Disclaimer: I am not responsible for your actions. if you cut, burn, electricute or hurt yourself in anyway i am not responsible. always be safe and use the appropriate protection. safety goggles are recommended.
I lost my bike light a while ago, and now with shorter days aproaching i will have to ride my bike to school in the dark and at night more often. So thats where the homemade one comes in. I wanted to make a bright, yet clean looking, and compact light. The total cost is VERY low (may be higher if you dont have the battery and charger...but i already had them laying around) below you can see the before and after from the stock light to the finished one(both pics are taken from the same spot and in complete darkness):
Step 1: Materials:
-small generic flash light
-krypton "kpr112" bulb from radio shack
-some wire that has the positive and negative connected together(if that makes sense) like an old light plug, or speaker wire.
-7.2v battery and charger + male connector
-some miscillanious screws
-a handle bar mounted reflector
-a heat gun or stove
Step 2: Battery Holder
Lets start with making the battery holder (gives your hot glue gun and soldering iron time to warm up) (another note: if you have soldering iron, i suggest investing in a soldering gun) To get the level of brightness and endurance i wanted, simple "aa" or "aaa" batteries would not work efficiently, or allow the light to be very small. I decided to use a 7.2v rc car battery i had. It is rated at 3300mah so it will last for many hours before a charge is necessary. to keep the actual light small, and the overall look "clean" i disguised the battery as a sport bottle. I simply removed the inner core of the cap with wire cutters so the wiring could come through the top. The rest of this will be included in the wiring section.
Step 3: Cut the Light
The first step to making the light is shortening it for practicality and it allows you to get at the inside. (NOTE: the following steps--mainly the ground(black) wire--- are so that the original switch can be used...this may not work out well...i have now stripped out the insides and wired in a push button switch i recommend this. the ground wire is soldered to the metal ring on the bulb holder)
To cut the light to shorten it i used a hacksaw, it was quick and painless:
Step 4: Start Wiring!
Now lets start with the wiring...the fun part! remove the bulb holder from the head of the light(should twist, unlock, and pull out) then use something with a fine point to pop the square metal plate in the center up as shown. Then wrap the stripped positive wire around the square and back on its self. then it should be ready to be soldered in place. i added a few dabs of hot glue after this to keep from pulling out.
Step 5: Wiring the Ground
Now put this in the top of the flashlight and feed the wire through the flash light body( make sure the positive end has enough slack and room to attach the bulb holder to the lens and put the top on/off). Split the two wires apart a bit so you can easily shorten and solder the ground. i wrapped the ground around the piece of metal that was attached to the spring and soldered it to its self. then i slid the wire up into the body, clip the piece of metal, and bent it a bit to keep the wire from coming off. Then cut a the small end cap off of the other half of the flashlight, drill a hole in it (put a knot in the wire so it cant pull stuff apart) feed the wire through the cap. then put a bit of hot glue to attach it, and electrical tape to finish off and make it look better. put the bulb and lens all together and the light part it pretty much done. (wiring it like this should make the original switch usable)
Step 6: Making the Handlebar Mount
Now to make the handlebar mount: get your handlebar mounted reflector and break the reflecting part off. (see pic) then i put leather gloves on (safety first!) and slowly heated it on the (gas) stove and formed to to the contour of the flashlight body. i then screwed it to the flash light to attach it.
Step 7: Finishing Up
To finish, feed the other end of the wire down through the cap of the water bottle. tie a knot so it wont be pulling on the battery. then solder the male connecter to the wire so you attach the battery. then pack the battery in there with some foam or something. to remove or attack the light its only one screw so for a homemade light its pretty practable, and very bright. i spent about $8-9 on the entire project (granted i did have the battery already)
here is what it looks like on the bike: (you can figure out a system to clean up the look of the wire...this was just for the pic)
here is a pic of what it looks like with the push button switch aswell(recommended...you should be able to figure it out, add a comment if you have a question)