## Carwings miles/kwh figures higher than Leaf's by 10% to 35%

DaveinOlyWA
Posts: 15564
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

### Re: Carwings miles/kwh figures higher than Leaf's by 10% to 35%

well, i just find it hard to explain the differences in the carwings mileage.

what makes it more confusing is the differences it comes up with on the same routes. my work commutes fall into 2 versions that vary by less than .1 of a mile and that straight there and back. 18.3 miles or there and pick up son on way home 20.5 miles. the Trip B is reset daily, Trip A reset every sunday morning.

i have more than a dozen of both trips above and all have the exact same mileage, but carwings is different on them but not the same figure.

for the 18.3 mile days i run from 17.7 to 18.3
on the 20.5 mile days it runs from 19.8 to 20.3

i mean, its weird.

same with other calculations, i have several days that tells me i have done 5.2 kwh on my RT work commute, but Carwings has numbers that run from 5.5 to 7.

so, its hard to correlate anything when there is this much variance in what should be similar statistical days
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 16,686 mi, 91.51% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

bowthom
Posts: 657
Joined: Sun Jul 18, 2010 12:22 pm
Delivery Date: 23 Feb 2011
Leaf Number: 307
Location: Portland Oregon

### Re: Carwings miles/kwh figures higher than Leaf's by 10% to 35%

Hello,
Maybe carwings is using GPS miles and the breadcrums cut off (shortcut) turns etc.
I guess I will jack up the car and run up 20 miles with no load and see what each reports. I may get to the top of the leaderboard in efficiency ratings that way.
Reserv Apr 20 - Ord Aug 31
Red - ETEC trim
P1213 4/29/11 - Charger repl 6/8/11
P1273 2/15/12 - P32270 10/2/13
TCU upgrd 2/15/17
-1bar 11/14 -2bars 6/16 -3bars 7/18 -4bars 9/19

Deliver 2/23/11 - 75k+ mi

wesly
Posts: 8
Joined: Mon Jan 17, 2011 2:18 pm

### Real Energy Economy calculation

I think you guys are making this far too complicated. I believe it is as simple as CARWINGS incorrectly subtracting the the regen kWh from the Consumption KWh to calculate the Energy Economy when the Consumption kWh figure already incorporated the regen figure, which means the regen figure is being subtracted twice before dividing by the miles traveled to calculate the all important miles/kWh figure.

This would also explain why the CARWINGS miles/kWh figure varies so widely between different trips and drivers. The more the regen kWh, the bigger the variation and the better your miles/kWh figures looks. When in reality, you are regenerating more because the route you driven has lots of elevation variation, more downhill opportunity for regen or because you are driving inefficient by speeding up and slowing down quickly too often.

In my case, I have been averaging about 6.8 miles/kWh so far in April according to CARWINGS, driven 193.7 miles while using only 29.2 kWh (53.2 kWh consumption - 24.0 kWh regen)! The truth is I have put in far more than 29.2 kWh into my Leaf this month, about twice that figure, so if you consider less than 100% efficiency in the charger, it will be pretty close to the 53.2 kWh consumption by the motor (not subtracting the 24 kWh regen).

I tested my theory by using the the highest energy economy driver so far this month - sofuten of Japan. His energy economy is 11.0 miles/kWh (over 260 miles out of the 24kWh battery pack? I don't think so!) over 11 miles driven which meant he only used exactly 1.0 kWh (11.0 miles driven divided by 11.0 miles/Kwh) but this 1.0 kWh net energy consumption figure is reached by CARWINGS subtracting his motor consumption by his regen energy figure of 0.8 kWh, which means his motor consumption was actually 1.8 kWh, and this is the figure I am proposing has already included the effect of regen. If you now divided his miles driven 11.0 by the motor consumption 1.8 kWh, you will get a much more believable figure of still fantastic 6.11 miles/kWh (146 miles from the 24kWh battery) versus the fantasy figure of 11.0

I also looked at the outrageous high efficiency figures for rest of the top 16 drivers so far this month and recalculate their actual energy efficiency by adding the regen kWh to calculate the actual motor consumption and divide the miles driven by this number, you will see the adjusted miles/kWh figures are much more realistic/reasonable. Please notice there are four drivers with the same CARWINGS energy economy figure of 8.4 miles/kWh, but as you can see, after my adjusted calculation, their figures becomes 4.37 to 5.34 miles/kWh. This is the reason why there is seemingly no direct correlation between the CARWINGS and the actual real-world figure (it is not a fixed percentage), because the regen figure varies widely. You guys are all welcome to put my theory in practice and please let me know if using the motor consumption figure (without subtracting the regen) matches better with your kill-a-watts/TED/Blink figures on how much you put into your Leaf.

11 6.11
9.7 5.54
9.6 4.96
9.5 5.08
9.5 5.36
9.4 5.32
9.0 5.77
8.6 5.99
8.5 4.69
8.4 5.04
8.4 4.37
8.4 5.05
8.4 5.34
8.3 4.50
8.2 4.80
8.1 4.51

evnow
Moderator
Posts: 11480
Joined: Thu Apr 22, 2010 11:41 am
Delivery Date: 25 Feb 2011
Leaf Number: 303
Location: Seattle, WA

### Re: Real Energy Economy calculation

wesly wrote:I think you guys are making this far too complicated. I believe it is as simple as CARWINGS incorrectly subtracting the the regen kWh from the Consumption KWh to calculate the Energy Economy when the Consumption kWh figure already incorporated the regen figure, which means the regen figure is being subtracted twice before dividing by the miles traveled to calculate the all important miles/kWh figure.
No - not in my case anyway.

Carwings shows
KWh_m (kwh for the motor)
KWh_r (kwh from regen)
KWh_a (kwh for Accessories)

If, what you are saying is correct

m/kwh = miles/(KWh_m + KWh_a)

But, that is not what I see. For me the following gives the best fit when compared to what Leaf shows as the miles/kwh.

m/kwh = miles/(KWh_m + KWh_a - 0.39*KWh_r)
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

hill
Posts: 1870
Joined: Wed Apr 21, 2010 4:05 pm
Delivery Date: 27 Mar 2011
Leaf Number: 0659
Location: Lake Forest, CA

### Re: Carwings miles/kwh figures higher than Leaf's by 10% to 35%

It's no wonder that I'm getting a pain behind my right eye

wesly
Posts: 8
Joined: Mon Jan 17, 2011 2:18 pm

### Re: Real Energy Economy calculation

evnow wrote:
wesly wrote:I think you guys are making this far too complicated. I believe it is as simple as CARWINGS incorrectly subtracting the the regen kWh from the Consumption KWh to calculate the Energy Economy when the Consumption kWh figure already incorporated the regen figure, which means the regen figure is being subtracted twice before dividing by the miles traveled to calculate the all important miles/kWh figure.
No - not in my case anyway.

Carwings shows
KWh_m (kwh for the motor)
KWh_r (kwh from regen)
KWh_a (kwh for Accessories)

If, what you are saying is correct

m/kwh = miles/(KWh_m + KWh_a)

But, that is not what I see. For me the following gives the best fit when compared to what Leaf shows as the miles/kwh.

m/kwh = miles/(KWh_m + KWh_a - 0.39*KWh_r)

Your formula does work very well when comparing to what Leaf is showing, but while the Leaf miles/kWh figure is much closer to reality, it is not still quite 100% accurate. What I am proposing is the amount of energy used to charge the Leaf's battery (wall to wheels) is closer to what CARWINGS stated as the Electricity consumed by the traction motor (KWh_m) without subtracting the regen. I am not sure what to think of the separate accessories figure, but it doesn't seem to make much difference (adding it or not) in my case since I have not used the A/C or heater. My accessories kWh figure is around 3% of the motor kWh, your mileage might varies.

I am interested to see if you have an accurate way of measuring the x amount of kWh going into your Leaf and make a note of the starting SOC % and drive it until the SOC % has returned to the exact starting SOC %, meaning you have used up exactly the x amount of kWh you put into Leaf's battery and see what is closer to x, kWh_m or (KWh_m + KWh_a - 0.39*KWh_r)? Personally I used Kill-a-watt and x is closer to KWh_m for me.

evnow
Moderator
Posts: 11480
Joined: Thu Apr 22, 2010 11:41 am
Delivery Date: 25 Feb 2011
Leaf Number: 303
Location: Seattle, WA

### Re: Real Energy Economy calculation

wesly wrote:Your formula does work very well when comparing to what Leaf is showing, but while the Leaf miles/kWh figure is much closer to reality, it is not still quite 100% accurate. What I am proposing is the amount of energy used to charge the Leaf's battery (wall to wheels) is closer to what CARWINGS stated as the Electricity consumed by the traction motor (KWh_m) without subtracting the regen.
You are comparing apples to oranges - at the wall kwh is expected to be different than what Leaf/Carwings shows. I see about 10% to 30% difference between kwh at the wall and what Leaf shows (miles * kwh/miles). A little high for charging losses - probably includes battery losses too.
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

DaveinOlyWA
Posts: 15564
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

### Re: Carwings miles/kwh figures higher than Leaf's by 10% to 35%

The other question is the difference. In charging. Efficiency verses 240 and 120.
The inaccuracies I c makes it look like the efficiency at 120 is around 73% which I believe to be incorrect
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 16,686 mi, 91.51% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

evnow
Moderator
Posts: 11480
Joined: Thu Apr 22, 2010 11:41 am
Delivery Date: 25 Feb 2011
Leaf Number: 303
Location: Seattle, WA

### Re: Carwings miles/kwh figures higher than Leaf's by 10% to 35%

DaveinOlyWA wrote:The inaccuracies I c makes it look like the efficiency at 120 is around 73% which I believe to be incorrect
Do you always get very close to that 73% ? What is the range ... ?

Yes, that number is too low.
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

DaveinOlyWA
Posts: 15564
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

### Re: Carwings miles/kwh figures higher than Leaf's by 10% to 35%

Well my latest theory is that it seems I am only accessing around 21 kwh based on info from car. Well we have been told it should be 24 kwh. So guessing car error is the same so recomputing efficiency based on multiplying car figures by 21/24 then determining efficincy which should bring me to the mid to upper 80's which should. Be about right.

Still running numbers but that appears to be the convoluted method required
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 16,686 mi, 91.51% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;