seattle_sun

It depends a lot on how often and how you drive the car. Starting the car will require driving 20 minutes to re-charge the battery. If you do a lot of short trips, it's easy to drain the battery.

FWIW, I found the Ctek chargers to be great if you have a healthy battery, but not strong enough to bring back a flat battery. I switched to this charger http://www.saveabattery.com/. It's a great charger/maintainer and works much better than the Ctek.