Hi, I am an absolute beginner, I want to be able to charge a 12v wheelchair battery while my car is running. The ideal use would be to simply plug the wheelchair battery into the 12v battery on the car or the 12v cigarette lighter. I think I would have to add some sort of Diode so that the current travels to and not from the wheelchair battery while plugged in. I do not want the car to use the wheelchair battery (if that makes sense) Once completed then I would like a second diagram to add some sort of led indicator. is their a led that will only light when battery needs charging or when battery is charged. I would like to have the whole thing run off the main car battery or 12v socket and not involve any ignition fed designs. main battery is 12 60amp second battery is 12v 20amp both are lead acid. I would like to use Anderson pole connectors what amps and wire size, I only want to charge the 12v 20 amp or keep it topped up.