The Steripen ultra is rechargeable, and I carry a battery for my phone, my Garmin Mini and watch, so if I ever do need a charge.. Im covered already. All my trips using it, only 1 time i forgot to charge it before I headed out and on the second night it needed a quick charge.. no biggie. Never had any problems with it though, so easy and fast to use also.. right into the smartwater bottle, upside down and swirl 90 seconds.. Done!! I usually wrap my dirty water bottle with black duct tape.. thats the one I will fill, sterilize.. then pour it into my other smartwater bottle. I sometimes also tank up and drink.. leave my clean bottle filled and ready to drink, then just fill the dirty water bottle, cap it and hike on.. can always Steripen it later.