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Energy Efficiency of EUC


Daan

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Hi all,

First post here :-) I just got my shiny new Solowheel Xtreme a week ago or so and had so much fun last week learning to ride it -- Later I'll do a review.

Anyway, I was just wondering about the energy efficiency of using a Solowheel for my commute and compared against a bunch of regular and electric cars -- nice, a EUC is about 300 times more efficient than a Hummer and about 32 times more efficient than a Nissan Leaf :-)

  BatteryRangeEnergy Efficiency
CarMPGkwhmileskwh/100mi
Hummer 201312  305
Subaru Forester AWD 201525  146
Prius 201250  73
Chevy volt 2014 16.53843
Nissan Leaf 2013 247532
Tesla S 85D (2014) 8627032
Solowheel Xtreme (2015) 0.155151
     

 

Assuming 36.6kwh per gallon of gassoline (ie. 3660/mpg  = kwh/100mi)

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Yes eWheels are incredibly efficient, but is there any evidence to show the XTreme's range is really 15miles? Even in a best-case track scenario, eWheels consume between 16-20Wh/Mile, I don't believe the XTreme will be able to achieve any more than half the rated range. 2-2.5 kWh/100mi is probably closer to the truth under 'ideal' track conditions.

Similar to the much touted 2000W power rating, I'm afraid there's some rather extravagant exaggeration in specifications from the marketing dept. which doesn't have much basis in fact.

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I concur, even if a monowheel is efficient (not more than a eBike), saying it can ride 15 miles with 155Wh is a lie !

At best, you can ride 15 km with 155Wh. For a 70kg rider, expect rather 12km, not 15km, no way.

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yeah -- I just used the quoted range. The power rating is 1800W though, not 2000W. No idea if the range is realistic and it is hard to say with all hills here. Mmm would need to test this on a flat trail some day and report here.

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About the power, SoloWheel's own website has two conflicting specifications on the same page! In reality, it seems unlikely that the real peak power comes anywhere near to 1800W or 2000W. 

I wrote about this in May. 

It will be interesting to hear how it compares to one of the other 18" Wheels. I'm very skeptical of the claim that the power output is 1,800W. At the battery level, the maths don't add up, even using the standard Chinese formula of peak-out. According to the data on the Xteme's product page, the Wheel uses Sony US18650V3 cells, which is well documented to produce sustained output of 10A. http://www.dampfakkus.de/akkutest.php?id=106

We know the capacity of the pack is 155Wh & the capacity of the cell is about 8.25Wh, depending on the way SoloWheel are calculating capacity, they're using between 16-20 cells. So 3.7v x 10A x 20 cells = 740W sustained, a far way off from the advertised 1,800W!  As an aside, vendors like Airwheel/IPS frequently use a standard power formula of 43.75W power per cell.  

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Hi Daan,

Looking forward to your Solowheel Xtreme review. Is it your first EU of do you have others as well??

As for range, on my 1500 Solowheel (classic) I can get up to 14km if I don't stand around too much with the Solowhee ls switched on. I am about 70Kg with and this is on a flat terrain and the tire at 3.0 bar.

However, most of the time, you waste energy with the EU switched on at traffic lights, talking to people while hopping around etc. 

The latest Solowheel classic models are (were?) sold with a 196 Wh battery, but I have no idea what their range would be.

 

 

 

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Just to put thing in perspective -- I love my wheel already and it is such a smooth ride; really enjoy the experience :-D Just got my coffee on the wheel and it worked out fine -- all the coffee arrived at my desk *in* the cup. It feels like the wheel has quite some power and I never felt it being unstable or unable to get me on a hump or slope -- but then, I have no experience at all and never been on anything else.

Anyway, I am going to take the wheel on the plane to Prague and Holland next week; Perhaps I get a chance in the Netherlands to ride a longer flat route and test how far I can get on a  full charge. I wish it had a internal gps and speed/distance tracker :-(  I can probably use my phone to do that.

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Cool, the criticism was nothing personal, at first the post looked like it may have been from a Solowheel agent, but it's now clear you are not. :ph34r:

Solowheel have a perfect right to market the features & innovations of their XTreme, but for me & others of this forum, we've all too often seen companies make outlandish claims that can't be backed up. Originally Solowheel were pretty good with keeping their facts pretty straight & consistent, let's hope the XTreme is the exception to the rule. 

However, there is one thing you can do, which many of us enviously cannot, that is taking the Wheel on the plane! 

 

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Cool, the criticism was nothing personal, at first the post looked like it may have been from a Solowheel agent, but it's now clear you are not. :ph34r:

...

However, there is one thing you can do, which many of us enviously cannot, that is taking the Wheel on the plane! 

Thanks Jason. Lol, I am no secret agent -- just enthusiastic :)   I contacted Inventist last week about the safety features / battery cut-off and they were very responsive and detailed in their answers; that was great. 

Anyway, I will test the range as soon as I can and let you all know. Btw. the <= 160kwh battery was one of my main reasons to choose this model (+safety features and 18" wheel) since I travel a lot and plan to ride it on my trips -- hope I won't get hassled too much when going through security B)

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Just to put thing in perspective -- I love my wheel already and it is such a smooth ride; really enjoy the experience :-D Just got my coffee on the wheel and it worked out fine -- all the coffee arrived at my desk *in* the cup. It feels like the wheel has quite some power and I never felt it being unstable or unable to get me on a hump or slope -- but then, I have no experience at all and never been on anything else.

Anyway, I am going to take the wheel on the plane to Prague and Holland next week; Perhaps I get a chance in the Netherlands to ride a longer flat route and test how far I can get on a  full charge. I wish it had a internal gps and speed/distance tracker :-(  I can probably use my phone to do that.

​Hi Daan,

Just read your post about your trip to Holland.

I live in Holland as well (Rotterdam). So if you would like to meet up I would appreciate that. Perhaps I can show you the original (classic) Solowheel.

I have no problem in driving to where you will be staying, I am quite mobile :)

 

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Hi all,

I had a fun ride in Holland and tried to test the range of the Solowheel Xtreme (160wh, 18") -- I rode 19km (12mi) on a full battery but about 7km of that ride was through steep hills (dunes), sandy and off-road forest terrain; super fun! at some time my wheel almost got stuck due to all the mud sticking to the wheel (I'll post a video later). Anyway, I thought this was very demanding of the battery and worried all the time that I got stuck in the woods with an empty battery but it just kept going B) (average speed outside the dune area was about 11km/h.

When I got home the battery still had power so I rode about 2km more in circles but there was still power and I didn't want to try any longer so I don't know yet the true range. However, this is already so good, that I am pretty sure that on a flat track you can surely reach 25km (15mi) at which the wheel is advertised.

This ride the wheel needed about 14Wh per mile... that seems incredible given the numbers on the Firewheel?!? perhaps it is the motor or bigger wheel?

 

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Here is a small video of the part of ride through the forest and dunes; quite demanding of the wheel I think:

(sorry, not quite as exciting as Vee's video's :-) but of course, it is only my third week with the wheel)

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Hmm, it starts to feel I just reply to myself :) but just in case anyone is interested:

Over the past two days I tracked the range from a full battery on a full charge and I rode 21.5km (13.4mi). About 5km was through the forest on rough sandy roads with some short( but steep) hills but otherwise it was flat terrain through the city, so it did have bumps, waiting for stoplights etc, So, very good I think, about 12Wh per mile (!)  much lower than the numbers Hobby16 gets -- no idea why; perhaps the 18" wheel?.

Given the foresty hilly part of the total I think that the Solowheel xtreme can indeed do 25km (15.5mi) under ideal circumstances -- yahoo :D

 

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About 5km was through the forest on rough sandy roads with some short( but steep) hills but otherwise it was flat terrain through the city, so it did have bumps, waiting for stoplights etc, So, very good I think, about 12Wh per mile (!)  much lower than the numbers Hobby16 gets -- no idea why; perhaps the 18" wheel?.

Indeed, I am mystified too since you rode a quite rugged terrain. My numbers with the Firewheel or the generic X3 on asphalt are around 12Wh per km and not per mile ! I can barely reach 25km with the FW's 260Wh, no way I can get them with 160Wh.

I have some hypothesis your wheel's "Xtreme" (and puzzling) efficiency, but nothing certain :

  • you ride a rough terrain but a low speed (I'll say max 15km/h). My data are for 25km/h where the efficiency is lower. I'll try someday riding at 12km/h with the FW to compare the numbers.
  • your distance estimate is not accurate (do you use a map, GPS or bike computer ?)
  • your Wh number is an estimate from charging, not a measurement (I measure Wh with Charge Doctor)
  • your wheel's battery has a bigger capacity than stated (so same error source than above)

 

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I also get roughly a bit over 12 miles from a charge on my Firewheel F260 which has very good batteries. If the Solowheel Extreme gets more I would be interested in whether they had to sacrifice something like torque to get there.

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Indeed, I am mystified too since you rode a quite rugged terrain. My numbers with the Firewheel or the generic X3 on asphalt are around 12Wh per km and not per mile ! I can barely reach 25km with the FW's 260Wh, no way I can get them with 160Wh.

I have some hypothesis your wheel's "Xtreme" (and puzzling) efficiency, but nothing certain :

  • you ride a rough terrain but a low speed (I'll say max 15km/h). My data are for 25km/h where the efficiency is lower. I'll try someday riding at 12km/h with the FW to compare the numbers.
  • your distance estimate is not accurate (do you use a map, GPS or bike computer ?)
  • your Wh number is an estimate from charging, not a measurement (I measure Wh with Charge Doctor)
  • your wheel's battery has a bigger capacity than stated (so same error source than above)

 

My guess would be on speed, the best I've got so far with batteries that have seen ~350 cycles at +19C (I haven't tried to run the battery entirely out on warmer days) was a little over 10Wh per km (around 16-17Wh per mile?) with average speed exceeding 20km/h and max speeds around 28-30km/h. Considering the higher speed accelerations and then keeping it constant really adds up to battery use the faster you go, I would see it as the most plausible explanation, especially because Solowheels are limited to somewhere like 16-20km/h at maximum?

See here how much the required power (Watts) goes up with speed & rider weight:  http://www.americanroadcycling.org/images/WiddersHump/Graphs/WattSpeed001.jpg  Although it talks about cycling, the required power is still the same to move the same amount of mass at same speed. And yes, they are theoretical numbers, real world power will be different, but the ratio is probably around the same more speed vs. more power required (consumed).

 

 

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Indeed, I am mystified too since you rode a quite rugged terrain. My numbers with the Firewheel or the generic X3 on asphalt are around 12Wh per km and not per mile ! I can barely reach 25km with the FW's 260Wh, no way I can get them with 160Wh.

I have some hypothesis your wheel's "Xtreme" (and puzzling) efficiency, but nothing certain :

  • you ride a rough terrain but a low speed (I'll say max 15km/h). My data are for 25km/h where the efficiency is lower. I'll try someday riding at 12km/h with the FW to compare the numbers.
  • your distance estimate is not accurate (do you use a map, GPS or bike computer ?)
  • your Wh number is an estimate from charging, not a measurement (I measure Wh with Charge Doctor)
  • your wheel's battery has a bigger capacity than stated (so same error source than above)

 

My theory is that the powerful motor has perhaps more efficiency in energy transfer?

With regard to the other points:

* I ride indeed quite slow in the forest terrain, probably about 8km/h on average??  (while about 12km/h on average in the city roads -- max is about 16km/h according to the GPS tracker; already I am wishing for a higher top speed :-D ) -- perhaps the relatively slow average speed is a big power saver?

* The distance was measured using my phone GPS tracker application that samples every 5s -- it looks very accurate when I look at the superimposed map.

* The torque seems very high -- sometimes in the forest on bumps or tree roots I pressed full power down to catch my balance and the wheel always corrects. But of course I have almost no experience with other wheels.

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My theory is that the powerful motor has perhaps more efficiency in energy transfer?

I have no doubt that Solowheels are really high quality devices, but brushless DC motors seem to be very efficient in general... the usual efficiency of the motor (ie. transfer of electricity into motion, rest is lost mostly as heat) is around 85-90%. Really high quality DC motors can get up to around 96+% (reaching 100% is of course impossible in real world). So the efficiency of the motor could be better than most (or all) other wheels, but the difference isn't that big. 

 

With regard to the other points:

* I ride indeed quite slow in the forest terrain, probably about 8km/h on average??  (while about 12km/h on average in the city roads -- max is about 16km/h according to the GPS tracker; already I am wishing for a higher top speed :-D ) -- perhaps the relatively slow average speed is a big power saver?

This is my guess, riding straight the required power goes up faster than linearly when the speed increases (ie. 10km/h vs 20km/h does not mean that 20km/h uses twice the amount of power vs. 10km/h, but more that twice). If you look at the chart, to which I posted a link in my earlier post, the power in watts about doubles between 10 miles/hour vs. 15miles/hour.

* The distance was measured using my phone GPS tracker application that samples every 5s -- it looks very accurate when I look at the superimposed map.

For longer trips, I'd expect GPS to be accurate enough. Personally I use bike computer on the wheel, which is very, very precise (as long as the wheel circumference is entered right).

* The torque seems very high -- sometimes in the forest on bumps or tree roots I pressed full power down to catch my balance and the wheel always corrects. But of course I have almost no experience with other wheels.

If it really is a 1800W peak motor, and the battery can really give that much power... Here are the specs from the Solowheel-site (http://solowheel.com/product/xtreme) :

 

Rated Speed16km/h
Motor Power1800W
Battery TypeSONY VC3
Battery Capacity155Wh

 

I couldn't find anything definite, but it looks like that the Sony US18650VC3 (NOTE: it seems that this is different cell than VTC3, but some sites mix it up?) can give out 18-20A CONTINUOUS discharge and up to 60A pulse(?!), so:

Rated max power at nominal voltage: 59.2V * 20A = 1184W

Rated max power at full voltage: 67.2V * 20A = 1344W

Peak max pulse at nominal voltage: 59.2V * 60A = 3552W

Peak max pulse at full voltage: 67.2V * 60A = 4032W

If these numbers are right, and the motor really is 1800W peak, there's a helluvalot of power in it  :P  There was some doubt in the forums before that the motor couldn't be 1800W, as the cells couldn't probably give that much current, but it looks the VC3's CAN!

 

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The VC3 cells are the same ones that were in your original Firewheel, Sony has a max output rating of 10A for these.

http://www.dampfakkus.de/akkutest.php?id=106

Even Solowheel's own product page has two different power rating, 1800W & 2000W. What's not certain is how the batteries are configured, since 16 of these cells in parallel is only 132Wh, with 19 cells the capacity numbers fit, but the resulting voltage is somewhat unusual...   

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If these numbers are right, and the motor really is 1800W peak, there's a helluvalot of power in it  

:P

  There was some doubt in the forums before that the motor couldn't be 1800W, as the cells couldn't probably give that much current, but it looks the VC3's CAN!

 

that's huge! I remember the funny catch phrase from Vincent, the Solowheel vendor in France : "it's as powerfull as two, three horses" (in fact, a horse is much more powerfull than that, but its official "equivalent power" takes a hit because ot the mean value over 8 hours).

But well, it's a 18" wheel, so more power is definitively needed to produce the same torque as a 14".  I personnally would be really frustrated to have such power wasted in a 16km/h max wheel :blink:. I presume Daan should be able to have it unlocked for higher speeds (Solowheel asks you about 70€ for the firmware change and you must sign a legal discharge).

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@hobby16, that's very interesting indeed, I was under the impression that SW were offering the upgraded 20kph max speed free-of-charge; to demand that owners payout another 70€ after dishing out $2,300 on the XTreme is a bit rich.   

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