This light is 11 watts so on this battery pack it should run just under 3 hours. I did a late night city ride last Friday night and it held strong for the 2 1/2 hours we rode.
Another of my bike lights https://www.instructables.com/ex/i/9129E65EFFBE102880EC001143E7E506/edit.jsp
Step 1: Get the Light "bulb"
Step 2: Next We Cut Off the Copper Tags
Then I put the screws in that come with the light. They will hold my wires to the bulb. Yeah.. no socket to buy, no soldering or nothn..
Step 3: Little Do Dads You Will Need
Conduit Hanger w/speed thread size #0 3/8-1/2 5pk $1.90 HD
Thumb Screw 1/4 " 3pk $1.29 HD
Wing nut #10-24 4pk $1.29 HD
Round head slotted bolt #10-24 x 3/4 4pk $1.29 HD
Lock washers #10 18pcs.
Male/Female RCA cable (cut one side short aprox 3" for the light and The other long for the battery pack)
and a little toggle switch ..you don't really need it but it is nice.
Step 4: Drill Holes in Cap
Next 3 holes on the side. Two to put 2 little screws though. They will bite into the back of the bulb to hold it all together. and one for the bolt to go though to hold the conduit hanger to the cap.
Did I go to fast????? Its really that EASY
Step 6: Battery ...now This Is Gonna Cost You a Little Bit (same As My Other Bike Light)
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 this 11 watt bulb and 10 2500 mAh batteries.
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
I got this bike water bottle battery pack that is 5 mah with the quick charger from http://www.batteryspace.com They have tons of great batteries on that site.