22.01= ~72% efficiency, using the 15.8 CW kWh use, about~0.8 kWh (~5% ) less than the 16.62 in the analysis above.


So it looks to me like each nominal kW I used, as reported on this range test by CW, may actually have held ~1,050 WH.

And I actually probably used ~16.6 kWh to drive the 94.7 miles between “100%” and ~VLBW, rather than the CW reported 15.8, IF we assume the recharge was equal in kWh to the charge I used.

For reasons l will eventually get to on my range test thread, a percentage error of this magnitude looks very plausible to me.

 

[RegGuheert]

Your results also show your LEAF to be an outlier on the high side in terms of available battery capacity.

No, they don't. As I calculated, my results are equivalent to 21.5 kWh from the wall with L2 from VLBW to full. If I multiply by 1/0.911 to get dead to full, I get 23.6 kWh. That is not an outlier.

I believe my range test results are fairly typical for a LEAF with the it's use history.

And I feel mine are also typical. If I use the NREL numbers as the reference, I calculate my remaining capacity percentage to be 23.6 kWh/25.414 kWh=92.8%. In other words, 7.2% degradation. Stoaty's model estimates 7.8% for our situation. That seems pretty much in line with what we are seeing.

Do you believe your LEAF range exceeds the norm by the ~8%-10% (IMO) that your kill-a-watt charge capacity results would seem to dictate?

I have no idea how TickTock came up with his L2-equivalent numbers. I have explained my L1-to-L2 conversion approach and given my calculations. I think they are correct.

BTW, I do not measure L1 results with a Kill-A-Watt. I use a Brand Electronics Model 20-1850 which should be capable of near-true-RMS measurements. I cannot speak to the accuracy of the meter other than to say that it measures line voltages within 1% of the Fluke 77 I have. Both are old, though, so who knows?

 

[TickTock]

Here is where I got the L1 and L2 efficiency numbers (L2 from NREL study and L1 from Phil's measurement).

 

[edatoakrun]

Very similar result below, are from a subsequent range test and monitored rechrge using a kill-a-watt.

Following 97.3 mile range test on 3/1/13, starting Odometer ~15,763 miles, where I got CW/nav screen report of of 15.6 kWh use from “100%” to the VLBW, dash indicated “15 hours” recharge time to “80%”. test began with 4 temp bars, and went to 5 ~18 miles into the test, where it stayed to the end.

Recharged overnight (~40 f low temp) on L1 and monitored with kill-a-watt, 18.33 kWh in 13 hours of charging, and showing 10 bars of capacity (but not to “80”, I had forgotten to set the 80% timer, so I stopped the charge manually, DOH! moment #1)

So I got the same 1.41 kW charge rate as I got from the 2/16 after-test recharge I posted previously on this thread.

I resumed L1 charging ~51 hours later in ~50 degrees temperature, and battery took three hours and two minutes and accepted another 4.31 kWh for 22.62 kWh total. BTW, during the two day it was parked I realized I needed to check the voltage while charging (DOH! moment #2), and observed voltages varying from 111.8 to 114.4 ,during the top off to “100%”.

The dash showed 4 temp bars and 50 f during the entire 3 hours, while ambient temps during the final change increased from ~ 50 to ~60 degrees at ~ 3 feet above ground level, but as measured at just above the carport slab ( and ~6 inches below the battery) stayed at a near- constant ~50F.

When I drove after this charge, I got the dash battery temperature gauge to cross from 4 to 5 bars at ~16 miles, about when I lost the 11th charge bar.

But since this was on a different route, after ~1500 ft. of net descent and ~2000 ft. in total descent, with minimal regen, as opposed to the 18 mile point of my 3/1 test where I got the fifth temp bar ~when I lost my 8th charge bar, with ~ 1,000 ft. of net ascent and ~2000 ft. in total, on a route where I got much more much more regen, I’d expect the 0.62 higher recharge capacity could be accounted for by the slightly warmer battery during this charge session, as well as the standby energy consumption (didn't Phil post that data?) during the much longer time parked and off, and the ~4 additional start/stops I made during the this 3/1-3/4 charge session to watch the dash temp info. (I was really hoping to see when the temp bars hit 5, for a more accurate battery temp estimate).

 

[edatoakrun]

Here is where I got the L1 and L2 efficiency numbers (L2 from NREL study and L1 from Phil's measurement).

I'm not sure what you mean.

Those are the same sources I referenced.

 

[RegGuheert]

Here is where I got the L1 and L2 efficiency numbers (L2 from NREL study and L1 from Phil's measurement).

Thanks!

Please note that Phil's L2 power efficiency numbers (90.1%) do not match NREL's energy efficiency numbers (86.7%). This is likely not due to an error on the part of either of the measurements but rather is due to the fact that power efficiency will change as the battery charges.

As such, using Phil's L1 power efficiency may not be an accurate number for L1 energy efficiency calculations. Unfortunately, we simply do not know what the best numbers to use are since we do not have ANY L1 energy efficiency measurements.

 

[edatoakrun]

="RegGuheert"]

Your results also show your LEAF to be an outlier on the high side in terms of available battery capacity.

No, they don't. As I calculated, my results are equivalent to 21.5 kWh from the wall with L2 from VLBW to full. If I multiply by 1/0.911 to get dead to full, I get 23.6 kWh. That is not an outlier...

I was referring to your first charge report where it is reported your capacity was 4.55% above "new" ,even though you LEAF was far from new then. I don't fully understand TickTock's methodology either, but am hoping he will calculate his results for my two charge reports I've posted here, for comparative purposes.

=RegGuheert...Stoaty's model estimates 7.8% for our situation. That seems pretty much in line with what we are seeing...

Are you correcting that for the temporary capacity reduction due to the low battery temperature during your recent charge session you reported?

=RegGuheert...I do not measure L1 results with a Kill-A-Watt. I use a Brand Electronics Model 20-1850 which should be capable of near-true-RMS measurements. I cannot speak to the accuracy of the meter other than to say that it measures line voltages within 1% of the Fluke 77 I have. Both are old, though, so who knows?

Thanks for the correction. You are listed as using a k-a-w in all your tests.

https://docs.google.com/spreadsheet/ccc?key=0An7gtcYL2Oy0dG9vbzBiMW8tc1c2UzFKM3RiUG5ORHc#gid=0" onclick="window.open(this.href);return false;

 

[RegGuheert]

Are you correcting that for the temporary capacity reduction due to the low battery temperature during your recent charge session you reported?

No, partly because I don't accept the temperature slope for battery capacity of 1% per 4F used around here. From what I have read, that result was obtained by using a single slope between 70F and 0F. As I have posted in other threads, there should be two different slopes with a breakpoint at around 30F.

Note that my previous recharge from VLBW to full at 70F required only 4.5% more energy than the recent recharge from slightly ABOVE VLBW to full at 35F. And this is a fully apples-to-apples comparison except the battery may be slightly more degraded in the recent test. My conclusion is that the slope of battery capacity between 70F and 30F should not be steeper than 1% per 8F. Then I believe there should be a steeper slope below that point.

So, yeah, I may be coming out about 4% high. My meter could certainly be off by that much.

 

[RegGuheert]

Rather than try to “L2-ise”, my L1 results, lets take a look at my 2/17 recharge session using Phil's L1 efficiency results to the battery, and other sources for the efficiency of the battery charge and discharge itself, to try to estimate “meter to Inverter" efficiency.

This is where I have an issue with your calculations. Using Phil's L1 power efficiency as the value for energy efficiency for a full recharge from VLBW to full is very suspect in my opinion. Note that Phil's L2 power efficiency comes out at 90.9% versus NREL's recharge energy efficiency of 86.7%. If the L1 numbers are that different, then this could create a large error in your results.

 

[edatoakrun]

...I don't accept the temperature slope for battery capacity of 1% per 4F used around here....

My conclusion is that the slope of battery capacity between 70F and 30F should not be steeper than 1% per 8F. Then I believe there should be a steeper slope below that point...

Well, we agree on something!

On 11/8(11) I attempted to replicate the route and conditions of an earlier trip, which I had kept careful notes of, to try to see what sort of range reduction is caused by reduced m/kWh due to lower temperatures, and what proportion of this reduction is due to reduced battery capacity....

I believe that I got about 5% reduction in battery capacity...(from) this approximately 40 degree decrease in temp (from ~75 to ~35 F) when charging...

http://www.mynissanleaf.com/viewtopic.php?f=31&t=6701&start=60" onclick="window.open(this.href);return false;

The only correction I'd make since I posted that ~17 months back, is that additional uncertainty caused by the uncertainty introduced by what I believe I've seen in kWh use report inaccuracy, would make me restate that ~5% (~1% per 8F) as more like between ~4% and ~6%.

I just have no confidence that the Wh content per reported kWh used was constant over the ~2 months between the two range test I used to calculate that ~1% per 8F.

 

[edatoakrun]

Rather than try to “L2-ise”, my L1 results, lets take a look at my 2/17 recharge session using Phil's L1 efficiency results to the battery, and other sources for the efficiency of the battery charge and discharge itself, to try to estimate “meter to Inverter" efficiency.

This is where I have an issue with your calculations. Using Phil's L1 power efficiency as the value for energy efficiency for a full recharge from VLBW to full is very suspect in my opinion. Note that Phil's L2 power efficiency comes out at 90.9% versus NREL's recharge energy efficiency of 86.7%. If the L1 numbers are that different, then this could create a large error in your results.

Couldn't much (but I don't see how it could be all) of that discrepancy be explained (as IIRC, Phil has stated) by his efficiency results being only for a single point in time and when his battery was at single percentage of charge capacity, and prior to the charge taper at the end of the L2, (when the slower charge rate reduces the efficiency significantly) while NREL is the average efficiency over the entire charge?

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....

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