Create a simple solar charger circuit diagram

Photocoupler

General DIY solar USB charger, the main raw materials required include the following:

2W, 6V solar panels; circuit boards; cables, chargers and batteries: tin tweezers, etc. The board needs to be processed first during the entire assembly process. This solar charger (see the figure below) is controlled by 89C2051, which can realize two-cell battery charging in turn, full of self-stop.

It can be set to discharge, let it go, and it is compatible with NiMH and NiCd batteries.

Working principle: The water supply of the whole circuit is controlled by the mercury day, and the power is cut off when the charger is reversed. C1 and R2 form the power-on reset circuit of the single chip microcomputer. The detection circuit is composed of analog comparators inside the LM324 and 89C 2051.

The intelligent solar charger op amp 1 detects the voltage of the battery A, and the RP1 sets the upper limit voltage of the batteries A and B, which is set to 1.4V. When the battery A is full, the upper limit voltage is exceeded, and the operational amplifier outputs 1 and vice versa.

Intelligent solar charger op amp 2 detects the light intensity, RP2 sets the light intensity that allows charging, and the photoresistor RL and Rl form a voltage dividing circuit. When the light is strong, the resistance of the photoresistor is small, and the potential of the positive input terminal of the op amp is high. When the positive input potential is large and the input potential is reversed, the op amp loses 1 and vice versa outputs 0.

The smart solar charger op amp 3 detects the lower limit voltage of battery B. RP3 sets the voltage value of the lower limit of battery B. Set here as 1V, the detection principle of the op amp 3 and the op amp 4 and the op amp 1 are not repeated.

The internal analog comparator of the 89C2051 is used to detect the power supply voltage of the system. If the power supply voltage is too low, the P3.6 position is set to l to stop the system, otherwise the P3.6 is set to 0. R13, VD1. VD2 constitutes a reference voltage circuit to provide a reference voltage to the detection circuit. VD1 is a 2.4V Zener, but the current may be too small. The voltage across VD1 is only 1.7V, so a 1N4148 is added in series to increase the reference voltage. R6, VT1 constitute the charging circuit of battery B. R7, VT2, and R11 constitute a discharge circuit of battery B. R8 and VT3 constitute a charging circuit of battery A. R3, R4, R5, and R9 are current limiting resistors of LED-_A, LED_B, LED_B2, and LED_P, respectively. LED_A indicates the status of battery A (æ´¼: In order to save power, all LEDs are always off, only after pressing the button, and only for 4 seconds). Steady light indicates that the battery is fully charged, of course, the sun is sufficient, and the A battery case will always be on when there is no battery; the flashing indicates that it is charging; the off indicates that the battery is insufficient, but it is not charging. LED_B indicates the state of battery B. The principle is the same as LED_A. It will not be repeated. LED_B2 indicates the discharge state of battery B. When it flashes, it indicates that it is discharging. When it is extinguished, it indicates that it is not discharging. LED_P indicates the power status, always on indicates that the power is sufficient, and blinking indicates that the power supply voltage is too low.

In addition, the solar cell used in the smart solar charger has a maximum output voltage of 2.5V and a maximum current of 120mA. Assuming that the battery with a maximum current of 1200mAh is charged for at least 10 hours, to increase the charging speed, the number of solar cells can be increased by paralleling.

The solar charger is designed to have a discharge function (only B battery has a discharge function), so it is compatible with nickel-metal hydride and nickel-cadmium batteries; since it can detect the upper and lower voltages, there is no need to worry about the battery being overcharged or over-discharged: due to the mercury switch As the system power switch, as long as the charger is reversed when not in use, the system power is automatically cut off. When it is used, the solar cell is up, just the mercury switch is turned on, and the automatic power-on is realized, which makes the use more convenient.

Instructions for use:

1. Put the battery on the battery box, the battery to be discharged (such as: nickel-cadmium battery can only be placed in the B battery box).

2. If battery B is allowed to discharge, press the discharge button. If battery B discharge is prohibited, please press and put on plating. After booting, the system disables discharge by default.

3. If the crash occurs unfortunately, just reverse the charger and restart it.

4. If you do not use the charger for a long time, please remove all the batteries (including the button battery) to prevent leakage and damage the charger.

After soldering the cable, you can connect the solar panel, battery and circuit board, and then solder the USB interface to the board. In this way, the entire production process is initially reported to the paragraph, and the charging test can be performed.

For professional welders, it takes only a few minutes to connect the capacitor resistor and the charger to the board, but for beginners, this is also a test.

If the solar charger works properly after the test, the rest of the work is how to secure the board with the USB interface in the tin box. Although the tin box is relatively simple, it is convenient.