Portable Options?

I have a kayak and want to get a fishfinder. I have looked online at the Humminbird PiranhaMAX 215 Portable. Does anyone use this to give me some input and if you think it be easy to use in a kayak? I can't find anywhere that shows the power source, dont really want to haul around a 12V battery, I got the yak because I can haul it & go by myself.

If anyone has any other suggestions, I'm open to any thoughts.
Thanks in advance!
Russ

i have a garmit fish,depth.fish finder it runs on 2aa batteries go to bass pro