There should be a generator in the car, driven by a belt. As long as the car starts running, the generator will generate electricity and use electricity for the power-consuming items on the car. If the battery is aging, there will be no power saving function, and there will be no electricity. There is no electricity when I get off the bus, so I can't start it. When you start it, there will be a slow sound, and there will be a knock of water droplets. The lights don't work, the horn doesn't ring or it rings slightly, which are all symptoms of power failure.