I a new toy, about the only one that doesnt have a plugin for external power supply, my Rio 300PMP special edition, but since I Cant plug into it like a car power supply, I have to use batteries, I've been more for duracell, but with the new types of batteries out, like Energizer E2 and so on, which is better, Duracell or Energizer.

(my Rio300 takes a single DoubleAA which is supposed to last 10 hours of use on a generic battery)