multiple 12 Volts wont stay charged

I've read numerous posts about 12-volt batteries draining suddenly and everyone is saying, "replace the battery" or "you need to charge it every time you aren't using it." Let me be clear, I have put three brand new batteries in my 08 Prius within the last year, and I'm having issues with all of them draining. For example, I replaced the battery, drove the vehicle every day for two weeks (Long distances only), and came out to start the car and it was completely dead. I replaced the battery three times and this happens to every single battery. I'll charge it, it will work for a little while, and then it'll die again. I just want the dang thing to start! Something is obviously pulling power from the battery.

Is there a common issue with this year of Prius that someone can say, "Oh ya! The capacitor that sits next to the battery craps out after 10 years." (That was just an example) Somebody, please help! Tired of getting stranded.