Solar NiCad battery charger

Solar NiCad battery charger

This circuit is designed for low power or low Ampere hours Nickel cadmium battery chargers. Up to 12 solar cells are used in this project to charge battery. This circuit can be used to charge small NiCad batteries. Charging current of battery should not be greater than 200mA. I have already posted many articles on high power or current solar charge controllers. You may check following articles:

If you want to design solar controller to charge high power batteries I recommend you to check above mentioned articles. This circuit is designed to charge low Ampere hour batteries.

List of components for solar NiCad battery charger:





Capacitors,”C1 / 16 volt,47uF,

Capacitors,”C2 /40 volt”,100uF,

Integrated Circuits,”U1″,MAX639 Integrated circuit

Diodes,”D1″,1N57117,Zener diode

Diodes,”D2″,1N57117,zener diode

Miscellaneous,”L1″,100uH, coil type inductor

 Circuit diagram of solar NiCad battery charger:

Circuit diagram of solar charger for NiCad battery chargers is given below. At the right side of circuit diagram, 12 solar cells are used to charge battery. Integrated circuit MAX639 is used to regulate charges from solar cells to NiCad battery.

solar NiCad battery charger
solar NiCad battery charger

 MAX639 function and working:

MAX639 is switching regulator which is used to step down voltage. It provides a wide range of output current. It can provide maximum output current of 200mA in safe range. It has a very high-efficiency due to pulse frequency modulation function. Input voltage range to MAX639 is 4-12 volt. It can provide output voltage from 1.5 volt to maximum input voltage.

 Applications of MAX639:

It can be used in various configurations in many projects. But some of the major application of MAX639 is given below:

  • Battery chargers
  • Solar chargers
  • Voltage regulator
  • Dc to dc converters

1N57117,Zener diode is used to provide constant voltage to battery. Share this article with your friends by clicking on social media icons shown below thanks 🙂

5 thoughts on “Solar NiCad battery charger”

  1. I’ve been looking to build your design but I am having trouble locating the Zener Diode with the number you provided and you do not define a specification or rating on the Diode. Could you please provide additional information on components?
    Thank you in advanced.
    Best regards,


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