Hot-swappable battery packs are a relatively new development in power technology that provide devices with a semi-infinite energy source without the need for power cords. The main power source is a removable battery pack. Once that runs low or dry, you just remove it, which is easy since, unlike the removable batteries that manufacturers once put in smartphones, hot-swappable batteries are easily accessible. The main hook of a hot-swappable battery device is its ability to remain connected during battery swaps. Unlike the removable power pack, this secondary battery is built into the device and takes over when the main battery is absent.