If i leave my car in the garage for more than 2 days the battery dies!!!

Now i just went out to put it on charge and it would not even charge it was flashing from charging to charged/maintaing and making funny noises! Also as it was doing this i could see the light on my alarm dimming up and down!

So disconected the sounds, tv's ect from the battery thinking this may be causing it......Put it on charge and still the same! Disconnect everything of the battery and charge it and it is fine! Something is seriously draining my power

Any idea how to find out what