Stay unplugged longer with these genuine thinkpad batteries these rechargeable batteries use lithium ion technology and can be used as replacement for aging system batteries or as a convenient spare battery features lithium ion li ion technology 9 cell system battery battery energy watt hours 94 wh compatible with the thinkpad external battery charger 40y7625 compatible with t4102030 t5102030 w5102030 l41012202130 l510122030 thinkpad l530 l430 l520 l421