Did you ever see those take along rechargeable batteries that you can jump a car or run small appliances....I use them to power my Foxpro caller....I saw recently that Basspro has them on sale this week. Get the proper jack and you can run your FX5 for hours on these jump start batteries...Make sure you check with Radio Shack when you get the jack or eleswhere...Some jacks are for charging only.. You want the one that is also for running small electronics.....The jack has a cig jack on it and it plugs into the battery...Make sure you get one with a universal or a set of male jacks so that it fits your light and or caller too.... I got mine at Best Buys electronics.....Also make sure you jack as the appropriate plug in for the take along..some might have the cig types some might have the prong type like a regular extension cord....
My caller FX5 last all week when I use this take along battery jumper and small appliance power unti....Note they are 12 Volt battreries....