I had a little 2/10 amp charger that lasted 15 years until i hooked it up to a six volt battery.

I bought a 53 chevy with a six volt gen and a 12 volt regulator that seemed to work as 12 volt. i used the gen as 6v on another car so don't know how long it would work.

"It ain't a truck if you can't hose out the cab."