How to detect the depletion of 18650 lithium battery pack?

1. Battery consumption performance: the battery voltage does not go up and the capacity decreases. Measure directly with a voltmeter, if the voltage across the 18650 battery is lower than 2.7V or there is no voltage. Indicates that the battery or battery pack is damaged. The normal voltage is 3.0V～4.2V (generally, the voltage of 3.0V battery will be cut off, and the voltage of 4.2V battery will be fully saturated, and some also have 4.35V). 2. If the battery voltage is lower than 2.7V, you can use a charger (4.2V) to charge the battery. After ten minutes, if the battery voltage rises, you can continue to charge until the charger prompts to be full, and then look at the full voltage. If the full battery voltage is 4.2V, it indicates that the battery is normal, and it should have consumed too much power last time and the battery is cut off. If the full voltage is much lower than 4.2V, it means the battery is damaged. If it is a battery that has been used for a long time, it can be judged that the battery life is up and the capacity is basically exhausted. Should be replaced. There is basically no way to fix it. After all, lithium batteries have a life span, not infinite. 3. If the 18650 lithium battery pack is measured and the battery has no voltage, there are two situations at this time. One is that the battery is good, and it is caused by long-term storage. This kind of battery has a certain chance to recover. Generally, it is activated by pulsed lithium battery. A meter (lithium battery charging and discharging meter) to charge the battery multiple times in a short period of time, and it may be repaired. Generally, the cost of repair is not low, and it is better to buy a new one. Another possibility is that the battery is completely worn out, the battery diaphragm is broken down, and the positive and negative electrodes are short-circuited. There is no way to fix this kind of thing, only buy a new one. 4. Check the battery capacity, set a multimeter to measure the amount of current passed per hour, and place two metal rods on the positive and negative metal ends of the battery. 5. Check the display of the multimeter. The fact that the milliampere hour mAh of a fully charged 18650 lithium battery pack is consistent with the label indicates that the battery is in good use. Measure the voltage change during use. When the discharge voltage drops, if the reading exceeds 5%, which is lower than the capacity on the label, please charge your battery until it is fully charged, and perform the battery test again, if the actual reading is still low Please replace the battery in time for the capacity affixed on the label, because the battery can no longer supply power normally. Appearance inspection Appearance is not damaged, rust, etc. Voltage judgment Use a multimeter to test the battery voltage, the normal voltage is about 3.7v, if the voltage is lower than 2.7v, the probability of more than 90% is a bad battery capacity test. If you have a capacity display You can see the actual charging capacity of the battery. Generally, the capacity of 18650 is between 2200-2800mAh. If the displayed capacity is low, it means that the battery has been reduced in capacity. Statement: Article published on this site Part of the pictures and content are from the Internet, if there is any infringement, please contact to delete