>>1258345Just get one with a lot of capacity, worth it unless you're really conscious about it's size or weight. I got mine for $60 5 years ago and it's 18,000mAh. I can charge my tablet 3-4 times or my phone/MP3 etc ~15 or more times. It's a bit of a brick though, but in the days before flights and busses had outlets and USB ports bring able to watch videos for 9h straight and only go through 40% of it's battery has paid off.
I dunno about waterproof though, but unless you're planning on hiking/camping in heavy rain you should be fine if you put it in a plastic bag deep in your pack.
