Extend the runtime of your ThinkPad with the Battery 57++. It has 9 cells and so lasts for an incredible 100 watt hours*. It can be used as a replacement or spare for older ThinkPad laptops. It is equipped with over-discharge protection, to help prolong the life of the battery, and is rechargeable.*Battery life varies due to many factors. These include: applications, battery conditioning, features, screen brightness, power management and other customer preferences.