The JVC stereo in my 2.0 roadster needs a constant small power source to remember the settings (radio stations etc.). When I was experimenting with replacing the JVC with a newer unit, this voltage was lost and the unit now does not remember the settings. I still want to use my JVC and I need a new source to constantly power it when the car is parked, to prevent loosing my settings.
I have tried connecting to a chargeable battery and charging the battery while the car is running, it seems to work but it is a bit complicated and the battery must be quite large and the guy helping me it can be dangerous if it charges at a too high amperage.
Do you know of a better way? Is there a constant 12 volts supply that can be accessed inside the hole for the stereo?