Stay unplugged longer with the ThinkPad Battery 75+. This rechargeable six-cell battery uses Lithium-Ion (Li-Ion) technology and can be used as replacement for aging system batteries or as a convenient spare battery- Compatible with the ThinkPad Battery Charger- Lithium-Ion (Li-Ion) technology- Six cell, rechargeable system battery, 62Wh- Standard system battery specifications- Over-discharge protection