Building a flashlight/power bank

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zak.wilson
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Building a flashlight/power bank

Any time somebody brings up a combined flashlight and USB power bank, somebody else inevitably posts the same response: one or the other is going to suck, so you should just get separate devices.

It doesn’t have to be that way though, and I want to build a better one for my own personal use, and possibly to give as gifts to people who haven’t discovered high-performance flashlights.

There’s enough information about LEDs, drivers, and the like out there that I think I can figure out what I want. It’s probably going to be a small, fairly floody reflector, XP-L or XM-L2, 3 Amps or so on high, preferably PWM-less. The power bank circuitry will be a Miller ML-102 V7.1 board with its housing and terminals removed.

I can make a battery tube with a housing for the charger board on the side and USB ports up front out of carbon fiber. I’m imagining bonding this directly to a head, or cutting the rear section off of a host like a Convoy S3 that lacks a separate head. I also imagine bonding a threaded metal tube to the rear for a screw cap.

For ease of construction and battery access, I’ll be putting all the ports and switches between the battery and the head. They’ll probably get bonded in place with epoxy for durability and water resistance, though that will make repairs harder should the need arise.

So I’m looking for advice what to use and where to get for the following parts:

  • Head – I’m looking for something with a medium flood reflector here and a small outside diameter. The Convoy S2 seems about right, but I’d appreciate any other suggestions.
  • Tube – Cutting the rear section off a complete host would work, but if I were to get a head alone, I need a separate source for a threaded section of tubing.
  • Tailcap – just a cap compatible with the threads on the tube, made of something conductive.
  • Spring – if the cap doesn’t include one.
  • Pocket clip – one that fits around the battery tube and is held in place by the tailcap seems ideal to me.
  • Positive contact – I’m imagining a metal pellet surrounded by plastic disc 18-19mm in diameter.
  • Switches – ideally, I’d like three: a forward clicky flashlight power switch, a momentary switch for a mode button and a 2-position or reverse-clicky for the charger.

Ceilingbounce – flashlight testing and runtime graphs for Android