Yes, I use off the shelf DX 18650 cells and a couple of Panasonics I have. Just unscrew the back cap and pop a new cell in. This is the number 1 criteria for me with a battery light. Back up cells are just a few bucks and very easy to carry. When the indicator switch turns from yellow to red then I have about 10% life left and I switch cells at next convenient opportunity. I can run the cells all of the way down this way, carry a very small and light spare, and never worry about leaving on a ride with an unknown amount of charge in the light. Other manufacturers seem to want to make a 'special' battery pack that you have to buy from them for a ridiculous price. Or the pack is not removabe at all and you are screwed if you find out your light is nearly dead when you are heading out for a ride. To me this is the best scenario. Now if they just would make a shaped beam versio!