Stay unplugged longer with ThinkPad Batteries 73 and 73+. These rechargeable batteries use Lithium-Ion (Li-Ion) technology and can be used as a replacement for aging system batteries or as a convenient spare battery. ThinkPad Batteries 73 and 73+ support our ThinkPad Edge 13” notebooks. (For battery life, go to lenovo.com/alldaycomputing)Lithium-Ion (Li-Ion) technology Six-cell, rechargeable system battery, 64Wh, 11.1 V dc, 5.6 Ah Standard system battery specifications Over-discharge protection Supports ThinkPad Edge 13” notebooks For more information on batteries, visit http://www.lenovo.com/support/batteries or http://www.lenovo.com/alldaycomputing