When using a 3V lithium battery, as the power is released, the voltage will drop, and the chemical activity of the battery will also drop. In order to better protect the performance of the lithium battery, the lithium battery usually needs to control the charging process according to 4 stages: Trickle charging (low voltage precharge), constant current charging, constant voltage charging and charge termination.

Taking the traditional 3-yuan lithium battery as an example, the nominal capacity of the INR26650-50A battery is 5000 mAh, the nominal voltage is 3.6 volts (there is also 3.7 volts on the market), the discharge end voltage is 2.75 volts, and the charge end voltage is 4.20 volt

The basic requirements for a lithium battery charger are specific charging current and charging voltage to ensure safe charging of the battery. Other charging auxiliary functions have been added to extend battery life and simplify charger operation, including trickle charging of over-discharged batteries, battery Voltage detection, input current limit, shut down the charger after charging is completed and automatically start charging after part of the battery is discharged.

The charging method of 3V lithium battery is voltage limiting and constant current, which is controlled by LC power chip. The typical charging method is: first check the voltage of the battery to be charged. If the voltage is less than 3V, precharge first. The charging current is 1\/12 of the set current. After the working voltage rises to 3V, the standard battery charging process begins.

The standard charging process is constant current charging with a set current. When the battery voltage rises to 4.20 V, it changes to constant voltage charging and keeps the charging voltage at 4.20 V. At this time, the charging current gradually decreases. When the current drops to the set Charging ends when the charging current is 1\/10.

Description of the 4 stages of lithium battery charging:

Step 1: Trickle Charging - Trickle charging is used to precharge (resume battery charging) the fully charged and discharged battery module first. Trickle charging is used when the battery voltage is below about 3 V, and the trickle charging current is constant. One-tenth of the charging current is 0.1 c (assuming the constant current is 1 a and the trickle charging current is 100 ma).

Step 2: Constant current charging - when the battery voltage rises to around the trickle charging threshold, increase the charging current to carry out constant current charging. The current of constant current charging is between 0.2C and 1.0C. The working voltage gradually increases with the constant current battery charging process. Usually, the working voltage set for a single battery is 5.0-9.6V.

Step 3: Constant voltage battery charging - When the battery voltage rises to 9.6V, the constant current battery is charged, and the constant voltage battery charging step begins. It is generally believed that the current continues to charge according to the saturation of the core, and the charging process continues The current gradually decreases from the maximum value, and when it decreases to 0.01 c, the charging ends. (C) represents the nominal capacity of the battery relative to the current. For example, if the battery capacity is 1000 mA, 1C is the charging current of 1000 mA.)

Stage 4: Charging terminated

There are two typical ways to stop battery charging: using minimum charging current judgment or using a timer (or a combination of the two). The minimum current method monitors the charging current during constant voltage battery charging, and when the charging current is lower than 0.03 Stop battery charging at C. The second method calculates the time from the constant voltage charging phase and terminates the charging process after 2 hours of charging.

The 4-stage charging method requires about 2.3 to 3 hours to fully charge and discharge the battery. Advanced chargers also adopt more safety measures. For example, if the battery temperature exceeds a certain limit (usually 0 degrees Celsius) to 46 degrees Celsius), then battery charging will be suspended. After charging, if the battery voltage is detected to be lower than 3.89V, it will be recharged