in my boat i realistically have about 2400 watts rms. i have two batteries dedicated to the system, and one dedicated to the boat only just in case i kill the other two completely. i charge them every time out and they are fine all day. i just leave the switch on batt #2 which is the two system batteries, rock all day and all night and i am fine to start up and go home on the same two batteries. i was even out all night over memorial day weekend. rocked out for 9 hours straight, started right up on the same two batteries. hope that helps. just make sure you get a decent battery and that it is wired correctly. i wouldnt use a battery isolater, because if the battery is too dead, it cant click over to make the connection to the other battery that is charged. i would use a manual switch from perko. they can be picked up at boat shops or west marine.