A method includes powering a device using one or more first power sources and coupling one or more second power sources to provide power to the device. The method also includes replacing at least one of the first power sources, where the one or more second power sources provide power to the device during replacement of the at least one first power source. The first power source(s) could include one or more first batteries in one or more first battery slots, and the second power source(s) could include one or more second batteries in one or more second battery slots. The second batteries could be inserted into the second battery slots prior to replacement of at least one of the first batteries. The first power source(s) could also include one or more batteries in one or more battery slots, and the second power source(s) could include a portable voltage source.