How to judge the fault of rechargeable flashlight

Battery problem judgment

You can use a multimeter, pointer multimeter, digital multimeter, and check the voltage at both ends of the battery using the DC voltage range. If the voltage at both ends of the battery is lower than 4V, and the battery voltage is still lower than 4V after charging, it means that the battery has a problem and cannot be used. Replace a new battery with a battery capacity of about 600-800mah.

Capacitance problem
Due to the low price of this flashlight, in order to reduce costs, manufacturers use relatively poor components in the selection of components. Capacitors with low withstand voltage values ​​are prone to bulge or explode due to grid voltage fluctuations and workmanship differences between different batches. Usually there is a brown step-down capacitor inside. When you find a capacitor bulge, you can replace it with a new one. You can replace the capacitor with a higher withstand voltage value to prevent it from being broken down again due to voltage.
lamp bead problem
When the detection finds that the capacitor is good, the output voltage is normal, and the battery is normal, that is the lamp bead problem, and you can directly replace the new lamp bead. According to the dismantling experience, some flashlights will connect a resistor in series at the 220V input end. This resistor is equivalent to a fuse. If it burns, it can be replaced or directly short-circuited.