The basic requirements of lithium ion battery chargers are specific charging current and charging voltage, and then ensure that the battery can be charged safely. Additional charging auxiliary functions are added to improve battery life and simplify the operation of the charger, including trickle charging for over-discharging batteries, battery voltage testing, input current limitation, shutting off the charger after charging, and active charging after partial battery discharge.
Stage 1: Trickling charge Trickling charge is used to precharge a fully discharged battery unit (recovery charge). When the battery voltage is lower than 3V or so, the trickling current charge is used. The trickling current charge current is one tenth of the constant current charge current, that is, 0.1c (taking the stable charging current as 1A for example, the trickling current charge current is 100mA).
Stage 2: Constant current charging When the battery voltage rises above the trickle-current charging threshold, the charging current is increased to carry out constant current charging. The current of a constant current charge is between 0.2C and 1.0C. The battery voltage gradually increases with the constant current charging process. Generally, the voltage set for a single battery is 3.0-4.2V.
Stage 3: Constant voltage charging When the battery voltage rises to 4.2V, the constant current charging is completed and the constant voltage charging stage begins. According to the full degree of the cell, the current gradually decreases from the maximum value with the continuous charging process. When the current decreases to 0.01c, the charging stops. (C is a way of stating that the battery's nominal capacity is compared to the current. For example, the battery has a capacity of 1000mAh, and 1C is the charging current of 1000mA.)
Stage 4: Charge stopper There are two typical methods of charge stopper: using the minimum charge current discriminator or using a timer (or perhaps a combination of the two). The minimum current method supervises the charging current at the constant voltage charging stage and stops charging when the charging current decreases to the scale of 0.02C to 0.07C. The second method starts at the beginning of the constant voltage charging phase and stops the charging process after two hours of charging.
Generally, the size of the battery capacity is indicated on the battery, in milliamps, the larger the value, the larger the capacity.
For example, 1200mAh states that the capacity of the battery is 1200 mah. At the same time, chargers are generally also marked with charging current, also in milliamps.
Thus, the battery charging time can be briefly calculated as follows: the battery capacity divided by the charging current, multiplied by a coefficient of 1.2 (or perhaps 1.1), and the time unit is hours. For example: the battery capacity is 1200 mah, the charger charging current is 600 mah, charging time is (1200 mah /600 mah) TImes; 1.2=2.4 hours, so the battery will be charged for 2.4 hours using this charger.
The above accounting method does not apply to new batteries. Generally speaking, when the first three times of charging the new battery, especially the nickel-cadmium battery and nickel-metal hydride battery, the specification of charging in about 15 hours (0.1c), so as to make the use of the battery time to reach the maximum. In the future, you can refer to the above method to calculate the battery charging time.
What is the charging current indicated on the charger?
To give you a simple formula: charge-discharge time (min) = capacity *1.1/ current (mA) *60
The relationship between the battery charging time and charging current is the battery capacity divided by the charging current to get the charging time. Considering the loss in the charging process, the calculated charging time is multiplied by the constant 1.1 or 1.2.
According to the sign, you can calculate the approximate time. If it is an ordinary charger, and the current is very small, the charging time must be very long.
