What are the balanced charging methods for lithium batteries
Time:2022-02-13
Views:2297
At present, there are mainly the following methods to realize the uniform charging of each single battery of series battery pack:
1. A parallel equalizing circuit is added to each single battery of the battery pack to achieve the function of shunting. In this mode, when a battery reaches full charge first, the equalizing device can prevent it from overcharging and convert the excess energy into heat energy to continue charging the unfilled battery. This method is simple, but it will bring energy loss, so it is not suitable for fast charging system.
2. Before charging, each monomer is discharged to the same level through the same load one by one, and then charged with constant current, so as to ensure a more accurate equilibrium state between each monomer. 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 monomer. Even if the same effect is achieved after discharge, new imbalances will appear in the charging process.
3. Detect and charge the single battery in the battery pack regularly, sequentially and separately. When charging the battery pack, it can ensure that each battery in the battery pack will not be overcharged or over discharged, so it can ensure that each battery in the battery pack is in normal working state.
4. Using the time-sharing principle, through the control and switching of the switch assembly, the additional current flows into the battery with relatively low voltage, so as to achieve the purpose of balanced charging. This method is more efficient, but the control is more complex.
5. Taking the voltage parameters of each battery as the equalization object, the voltage of each battery is restored to be consistent. As shown in Figure 2, during equalizing charging, the capacitor is alternately connected with two adjacent batteries through the control switch, receives the charging of high-voltage batteries, and then discharges to low-voltage batteries until the voltages of the two batteries tend to be the same. This equalization method solves the problem of voltage imbalance of battery pack, but this method is mainly used in the situation with a small number of batteries.
6. The whole system is controlled by single chip microcomputer, and each single battery has an independent set of modules. The module manages the charging of each single battery according to the setting program, and automatically disconnects after charging. This method is relatively simple, but when the number of single cells is large, the cost will be greatly increased, and it is not conducive to the reduction of system volume.
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