Now, the single cells of the series-connected battery pack are equally charged. At present, the following methods are mainly used.
1. Add a parallel equalization circuit to each single cell of the battery pack to achieve the purpose of shunt. In this mode, when a battery reaches full charge first, the equalizer prevents it from overcharging and converts the excess energy into heat, continuing to charge the battery that is not fully charged. This method is simple, but it will cause energy loss and is not suitable for fast charging systems.
2. Before charging, discharge each cell one by one through the same load to the same level, and then perform constant current charging to ensure a more accurate equilibrium state between each cell. However, for the battery pack, due to the physical differences between individuals, it is difficult to achieve a completely consistent ideal effect after deep discharge of each cell. Even if the same effect is achieved after discharge, new imbalances will appear during charging.
3. Detect and evenly charge the single batteries in the battery pack on time, in sequence, and individually. When charging the battery pack, it can be ensured that each battery in the battery pack will not be overcharged or overdischarged, thus ensuring that each battery pack in the battery pack is in a normal working state.
4. Using the time-sharing principle, through the control and switching of the switch components, the extra current flows into the battery with a relatively low voltage to achieve the purpose of balanced charging. This method is more efficient, but the control is more complicated.
5. Take the voltage parameters of each battery as the equalization object, so that the voltage of each battery is restored to the same. During equalization charging, the capacitor is alternately connected to the two adjacent batteries through the control switch, accepting the charging of the high-voltage battery, and then charging to the low-voltage battery. The battery is discharged until the voltages of the two batteries converge.
This equalization method can better solve the problem of unbalanced voltage of the battery pack, but this method is mainly used in occasions where the number of batteries is small.
6. The whole system is controlled by the single chip microcomputer, and the single battery has an independent set of modules. The module performs charging management for each single battery according to the set program, and automatically disconnects after charging is completed.