Hello and good evening, I would need a little help and hope that I am right here. Starting situation is a camper with starter battery and build-up battery (i.e. 2 circuits). The radio is switched on and off via the ignition, that is to stay that way. Operating current comes over the starter battery. My idea is now: to switch the radio over a relay to the build-up battery if necessary to listen to music when the ignition is switched off. So, could you have a touch switch If this relay then gets power via the ignition, it switches back to the circuit of the starter battery. If the ignition is switched off, the relay remains on the starter battery circuit and the radio goes off. If I press the button, the relay switches back to the builder battery. If I press the switch again, without switching on the ignition, the circuit will be switched on. the starter battery restored –> Radio goes off. 1. I would be interested in your opinions/ideas about it. 2. Is there a relay what can do that or do you have to solve it via two relays? Problem is maybe that comes over the ignition continuous current and over the button only one impulse!? Have attached a very simple drawing. Hope you get out there! Looking forward to your answers. Have a nice evening. Sven