Hi,wondering if anyone has experience with Hyperjuice and their external batteries for extending the life of devices like Macs, iPhones and iPads.

I have a 2012 Macbook Air 11" which doesn't get a lot of battery life, even with Bluetooth off, keyboard unlit, wifi off and screen slightly dimmed. My usual routine is web surfing; using Word, and emailing. Occasionally I use iPhoto but I don't do anything really intensive like gaming or video or photo editing.

So I've started poking around looking at power sources and Hyperjuice seems pretty popular.

Thanks in advance for any input!