batteries are lithium, and last 6 mos. they are easy to replace, but you have to readjust the cameras afterwords. the recording on these are sporadic at best. They did not work for me when I was robbed for 10k of product. this was why I bought this thing. then when we went on vacation, the thing wouldn't record at all on one camera. It sent the signal to camera A to record on camera B, even tho the motion was in camera A. they whole thing is micky mouse, a waste of money