The 6-cell ThinkPad battery 77+ is a replacement/spare battery for P50 systems. The battery is rechargeable and can be used as a replacement or as a convenient spare for mobile workstation ThinkPad P50 systems. This battery is powered by Lithium-ion technology and has a safeguard chip which authenticates with Lenovo systems. The battery lasts on average 90 Watt-hours and utilises over-discharge protection to ensure a secure flow of power. Many factors affect battery life. These include: screen brightness, battery conditioning, features, applications, power management and other customer preferences.Lithium-Ion (Li-Ion) technology 6 cell system battery Over-discharge protection to prolong the life of the battery Battery energy (Watt-hours): 90 Wh Battery Safeguard chip authenticates with Lenovo systems Application/Usage: Notebook Battery Chemistry: Lithium Ion (Li-Ion) Application/Usage: Notebook Battery Chemistry: Lithium Ion (Li-Ion) Product Type: Battery Product Type: Battery Compatibility: Lenovo ThinkPad Mobile Workstation Models: P50 P70 Manufacturer Part Number: 4X50K14091 Limited Warranty: 1 Year Weight (Approximate): 1.04 lb Manufacturer: Lenovo Group Limited Product Model: 77+ Product Name: ThinkPad Battery 77+ (6-cell, 90 Wh) Product Line: ThinkPad Brand Name: Lenovo Brand Name: Lenovo Height: 0.7 Width: 8.1 Depth: 2.3 Battery Size: Proprietary Battery Size Battery Rechargeable: Yes Product Family: ThinkPad Battery Size: Proprietary Battery Size Battery Rechargeable: Yes