A parallel balancing circuit is added to each individual cell in the battery pack to achieve current distribution. In this mode, when a cell reaches full charge first, the balancing device prevents it from overcharging and converts the excess energy into heat, continuously charging the remaining cells. This method is simple but results in energy loss and is not suitable for fast charging systems.
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 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.
The individual batteries in the battery pack are tested and averaged on a regular, sequential basis. This ensures that each battery in the battery pack is not overcharged or over-discharged during charging, thus guaranteeing that each battery is in normal working condition.
By employing the time-sharing principle, additional current flows into the battery with a relatively low voltage through the control and switching of switching components, thereby achieving balanced charging. This method is relatively efficient, but its control is quite complex.
The equalization method uses the voltage parameters of each battery as the balancing target to restore the voltage of each battery to a uniform level. As shown in Figure 2, during equalization charging, the capacitor is alternately connected to two adjacent batteries via a control switch, receiving charging from the higher-voltage battery and then discharging to the lower-voltage battery until the voltages of the two batteries tend to be consistent. This equalization method effectively addresses the problem of voltage imbalance in the battery pack, but it is primarily suitable for applications with a small number of batteries.
The entire system is controlled by a microcontroller, with each individual battery having its own independent module. The module manages the charging of each battery according to a pre-programmed sequence, automatically disconnecting the circuit upon completion of charging. This method is relatively simple, but it significantly increases costs when dealing with a large number of individual batteries and hinders the reduction of system size.
