Told a guy I'd do some research for him into a small simple solar system for use in maintaining the charge on a 12 volt automotive battery. Found this at Harbor Freight:
I'm thinking that all he needs to do is wire it up to his battery to trickle-charge it. I think I'd add a diode (IN200x) in series for protection. So will this work?
Since they don't list the output voltage for the panel, except to say "12 volts" in the description, I guess one could opt for this larger one:
which says it maintains a charging voltage of 17.5 volts, which seems a little high: perhaps a string of 3 or 4 diodes in series would drop the voltage just enough to bring it down to the recommended 13.6 volts or so.