Battery drain

when i got the car i put a new battery and about to change the alternator. after 2 days the battery is dead and i`m about to put the alternator in but dont want to fry it.how do i check where the discharge is?

More data:

  • Why did you put a new battery in?

  • Why do you plan to put a new alternator in?

    It appears you put a new battery in a car that you believed may have a problem with the alternator. Why did you put the battery in before the alternator?

    The point I am making is while the two are related to each other why do you think in this case it is both of them. I might add it could have been caused by neither of them.