Three stages of 18650 lithium battery charging
The three stages of 18650 lithium battery charging are divided into trickle, constant current, and constant voltage.
If the battery power is very low at the beginning of charging, it must start charging with a small current, that is, trickle charging.
Low-current charging is to protect the battery and avoid damage to the internal structure of the battery caused by high-current shocks (the battery will suffer much higher damage when encountering a large current when the voltage is low than when the voltage is high).
If the battery voltage is not low, you can start charging with high current, that is, charging with the maximum current allowed. This is to save the charging time. Charging with the maximum current is the most time-saving, so it is the so-called constant current charging. As charging progresses, the battery voltage gradually increases.
When the battery voltage reaches or is close to the full voltage (such as about 4.2V), it will start to switch to constant voltage charging, because the full voltage is reached, then the voltage can be kept basically unchanged, and the charging current can be gradually reduced. When charging with a small current, it may cause the voltage to be too high, and there is a danger of overcharging. Overcharging is also harmful to the battery.
Just like filling a thermos with boiling water, you can pour it hard at the front, and when it is almost full, you need to reduce the water flow, so that the water will not overflow easily when it is full. The process of constant voltage charging is actually not short, and the power charged during this time is about one-fifth of the total power.
Of course, this charging process is also determined by the characteristics of the lithium battery. For nickel-cadmium, nickel-manganese or nickel-hydrogen batteries, the charging method is different.
There are roughly three reasons for a battery to explode:
(1) The reason for the battery itself. Due to internal defects of the battery, the battery itself explodes without charging or discharging;
(2) The battery is overcharged for a long time. The battery may be instantaneously discharged to generate a large amount of current under special temperature, humidity and poor contact conditions or environments, causing spontaneous combustion or explosion;
(3) Short circuit. This is less likely. In addition, placing the battery near high temperature or flammable objects may also cause an explosion.
The above is the introduction of all the articles of Keheng lithium battery new energy manufacturers about the three stages of 18650 lithium battery charging.