DaveinOlyWA
Posts: 15335
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

Re: Miles per kwh so far... my calcs vs. the LEAFs calcs

Tue Jan 25, 2011 6:19 am

now that i have enough data to make one, i am creating an excel sheet (actually open office calc) to track progress since i dont have Carwings working yet.

as i was generating columns a thought came to me; i am reseting the MPK estimate from the car daily (thought about per trip, but without charging, it would be valueless) and was using that divided by MPK estimate from the wall (AC-MPK...make that AMPK the other DMPK) in an attempt to get a guideline on charger efficiency, but without knowing the value of the trees (the more trees, the lower the efficiency) that would be less meaningful as well.

so perhaps the inverse would give me an indication of how much more of a role regen played?
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, 92.44% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

DaveinOlyWA
Posts: 15335
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

Re: Miles per kwh so far... my calcs vs. the LEAFs calcs

Sat Jan 29, 2011 11:51 am

i am trying to verify how efficiently the charger is working and not getting good numbers here. now the only thing i seem to be missing is how much power the climate controls use. i am not finding them on the carwings website. everything else seems to be listed.

any one know where or is it even available. i would think that to be very unusual considering all the details carwings does provide
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, 92.44% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

User avatar
wsbca
Posts: 505
Joined: Tue Aug 03, 2010 4:33 pm
Delivery Date: 0- 0-2011
Location: SL-E powered by 3KW AC Solar in SoCal

Re: Miles per kwh so far... my calcs vs. the LEAFs calcs

Sat Jan 29, 2011 1:13 pm

DaveinOlyWA wrote:i am trying to verify how efficiently the charger is working and not getting good numbers here. now the only thing i seem to be missing is how much power the climate controls use. i am not finding them on the carwings website. everything else seems to be listed.

any one know where or is it even available. i would think that to be very unusual considering all the details carwings does provide
Log in to the owner's portal
'launch CARWINGS''
select Driving History from the menu bar (adjacent to the Home icon)
select My Driving Style (second item on the sub-menu line at the top)
You'll see detail for the most recently recorded day, and at the bottom, a scrollable table (Past Records) which shows other days, with 3 values, Electricity consumed by the traction motor, captured by regenerative braking, and consumed by vehicle accessories. The climate control usage is reflected in that third category. Yes, it has "other things" in it as well, but you can extrapolate how much that additional relatively constant load might be by examining days when you didn't use climate control. (We generally aren't using climate control so our accessory figure is typically .2 per day for anywhere from 25-35 miles of driving)
I was promised a jet pack!

DaveinOlyWA
Posts: 15335
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

Re: Miles per kwh so far... my calcs vs. the LEAFs calcs

Sat Jan 29, 2011 2:08 pm

ok i have seen the accesories category but it does not reflect what i had expected. the 28th, it listed only 1.5 kwh used and this would be a trip that had heat/defrost for nearly all of the 57 miles traveled
verses the previous day where i only pulsed defrost on once in a while to clear the windows but had the radio running most of the time along with charging my cellphone.

i have to say, my figures are plausible but climate controls seem not to be included. now because of the hiccups i had with getting carwings started, i only have 2 days to review. i guess we will see what happens down the line.
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, 92.44% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

User avatar
garygid
Gold Member
Posts: 12469
Joined: Wed Apr 21, 2010 8:10 am
Delivery Date: 29 Mar 2011
Leaf Number: 000855
Location: Laguna Hills, Orange Co, CA

Re: Miles per kwh so far... my calcs vs. the LEAFs calcs

Sat Jan 29, 2011 4:39 pm

Is the energy "consumed by the traction motor":
1. the TOTAL consumed, part of which came from the WALL, and some came from REGEN.
2. or, the NET energy consumed, total into the motor (or inverter) minus the Full Regen'd amount (that is used to re-charge the battery)?

The "used" kWh (reported by some) does not appear high enough to be #1.

The Full Regen amount is almost like From-Wall energy, it has losses going into the battery, and losses coming back out of the battery for use. The anount out would be Reclaimed-Regen, always significantly less than the Full Regen amount.

So, 4 kWh of Full Regen might only provide 3 kWh of "motor" power (Reclaimed-Regen).

Assuming 11 (net, #2) used and 4 Regen (only 3 recovered for use), the actual Total motor usage might be 11+1=12, not just the 11 "reported".

Does that help explain the "strangeness" of some CARWINGS numbers?

Of course, not properly including A/C or Heating in the "acc" amount might also explain some things.
See SOC/GID-Meter and CAN-Do Info
2010 Prius
2011 LEAF, 2014 Tesla S85
2018 & 2019 Tesla Model 3
PU: SDG&E
Solar PV: 33 x 225W -> 7 kW max AC
Craigslist: Xm5000Li Electric Motorcycle

leafme
Posts: 108
Joined: Thu Apr 22, 2010 2:27 pm
Delivery Date: 04 Jan 2011
Leaf Number: 0200
Location: San Diego, CA

Re: Miles per kwh so far... my calcs vs. the LEAFs calcs

Sat Jan 29, 2011 9:14 pm

garygid wrote:The "squared" increase in energy usage for the aerodynamic drag applies only to the portion of the energy being used to overcome aero-drag.

So, if the aero-drag is about 50% of the total, then only that part goes up by 21% when the speed increases by 10%.

The part (maybe 30%) that is velocity-related (like rolling resistance) only goes up by 10%.

And the Heater and other "constant" energy uses do not increase ... their energy usage PER MILE actually decreases, since you are shortening your trip with the higher speed.

So, a 10% increase in speed typically does not require 21% increase in energy, at least until speeds at which the aero-drag becomes the dominant energy-hog!
The aero drag is the dominant energy hog quite early on (40-45+ mph??). My guess is the aero drag is MUCH higher that 50% above that. I mean what else is there? Some wheel rolling resistance, wheel bearing resistance, slight increase in motor losses? What else am I missing? Can't imagine those amount to a whole lot (but maybe I'm wrong).

Malcolm :geek:


User avatar
akohekohe
Posts: 111
Joined: Mon Jun 28, 2010 8:36 pm
Location: O'ahu

Re: Miles per kwh so far... my calcs vs. the LEAFs calcs

Mon Mar 07, 2011 12:50 pm

Carwings has been telling me I have been getting 5.7 miles/kwh. So i thought I should check this against reality. I've been charging to 80% using the timer. Yesterday I drove 27.9 miles. I hooked up the trickle charger to a kill-a-watt and charged the car back to 80%. It took 9.86 kWh to do this. This is 2.8 miles/kWh. I'll keep track over a longer period but a suspect this trend will hold.

Observations:
1. apparently I should just take the Carwings figures and divide by two.
2. Where I live electricity is $0.27 /kWh at the moment. So the 2.8 miles/kWh translates to 0.095 $/mile. I traded in my 2002 VW Golf TDI for the LEAF. It got 42 miles/gal. Currently Diesel is $3.88/gal here so that comes out to 0.092 $/mile. So, my fuel costs are slightly more per mile by going with the electric car. So much for the electric car yielding fuel savings!

Question:

These results are based on using the level 1 trickle charger. Is there any reason to believe my results will be any better using the level 2 charger (I don't have an easy way to measure the current consumed by my level 2 charger)?

User avatar
DaveEV
Posts: 6251
Joined: Fri Apr 23, 2010 3:51 pm
Location: San Diego

Re: Miles per kwh so far... my calcs vs. the LEAFs calcs

Mon Mar 07, 2011 1:19 pm

akohekohe wrote:These results are based on using the level 1 trickle charger. Is there any reason to believe my results will be any better using the level 2 charger (I don't have an easy way to measure the current consumed by my level 2 charger)?
People "seem" to be getting slightly lower wall-to-wheels efficiency using only the L1 charger. It's quite likely that the on-board charger is less efficient at converting 120V AC to 400V DC than 240V AC to 400V DC. Most power supplies I have seen that handle dual voltages are slightly less efficient on 120V. I don't know that anyone has tested both with accurate enough equipment. Certainly 2.8 mi / kWh seems to be a bit low compared to what others seem to be reporting.

User avatar
garygid
Gold Member
Posts: 12469
Joined: Wed Apr 21, 2010 8:10 am
Delivery Date: 29 Mar 2011
Leaf Number: 000855
Location: Laguna Hills, Orange Co, CA

Re: Miles per kwh so far... my calcs vs. the LEAFs calcs

Mon Mar 07, 2011 1:35 pm

1. You are measuring kWh from the wall, whereas CARWINGS is attempting to show the energy (again kWh) recovered OUT of the battery. So, the CARWINGS figure is ignoring the following three significant losses:
a. in the charger,
b. in the battery while putting energy in,
c. in the battery while recovering energy from the battery.

2. It appears to me that the CARWINGS calculation of the energy used contains an error, most likely in how Regen Energy is handled, subtracting it almost twice. This makes it seem like the energy used us substantially smaller than it actually is, so their mi/kwh is much too high, especially when there has been a lot of regeration on the "trip".

I think that both these issues contribute to the Hyper-Efficient numbers we see on CARWINGS.
See SOC/GID-Meter and CAN-Do Info
2010 Prius
2011 LEAF, 2014 Tesla S85
2018 & 2019 Tesla Model 3
PU: SDG&E
Solar PV: 33 x 225W -> 7 kW max AC
Craigslist: Xm5000Li Electric Motorcycle

Return to “Range / Efficiency / Carwings”