Equalizing charging method for protection board of lithium ion battery pack

Commonly used lithium-ion battery pack equalization charging technologies include constant shunt resistance equalization charging, on-off shunt resistance equalization charging, average battery voltage equalization charging, switched capacitor equalization charging, step-down converter equalization charging, inductance equalization charging, etc. When charging a group of lithium-ion batteries in series, ensure that each battery is charged in a balanced manner, otherwise the performance and life of the entire group of batteries will be affected during use.

1. Attach a parallel equalization circuit to each single cell of the lithium-ion battery pack to achieve the purpose of shunting. In this mode, when a battery reaches full charge first, the equalization device can prevent it from overcharging and convert the excess energy into heat energy, and continue to charge the undercharged battery. This method is simple, but it will cause energy loss and is not suitable for fast charging systems.

2. Before charging, each cell is discharged to the same level through the same load one by one, and then constant current charging is performed to ensure a more accurate equilibrium state between the cells. However, for battery packs, due to 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 discharging, a new imbalance will appear during the charging process.

3. Test and charge uniformly the single cells in the lithium-ion battery pack on time, in order, and individually. When charging the lithium-ion battery pack, it can ensure that each lithium-ion battery in the battery pack will not be overcharged or over-discharged, thus ensuring that each battery in the lithium-ion battery pack is in normal operation 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.