On 10/8/2018 12:24 PM, Jeff Liebermann wrote:

snip

Anyway, I would be quite satisfied if Emanuel Berg were to build
something resembling a bicycle light from scratch, measures the
lumens, lux, candelas, beam pattern, variation in intensity across the
beam pattern, power draw, operating temperature, and then improves the
design updating the measurements as he makes changes.

What are really nice for a homebrew system are the MR16 LED lamps
because they have an integrated thermal solution and are available in
many different beam patterns. The beam pattern of a two lamp MR16 system
is close to ideal, with sufficient spread to illuminate street signs,
while not blinding on coming traffic.

There used to be commercially available MR11 and MR16 dual beam systems
but there was overhead involved in using those lamps which made them
larger and heavier than what can be achieved now. They also require too
many cells to achieve the proper voltage. You can run them with 3 or 4
Li-Ion cells in series for 11.1V or 14.8V.