Hey, my PGL III C came today and I need to know if I can use the 18650's with 2 flat poles or do I need one with only the negative pole flat. Thanks, here's a picture:
Yes, that is for an 18650 lithium ion, non-protected. You don't need the protection circuit board in the battery since you are using them as single cells. Because the protected batteries are a bit longer you could end up stripping the threads on the body if you try to tighten the cap too much. Oh, the two flats are fine.