MacBook Pro keyboard replacement: Refurbished or new components?
Batteries are never refurbished and installed brand new. The usage status of a battery can be determined by looking at the consumed charge cycles (1 full charge and discharge constitute 1 charge cycle).

You can easily determine the battery charge cycles consumed by going to  → About This Mac → System Report... → Hardware → Power → Battery Information → Health Information → Cycle Count. It should look something like this:



There's also an excellent 3rd party tool called coconutBattery which is very easy to use.