The ThinkPad battery 47++ offers extended battery life for the ThinkPad X200 and X201 models. The 9-cell battery can be added to your existing 4-cell system (selected models), or used as an extra to extend your unplugged computing time. It's compatible with the X200 and X201 systems, and the design allows it to be used in a system connected to the ThinkPad X200 UltraBase. The rechargeable system uses Lithium Ion (Li-Ion) technology and ensures a consistent and safe flow of power with over-discharge protection. The current is 11.2 VDC and 2.12 Ah.*Battery life differs due to many aspects. These include: screen brightness, applications, battery features, conditioning, power management and other customer preferences.