So are you guys saying that a 30 day run time is impossible because you would charge your battery after 10% of its usage???
If I'm not going to be using certain cells, they get discharged down to 3.6-3.7v, placed in plastic snap cases, then ZipLocked and off to the fridge they go.
I run cells down to 3.4v, 3.5v and even further, just for shits and giggles, so I'm not too worried, but I don't want to kill things prematurely if I don't have to.
Li-ions can be recharged after even a drop to 4.10v, but I don't fret over that too much.
I remember starting out with them and my Xtar WP2 II charger would undercharge a bit and I'd take the cell off and reinsert it to get it up from say 4.17v, to 4.19v just because this is America and bigger is better!
Smarter people than I thought that this might not be a good practice for the cell, so I stopped.
When they get down to that 3.5v-3.6v level, it's probably a good idea to charge them back up.
Now, if you're going to be out 'caving' and your cells are at 3.9v, I'd probably charge them up before I went traipsing off.
Chris