I am looking to fit a 400W, 12V power supply to my car for using the lights and such without draining the battery.
My plan is to have a rotary switch to disconnect the battery and connect the mains->12V power supply in quick succession.
I think I have pretty much solved it apart from 1 final step - using capacitors to maintain my clock and stereo settings in the moment between the two power sources being switched over.
I have bought 4 x 1mF capacitors rated for 50V (so as not to risk damaging them with the voltage) and plan on using them in parallel to provide the momentary power. As I understand it, this should provide 48mA for about 1 second when charged to 12V (and as I will be twisting the rotary switch straight around, this shouldn't be an issue... as far as I understand it).
I would have the capacitor bank connected with the negatives to my car's ground, and the positives directly to the feed to the car (as in, after the switch) so that they are permanently connected to my car.
So now you know my plan, my question is this: would I need to put a resistor in series with the capacitors to limit the current, or would they only provide what current is needed by the clock and stereo in the same way as the battery currently does? I don't want to go firing a massive current down the line if it could damage my electronics!
Thanks in advance guys, and sorry for the long post!