Solar Power Li-Ion Battery Charger Circuit

Last Updated on March 16, 2024

Simple Solar Power Li-Ion Battery Charger Circuit designed by using IC CN3065 with few external components. This circuit delivers constant output voltage and also we can Adjust constant voltage level with Rx (here Rx = R3) Value. This circuit takes 4.4 Volt to 6 Volt from solar panel as a input power supply, Output voltage to charge Li Ion battery at J2 can be calculated as.

Vbat = 4.2+3.04*10^-6*Rx


Vbat (J2) = 4.2+3.04*10^-6*R3

Vbat (J2) = 4.2+3.04*10^-6*10

Vbat (J2) = 4.2 Volt.

The IC CN3065 is a complete Constant Current, Constant Voltage Linear charger for single cell Li-Ion and Li Polymer rechargeable batteries. This IC provides Charging status and Charge Done status. It comes in 8 Pin DFN Package.

Circuit Diagram

Components Required (BOM)

7GREEN1, RED1LEDLED_0805_2012Metric2

Construction & Working

IC CN3065 comes with on chip 8 bit ADC and it can Adjust Charging Current Automatically based on the output Capability of input power supply. This IC suitable for solar power system. This IC has Constant current and constant voltage operation with thermal Regulation to maximize charge rate without risk of overheating. This IC provides battery temperature sensing.

In this Solar power Li ion battery charger circuit we can use any 4.2 V to 6V Solar panel and charging battery should be 4.2V li ion battery. As mentioned this IC CN3065 has all the required battery charging circuit on chip, we don’t need much external components. Power supply from solar panel directly applied to the Vin pin through J1. C1 Capacitor performs filter operation. Red LED indicates charging status and Green LED indicates Charging done status. Output voltage to the battery obtained from BAT Pin of CN3065. Feedback and Temperature sensing pins are connected across to the J2. Refer datasheet for current and voltage regulation details.

Printed Circuit Board

Solar power li ion Battery charger circuit PCB Gerber Files.

Interactive Board Viewer


3 thoughts on “Solar Power Li-Ion Battery Charger Circuit

  1. Interesting project! Thanks alot

    But can i hook up a load to the battery and charge it simultaneously?

    Or is this circuitry just able to charge LiOns?

  2. If I want to chargeb the battery with Solar Panel, with a provision for charging the battery from Mains power whenever Solar Energy is not adequate or not availablelike rainy days, how do I do it?

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