You are so lucky that I spotted your post.I have been searching for that
answer myself and I have the perfect solution for you. Two ways to do this
(I picked number 2):

1) I am not sure about your Pocket PC but, check your manufactory to see if
they are selling battery that last longer than your original battery. This
product tend to be expensive.
2) Or you can create your own charger. Very cheap and very easy to put this
together. Checkout this website and look at very bottom of page:

http://www.pocketgpsworld.com/aeroplane.php

Hope that you like my answer!

By the way, what software do you use for this type of flying? I'm curious.

Toks Desalu
PP-ASEL
Dyin' to soar!