Most good rechargeable tungsten halogen Bike Lights that put off a good deal of light (200 to 600 lumen) cost a ton of money 75 to 200 bucks. I took my really expensive light apart and found that its just a bulb you can buy anywhere for $ 4.00 and some rechargeable batteries. So here is a CHEAP way to build your own with part that you can get from Home Depot (mostly) This is a no frills light. I didn't put a switch on this one. I have been adding switches to my new ones.
........................NEWS FLASH.. I have added an LED for better energy management See the last step for LED upgrade......................................
I have another bike light https://www.instructables.com/ex/i/333304260366102985CB001143E7E506/
Step 1: First You Need a Body. I Found That a Trap Adapter and a PVC Female Cap From HD Plumbing Dept Works Good.
Trap adapter ABS-DWV 1 1/2 x 1 1/4 $1.14
Female Cap VPVC Sch 40 1 1/4 (threaded)$.78
Step 2: I Use a MR16 Bulb Its the Kind Made for Track Lighting
Next I use a MR16 (WITH THE LENS BUILT IN) bulb its the kind made for track lighting. I use 12 volt only and I like a 10, 15, or 20 watt bulb. You can get the 20 watt from HD for 4.95 the lower watts bulbs you need to get online from a lightbulb dot com place or a specialty light bulb store in your area. You will also need a MR16 socket that you get from a specialty place for $2.00 and a Conduit Hanger and 1/4 inch thumb screw to replace the screw that comes on the hanger (to make it easy to adjust or leave the screw on and crank it down and forget about it ) and a nut and bolt to hold it to the Body
Conduit Hanger w/speed thread size #0 3/8-1/2 5pk $1.90 HD
MR16 Bulb 20 watt Aprox $5.00 HD
Thumb Screww 1/4 " 3pk $1.29 HD
Lock nut (nylon insert) #10-24 4pk $1.29 HD
Bolt 1 inch long #10-24 4pk $1.29 HD
MR16 Socket $2.00
Step 3: No Hub Coupling From the Plumbing Dept
Next a No Hub Coupling from the plumbing dept to make a tight sleve to hold the light bulb in place and make it water (tight??). You are gonna pull the rubber part out and cut it in half but leaving the middle rim on one side then trim it to abot 3/4" to an inch total width. (I hope that makes sence once you start cutting it)
No Hub Coupling 1 1/2" to 1 1/2"
Step 4: Kinda Together Showing the Rubber Seal Holding the Bulb
We kinda jumped ahead with this pic so you could see what this was for.
Step 5: Drill a Little Hole and Tighten the Hanger on the Hub
Just use any small nut and bolt to hold it on. I have been using wing nuts, and lock washers so I don't need any tools for this step. FLASH new pic update The wing nut and bolt and lock washers is the setup I like to use now.
Step 6: RCA Male/female
I like to use an RCA cable. Cut it about 3" from one end. Drill another small hole in the cap or body and stick the short piece through and soider it to the socket.
RCA male/female end cable $3 Radio Shack
Step 7: Battery ...now This Is Gonna Cost You a Little Bit
You need to find at Radio Shack or a specalty electronics supply for a 10 AA batteries holder. Solder the other end of the RCA cable to it and ....
The best battery to use is a Nickel-Metal Hydride or NiMH 2500 mAh I found the Energizer from HD the best price. You need 10 cuz they are 1.2 volts each 10x1.2 = 12 volts. Put the battery pack in your underseat bag or in a water bottle. The light should work for 3 hours with a 10 watt bulb and 10 2500 mAh batteries. Or 1 1/2 hours with a 20 watt.
If you have any questions drop me a line....
10 AAbattery holder $1.00
Energizer 4-Pack AA NiMH Rechargeable $8.97HD
Energizer 4-Pack AA NiMH Rechargeable w/charger 17.95
Step 8: Put It All Together And...
It should work like a charm..
I got this bike water bottle battery pack that is 5 mah with the quick charger from batteryspace.com. They have tons of great batteries on that site.
Step 9: LED Is All the News. So... I Have Added a Simple LED Upgrade
Everyone is running LED on their bikes now, and why shouldn't they?? LED lights are cheap, have tons of light and use a lot less power. When I posted this project in 2006 LED's were just hitting the market and cost a ton of money. The market has changed and now you can buy good LED lights for a great price.
But.... There is still the DIY factor (that's why we are all on here, right?)
Here is a simple way to build a LED bike light without having to mess with any circuitry, little parts or soldering.
I just went to my local hardware store, light bulb store or online and bought a 4 Watt LED MR-16 It is rated at 300 lumens or a 5 Watt at 500 lumens and plug it in.... POOF!!! like magic your done!!!