i know i've seen allusions to this request before, but either never quite what i'm looking for or i've missed it.

i've got two 6 volt pv panels, and i want to build a trickle auto battery charger, but i know just enough to be dangerous. i need a circuit diagram (preferably w/specs) to build the circuit i need to get the job done.

any help/references/links would be very much appreciated!!

thanx all!

-- Cowardly Lion (cl0001@hotmail.com), December 16, 1999

Answers

Hook the + of panel A to the - of panel B. You now have 12VDC from A- to B+. You did not say what the AH (amp hours) of the battery is or the amps/watts of the panels are. IF the battery is big and the panels small, just hook them up directly and check voltage and electrolyte density every couple of hours. See both http://www.windsun.com/Batteries/Battery_FAQ.htm and http://www.dcbattery.com/faq.html for information that will help you a lot. You will get a "feel" for how often you need to check things. Start by checking every 1/2 hour for learning purposes and write everything down.

You can get nice charge controllers that will do this automatically and also tend to keep your battery desulphated for $50-200 from Wind and Sun (they sell Trace). You need a charge controller that is matched for the absolute peak (+ 20% for Kentucky windage) output of your panels.

-- Ken Seger (kenseger@earthlink.net), December 16, 1999.

thanx, Ken, i'll check both those references. i *do* know how to get 12vdc total, and right now i don't know the specific Ah values for battery or panels. i was looking more for a diagram that showed diode hookups for current flow, knowing full well i'd have to check charge manually.

the panels were scrounged from two solar fence chargers, i can't afford a 'store-bought' charge controller. this will be something that sits in the sun on bright days and hopefully powers a radio or light for a few hours a night.

thanx again, i've enjoyed your work before, and i'll get on those links right now.

-- Cowardly Lion (cl0001@hotmail.com), December 16, 1999.

Those panels might have a built in diode in them already. To find out, take the panels to a dark room and with a small flashlight to read your ohmmeter measure the ohmage of the panels in both directions. If not, just findout the max. amps of the panel and buy a diode from Radio Shack that is a bit larger and put it in series anywhere in the circuit.

You can get digital multimeters very cheap, and are probably a lot more accurate than a cheap analog meter. A really good all glass (breakable!) hydrometer should be about $12-15. A very reasonable all plastic (including the float!) should be about $10.

-- Ken Seger (kenseger@earthlink.net), December 16, 1999.

P.S. Do you follow http://206.67.59.5/wwwboard11/ GN's Power forum? there is a lot of good stuff there, except that it all scrolls off every two weeks.

-- Ken Seger (kenseger@earthlink.net), December 16, 1999.

thanx again. i've already got a good multi-meter (except it's analog). i can't get your first link to open. have you checked it lately?

-- Cowardly Lion (cl0001@hotmail.com), December 16, 1999.

Need more info....battery AH capacity, panel AH capacity or size, open circuit panel voltage or even some rough guesses, dimensions, etc. You may not need a regulator. A $50 BZ Products 8/12A controller would be a good candidate if you need one.

DCK

-- Don Kulha (dkulha@vom.com), December 16, 1999.