this might sound dumb to some people, but, if you have an extra battery for the evo and is completely charge but dont use it for about three days after you had charge it, will it still be fully charged? why is every one making such a big deal over this battery thing...does it really drain quickly?
It will slowly lose charge over the course of several weeks, but nothing significant in just a few days. If you swap them out on some sort of routine schedule, you shouldn't have any problems. This is based on my experience with lithium polymer battery chemistry in RC airplanes. I can't imagine cell phone batteries are that different, but I could be wrong.

