Keep your device unplugged for longer with the 9-cell ThinkPad Battery 70++. The average run time is 94 watt hours and the battery can be recharged with the ThinkPad External Battery Charger (40Y7625). Each power source uses Lithium-Ion technology and can be used as replacement for damaged system batteries or as a convenient spare. The battery is compatible with T410, T420, T430, T510, T520, T530, W510, W520, W530, L410, L412, L420, L421, L430, L510, L512, L520 and L530 systems.*Battery life varies due to many factors. These include: applications, battery conditioning, features, screen brightness, power management and other customer preferences.