This is inaccurate. Regardless of whether or not the car is on or off, the auto-wipers do not trigger any sort of beeping.

The long solid tone you hear when you start washing your car with the key still inside is water running over one of the 4 lock touch sensors on the door handles. The car thinks you are trying to lock it but forgot your key inside. This is the only meaning behind the long solid beep.

Multiple chirps/beeps means you've got out with the key & closed the door but left the engine running. This is literally the car saying "hey, don't forget to turn me off before you go so you don't die from carbon monoxide poisoning."

Just as signdetres said. It's page 101 in the manual. Attached is a picture from the manual on how to turn on battery saving. Just remember it turns off the radio waves so if you leave it in the car and you lock it, the car will lock since it can't detect the key.

Speaking of wipers you know you can move them to the service position, when washing also . the same for changing blades. Right after turning off car move the wiper switch to the mist position and hold for 2 seconds, they'll go to the up position on the windshield.

I remember seeing posts on the 8th gen Camry forums and 5th gen Avalon forums talking about the windshield wipers and that it is a 'major design flaw' because when you lift it up, it will hit the top of the hood. Criticizing Toyota on the poor design choices and so on and so forth... until someone pointed it out that you must put it in service position so you can lift it up without hitting the hood... I really like that it retracts below the hood and praise Toyota for doing it even though other car manufacturers like BMW and Mercedes have been doing this for years.