Commonly used lithium-ion battery pack equalization charging technologies include constant shunt resistor equalization charging, on-off shunt resistor equalization charging, average battery voltage equalization charging, switched capacitor equalization charging, buck converter equalization charging, and inductor equalization charging. When charging lithium-ion batteries in series, it is essential to ensure that each cell is charged evenly; otherwise, the performance and lifespan of the entire battery pack will be affected during use.
1. A parallel balancing circuit is added to each individual cell in the lithium-ion battery pack to achieve current distribution. In this mode, when a battery reaches full charge first, the balancing device can prevent it from overcharging and convert the excess energy into heat to continue charging the batteries that are not fully charged. This method is simple, but it results in energy loss and is not suitable for fast charging systems.
2. Before charging, each individual cell is discharged to the same level through the same load, and then constant current charging is performed to ensure a relatively accurate balance between the individual cells. However, for battery packs, due to the physical differences between individual cells, it is difficult to achieve a completely consistent ideal effect after deep discharge. Even if the same effect is achieved after discharge, new imbalances will appear during the charging process.
3. Perform timely, sequential, and individual testing and uniform charging of each individual cell in the lithium-ion battery pack. This ensures that no lithium-ion cell in the pack is overcharged or over-discharged during charging, thus guaranteeing that each cell is in normal working condition.
4. Utilizing the time-sharing principle, additional current flows into the battery with a relatively low voltage through the control and switching of switching components to achieve balanced charging. This method is relatively efficient, but the control is more complex.
5. Using the voltage parameters of each battery as the balancing object, the voltage of each battery is restored to be consistent. During equalization charging, the capacitor is alternately connected to two adjacent batteries through a control switch, receiving charging from the high-voltage battery and then discharging to the low-voltage battery until the voltages of the two batteries tend to be consistent.
