Also, keep in mind that the hd-p2 will seamlessly transition from internal batteries to external. I used a pair of wooden dowels to make two fake internal batteries and used screws at the ends of each dowel to feed power to an external battery adaptor -- this allowed me to use two dvd batteries to run my hdp2 and avoid any concern of losing power. In retrospect, I believe that if I simply used nimh aa batteries in the internal battery slot, I'd have had all the power I'd ever need -- my hdp2 would run for 8-10 hours on a dvd battery while providing phantom power