Here's my Popular Science How 2.0 article on turning yourself into a walking hotspot by using a mobile power source and a cellular-to-Wi-Fi gateway. The Voltaic Systems backpack makes a great platform to build from due to all of the internal wiring and myriad power adapters included in the kit. And I like the Junxion Box as a simple, clean appliance to handle the Wi-Fi to Cellular interface.
The Junxion Box requires a 12 volt power source. So, natch, a lead-acid battery would feed it the juice it needs. Starting with a 1.2 Amp-hour battery will let the whole kit run a few hours. (The Box draws between 200 mA and 500 mA of current while active.) Adding a bigger battery will lengthen your run time. Solar adds a bit of extra runtime and will keep your battery topped off when the system isn't running.
The full article gives step-by-step and a parts list for you to make your own. Fun stuff!
1. Wow, is THAT expensive! About $800!
Posted at 5:29AM on Dec 19th 2005 by gemixman