Self-use lithium battery charger

The following is the information I consulted when designing this charging module. If I find it useful, I will share it with you.

The most suitable charging process for lithium-ion batteries can be divided into four stages: trickle charging, constant current charging, constant voltage charging and charging termination. Phase 1: Trickle Charging – Trickle charging is used to first precharge (restorative charge) a fully discharged battery cell. When the battery voltage is lower than about 3V, the battery is first charged with a maximum constant current of 0.1C. Stage 2: Constant current charging - When the battery voltage rises above the trickle charging threshold, the charging current is increased for constant current charging. The current of constant current charging is between 0.2C and 1.0C. The current during constant current charging does not need to be very precise, quasi-constant current is also acceptable. In linear charger designs, current often rises as battery voltage rises to minimize thermal issues on the pass transistor. Constant current charging greater than 1C will not shorten the entire charging cycle time, so this approach is not advisable. When charging at higher currents, the battery voltage rises more rapidly due to overvoltage from the electrode reactions and the voltage rise across the battery's internal impedance. The constant current charging phase will become shorter, but since the time of the following constant voltage charging phase will increase accordingly, the total charging cycle time will not be shortened. Stage 3: Constant voltage charging - When the battery voltage rises to 4.2V, constant current charging ends and the constant voltage charging stage begins. For optimal performance, the regulation tolerance should be better than +1%. Stage 4: Charge Termination – Unlike nickel batteries, continuous trickle charging of lithium-ion batteries is not recommended. Continuous trickle charging can cause plate plating effects on lithium metal. This can make the battery unstable and potentially cause sudden automatic rapid disintegration