Dan,

My experience with the Portable PowerFlarm is that I need to replace the alkaline batteries every 4-5 hours.

I just went to the local low cost warehouse and bought a brick of alkalines and replace them every flight.

A better choice is to put rechargeable cells in the unit and the use ships power to run it. That leaves the internal battery for backup. Be sure to change the setting in the unit for the correct type of battery.

Mike