ive got 4 200mah 9v powermax rechargeable and get @ 3 hours or so from each batt in the ps2 and about 3.5-4 hrs in the ad20.....they dont last as long as the regular alkalines but after several uses it pays you back....i dont mind using them and for the standard 2.5 hr show they are perfect....also a few alkalines in your bag and you have a decent amount of hours to run at festies without paying out the ass for more batts....the 4 batts and the smart charger werent the cheapest, but i use the batts in other devices as well so for me the cost was fine.....the box from soundprofessionals powers both ps2/ad20 and is supposed to extend the run time by alot, but its not cheap either....