The one question which I have not seen here is: How long did the car sit before the battery was discharged? Also, were any lights on in the car? Either condition could discharge the battery. If no lights were left on and it was only a few days, it is time to consider whether there is a short in the system or whether your battery is nearing the end of its life. The time to replace a battery is before the winter not when it craps out in an inconvenient place.