The Lenovo Think Pad battery 47+ means that you can increase the capacity of your 4-cell system battery on selected models or extend your unplugged computing time by carrying a spare. It is compatible with the X200 & X201 systems, & the design allows it to be in a system connected to the Think Pad X200 Ultra Base. The 6-cell, rechargeable battery utilises advanced Lithium Ion (Li-Ion) technology to create an efficient & balanced power source. The current is 10.8 volts & 5.2 ampere hours. The over-discharge protection safeguards against incorrect voltage & ensures a safe flow of power. * Battery life varies due to many factors. These include: applications, battery conditioning, features, power management, screen brightness & other customer preferences. For more battery life information, go to lenovo.com/alldaycomputing.