Efficiency?

Highlights & Index

Attack Them Hills!
Determining Peak Motor Output - Simple-Cheap Method
Electrical Input Watts vs Motor Output Watts
Motor Output Watts vs Speed - Aerodynamics
Motor "Watts" ... Input or Output?
Speed vs Range

Winter efficiency(?)
Well, getting acceptable use from batteries during cold weather.

See - Batteries vs Cold ☃

• Discusses:
• Battery performance loss when cold
• Keeping battery warm
• Larger capacity battery to offset cold
• Capacity not diminished as much as IR (Internal Resistance) is amplified, by cold
• etc.

This thread has been idle so long it's pretty much fallen off the charts.
Been resurrecting an old hub motor and the issue of efficiency raises it's head ...
Rescue Motor - Aotema (Wilderness Energy BD-36)
Mapped the power curve of a 2005 era BD36 front hub motor.
(Volts, Amps and tire size modified to match actual performance curve.)

26" wheel vs 20" wheel
Yes 20" for 20mph @ 36V looks optimal!
Simply resizing by the proper ratio (36" / 26" x 20" = 27.7") I was able to plot motor with 20" wheel.



Full throttle:
drops speed from 23mph >> (legal) 20mph;
improves efficiency from 72% >> 80%;
improves hill (below 12mph) and starting (35lb >> 45lb) torque;
increases range from 23 miles to 32 miles!!!

Proper 20" front wheel application is the problem!
Small 20" trike?
Will test alternate voltages before deciding anything ...
.

Hm, I search optimal efficiency, and find 420 results

Probably should smoke more

.
... Aerodynamics as the major factor in efficiency

Using the same WE motor simulation, I compared MTN Upright vs MTN Tuck. Presumably the is an upright seated posture vs a crouched down over the handlebars position.




Note the increased range at the increased speed!
23 miles@23mph vs 30 miles@24.5mph

More reasonable, and impressive, in my opinion, is the comparison when both are throttle regulated at 20mph!




29 miles vs 41 miles range!!!

Comfort is the drawback, especially with prolonged range. I have experimented with using a large low comfort seat, then sat behind it on the rack, resting midsection on seat and using seat against legs as something of a seat belt, holding me back and stable during braking.
Padded motorcycle type seat extending onto rear rack is the next logical step, then drop handle bars.

Alternately, the application of some form or degree of fairing should prove similarly effective!

See also - Aerodynamic Factors

Implication of wind as an efficiency factor seems to, obviously, demonstrate that a more aerodynamic positioning is more efficient than the assist applied by pedaling from a more upright seating posture ... dependent on cyclist capability, of course.

Somewhere between 20 and 30 mph a more aerodynamic posture out performs the continuous capability of pedal assist.

20mph = ~80w differential
30mph = ~300w differential

Not that I am recommending against pedal assisting!

• Pedal assist is instrumental in:
  Getting up to speed
  Going up hill
  Casual cruising, where range is greatly extended
  In traffic, where better vision and acceleration are essential