Originally Posted by Sweetpea
I've got another for you:
When we go on holiday, we generally go with a tent. We don't need electricity (it's only a small tent). Now, let's assume I've an e-ink reader. We'll be going at least 3 weeks. So, that's 3 weeks without electricity. 3 weeks without a chance of charging any batteries. That's not problem for my camera because I have two batteries. It's no problem for my phone as I'll have that turned off unless I need it to make an emergency phone call. But, after two weeks the battery of my e-ink device is dead. It would have been very handy if I had the possibility to bring a spare battery. This is why I like user replacable batteries (and why we always bring a photo camera with us that takes ordinary AA batteries)
Well, that's easy to solve: http://www.amazon.com/MACALLY-Extern.../dp/B000CGG8LW
Or something similar.
As long as you can charge your unit via USB, you can charge it via external battery as well.
I've got 2 such batteries, each about the size of a video iPod.