To check whether the 18650 battery is damaged, the method is as follows:
1. The label of the checked 18650 lithium-ion battery confirms that its voltage output is 3.7V, but the capacity may be larger or smaller than 2000mAh (some are 3000mAh)
2. Find the positive and negative poles of the 18650 lithium-ion battery. The round protrusion of the battery is the positive pole of the battery, and the flat bottom is the negative pole.
3. Use a multimeter to check the output voltage. Make sure it’s set to measure voltage. Place the small metal rod at the end of the red cable onto the positive terminal of the 18650 Li-Ion battery. Place the metal rod at the black end of the multimeter on the negative end of the battery.
4. Check the multimeter display panel. If the battery is in normal condition, it should show between 3.6 and 3.7V. If the reading is below 3.5V, fully charge the battery. If it’s still below 3.5V after charging, it means you need to replace it, as these are all signs that the battery charge is slowly depleting.
5. Check the battery capacity, set the multimeter to measure the amount of current passing through each hour, and place two metal rods on the positive and negative metal ends of the battery.
6. Check the multimeter display. A fully charged Li-Ion 18650 battery whose mAh matches the label indicates that the battery is in good use.