[atropos333]

Yeah, like a couple of people above said, it's because the battery overheats, which stops the charging, so then you only have until the battery dies. This is one of the changes they made to Lithium ion batteries after those Sony laptop fires - they quit charging once they hit a certain temp. If you don't use your internet for long periods you may not have noticed it quit charging.

That's an interesting idea about the window, but I think I'd be worried about theft/rain/etc. I've tried a number of things to keep the battery cool (take off the back cover and put my phone on a fan, etc.), but I honestly haven't noticed that make a difference.

I'm thinking the easiest (and maybe the only) solution is to get myself one of those extra thick 3000+ mAh batteries. That way, even if it does stop charging on me at some point, the battery will take a lot longer to die. I don't know if that will get me all the way to 8-12 hours, but I would think it would definitely help.

I was hoping maybe someone had found a way to absolutely minimize the power consumption of tethering, but it sounds like bigger battery may be the way to go.

Thanks for all the input and brainstorming! This has been pretty much my first post to ask this question - but that's only because the site already had the answers to everything else! Too many for me to remember to thank, but lots of people put in lots of hard work here just to help other nerds enjoy our nerd toys. Good stuff.