The 6-cell ThinkPad battery 71+ is rechargeable and can be used as a replacement battery. This battery is powered by lithium-ion technology and has a safeguard chip. The battery lasts on average 48 Wh and utilizes 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 technology 6-cell system battery's over-discharge protection prolongs the life of the battery.