Intro: Deodorant Solar Bike Light
I saw a guy in SF with a bike like that looked like a deodorant stick which gave me the idea to hack a solar garden light into a deodorant stick for easy weather proofing (and aerodynamic goodness).
This is a simple hack, re-packaging a solar garden light. All you need is a deodorant stick, a solar light, and some silicone.
This is great for people who bike to work and park outside. Free renewable energy from the sun!
Step 1: Get Yer Bits Together
Remove the left over deodorant bits from the stick. Pull out the screw mechanism which drives the deodorant up to your armpit.
Now you've got an empty chassis into which you can insert the battery and circuit board from your solar light.
Disassemble the solar light. It should just be a solar cell wired to a circuit board, and a battery pack.
Keep an eye out for the light sensor. A little cadmium cell that is usually somewhere near the solar panel. The cadmium cell acts as a switch, so the light turns on in darkness and stays off in light while the battery charges. I chose not to wire an on/off switch since the battery usually stays charged until at least midnight after a day in the sun and I wanted to keep this light simple.
You could wire in a switch (and use the spinny bit on the deodorant stick for a weatherproof switch actuator.) if you like late night (early morning) bike rides...
Step 2: Cut a Hole for the Solar Cell
I wanted the solar cell to lie a flat as possible in the deodorant stick, so I cut out a hole into which the solar panel could fit snugly. The ideas is to get the panel to sit snug and then fill around the solar panel with silicone to make it relatively waterproof.
The easiest was to do this would be to just drill a hole and run the wires through it. But that's not as slick as sinking the solar panel into the body of the deodorant stick. (And not as aerodynamic)
Step 3: Fit Yer Bits Into the Case
The circuit board and battery pack should slide easily into the "chassis". I used hot glue to hold things in place temporarily. Position the circuit board so the LED's point out through the "lens" as desired.
I used silicone adhesive to fix and seal the solar cell. With a good seal, the light should work in wet conditions short of full submersion.
Techy people might choose to rewire their own LEDs for more light, fancy colors, etc. Just beware the voltage output of the battery pack and the amp hours for which it's rated (or swap it out for a gel cell).
Step 4: Affix Ye Olde Light to Yer Bike
I drilled and tapped two holes to mount a conduit clamp by which the light can be attached to handlebars. Rubber bands work pretty well too...
Or course this is easier to do before the circuit board and solar cell are installed in the case. But, why make it easier on ourselves?
Step 5: Enjoy the Result
Smell yer fingers when you get done and enjoy fresh deodorized scent.
Ride yer bike to work, park it outside and let the light charge up for the ride home!