The thinkpad 28 9 cell battery can serve as a more powerful replacement for your standard t or w series notebook battery these 94 wh rechargeable batteries use lithium ion technology and can serve as replacements for ageing system batteries you could also use the thinkpad 28 battery as a convenient spare battery to keep on hand when you need to keep your system powered for several hours on end this thinkpad battery is compatible with t4102030 t5102030 and w5102030 series notebooks