Jim Yanik wrote in
:

Chris Hill wrote in
:

On Thu, 26 Feb 2009 11:26:00 -0800, David Nebenzahl
wrote:

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:

http://www.harborfreight.com/cpi/cta...emnumber=96418

It's a 12 volt, 15 watt panel for cheap ($70).

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:

http://www.harborfreight.com/cpi/cta...emnumber=40085
(20 watt panel, made for charging auto & RV batteries, $190)


Without a charge controller, it will probably boil the battery.
There are items made to do what you want, a plain solar panel with no
regulation isn't one.


to -maintain- a charge,all you need is a few 100milliamps into the
battery. You won't boil it with that low a current.HF sells a small
solar panel,IIRC,1-1.5W. It plugs into a cig lighter socket.


You must mean this one:
http://www.harborfreight.com/cpi/cta...emnumber=44768

If solar is not a groundrule a couple more possibilities:

http://www.harborfreight.com/cpi/cta...emnumber=42292

This one looks interesting since it's mounted under the hood and you
just plug it in to an extenion cord.

http://www.harborfreight.com/cpi/cta...emnumber=99857


Of course, I have no idea if any are worth anything or if they will
trash the battery.