As I mentioned early in this thread, a 12V motorcycle battery would be plenty adequate for several days' running even without the voltage doubler. Just plugging in a battery maintainer when the vehicle is parked would keep it charged well enough to dispense with any sort of sophisticated electronics. It's the cheapest, simplest way to address the need for 12 volts in a 6V vehicle, but some of our bunch aren't happy unless they're throwing boatloads of dollars at a problem.
Back in the late 1960's I had a friend who drove a 6V Volkswagen Beetle with an 8-track tape deck in it. He powered it with a small 12V battery, and charged the battery about once a month. He used that tape deck a lot, and those things had motors, solenoids, and some pretty powerful amplifier channels. They used several times the current a modern sound system does, unless somebody's trying to power a truck bed full of subwoofers and playing rap music that will bend street lamp posts!
Jerry
