The 3 cell thinkpad battery 68 powers x240 x250 w550 l450 t450s t450 t550 t440 and t440s systems for longer the rechargeable battery lasts for approximately 235 watt hours and can be used with the t440 t440s and x240 systems each one utilises advanced lithium ion technology and over discharge protection to prolong the life of the battery the battery is safeguarded with a chip which authenticates with lenovo systems battery life is affected by a multitude of factors including fe