No, on a 2a charger it should be taking well over 4 hours to fully charge from flat. Either the battery is coming to the end of its life, and losing capacity or there is an issue with the charger causing it to stop charging too early.
Have you got a multimeter to measure the battery voltage with? If so charge the battery and post back saying what the voltage reading is from the connector pins on the battery. Should be around 41-42v fully charged, and around 34v empty.