Simple 1.2V AA battery Solar charger circuit

This is simple 1.2V AA battery Solar charger circuit. If you want to charge only one 1.5V AA battery and must used at outdoor that don’t has home electricity. We will also use fast it so we need to application devices near us.

measure voltageof solar cell about about 3_3V

This project is very easy and cheapest because we use a solar cell 3V 160mA and I measure voltage about 3.3V as Figure 1 so enough for charging.

And I will use AA 1.2V 700mAh Rechargeable Nickel metal Hydride Battery.

In addition, we need to have a diode. To prevent reverse voltage from a battery to the solar cell when no sunlight.

circuit-diagram-of-aa-1-2V-Rechargeable Nickel metal Hydride Battery

We use a number 1N4007 diode because it is cheaper and high pressure 1000V 1A general enough to use it.

AS Figure 2 we connected them in series are simple circuit.

aa battery is charged fully

We will take a charge of about 8-10 hours, or about 8.00 to 17.00 clock.
It will have full power, can measure voltage of approximately 1.3V. as Figure 3

Simple solar radio battery charger

This is the simple solar solar radio battery charger circuit. A solar cell radio used a 3V (or two 1.2V) nickel-cadmium battery or nickel-metal hydride battery in it. The battery can not be removed.

It uses a mini-jack socket for charging. It is quite difficult to find such a voltage charger. Here is the circuit to convert the voltage from the general power supply or Solar cell.  This circuit cause voltage drop across the battery is 3 volts.

Ni-Cad Charger for Solar Cell Radio using BD140

How it works

Simple solar radio battery charger circuit

In circuit, we use two transistors for controls a steady current to the battery.
The resistor R-22 ohms and 3.3K are connected as voltage divider circuit to bias NPN transistor BC547 works.

Then LED1 light up and voltage is steady so the current through the PNP transistor BD140 is the fixed(steady) current to charge the battery.

We can use  the Vin  as both 5V and 6V, which we need to change:
R1=22 ohms for 5V and R1= 27 ohms for 6V ,and then
R3=270 ohms for 5V and R3=330 ohms for 6V

Parts you will needs
Q1_BC547_45V 100mA NPN Transistor; Quantity = 1
Q2_BD140_80V 1.5A PNP Transistor; Quantity = 1
R1_22ohms(5V),27ohms(6V)__1/4W Resistors tolerance: 5%
R2_3.3K__1/4W Resistors tolerance: 5%
R3_270ohms(5V), 330ohms(6V)__1/4W Resistors tolerance: 5%
R4_47ohms__1/4W Resistors tolerance: 5%

What is more? Not only that. Look:

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I always try to make Electronics Learning Easy.


  1. thomas

    nice sir but where we get that solar cell 3v and what will the cost

  2. Sean Straw

    A 2V solar cell would be more appropriate for charging a single rechargeable battery. With the standard 0.7V drop of a diode, you’ll have 1.3V of charge voltage, which won’t be high enough for a maximum charge, but a Schottky rectifier diode selected for 0.5V forward voltage drop would get you 1.5V charging.

    The 3V cell could charge two 1.2V rechargeable cells in series. While series charging isn’t a great approach (individual batteries have different characteristics, and when one of your batteries is going bad, series charging will present problems for the other battery), it’s not as if this solar cell + diode approach is a battery monitor with current regulation anyway. Use a Schottky diode with a circa 0.25V drop, and you’ll have about 2.75 charge voltage: 1/2 = 1.375V charge for each battery.

    I get epoxied 2V 100mA cells off of for about US$1.00 each in quantity.

    Additionally, you should note charge current – a good rule of thumb is not to exceed 1/10 of the battery capacity – so a 2000mAh battery can take a 200mA charge – much more than that, and you’ll be damaging the battery by trying to charge it too rapidly.

  3. nicole

    I want to run 2 volt solar Christmas tree led lights that currently have a AA battery running it in a remote area during the day as well as night. it only operates at night now, the lights are 170 mA. I tried modifying with using an additional D battery hooked to another small solar charger and covered the sensor closest to the lights and it runs barely during the day and is dead by night. what do I do? this is a month long use so I don’t want to spend a lot.

  4. sandeep

    a 3 volt solar cell used here for 1.2 volts. isn’t it feasible to use 2 rechargable batteries in series. 3 volt solar cell won’t trouble a 1.2 volt battery?
    and second question is how will it take 8-10 hours? 700mAh battery , won’t it take approx 4,5 hours to recharge?
    must reply please.

  5. Jan Wixon

    Wanting to buy a solar panel to charge 1 Aa 1.2 volt battery

  6. Doug Scherer

    I have a unique solar powered revolving colored lites. It is old and the solar panel is all weathered over. It works great for about 3days on a new 1.2 AA battery, then dies out. I just want to tie a new panel to the existing battery leads.
    Can you help me out?

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