Introduction: Solar Charged 12V Lead Battery

By http://asi.lv/alnis/
About: I am a researcher leading quantum optics labiratory. Previously I was working on development of optical atomic clocks. Electronics is my hobby since childhood when my uncle was bringing me old phones to play a…

Here is described how to make a solar charging station for a 12V lead battery. 8Ah capacity allows to keep alive a wireless webcam 24/7.

Lead battery needs protection against overcharging and deep discharge that is realized by  two black boxes.

One box switches off solar cell when the battery voltage becomes 13V. Construction is done using a prototyping board.

Another black box protects battery for deep discharge. It switches off the load when voltage decreases below 10V and switches it back when voltage increases above 12 V. Emphasis is on low idle discharge current tha tis 5 mA.

Nice internet link about the solar charging topic is here
http://ludens.cl/Electron/solarreg/Solarr~1.htm

There is also a 12V to 5 V converter to supply digital devices, for example, cell phones that can be charged from USB. DC-DC converter  one on picture is from Traco Power and draws 25 mA when idle.  That is quite much. The one with smallest idle current of  5.5 mA was found from PowerTrends 78 SR 105 VC with specs 30 V in, 5V 1.5A out.