On Tue, 14 Mar 2017 10:46:19 -0400, Frank Krygowski
wrote:

On 3/13/2017 11:00 PM, Jeff Liebermann wrote:
I was thinking of building a benchtop dynamometer sized for bicycle
lighting. I don't have the equipment to calibrate it so I could
measure overall efficiency, but certainly can make comparative
measurements of the input power(s) required to light an oversized load
or bulb. Basically, just a DC motor with a DC wattmeter on the power
leads.
http://www.ebay.com/itm/122373782338
(Yet another project that I'll never finish).

What are you intending to measure? Input power to a bike dynamo?

Ideally, overall efficiency of the lighting system and verification of
the simulation and dynamo model.

Mechanical power (watts) in, as simulated by an electric motor vs
optical power out, measured in lumens or lux. The main exercise would
be calibrating the major components so that the measurements would be
accurate and meaningful. It would be something like the
Friction-Facts chain and lubricant test fixture in:
http://www.friction-facts.com/equipment-overview
Oh swell, all the links are broken. 2nd best:
http://www.bikeradar.com/news/article/friction-facts-measuring-drivetrain-efficiency-35694/
or something like this:
http://pages.jh.edu/news_info/news/home99/aug99/bike.html
but with the gearing replaced by a dynamo.

I vaguely recall a Friction-Facts web page mumbling something about
calibrated motors and generators being rather expensive.

Initially, the simulation part didn't seem too difficult. Just some
non-linear parts, such as core saturation and LED light output, needed
to be accommodated. I added kinematics model, so that changes in
wheel diameters and gearing could be shown. Well, after entering
idealized versions of all the possible formulas and parameters into a
spreadsheet to estimate the complexity, I decided that building a
dynamometer was far too messy for my available time, work area, and
abilities.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558