This is the circuit that can prevent overcharge to the battery (regular 12 volt of the vehicle battery)
1.When the charge voltage higher then "maximum charging voltage(15.3volt)" the system will open loop the "left hand side transistor"
2. The left hand side transistor controlled by the "zener diode" in the circuit
3. Zener diode's breakdown voltage is set on"14.5" volt
4. When the zener diode get 15.2 volt(14.5+0.7 or more) , the right hand side transistor will set on "ON" cause the zener diode
(On=Collector and Emitter pin are connected)
5. The left hand side tansistor will set on"OFF" cause the "right hand side tansistor"
(OFF=Collector and Emmiter are disconnected)
6. Left hand side resistor act as "field coil" in the alternator
(when overcharging , this should be disconnect)
7. The alternator and the battery are parallel
,so the voltage will be the same
(output voltage of the alternator
= battery voltage)
8. You can switch the voltage source in the circuit , it's 15.3 volt , but if you add 0.1 volt , you will see the prevent circuit works
