Where did you buy yours? I bought an old X61 and the battery was crap. I can only find affordable genuine ones on eBay. The ones on Amazon were $200... So it didn't make sense to buy them
I buy 3rd party replacement batteries on Amazon. The original batteries have degraded by now, and replacing the cells is a tricky operation: https://hackaday.io/page/247-replacing-lenovo-laptop-lithium...
That's probably a fake or aged battery, or your power management is set up incorrectly. A X62 with a fresh battery lasts a lot longer than 2 hours.