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Monday, November 16, 2009

CFL Taillight

I looked for my light meter as long as I could today, but never found it. I wanted to do before/after comparison testing in lumens with the lens and without, and with whatever new reflector I come up with. I guess I'll try it when I do run across the thing.

I did find a few of my higher voltage inverters, for laptops. A few Apple Powerbook 24V adapters, which are isolated but won't start on even 40V. Neither would two of the 19V generic adapters (one Targus and one no-name), but the lightest and smallest, an Averatec, did, and kept running down to at least 30V, where I stopped worrying. :) At least *something* from Averatec is actually useful. :P

The 24V Apples are lighter than the typical 19V laptop adapters I have, although the Averatec is lighter than all but one of the Apples. All the 19V will do around 3A, while the 24V will only do 1.25A; this doesnt' matter for this application unless I need to run more than 6 or 7 of these. ;) I think two ought to do it--one rear and one front. I might go for two on each end for redundancy, though.

I also found a little plastic box that will be perfect for the rear end. I don't know what it used to be, but it's ABS and about 3/16" thick walls. Black plastic, so will enclose light very well. I can just take white plastic drink cups and cut them up for the inside diffuser/reflectors, to line the box with to make most of the light go out. Then secure red bike reflectors (minus their backings) to the open areas to the rear. Cut some holes on the ends, and put more red reflectors there, for side markers. One light in the center ought to be plenty, but one on each end would be even better.

Still pondering for the front canister.

I made a temporary taillight out of the old Honda scooter's taillight casing, which is cracking from age and abuse. It'll last long enough to give me time to build the other one above.

Had to remove the incandescent mounting fixture and reflector (you'll see where I painted it white inside instead of black to help reflect more light out of it with the incandescent, during early tests with CrazyBike2's lighting, until I gave up on it due to too much power wasted on the incandescent).

Then I had to drill out the hole large enough for the base of the CFL to fit thru. So out comes MEGA DRILL, a very old B&D drill (still has a ground plug!) with a completely metal case (rescued by a friend from a trashcan especially for me), with a reduction-gearing hand-gripped drill extension to allow me to use the much larger-shafted Unibit for panel holes.

And a test-fit:

Then I setup a test rig to determine which of those AC adapters would work, using three identical batteries to what is on m bike, with about 3/4 charge on them. A back plate off the UPS they came from, holding all the AC outlets, is held between the third battery and the other two, and one outlet pair is wired across the pack, so I can just plug in adapters and meter their outputs.

Then I wired up the Averatec 19V adapter (which is isolated) so it's plugged into the pack for it's voltage input, with it's negative output wired to pack positive, and it's positive output wired to the screw base of the CFL. The tip of the CFL base is wired to the negative of the pack, with the Fluke measuring across pack plus Averatec, at 53.8/9VDC.

The pic above is with the camera flash on by accident. Below is no flash, with room lighting of 2x 40W 4-foot fluorescent tubes overhead at cieling height.

Then a pic of it with lights off, camera in auto mode no flash (ISO320)

and a pic of the wall facing it, about 5 or 6 feet away.(ISO320)

Then some manual-setting pics, first at ISO1000 (exp 1/5 sec) then at ISO80 (exp 1/60 sec):

then with the room lights back on

Then some other lighting comparisons, such as a CFL on battery at 56VDC compared to an identical CFL on 115VAC. Room lights off, ISO1000, F/7.1, 1/2000sec:

Same camera settings, both taillight and the battery CFL in parallel on pack/Averatec:

Then a 12V 43W halogen I found when looking for edison-base screw in sockets for testing:

It sucks 3.25A constantly at 12.1V (current battery state) for that light, which is not a lot more than a single CFL puts out, but is mostly focused in one direction. Roughly 40W of power. It also gets too hot to touch in a fairly quick time.

The CFL does not get hot (just warm), but heat still ages parts, and will probably affect this, too. It only draws 380mA for BOTH the CFLs together, INCLUDING the inverter power of 100mA, for a total of 3.8W + 16.5W = 20.32W, for even more light output than the halogen, and little heat.

Oh, and this is basically what my old CCFL headlight looks like inside:

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