The reason Eneloops are so popular is they are the "LSD" type, or low self-discharge, meaning they lose very little charge by sitting dormant (not that I've ever had flash batteries sit dormant). What many people dont know is that there are some other great brands producing these. Powerex/Maha (makers of the famed AA charger) have the Imedion line of LSD's. And the Tenergy Centuras are an excellent value. The Centuras are the only brand I know of that also make C & D cell LSD cells. I'm a team leader for a search & rescue team and have implemented these Tenergy D cells in all our search lights. This is a classic good example of what LSD's are best for: A very important device that may have to sit for a month or three then get called into critical action immediately.