I have a 1995 325i convertible that gets part time use. It sometimes sits and the battery starts to wear down. Over Christmas I received a solar panel trickle charger for the car. It can plug into the cigarette lighter of the car to keep up the battery charge. Will this mechanism work in this car? I am wondering if the battery will receive charge when the power is off in the car, or will the circuit to the lighter only function with the car operating?