(redirected) MY Dell vostro 1550 charging with very very slow rate ?

i am using dell vostro 1550 which 2 years old . Now i am facing this issue .

My laptop charging at  with very very slow rate . The charging rate was only 2.1 W . It will take 8 hours to charge , First 30 seconds it's charging at 8.4w , then 6.2 w , Then 5.1w at the end 2.1 w.

Can i know what is the normal rate of Watt

The problem is only on charger it seems . But this issue started 2 days back(1.5.2014) . before that i never faced that issue . 

Can any one help me ?? plz