MPGe of EUCs

[Thai-lad]

The EPA formula for calculating the equivalent of MPG for electric vehicles is 

where Em is the amount of electricity in watt-hours consumed per mile.

 

Using a conservative figure of 33 watt hours per mile gives EUCs an MPGe of 1000 (about 425 km/liter)

Just sayin...

[Thai-lad]

To put it anothet way, New York to San Francisco on 3 gallons of gas.

[Marty Backe]

19 minutes ago, Thai-lad said:

To put it anothet way, New York to San Francisco on 3 gallons of gas.

Seems a little bit optimistic, but not by much.

I think your 33wh/mile is a good average value based on my real-world experience.

The rest depends on your cost of electricity. Where I live, in California, I pay on average about 20-cents per kilowatt-hour.

So lets say I decide to use my ~1000wh Gotway Tesla to make the trip.

• Google tells me this is ~2900-miles
• My Tesla would require ~88-charges to make the trip
• Using my California electricity rates: Due to the inefficiency of the charger brick, I'm going to assume that it actually takes ~1.3KW to charge the ~1KW Tesla. So that's 88 x 1.3 equals ~114kwh @ 20-cents/kwh equals ~$23 
• California gas is ~$3.50/gallon so that's ~6-1/2 gallon equivalent. A car that gets 30mph would require about 96-gallons. It might get there a little quicker though 

Fun calculations aside, I probably average around 3000-miles a year across my EUCs. Cool to think that my operating costs are only about $25 for the privilege 

[Thai-lad]

2 hours ago, Marty Backe said:

Seems a little bit optimistic, but not by much.

I think your 33wh/mile is a good average value based on my real-world experience.

The rest depends on your cost of electricity. Where I live, in California, I pay on average about 20-cents per kilowatt-hour.

So lets say I decide to use my ~1000wh Gotway Tesla to make the trip.

• Google tells me this is ~2900-miles
• My Tesla would require ~88-charges to make the trip
• Using my California electricity rates: Due to the inefficiency of the charger brick, I'm going to assume that it actually takes ~1.3KW to charge the ~1KW Tesla. So that's 88 x 1.3 equals ~114kwh @ 20-cents/kwh equals ~$23 
• California gas is ~$3.50/gallon so that's ~6-1/2 gallon equivalent. A car that gets 30mph would require about 96-gallons. It might get there a little quicker though 

Fun calculations aside, I probably average around 3000-miles a year across my EUCs. Cool to think that my operating costs are only about $25 for the privilege 

You're comparing apples to oranges here.  It only takes the energy contained in 3 gallons of gas to cross the country on an EUC.  But if you are overcharged for electricity, as you obviously are, then it will of course cost more.  Here gas costs about the same as it does for you, I expect in Europe it might well be higher.  But our electric rates are half yours, as I suspect they are in much of the continental US, outside of California. So comparisons based on the relative cost for 33 kw-hours of electricity vs a gallon of petrol will obviously vary for everyone based on their location.

Still, 1000 MPGe is a useful starting estimate, and can be compared to something like a Tesla model 3 automobile, which Google says is about 130 MPGe. 

Being that 1000 mpg is so far out of everyone's daily experience, I included the 3 gallons of gas to cross the country as a visual aid.  Like you pointed out, the chargers are at best 90% efficient and will waste some energy.  The bigger issue is the limited range wheels can run and the long amount of time it takes to recharge them. Not an issue for local daily commutes, but makes a cross country camping tour a bit impractical.

 

Besides just being a fun calculation, I think it's also useful knowledge for those working on legislation issues.  Hard to justify resticting the usefulness of a transportation device that gets 1000 mpg(e).

[Seba]

Ok, I've made some calculations that are valid for me. I'm located in Poland and have dual energy tariff. Electricity costs me:

• High tariff - 0.5711 PLN (0.13 EUR, 0.15 USD) per 1 kWh
• Low tariff - 0.2639 PLN (0.06 EUR, 0.07 USD) per 1 kWh

Low tariff is effective during weekends, holidays and off-peak (22:00-06:00 and 13:00-15:00). I charge mostly overnight, so mainly use low tariff with my KS18L. It's best to assume that I get 55 km from single charge of 1036 Wh King Song KS-18L. It's proven range, measured with GPS during normal, non-conservative rides with mean speed > 20 km/h. This gives me 18.9 Wh/km. Adding 20% for charging losses gives 22.6 Wh/km. How it relates to costs of electricity?

• High tariff - 1.29 PLN (0.30 EUR, 0.35 USD) per 100 km
• Low tariff - 0.60 PLN (0.14 EUR, 0.16 USD) per 100 km

In Poland diesel is most popular and it costs about 5.10 PLN (1.19 EUR, 1.37 USD). Gasoline is only slightly cheaper. Taking all above into final equation I get following results:

• High tariff - 395 km per liter of diesel → 0.25 l per 100 km → 918 MPG of diesel
• Low tariff - 850 km per liter of diesel → 0.12 l per 100 km → 1999 MPG of diesel

[Chriull]

12 minutes ago, Seba said:

It's best to assume that I get 55 km from single charge of 1036 Wh King Song KS-18L.

1036 Wh is the "nominal" charge calculated from the amount of cells and the cell manufacturers data. Normally they measure the charge of a cell by discharging the cell down to 2.5V (presumably with very low burdens==current). So, for instance a LG MJ1 "advertised" with 3.500mAh (down to 2.5V) delivers discharged with 2A down to 3V ~3000mAh and down to 3.3V ~2600 mAh. Afair most EUCs stop at around 3.3V?

So this advertised 1036 Wh could leave a usable charge of ~1036/3500*2600 ~ 770 Wh.

(I have no idea of the really used cells in the KS18L nor how accurate these discharge numbers are i took from dampfakkus.de - however it should give a rough idea... BTW: this kind of calculating the Wh numbers is used by all EUC manufacturers, afaik)

12 minutes ago, Seba said:

It's proven range, measured with GPS during normal, non-conservative rides with mean speed > 20 km/h. This gives me 18.9 Wh/km. Adding 20% for charging losses gives 22.6 Wh/km. How it relates to costs of electricity?

So best for estimating the Wh/km would be to measure the power consumption while charging the wheel - then one has already the loss of the charger included, too...

[US69]

29 minutes ago, Chriull said:

1036 Wh is the "nominal" charge calculated from the amount of cells and the cell manufacturers data. Normally they measure the charge of a cell by discharging the cell down to 2.5V (presumably with very low burdens==current). So, for instance a LG MJ1 "advertised" with 3.500mAh (down to 2.5V) delivers discharged with 2A down to 3V ~3000mAh and down to 3.3V ~2600 mAh. Afair most EUCs stop at around 3.3V?

So this advertised 1036 Wh could leave a usable charge of ~1036/3500*2600 ~ 770 Wh.

(I have no idea of the really used cells in the KS18L nor how accurate these discharge numbers are i took from dampfakkus.de - however it should give a rough idea... BTW: this kind of calculating the Wh numbers is used by all EUC manufacturers, afaik)

So best for estimating the Wh/km would be to measure the power consumption while charging the wheel - then one has already the loss of the charger included, too…

 

Something -i guess- must be wrong in your calculations  (i think it is that announced 3500mah means down to 3,3, which is the normal end of life for a Lithium cell, 2,5 Volts is just the absoulut max you can go down to without damaging it) The effect that as higher the Amps draw is, the less mah you get is the Peukert law:

https://www.researchgate.net/figure/Peukert-constant-of-various-lithium-ion-battery-brands_fig12_231169804

In my practical daily use i am always using a charge doctor, which on recharging Shows/measured me the the exact Watthours which where running through it (after charger) and pumped back into the battery….

When i drove my 18S (1680wh) down to 10% i normally on recharging push About 1500wh back into the battery….So this works out Pretty well to the announced WH numbers. Also on other percentage recharges the percentage Matches the announced Watthour...for example 50% = 800wh.

And just 1 week ago i had my 18S 1680wh in general maintenance/check at 1radwerkstatt....he measured my batterys  (emptied them to 3,2Volts and recharged them) and they still take a total charge of 1650wh...(after 3300km)

[Seba]

1 hour ago, Chriull said:

So best for estimating the Wh/km would be to measure the power consumption while charging the wheel - then one has already the loss of the charger included, too...

I've already did it. Discharged the wheel to such extent that it shown 0% of charge even during trolleying and eventually tilted back 45°. Then connected charger to power meter and charged wheel overnight. Next day morning, when power consumption dropped to about 6 watts, I checked total energy consumed and it was 1.02 kWh.

[Chriull]

1 hour ago, US69 said:

Something -i guess- must be wrong in your calculations  (i think it is that announced 3500mah means down to 3,3, which is the normal end of life for a Lithium cell, 2,5 Volts is just the absoulut max you can go down to without damaging it)

I think read somewhere that manufacturers measure the cells by dischargung down to 2.5V . And wheels discharge down to 3.3V.

For my calculation i just used the charge measured by dampfakkus.de down to 3.3V against the 3500 announced. Could be that some wrong/faulty table occured to them? They had a bad cell for the test? Or my considerations are just soehow wrong? (*) As every theory

Quote

….

When i drove my 18S (1680wh) down to 10% i normally on recharging push About 1500wh back into the battery….So this works out Pretty well to the announced WH numbers. Also on other percentage recharges the percentage Matches the announced Watthour...for example 50% = 800wh.

has to fit reality - which here definitely is not the case...

Ps.: (*) Or everyone is right and its just a simple solution as manufacturers announce as battery capaxity the charge that can be "put inside" the cell, dampfakkus.de measure the charge that can be taken out and the difference are all the different losses inside the cell... So for the consumption discussion here it seems the "nominal" manufacturer numbers or relevant (more or less already including charger losses) and my points were off-topic...

[Marty Backe]

6 hours ago, Thai-lad said:

You're comparing apples to oranges here.  It only takes the energy contained in 3 gallons of gas to cross the country on an EUC.  But if you are overcharged for electricity, as you obviously are, then it will of course cost more.  Here gas costs about the same as it does for you, I expect in Europe it might well be higher.  But our electric rates are half yours, as I suspect they are in much of the continental US, outside of California. So comparisons based on the relative cost for 33 kw-hours of electricity vs a gallon of petrol will obviously vary for everyone based on their location.

Still, 1000 MPGe is a useful starting estimate, and can be compared to something like a Tesla model 3 automobile, which Google says is about 130 MPGe. 

Being that 1000 mpg is so far out of everyone's daily experience, I included the 3 gallons of gas to cross the country as a visual aid.  Like you pointed out, the chargers are at best 90% efficient and will waste some energy.  The bigger issue is the limited range wheels can run and the long amount of time it takes to recharge them. Not an issue for local daily commutes, but makes a cross country camping tour a bit impractical.

 

Besides just being a fun calculation, I think it's also useful knowledge for those working on legislation issues.  Hard to justify resticting the usefulness of a transportation device that gets 1000 mpg(e).

This is all back-of-the-envelop type work, but fun to do. Yes, my California example is probably a worse-case scenario. But still, ~500mpg ain't bad 

[Michael Vu]

I did a similar analysis comparing different cars with EUCs and I calculated that an EUC efficiency is 24 Wh/mile (35 miles of range from a 840 Wh battery and 100 miles of range from a 2400 Wh battery). Electric cars like my Tesla (not Gotway) get around 250 Wh/mile. In the end based on $0.11/kWh, it costs $0.03/mile to drive an electric car while it cost $0.0026/mile for an EUC. While it cost $0.07/mile to $0.10/mile for a typical gas car at $2.50/gallon.

[LanghamP]

I don't see very many EUCs with 5000 miles. My own KS16s has a mere 3000 miles, my Gotway about 1000 miles, but it takes a lot of 10 mile journeys to get there. In contrast I'll rack up 30 miles easy on my bicycle.

While I think the operating costs for EUCs are low, I think their costs per mile is rather high ($1000 lasts  6000 miles is about 16 cents per mile) but obviously if you can get 10k out of a wheel then that's 8 cents a mile. I'm unsure of the reasonable lifespan of a wheel. 5k is too low for sure but 10k? 20k? 50k?

I think 50k might be reasonable if you charged to just 85%. I'm guessing the point of likely failure is the pedal joint which can be easily replaced.

[Seba]

Today I fully charged my KS-18L then travelled 8.9 km from work to my home. Then I connected my new quick charger to the energy meter and charged the wheel to the full. Finally, when balancing process ended (charge current decreased to < 50mA) energy meter displayed 0.195 kWh as drawn by the charger. So by simple calculation I've got 21.9 Wh/km brutto (including all charging losses). It's worth to say that I used my big & inefficient, 500 W quick charger with large fan and LED A/V meter. Stock charger seems to be much more energy efficient.

[Zhut]

I'm noting that a lot of the discrepancies in these calculations pertain to cost of fuel vs cost of electricity, but I have to say that my understanding of MPGe as a rating doesn't pertain to cost at all, but only to energy efficiency, as described by the OP.  I drive a LEAF, so I don't ride an EUC to save money on fuel... it's all about the fun.  But it's still worthwhile to understand the energy consumption part of our hobby, such that it can be properly presented when regulations are being discussed.