Now my Z5 (v2) battery cannot last longer than 3 hours during normal usage (surfing web, youtube, etc.). The battery can't even fully charged in one shot, eg. it will charge till 55% then stop and continue for charging after 1 or 2 hours. Sometimes the battery will take more than 8 hours to be fully charged.

Does it mean that my battery is dying and need to be replaced soon?

Btw, my laptop is 2 years old.