Our Gas Free Miles Travelled

[kiev]

A nagging question is why the similar average efficiency (miles/kwh for example); across such seemingly different platforms.

Did you have some example numbers?

i have seen 3 to 4 miles/kwh across several cars, even up to almost 5 when hypermiling a laef.

Assuming you are driving in a somewhat EV-energy-conservative manner, the biggest factor is Weight. The next is Aerodynamic Drag determined by the front cross sectional area and the aero coefficient.

One of the rules-of-thumb in diy EV conversions is that a good EV build would get an average efficiency in Watt-hrs/mile of about 10% of the weight in lbs. So for example a 3000 lb EV might be able to get 300 Wh/mile, or 3.3 miles/kwh.

Tesla seems to be an exception in that they are heavier and should suffer, but they have a much better aeriola factor than the rest to make up for it.

 

[JoeS]

aeriola factor - ooh, that's a new one on me! Certainly, Tesla has worked very hard to reduce their cars' Coefficient of Drag, resulting in superb efficiency, especially considering their weight. As far as metrics are concerned, don't forget to separate Wall-to-Wheels (which is what the EPA uses) from most cars' display (which is Battery-to-Wheels).

As far as our i-MiEVs are concerned, early in my first i-MiEV's life I dutifully recorded everything for over 8000 miles.
https://myimiev.com/threads/measured-wall-to-wheels-consumption.403/page-2#post-5744"(for over 8000 miles) I can categorically say that, on average, my iMiEV goes 4.2miles/kWh (6.77km/kWh). Put another way, my iMiEV has a superb efficiency of 0.238kWh/mi (0.148kWh/km) in roughly a 50/50 mix of city/highway travel", or 238Wh/mi (148Wh/km) WALL TO WHEELS in mild California weather - take that, Tesla!

 

[pbui19]

Did you have some example numbers?

i have seen 3 to 4 miles/kwh across several cars, even up to almost 5 when hypermiling a laef.

Assuming you are driving in a somewhat EV-energy-conservative manner, the biggest factor is Weight. The next is Aerodynamic Drag determined by the front cross sectional area and the aero coefficient.

One of the rules-of-thumb in diy EV conversions is that a good EV build would get an average efficiency in Watt-hrs/mile of about 10% of the weight in lbs. So for example a 3000 lb EV might be able to get 300 Wh/mile, or 3.3 miles/kwh.

Tesla seems to be an exception in that they are heavier and should suffer, but they have a much better aeriola factor than the rest to make up for it.

Our Boltev & Tesla 90D have average consumption display, which give decent figures over long enough statistics. For such a lighter vehicle, I was expecting the iMiev to have an outside mile/kwh; but it's right in the average with the Bolts, and heavy Tesla. These figures are averages of highway & city miles. At 70mph, the Tesla90D gets only 3 miles per kwh.

Of course, it's all relative, especially comparing to the Lightning at 2-mile/kwh. I was looking at some e-motorcycles with roughly 8-10 miles/kwh; but just loves my monster ebike figure of 50+ mile/kwh (not counting food calories

So, what's the explanation for the iMiev number ?

 

[michael8554]

Maybe my science is wrong, but won't a heavy Tesla coast for longer, and Regen more on steep hills ?

Potential Energy proportional to mass ?

And the skinny non-USA MIEVs should have reasonable Cd ?

 

[martinwinlow]

Maybe my science is wrong, but won't a heavy Tesla coast for longer, and Regen more on steep hills ?

Potential Energy proportional to mass ?

And the skinny non-USA MIEVs should have reasonable Cd ?

Yes, but not proportionately more (other than that due to a lower Cd)... and it will have used up more energy to get where it is anyway... (ie 'up')...

 

[jray3]

I second Kiev's rule of thumb on 10% of mass= Wh/lb My dc series-motored Karmann Ghia conversion weighs 1850 lb and on a local loop that's perhaps 40% highway, with ABA testing of both cars, it and the i-MiEV both scored 180 Wh/mi!

 

[pbui19]

Assuming you are driving in a somewhat EV-energy-conservative manner, the biggest factor is Weight. The next is Aerodynamic Drag determined by the front cross sectional area and the aero coefficient.

One of the rules-of-thumb in diy EV conversions is that a good EV build would get an average efficiency in Watt-hrs/mile of about 10% of the weight in lbs. So for example a 3000 lb EV might be able to get 300 Wh/mile, or 3.3 miles/kwh.

Tesla seems to be an exception in that they are heavier and should suffer, but they have a much better aeriola factor than the rest to make up for it.

not just the Tesla, the Bolts as well. All my limited sample, iMiev, 2-Bolt, 1-90D, have similar mile/kwh in non-highway speed. Am toying with getting the Lightning, which is even heavier, plus those high rolling resistant tires. Of course my samples are all anecdotal, the specs at fueleconomy.gov certainly reflect vehicle mass