I dont have the booklet that came with this Craftmaster 7.2v cordless drill. I am not sure of time to charge the battery but I assume it should be at least 3 hours or more. Is this correct?
It is going to depend on a couple factors - how deeply the battery is discharged, the temperature of the battery, and the condition of the battery itself. I'd just leave it on the charger until the charge light goes off.
For other battery tips including some notes on charging, see this post.