I am wondering how often Prius drivers service their 12 volt battery? The 12 volt Prius battery being located under the trunk floor is kind of “out of sight - out of mind”. Although the Prius AGM battery case stays fairly clean and the terminals do not get heavily corroded, the terminals still get a layer of oxidation. It is the gray/black colored film that covers the terminals. This film creates resistance, voltage drop and shortens battery life. A clean terminal is bright and shiny. Servicing the battery generally involves: · remove the battery cables and hold-down bracket(s), · clean the top of the battery case, terminals and cable ends with a battery cleaner, · using a battery brush with soft brass bristles, lightly brush the battery terminals and contact areas inside the cable ends until they are bright and shiny, · reinstall the battery cables and hold-down bracket(s), · coat the reinstalled battery terminals and cable ends with a battery terminal protector. This is an inexpensive and easy task that if done once per year will prolong battery life and keep it in top condition. I just cleaned my battery which is now three years and 50,500 miles old. The resting voltage is 12.8 volts and the car has had no battery/electrical problems. Below are the three battery cleaning products I use. Edit: I meant to post this in the Gen III forum but it applies all Prii.