I have just recently installed a Pioneer video system in the Odyssey. The system looks and works great, but I have some conern for the van's battery. Usually a movie is around an hour and more long which would leave me running on the car's battery. I am afraid if I use it for too long my battery will die which would leave me no battery to run the engine. On the other hand if I leave the car's engine running, I would waste a lot of gas. What should I do ??