Portable batter power for your devices is now inexpensive an a necessity for every device user.
Nobody does it better that iFrogz.
http://www.ifrogz.com/portable-power
They have a charger or batter device to meet your needs.
I use the GoLite 7800 and unfortunately it says it is backordered right now through iFrogz. Maybe you can get it at retail store or somewhere else online. It holds enough juice to charge about 5 devices at a cost of around $50.
Get one for yourself and one as a gift.