yeah my protege had a small power drain in it, and i completely forgot about it, so after letting the car sit for a week in it's winter resting spot, and then decided to take the battery out without recharging it, i left the battery sit "dead" all winter long in a heated garage and then decided to charge it after 3-4 months. it was toast.
moral of the story, keep it charged when not in use! buy a 2amp Dry Cell battery charger that stops charging when full and you will be ok.