12% capacity loss in 9 months is "normal"

[TonyWilliams]

Or, to find your LEAF battery pack's available kWh capacity to a given level of discharge, such as LBW, VLBW, or turtle:

You can just forget about the uncertainties inherent in the gid Calculation, and all the uncertainties and errors in the range chart, as illustrated in the several voluminous posts above, and simply look at Carwings calculated kWh use for the trip(s) taken.

You probably will get a much more accurate calculation, of kWh use.

Of Course, this requires great exertion that many LEAF drivers seem unable to undertake.

You have to "accept" Carwings, and actually look at the results...

Interesting. Gids are bad (reported by the car) but CarWings (reported by the car) is the sh*t.

None of my post concerning a range data run included a range chart (bad, obviously), so that can be excluded from your soliloquy.

So, to sum up my thoughts, this is the "one trick pony" that seems to solve all issues. I prefer to rely on methodical, proven performance.

Edit: I added CarWings as an optional data point.

 

[edatoakrun]

"edatoakrun"
Or, to find your LEAF battery pack's available kWh capacity to a given level of discharge, such as LBW, VLBW, or turtle:

You can just forget about the uncertainties inherent in the gid Calculation, and all the uncertainties and errors in the range chart, as illustrated in the several voluminous posts above, and simply look at Carwings calculated kWh use for the trip(s) taken.

You probably will get a much more accurate calculation, of kWh use.

Of Course, this requires great exertion that many LEAF drivers seem unable to undertake.

You have to "accept" Carwings, and actually look at the results...

"TonyWilliams"
Interesting. Gids are bad (reported by the car) but CarWings (reported by the car) is the sh*t...

CW appears to use the accurate kWh use value, which you are approximating by the using the method you have proposed below:

"TonyWilliams"
Here we go..... I knew when 80 was announced as a Gid, this comment would come up over and over. Yes, Nissan says 80, HOWEVER if you use the equipment provided (the dash instruments), it will equal about 75.

When we all have LEAFscans, we will be able to see actual battery capacities, etc. We don't have that yet: 281 Gids times 75 watthours equals 21kWh. NOTE: with LEAFscan, we will observe 80, and therefore measure a higher 22.5kWh (281*80)...

"TonyWilliams"
...I prefer to rely on methodical, proven performance.

And you might actually have seen that, in your many runs to turtle or dead, if you had been watching CW, rather than the relatively unreliable performance, you seem to have from the use of your "system".

And you might now have a much better idea of when LBW, VLBW, and turtle, are to be expected, in future trips.

But I might be wrong.

Just because all my observations, since last August's CW update, and all the other observations I've read on this site, posted by other LEAF drivers, with the same correction update, lead me to believe CW is probably now reliable, does not make it so.

You (and the other CW refuseniks) could easily test CW reliability, in your own LEAFs, by comparing CW against other kWh use estimation methods.

Just too difficult for you to accept, I guess.

 

[Weatherman]

I've looked at the CW data closely, for my car, and the number of miles registered on trips seems about 2.5% too low. For example, my commute is 39 miles (which I've confirmed by several other methods over the past ten years) and CW shows 38.

For the last range test I did, CW indicated I used 16.5 kWh. Given it took 5 hours and 20 minutes to recharge to 100%, 16.5 kWh seems a bit on the low side. FPL recorded that I used nearly 20 kWh to recharge my car's battery. Yes, I know that there's a considerable amount of overhead on an L2 charge, but 82.7% efficiency? I'll bet it was closer to 87%, which would give about 17.3 kWh deposited into the battery. So, CW measures about 5% too low on the kWh used.

By the way... I'm not too concerned about my car, anymore. Certainly not enough to re-run any tests or take it to the dealer. My best guess is that my car's usable battery capacity is somewhere between 20 and 21 kWh, which seems to be the consensus for what should be expected from a relatively new battery.

 

[TonyWilliams]

I've looked at the CW data closely, for my car, and the number of miles registered on trips seems about 2.5% too low.... So, CW measures about 5% too low on the kWh used.

Thanks for your dataoints concerning CarWings.

 

[edatoakrun]

I've looked at the CW data closely, for my car, and the number of miles registered on trips seems about 2.5% too low...

You would seem to be seeing the same discrepancy I first saw last September, as quoted below.

I believe this may be due simply to variable tire circumference, causing the LEAFs odometer, on cars with new stock tires, to be more accurate than the circumference value used by CW.

I also suspect the m/kWh figures reported by CW are likely under-reported by the same percentage.

This would be a useful question, for someone with a gid meter, to pursue.

edatoakrun:

...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...

http://www.mynissanleaf.com/viewtopic.php?f=31&t=5423&hilit=carwings&start=10" onclick="window.open(this.href);return false;

 

[EVDRIVER]

Carwings reads static SOC about 5% higher then actual.

 

[edatoakrun]

Carwings reads static SOC about 5% higher then actual.

How is is it that CW "reads static SOC"?

I only see CW reports of kWh used.

The largest part of the difference between these and the gid count calculations, presumably, is the energy inefficiency of the discharge process, resulting in battery heating.

 

[TonyWilliams]

Carwings reads static SOC about 5% higher then actual.

How is is it that CW "reads static SOC"?

I only see CW reports of kWh used.

The largest part of the difference between these and the gid count, presumably, is the energy inefficiency of the discharge process, resulting in battery heating.

When I get my LEAFscan, I fully intend to run baseline tests (precisely what I outlined several posts up that you poo poo) with speed corrected by GPS and time over known distances, and we can log all the data alongside Gids, CW, etc. Everything except the GoM.

 

[EVDRIVER]

Carwings reads static SOC about 5% higher then actual.

How is is it that CW "reads static SOC"?

I only see CW reports of kWh used.

The largest part of the difference between these and the gid count calculations, presumably, is the energy inefficiency of the discharge process, resulting in battery heating.

Carwings gives a percent charged figure, it is over the actual SOC by about 5%.

 

[edatoakrun]

Carwings reads static SOC about 5% higher then actual.

How is is it that CW "reads static SOC"?

I only see CW reports of kWh used.

The largest part of the difference between these and the gid count calculations, presumably, is the energy inefficiency of the discharge process, resulting in battery heating.

Carwings gives a percent charged figure, it is over the actual SOC by about 5%.

You are talking about the percentages shown on the owner's site, not anything at the CW site, right?

So, you are saying that while charging, the owner's site will show my car fully charged at 12 bars 100%, when, the gid count is still about 5% below the maximum?

If I unplug at close to full charge, when there is a "x minutes to fully charged" report at the owner's site, and the car's bar display is at 12, I will get a "charge completed" email.

 

[edatoakrun]

...
For the last range test I did, CW indicated I used 16.5 kWh. Given it took 5 hours and 20 minutes to recharge to 100%, 16.5 kWh seems a bit on the low side. FPL recorded that I used nearly 20 kWh to recharge my car's battery. Yes, I know that there's a considerable amount of overhead on an L2 charge, but 82.7% efficiency? I'll bet it was closer to 87%, which would give about 17.3 kWh deposited into the battery. So, CW measures about 5% too low on the kWh used...

IIRC, 82%-83% efficiency is the lower end range, reported, using L2.

The lower efficiency of the final "top-off", at L2 would be expected to lower the total charge average, depending on exactly how depleted your battery was at the beginning of your charge.

But somewhere closer to 87%, may actually be correct. Remember, CW is probably reporting the kWh coming out of your battery, not the higher number of kWh coming from the wall, as reduced by charging inefficiency.

Inefficiency in discharge (resulting in battery heating), may account for most of the total difference.

So you may also just seeing about the same discharge efficiency the gid counters are, when assigning gid values of 75 and 80 Wh.

 

[ztanos]

I took a test drive last week and the dealer actually told me that Nissan has come out with numbers for the battery. Now I took this with a grain of salt, and you probably should, also. He said "After 20 years, the battery should still be at 50%."

 

[garygid]

GIDs might be 80 Wh into the battery, but you do not recover
the full 80 FROM the battery.

Since we drive with the recovered energy, not what was put in,
the "usable" 75 Wh per GID accounts for that loss.

 

[Herm]

I took a test drive last week and the dealer actually told me that Nissan has come out with numbers for the battery. Now I took this with a grain of salt, and you probably should, also. He said "After 20 years, the battery should still be at 50%."

Could be, assuming a period of 7 years to 20% degradation.. start at 100 miles x 0.80 x 0.80 x 0.80 = 51 miles and 21 years.. this assumes you dont start cycling your battery 100% once it starts to drop capacity, that will speed up degradation, also assumes you can live with the lower range. Also ignoring calendar aging but Nissan may have designed to counter that problem.

We should know more about battery life this year, we have some members that will pass 30k miles.

 

[Herm]

GIDs might be 80 Wh into the battery, but you do not recover
the full 80 FROM the battery.
Since we drive with the recovered energy, not what was put in,
the "usable" 75 Wh per GID accounts for that loss.

Supposedly GIDs are WHAT IS STORED in the battery, it took a bit more than that to fill those batteries but we dont care about that.. extracting those kWh out of the battery wont be 100 percent efficient, especially if you drive aggressively.. but 75 sounds like a reasonable number with motor/inverter, tires and gearing losses. The battery itself will be close to 100% efficient while discharging, otherwise it would get very hot.

 

[edatoakrun]

GIDs might be 80 Wh into the battery, but you do not recover
the full 80 FROM the battery.
Since we drive with the recovered energy, not what was put in,
the "usable" 75 Wh per GID accounts for that loss.

Supposedly GIDs are WHAT IS STORED in the battery, it took a bit more than that to fill those batteries but we dont care about that.. extracting those kWh out of the battery wont be 100 percent efficient, especially if you drive aggressively.. but 75 sounds like a reasonable number with motor/inverter, tires and gearing losses. The battery itself will be close to 100% efficient while discharging, otherwise it would get very hot.

I doubt it.

Just by watching the battery temperature bars while driving, I'd expect the discharge efficiency will be found to be somewhere in the mid 90's percent, once it is accurately calculated. Both the 80/75 gid count and Carwings available battery capacity reports, as compared to Phil's calculations of total battery capacity, point to this eventual conclusion.

95% discharge efficiency would mean about 1 kWh was released as heat over a full LEAF battery pack discharge cycle.

The battery does not get "very hot", since that's not very much heat, given the thermal mass of a 600 lb battery pack, which is constantly being passively cooled, while you drive.

 

[palmermd]

Just by watching the battery temperature bars while driving, I'd expect the discharge efficiency will be found to be somewhere in the mid 90's percent...

Your car must have a much better set of bars than mine. I agree that 90% is probably close, but not based on any instrumentation in the car. It is based on knowledge of other batteries. It does not necessarily translate, but it is a good guess. In order to know for sure, you'll need to install some better instrumentation than Nissan included with the car.

 

[edatoakrun]

Just by watching the battery temperature bars while driving, I'd expect the discharge efficiency will be found to be somewhere in the mid 90's percent...

Your car must have a much better set of bars than mine.

Actually, this time of year, when I can watch for when it goes from 4 to 5 bars as I drive (and only once so far this Spring, to 6 bars) it gives some useful information, IMO.

 

[surfingslovak]

Supposedly GIDs are WHAT IS STORED in the battery, it took a bit more than that to fill those batteries but we dont care about that.. extracting those kWh out of the battery wont be 100 percent efficient, especially if you drive aggressively.. but 75 sounds like a reasonable number with motor/inverter, tires and gearing losses. The battery itself will be close to 100% efficient while discharging, otherwise it would get very hot.

AFAIK Gids are derived from a Coulomb count of what went into the battery, and they don't reflect the amount of energy the battery is physically holding perfectly accurately. It can only be an estimate, a close guess, but still an estimate.

 

[garygid]

Each of the "center" Battery Temp Bars cover 24 ºF,
so seeing it change from 5 bars to 6 (or 4 to 5 Bars)
could be a 1ºF change, or a 47ºF change.

For me, that is NOT very helpful.

If only Ingineer would tell us where the Battery Pack
Temperature values are in the CAN data,
I could add that to the SOC/GID Meter.