Calculating usable battery capacity using Carwings...

[RegGuheert]

I pretty much lost faith in the carwings range estimate during winter time when it would spit out numbers horribly inaccurate. I was regularly seeing 35-38 miles for a full charge on carwings....if that happend I wouldn't make it to work and back (55+ miles), yet I did, with an easy 3 bars left during cool temps (in the 50's). After a few rounds of seeing this in CW when I would pre-heat the car, I just stopped looking at it. The GOM is way more accurate than carwings is and if I had to choose, would shoose the GOM.

I hope I didn't imply that the Carwings range estimate was accurate. Rather I think I indicated that I quickly convinced myself that it was WAY off. Instead, I am proposing that the estimate it gives might be a good way to obtain an accurate back door report of available battery capacity.

 

[RegGuheert]

Our generally accepted number is 73% at 120v, but you've got a drop in voltage? Not sure what is normal there.

Thanks! 73% works out much better for my charging calcs for last night than the 80% guesstimate I used.

 

[DaveEV]

- I drove 52.9 miles yesterday.
- Yesterday's efficiency was 5.8 miles/kWh.

If you reset your mi/kWh meter for yesterday's drive and it reported 4.6 mi/kWh, then you don't have all the latest updates.

Carwings will match the dash reading +- 0.1 mi/kWh with the latest updates most of the time.

 

[RegGuheert]

If you reset your mi/kWh meter for yesterday's drive and it reported 4.6 mi/kWh, then you don't have all the latest updates.

Thanks! No, I didn't reset it. I'm still in the habit of resetting it when I get gas!

The dealer has checked that the car is up-to-date and I have checked the firmware version against the Update Instructions. I have seen that some of my firmware versions are lower than those provided by others here, but I am up to at least the update levels.

Carwings will match the dash reading +- 0.1 mi/kWh with the latest updates most of the time.

That's good to know. I'll need to learn to reset the meter before my first trip each day!

 

[edatoakrun]

I pretty much lost faith in the carwings range estimate during winter time when it would spit out numbers horribly inaccurate. I was regularly seeing 35-38 miles for a full charge on carwings....if that happend I wouldn't make it to work and back (55+ miles), yet I did, with an easy 3 bars left during cool temps (in the 50's). After a few rounds of seeing this in CW when I would pre-heat the car, I just stopped looking at it. The GOM is way more accurate than carwings is and if I had to choose, would shoose the GOM.

I hope I didn't imply that the Carwings range estimate was accurate. Rather I think I indicated that I quickly convinced myself that it was WAY off. Instead, I am proposing that the estimate it gives might be a good way to obtain an accurate back door report of available battery capacity.

The "Telematics Service by CARWINGS" page does not, to my knowledge, provide an estimate future range.

I assume you are talking about the GOM (guess-o-meter) as compared to the "estimated driving distance" on your Account page?

I'd suggest you generally ignore both of those numbers, as range predictors though either might be useful, in certain circumstances.

You can open CW at the bottom of the your account page.

If you "accept Carwings" on start-up, records of each start/stop cycle, as well as compilations of daily, monthly, and annual energy use by category, are available.

As I have posted many times before, the only error I can find in this data, is about a 2.5% constant underestimate of "miles driven" in contrast to my (correct) odometer readout.

 

[RegGuheert]

The "Telematics Service by CARWINGS" page does not, to my knowledge, provide an estimate future range.

I assume you are talking about the GOM (guess-o-meter) as compared to the "estimated driving distance" on your Account page?

Actually, I used the mobile app to get the data, but it appears to be the same as this page. As mentioned, the number on that display matches the car's GOM except in the situation I described.

I'd suggest you generally ignore both of those numbers, as range predictors though either might be useful, in certain circumstances.

Agreed. As mention, I'm not suggesting the range estimate is accurate. I'm suggesting you can use it to determine battery capacity.

 

[edatoakrun]

The "Telematics Service by CARWINGS" page does not, to my knowledge, provide an estimate future range.

I assume you are talking about the GOM (guess-o-meter) as compared to the "estimated driving distance" on your Account page?

Actually, I used the mobile app to get the data, but it appears to be the same as this page. As mentioned, the number on that display matches the car's GOM except in the situation I described.

I'd suggest you generally ignore both of those numbers, as range predictors though either might be useful, in certain circumstances.

Agreed. As mention, I'm not suggesting the range estimate is accurate. I'm suggesting you can use it to determine battery capacity.

Unless I misunderstand your meaning, the answer is clearly no, except for specific conditions and points of past energy use, as both are always calculated by looking back, at prior energy use.

edit-<Every day that I begin my driving my car with a 100% charge, I always have, IIRC, a 40-something estimate from my owner's page, and 50-something from the GOM, as a result of the about 2000 ft of ascent (and about 500 ft of descent) in the last 7 miles to my home.>

Seven miles, later, on the same road, but now after 1,500 ft. of net descent, the GOM reads 100 to 110 miles, depending on temp, driving style, etc.

This does give me a fairly consistent statement of battery capacity at any fixed point, on this known route.

Ten miles from the start of my drive, I pass a landmark "ghost ranch" and sometimes, for fun, try to get the highest possible number.

114 so far, IIRC. I can't crack 110, and often max closer to 105, with a cold battery, though.

I expect to be able get a higher number than 114, later this summer, as I didn't pick up this "game", till last fall.

 

[RegGuheert]

Every day I begin my driving my car from a 100% charge, with a 40-something estimate from my owner's page, and 50-something from the GOM, as a result of the about 2000 ft of ascent (and about 500 ft of descent) in the last 7 miles to my home.

Seven miles, and miles and the same descent later, the GOM reads 100 to 110 miles, depending on temp, driving style, etc.

O.K. It sounds like you do this practically every day! Would you mind recording the exact conditions tonight and tomorrow morning and posting them here?

Tonight: Bars remaining before shutdown, GOM and efficiency number from main dashboard.
Tomorrow morning: Predicted range from home page BEFORE starting your car.

TIA!

 

[Bassman]

With the update, Carwings reads pretty consistent with the cars GOM. Not always exactly, but pretty close.

Have you tried it under the conditions I specified? That is the only case where I have seen a large discrepancy.

They don't call it a guessometer for nothing. I usually subtract 15 miles from the initial guess and that usually is pretty close to what I actually use. Typically I end up around 4.2 mi/Kwhr going to work (downhill) and 3.7 mi/Kwhr for back home.

 

[edatoakrun]

Every day I begin my driving my car from a 100% charge, with a 40-something estimate from my owner's page, and 50-something from the GOM, as a result of the about 2000 ft of ascent (and about 500 ft of descent) in the last 7 miles to my home.

Seven miles, and miles and the same descent later, the GOM reads 100 to 110 miles, depending on temp, driving style, etc.

O.K. It sounds like you do this practically every day! Would you mind recording the exact conditions tonight and tomorrow morning and posting them here?

Tonight: Bars remaining before shutdown, GOM and efficiency number from main dashboard.
Tomorrow morning: Predicted range from home page BEFORE starting your car.

TIA!

Well, I didn't think that would be of interest, or i would have explained using more more precise words (see edit).

Every day that I begin my driving my car with a 100% charge, I always have, IIRC, a 40-something estimate from my owner's page, and 50-something from the GOM, as a result of the about 2000 ft of ascent (and about 500 ft of descent) in the last 7 miles to my home.

In fact, I only drive 3-4 days a week,and since I start with the descent, I usually charge only to 80% by timer, and (in winter) to about 90%.

A 100 % charge for me, is a fairly unusual event, used only when I expect to need max range. It would be easier for me to get a large numbers of reports at 80%, and only once the weather warms up.

Right now, at 80% charge, the account page shows 36 miles, no CC, and the GOM reads 43, with no CC, if that helps.

Again these numbers vary with how quickly I drive the last miles home, and the only one I've ever kept a close eye on, is my "high score" at ten miles with 100%.

 

[TonyWilliams]

... Cave men found great value in rocks as tools.

The image just appeared in my mind, of Tony the Caveman picking, up a rock to defend himself from a charging sabre tooth tiger, and pulling out his laboriously constructed chart to calculate the initial angle and direction, to throw the rock.

Too bad Tony the Caveman had that rather significant error, on his chart...

That's is funny. Feels like the way we prepared for the moon launch; lots of tables and slide rules. They landed the first time, having never done it before, with a multitude of forces and factors that our LEAF will never experience, with a 50 second reserve of fuel. 250,000 miles. Computer technology that doesn't equal my iPad.

Yep, there should be a nice little number presented to the driver that displays an accurate presentation of range, and it will happen. Until that day, it is laborious, no question.

 

[TonyWilliams]

The estimated 20 miles remaining on about a 30% "tank" shows how aggressively you were driving during something like the last 5 minutes (or so): 20 miles to use about 6 kWh, or about 3.3 mi/kWh, not "conservative" driving.

Nope. That's nowhere close to accurate. For the last 10 minutes of my drive yesterday, I had no one on my tail and I was on the familiar, flat back roads to home. Climate control was off all day since the weather was excellent. Certainly these were the most efficient of the 5.8 mile/kWh day. Certainly over 6 miles/kWh over those last 10 minutes. More likely the GOM was using the 3.3 miles/kWh displayed on the console.

But perhaps you are correct that ratio displayed at the end of the trip is what was used for the range estimation during the charge.

See what I mean... Dog chasing his tail. We know the GoM is not accurate, yet round and round we go.

 

[RegGuheert]

Well, I didn't think that would be of interest, or i would have explained using more more precise words (see edit).

O.K. Thanks for the details! It's not too critical. I'm going to keep an eye on this to see if I can either confirm or disprove it.

P.S. Do you use your GPS to estimate changes in altitude, or is it too inaccurate in the Z direction? If not GPS, what do you use? We have a mountain about 12 miles away that is maybe 500 to 1000 feet high that we cross occasionally and I need to figure out how much range we will have on the other side and still be able to get back home.

P.P.S. I've been staring at your screen name trying to figure out what I can call you. Finally, I see it! Can I call you "Ed"?

 

[edatoakrun]

Well, I didn't think that would be of interest, or i would have explained using more more precise words (see edit).

O.K. Thanks for the details! It's not too critical. I'm going to keep an eye on this to see if I can either confirm or disprove it.

P.S. Do you use your GPS to estimate changes in altitude, or is it too inaccurate in the Z direction? If not GPS, what do you use? We have a mountain about 12 miles away that is maybe 500 to 1000 feet high that we cross occasionally and I need to figure out how much range we will have on the other side and still be able to get back home.

P.P.S. I've been staring at your screen name trying to figure out what I can call you. Finally, I see it! Can I call you "Ed"?

Yes, it's Ed (actually, near Oak Run, CA)

No GPS, I use:

http://www.mynissanleaf.com/viewtopic.php?f=38&t=3721" onclick="window.open(this.href);return false;

And estimate by adding up all the grades on a route, ascents and descents, for the total. If you have a more precise option, use it.

BTW, I also use the approximation that 800 ft of ascent consumes about 1 bar, or about 1.5 kWh, and 1,000 ft of descent recovers about 1 bar, or about 1.5 kWh, for the purpose of estimating range, on a given trip, using total ascent and descent, not just change in altitude, between high and low points.

These adjustment factors seem to work best for me, on the well-graded highways I usually travel, at 40-55mph, when I don't undertake large descents with 100% capacity, limiting regen recovery (such as when I leave home, and quickly descend a total of close to 2,000 ft., if I have a 100% charge).

Others use somewhat different adjustment factors, to calculate the effect of grade, on range estimates.

This is another area, where SOC/gid readings would certainly give greater accuracy, but I haven't seen posts, with these reports.

 

[RegGuheert]

See what I mean... Dog chasing his tail. We know the GoM is not accurate, yet round and round we go.

Yes, the GOM is wildly inaccurate. But that fact is completely immaterial to this discussion. Why? Because that wildly inaccurate number is almost certainly the product of a very accurate number and a second, less trustworthy factor. If We know the value of that second factor, regardless of how good or bad it is, we can calculate directly the other number, which is what I am looking for. So, please, let's quit stating the obvious and if you have evidence that will support or disprove my theory that the efficiency factor is coming from the main dash display, please post it here. That number has to come from somewhere and in my case, it appears to *only* match that efficiency. (Yes, it matches the final GOM value, but that apparently was coming from the same source.)

I guess the main question I have left is whether these things might pull from multiple sources and select the most pessimistic value in order to try to prevent a LEAF-on-roadside-dead occurrence. That seems perfectly reasonable and it would render this idea quite unworkable.

 

[RegGuheert]

Yes, it's Ed (actually, near Oak Run, CA)

No GPS, I use:

http://www.mynissanleaf.com/viewtopic.php?f=38&t=3721" onclick="window.open(this.href);return false;

And estimate by adding up all the grades on a route, ascents and descents, for the total. If you have a more precise option, use it.

BTW, I also use the approximation that 800 ft of ascent consumes about 1 bar, or about 1.5 kWh, and 1,000 ft of descent recovers about 1 bar, or about 1.5 kWh, for the purpose of estimating range, on a given trip, using total ascent and descent, not just change in altitude, between high and low points.

These adjustment factors seem to work best for me, on the well-graded highways I usually travel, at 40-55mph, when I don't undertake large ascents with 100% capacity, limiting regen recovery (such as when I leave home, and quickly descend a total of close to 2,000 ft., if I have a 100% charge).

Others use somewhat different adjustment factors, to calculate the effect of grade, on range estimates.

This is another area, where SOC/gid readings would certainly give greater accuracy, but I haven't seen posts, with these reports.

Thanks, Ed! That's awesome information! We'll be scaling mountains in our LEAF before we know it!

 

[davewill]

See what I mean... Dog chasing his tail. We know the GoM is not accurate, yet round and round we go.

Yes, the GOM is wildly inaccurate. But that fact is completely immaterial to this discussion. Why? Because that wildly inaccurate number is almost certainly the product of a very accurate number and a second, less trustworthy factor. ...

Actually, we know that it's based on a time weighted average of historical efficiency numbers, it's definitely NOT a simple product involving the displayed mpk value*. I don't think you can turn this sausage machine backwards and get a pig out it.

* I really wish they WOULD have a mode like that...THAT would be useful.

 

[DaveinOlyWA]

Since that efficiency setting is resettable, I think a good test of my theory would be to reset it and drive like a bandit to make the reading very low, like 1.0 and see what my test reports. Sounds like fun!

cant be done but have fun trying

if you are using 120 volt charging, get a Kill a watt. your OP is making too many assumptions. the GOM, estimated range and Carwings is not giving you enough info anyway.

 

[edatoakrun]

Yes, it's Ed (actually, near Oak Run, CA)

No GPS, I use:

http://www.mynissanleaf.com/viewtopic.php?f=38&t=3721" onclick="window.open(this.href);return false;

And estimate by adding up all the grades on a route, ascents and descents, for the total. If you have a more precise option, use it.

BTW, I also use the approximation that 800 ft of ascent consumes about 1 bar, or about 1.5 kWh, and 1,000 ft of descent recovers about 1 bar, or about 1.5 kWh, for the purpose of estimating range, on a given trip, using total ascent and descent, not just change in altitude, between high and low points.

These adjustment factors seem to work best for me, on the well-graded highways I usually travel, at 40-55mph, when I don't undertake large ascents with 100% capacity, limiting regen recovery (such as when I leave home, and quickly descend a total of close to 2,000 ft., if I have a 100% charge).

Others use somewhat different adjustment factors, to calculate the effect of grade, on range estimates.

This is another area, where SOC/gid readings would certainly give greater accuracy, but I haven't seen posts, with these reports.

Thanks, Ed! That's awesome information! We'll be scaling mountains in our LEAF before we know it!

I don't know why I never see the bonehead errors till my posts are quoted back to me. I hope you caught the error above, which should read:

These adjustment factors seem to work best for me, on the well-graded highways I usually travel, at 40-55mph, when I don't undertake large descents with 100% capacity, limiting regen recovery (such as when I leave home, and quickly descend a total of close to 2,000 ft., if I have a 100% charge).

And you probably noticed Tony's range chart has different adjustment values for ascent/descent. See which works best for you, and report back. I remember, last year, when several very credible reports of 1,000 ft per bar, in ascent were posted, thinking battery temp, road speed, and whether the trip began with an ascent (mine always do, for 5k ft.+ trips) or a descent, might have been factors, in the different observations.

I just never have seen bars last for 1,000 ft. of ascent, on the few big hills I've driven up, like this one:

http://www.mynissanleaf.com/viewtopic.php?f=31&t=5022&hilit=+lassen" onclick="window.open(this.href);return false;

 

[TonyWilliams]

See what I mean... Dog chasing his tail. We know the GoM is not accurate, yet round and round we go.

Yes, the GOM is wildly inaccurate. But that fact is completely immaterial to this discussion. Why? Because that wildly inaccurate number is almost certainly the product of a very accurate number and a second, less trustworthy factor. ...

Actually, we know that it's based on a time weighted average of historical efficiency numbers, it's definitely NOT a simple product involving the displayed mpk value*. I don't think you can turn this sausage machine backwards and get a pig out it.

* I really wish they WOULD have a mode like that...THAT would be useful.

We were permitted to see all the variables that go into the DTE (distance to empty, aka GoM) by Nissan on Dec 3 in San Francisco. The one piece to the puzzle doesn't exist, as there are many. And the dog keeps chasing his tail....

PS: I too wish they would give a simple "available kWh * displayed miles per kWh = DTE"