Nano Motor - a breakthrough?

[Krow]

I read the new issue of A to B this week. They did an in depth review of a bike available in Britain called the Nano Brompton. It's a regular 3 speed folding Brompton L3 bike fitted with a new motor - the Nano.

These guys have been reviewing electric bikes and folding bikes for years now and are generally pretty skeptical. The total weight (including battery) is 18.8 kg (41.3 pounds). The motor+battery is about 11.6 lbs. They suggested other Brompton models (the 52LX) that would bring the weight down to 12.8 kg (28.1 lbs)

The lithium polymer battery was rated for 266 Wh.

The amazing thing is that they rode this bike, with pedalling and motor assist, for 47.9 miles at an average speed of 13.4 mph. And, just as I'd want, the motor responds to slowing speed on hill climbs by contributing more power with it's peak power tuned to around 10 mph. The bike climbed reasonable hills at over 13 mph and could do steep ones (16%) at 7-8 mph.

This sounds like a pretty big breakthrough in range. A to B was very surprised by this result. It's more than twice what their favorite electric bike of all time (the Giant Lafree/Lite) can do. And the bike, with motor and battery, is still light enough to ride without assist.

Anyone have any experience with this Nano motor?

 

[Miles]

See here, Krow.

 

[markcycle]

I don't think those numbers are any kind of breakthrough

I just got done doing a 30 mile ride averaging 17.8 mph using 15.6AH
with plenty of energy left in my battery

My battery is a 37 volt 27AH LI-ION cobalt battery I configured using a total of 120 cell with included BMS.

The ride was a blast just pure fun and I did something good as the ride was to my father's house for a visit.

All the best
Mark

 

[josh]

Hi Krow

Anyone have any experience with this Nano motor?

I've not heard of any other test of it, but there is more information including pictures and a torque curve for that motor in http://endless-sphere.com/forums/viewtopic.php?t=238.

I was going to say that around 19 miles of that distance must have been legpower only, but on reflection I think 48 miles is about right for that motor & at that speed, on flattish terrain anyway and with a good amount of legpower added: using about 80W continuous motor power would give you nearly 3.5 hrs at ~13.4mph which amounts to ~47miles. Not very fast, nor pedal-free, but motor efficient!

What amazes me though is the hill climbing ability: from that torque curve, the motor looks like it would hardly help at all on a 16% slope: the power would be almost all from the rider - are you sure it wasn't 1 in 16 instead?! That I could believe! :wink: the bike would perform much better on hills with more low speed torque: it has a low peak torque which occurs at high rpm: the peak torque is at 10mph but the maximum motor speed is only ~14mph. Some bikes that can do around 20mph have lower speed maximum torque (for hills) than that.

BTW Mark, the power consumption on your trip was nearly 3.5 times that of the brompton, for a 4mph speed gain: 15.6Ah @ 37V is 577Wh of energy, over 30 miles, more than twice the 266Wh the brompton used over 47miles: your average energy usage ~19Wh per mile vs 5.54Wh per mile for the brompton , but judging from your figures, your route was possibly slightly hilly or you had a slight headwind? Still, at least you can probably climb hills ok on your bike?! .

 

[Geebee]

My kind of power assist, light enough to not interfere with human power and geared for hill climbing assist.
I have the Tongxin hub, similar concept but I am lugging lead around as I can't justify a lithium pack.

 

[josh]

Hub motors seem to work very well for energy efficiency when you can pedal beyond their top motor rpm: I'm guessing the brompton has a 260rpm motor in 16" wheels, so pedal at 13mph+ and you're already exceeding the motor speed and, I think, increasing its efficiency aswell as reducing its power consumption, which is how I think the brompton gets such a good range?

In principle, I think you could get the same effect at higher speeds say 15-16mph and maybe in larger wheel sizes, but pedalling harder.

What sort of gradients can you climb with yours geebee (and pedalling how hard?!), and what battery, controller & motor gearing (wheelsize & max speed) do you use?

 

[Geebee]

First up, I always pedal and am a passably fit cyclist.
The hub is the 210rpm version in a 20" wheel, a shade over 20kph motor speed.
The speed contoller is a Tongxin standard non pedal start one.
I have no trouble climbing 20~25% grade, I have to every time I ride I pedal fairly hard on the hills but it's hard to quantify that, speed up that type of incline is fairly easy to maintain at around 10 kph, will do steeper without to much worry and up anything lesser it is easy to sit on 20 kph.
I spend a lot of my time riding above the 20 kph mark, and a lot of time climbing steep hills so range is hard to quantify as well.
Batteries are 2 x 7 and 2 x 9 amp hour 12 volts in 2 x 2 configuration for 24 volts output. 12 bl..dy kilo's of lead.
I have to carry so much as the low voltage cutoff is very high (good for battery life a pain for range), I can only pull 4 to 5 amp hours before cutoff, good for around 20 klm in very steep terrain.
Oh and it's mounted on the rear wheel of a front wheel drive delta trike.

 

[josh]

Thanks for the information GeeBee

I'm leaning towards this kind of power assist myself (except I need to rebuild my fitness!): I always pedal too, but also want the assist on hills.

I tend to agree on the lithium too :? .

To add to what I said re efficiency & economy, another 20" bike here, geared for ~16mph/26.6km/h (~270rpm) can do 17.4mph/29km/h average in mixed terrain, climb 20% grade with little help in 2nd gear (~500W peak output) @ 8mph/14.3km/h on an energy consumption of ~10wh per mile/16.6 Wh per km, or ~35miles/58.33km on a new 37V 10Ah lithium battery (~3kg). The motor weighs ~3kg or less, bike about 25kg total.

The bike also does 6mph/10km/h up a 22.5%/1 in 4.5 (75kg rider) from a stationary start. That was the steepest hill available, but it could easily do more: it towed a big trailer up a 20% incline too!

With the weight batteries are, efficiency & economy make a big difference to how much a bike can still feel like a bike, and still give good power assist & range too.

Compare that with the previous example of 17.8mph average, which still has double the power consumption (so twice the battery weight) of the 17.4mph average above. Twice the power for the same speed?