How to make the 12 volt battery last longer on the 2004 to 2009 Prius
If you have Smart key you should turn it off when ever you are going to leave the car parked for more than a few days.
Why is that? When the Smart key system is working you do not have to push a button (originate a communication to the car) to unlock the car or unlock the ignition. Consequently, the car has to originate communication to the FOB regularly. (Are you there? Are you there? ...) This requires power and after a many days can drain your battery.
In the 2010 Prius the engineers got around this problem by turning the Smart key system off automatically after a few days.
For 2004 to 2009 owners you can manually do the same thing whenever you are going to leave the car parked for more than a few days. Turn if off by pushing the button pictured above in. When it is off you will have to fish the fob out of your pocket or purse and push the unlock button to get into the car. (A lot easier than jump starting the car.) This also promotes battery life.
When you do need a battery we recommend the Optima because we have had very few warranties claims on it and many of our customers have now had their battery for over five years. The one in my Prius is now about nine years old and I can still leave a dome light in the car and start it the next morning no problem. For more information go to: http://www.elearnaid.com/opdsopbadifi.html