Self-contained lead-acid battery charging LED emergency light circuit diagram

　　The circuit working principle diagram drawn based on the actual object is shown in Figure 5. The 220V AC mains is charged to the lead-acid battery after capacitor step-down and diode rectification, and the red LED is used as a charging indicator. When the button switch K is closed after charging, 3 colored flashing LEDs will be turned on first, emitting a dreamy and unpredictable colorful light, adding some fun to life at night. Press the switch K again to turn off the colored flashing LEDs, and then press it again to turn on the 24 parallel high-brightness LEDs. Due to the large number, the lighting effect is very good.

　　When the lead-acid battery voltage is 4V, the measured working current of the colored lights is about 60mA, and the current of the high-brightness LED is as high as more than 600mA. Such a large current not only makes the lighting time not too long after each full charge, but also damages the internal structure of the battery and shortens the service life. Therefore, a small resistance current limiting resistor must be connected in series with the high-brightness LED. After multiple tests, the working current is finally reduced to 320mA when 1.2Ω is selected, and the brightness change is not obvious. Because the changes to this lamp are not big, the circuit schematic diagram after the modification is omitted.

　　Through the above analysis, it is found that most of the various LED lamp circuits sold on the market are too simple. Although the price is very cheap, it will objectively cause energy waste. Only through reasonable improvements can we retain its economical and portable advantages and effectively improve its safety and reliability.