Hej everybody!
I have been thinking a while about how to convert some 3xAAA headlights into 1 x 18650 lights in an easy and budget DIY-way when I remembered that the UF 501B battery tube can be turned around to make it tailcap-lockout-able (<- yes, english is not my first language).
If you have at least two 501 series flashlights you can therefore lego a flashlight with two tailcaps and no head or two heads and no tailcap.
While this is not really useful it gave me the following idea (I don't know if this is maybe a common solution (didn't find anything on google), but I thought I'd share my idea with anyone interested here on BLF anyway):
You need:
A 501B (or body with tailcap) you don't really use anymore
A remote pressure switch for the 501 series:
And one of these extension cords (mine is a Magicshine cord from DX):
As you can see I have already cut the cord into two pieces and everyone with enough imagination can stop reading now and change to a more interesting thread. ;)
For the rest: You disassemble the pressure switch tailcap and desolder the pressure switch cable from the board. Then -after possibly widening the hole in the plastic cup sitting inside the pressure switch tailcap, in my case from 3.5 to 4.5 mm- you solder one piece of the extension cord to the board.
To make it more waterproof I filled the cavity of the black plastic cup with epoxy glue and added an o-ring before reassembling the new "headcap".
Et voilà:
The other part of the extension cord can now be attached to a 3xAAA headlight replacing the original battery holder taking weight from your head. Apart from being able to keep the battery closer to your body thus protecting it from cold temperature the new battery holder also has the advantage of a hardware switch thus preventing any parasitic drain the original headlight configuration might have had. Of course you can also attach the new battery holder to the headstrap, but it's rather heavy compared to the usual plastic 3xAAA holders.
Why I think it's versatile? I chose the male connector for the battery holder and also trimmed it a little to make it fit my bike light connector. Now I can use it for my headlight (did not decide yet which one first) and for my bike light and if I want to make more 3xAAA headlamps 18650-able I only need additional dirt cheap extension cords!
