The rechargeable lamp can not be charged, but the power switch can be switched on when charging, and the lamp can be lit, which is generally a problem with the battery in the lamp.
BT1 is a 4V battery, and S1 is the power switch of the lamp. Capacitor C1 and diodes D1, D2, D4, D5, etc., constitute a simple resistant-capacitance buck charging circuit, D6 is the charging indicator. During charging, AC220V is charged to the 4V battery after C1 step-down current limiting and diode rectification.
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Assuming that the battery is used for a long time, the internal resistance becomes larger, and the electrical storage capacity becomes worse, even if the battery is fully charged to power the lamp, it can only be lit for a short time.
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To determine whether the lamp battery is good or bad, you can first fully charge it, and then switch on the lamp power switch, so that the lamp is lit, while using a multimeter to measure the battery voltage, if the voltage drops quickly, it indicates that the battery is broken, the battery needs to be replaced. Generally, you can replace the battery of the same model.
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If this lead-acid battery is not durable, you can also replace the lamp battery with 18650 lithium battery power supply. In order to charge easily, you can install a USB charging port on the desk lamp shell, and charge the 18650 lithium battery with a universal charger.
You can change the lamp switch cable, try again
If the lamp is charged, it is generally plugged into the power supply. If you don't want him to light up at the power source, then you can buy that. Battery lamps or buy some. Guest continuous discharge lamp