I found this thing called a "cell rescue" it was on clearance at compusa for like 1.94 or something. it takes 3 AAA batteries and can charge a Nokia phone. I use it with a CA-44 and it can power the 770. This could be one idea use some velco or something to attach it to the back of the 770 or something. Plus it has a built in flashlight, lol. Here is the link to compusa.

http://www.compusa.com/products/prod...310&pfp=SEARCH