It simply depends on the model you buy. Some units will be powered via replaceable batteries but the more advanced units will typically require 12 to 24-volt power sources. These same models will also come with a cord (typically several feet in length) and this can be used to connect to an appropriate battery. Now, if you are using the lights on a boat then you will want to avoid using the boat’s battery. Though most options will be highly efficient, using a separate battery will not drain the boat’s battery.