Efficiency?

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DrkAngel
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Re: Efficiency?

Post by DrkAngel » Dec 05, 2016 10:05 am

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.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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DrkAngel
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Re: Efficiency?

Post by DrkAngel » Dec 13, 2017 8:09 am

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.

Image

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 ...
.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

marvak
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Re: Efficiency?

Post by marvak » Dec 25, 2017 4:47 pm

Image

Hm, I search optimal efficiency, and find 420 results

Probably should smoke more
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DrkAngel
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Re: Efficiency?

Post by DrkAngel » Dec 27, 2017 10:13 am

.
...
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.

vs Tuck.jpg
vs Tuck.jpg (214.71 KiB) Viewed 240 times
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!

2020.jpg
2020.jpg (216.06 KiB) Viewed 240 times
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
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

User avatar
DrkAngel
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Posts: 4583
Joined: Dec 15, 2010 11:14 am
Location: Upstate-Western-Southern Tier NY. USA

Re: Efficiency?

Post by DrkAngel » Dec 30, 2017 5:07 pm

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
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

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