My car (a Toyota Avensis 2001 Diesel 2.0L) often lays idle for long periods. During these periods the battery runs down and it is unable to start. I recognise that the car should be driven more often but unfortunately it is not possible sometimes.
I have a portable jump starter device (http://www.walter-service.at/index.php?page=product&info=1604) that I have used for previous car, however it does not work with this car.
It has been suggested to me that a device with a higher current might be more capable of starting the car. Is this true? If so, how can I determine if the current is large enough for my car?
In summary, how can I best choose a jump starter which is suitable for a car?