Hi Tom Hammond suggested I mention that my solar controller does not really need a solar panel to work as a battery charge controller. Any power supply that can be current limited in the 16 to 24 volt range can be used as well. A 18 volt transformer, rectifier and filter cap and large limiting resistor will work.
To figure the limiting resistor use ohms law to get the value. For example for 2 amps charging current and a 20 volt power supply subtract 11 volts for the discharged battery voltage from the power supply voltage. That is 9 volts divided by 2 amps is 4.5 ohms. To get the power rating for the resistor square the voltage drop that equals 81 and divide by the resistance 4.5 ohms that equals 18 watts. Add some margin to the resistor for safety and a 2 amp fuse to protect the power supply in case the battery should have a shorted cell or other defect. I would use a 20-25 watt resistor. You can use this power supply or a solar panel to charge the battery with the controller depending on your needs. The controller can be mounted in your battery box and either the power supply or solar panel can plug into the controller. Thanks Don Brown KD5NDB _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
