Dual USB 18650 Battery Charger Protection Module 4pcs, Power Bank PCB Module Board, Dual USB 5V 1A 2.1A

It is possible to connect either a single lithium battery or multiple lithium batteries in parallel. The total capacity of the connected battery must not exceed 200, 000 mA, and any battery with a voltage of 3.0 - 4.2V can be utilized. The display will show the word "IN"; for output, long press the LED button after turning on the load to begin output. The display will then show the word "OUT" along with the current and voltage of 5.0V 1.0A or 5.0V 2.1A. LED indicator and
LCD display: During charging, the display shows "IN"; after the load is connected, long press the LED light button to start output, and the display shows "OUT" with the corresponding output voltage and current of 5V1A or 5V 2.1A. The boosted lithium battery has an integrated protection circuit, providing protection against over-discharge, over-charge, overload short circuit, over current, and over temperature.
Note: Connect the positive pole of the battery to B+ and the negative pole to B-; do not reverse the connections. If reversed, it will cause damage!