The defining feature of the Lenovo ThinkPad X240 battery system is its Power Bridge Technology, which combines a built-in internal battery with an external hot-swappable battery. This design allows you to change the external battery on the go without shutting down your laptop.
Hot-Swapping Ability: The system drains the external battery first. When it runs out, the internal battery takes over immediately, letting you slide out the dead battery and pop in a fresh one while keeping Windows running.
Intelligent Discharging: Lenovo's power management prioritizes discharging the removable external battery first to preserve the lifespan of the harder-to-replace internal unit