Unfortunately a number of hybrid owners have experienced similar problems to you, and it appears that it tends to be how the vehicle is used that is causing the battery to go flat. Frequent short journeys can mean the 12V battery has insufficient time to recharge, and leaving the car parked for a period of time can cause the battery to drain. Some owners have reduced the likelihood of this issue by taking longer drives more regularly, using a trickle charger or fitting a larger capacity 12V battery. Some owners have also found that storing the keys further away from the vehicle when parked at home has helped the issue, as it prevents the car from 'searching' for the keys which can also drain the battery.

There are no guarantees that a different hybrid will not experience the same issues, as it is the use of the vehicle that plays the biggest part in battery issues.