So one guy at work "lost" a x220 battery, being that its really expensive and he said it might lost at home.. I ordered a AGPTEK battery for the x220. Wont know the long term but its interesting that this one did not display that you are not using an original Lenovo battery warning.

Unfortunately cells are Sanyo, manufacture date 2012/03. For 35 bucks for a 6cell, its a lot cheaper, hopefully long term it'll work well

heres a different review
http://nookkin.com/blog/2010/2/agptek-l ... review.php

Huh. Whats the rated capacity of the battery? And where did you buy it from?