Toyota Repair: 2002 Toyota RAV4 Battery Problem, toyota rav4, trickle charger

Question
When the car is left in the garage for about two weeks the battery is flat. This could maybe be explained by the weather. We also do only limited milage (4-5000 miles annually). But today the battery was flat when I came back from the Supermarket, all was fine in the morning. The battery is just a bit over one year old, garage could not find any faulty drainage. Any other suggestions?

Answer
Have the alternator tested to make sure it is charging the battery as it should, I also recommend that you start the car and let it run for at least 15 minutes every two to three days if not driving for an extended period of time or attach a small trickle charger, some batteries can go dead if not charged up by either the alternator or an external means if left for two weeks or more.