I'd get yourself a battery conditioner. The CTEK ones are good and just plug it in and forget. I bought the CTEK MXS 5.0 and I'm impressed - before when the battery was low the car ran a bit lumpy when started, guess the alternator was working flat out. Now its much smoother... so its not just about being able to crank the engine.
Wouldn't leave the car as it is for a month at this time of year, the cold won't help the battery life. Newage scoobs have been known to trigger the alarm when the battery drops too low too... no idea about the newer ones but not worth risking it if you're in South America
