I'm about to invest in some rechargable batteries for my flashlight collection. After reading lots of posts here about Li-ion rechargables and reading lots of stuff I didn't really understand over on CPF, I haven't found much mention of Eneloop cells. I'm just looking for advice about best practices for using/recharging these cells. Is it dangerous to use them till the very last drop of power? Is it necessary to check voltages and match voltages with one of those ZTS thingies? I've been using either primary alkalines or Energizer lithiums in my AA lights so far, would I notice an output difference using eneloops in something like my nitecore D10 on high? Any advice welcome, I'm obviously new at this and I don't want to destroy any of my lights by being dumb with batteries!