Streamlight PolyStinger Li-Ion battery pack

About three years ago I bought a used Streamlight PolyStinger. Like any light, it has positve traits and some not-so-postive traits. And for me, Nicads are a not so positve trait. Charge them up, forget about them, (which you're likely to do if your interests go towards LEDs) and the cells are pretty much depleted in three months. Being a Lithium / Li-Ion fan and having a couple of 18650 cells handy, I decided to see if I couldn't make a Li-Ion pack for the Stinger. First problem was the length. I wanted to wire two 18650 in parallel for greater capacity. But I lucked out. Two 18650 cells are equal in length to three sub-C cells, but because I had to add extra insulatation (wiring in parallel, not series), my pack was longer by about a 1/4 inch. The good news is that the extra length fit into the PolyStinger's tailcap. I sacraficed not having room for a spare bulb. (Which I don't have anyway)



The next issue was replicating the Stinger's unconventional placement of both the positive and negative battery contacts at the top of the pack. I had to use Solder Wick (copper braid) to form my own washer (negative contact).



It works. I now have a Li-Ion powered PolyStinger with a 4.8AH pack vs. the 1.8AH nicad pack. It should be good for 2 1/4 hours of run time. And it can sit neglected on the shelf for two years and still fire up if needed. (Self discharge of Li-Ion is 4 to 5% the first month, 1 to 2% thereafter. Worse case after two years is still 49% charge remaining).

Looks like the circuit protection was also removed. This is only an issue if you reach an over charge condition as Li-Ion cells tend to vent with fire. Polymerw are safer, but the prismatic packs don't fit to well in tubes yet, unless you have a custom shape made.

Would really be interested if one could get their hands on Lithium-Sulfer packs or Zinc-Air. To bad these are not readily out yet, of course they need to get to be a bit more stable.