For high series of lithium/LTO/Lead acid pack , control them a healthy SOC by using active /passive battery balancing tech is important
Passive : balancing via using resistance to do discharging for high volt cells ,make volt of each cell with almost same SOC,
but can’t extend the lifespan of whole system,But his main function is keep whole system in a safe range,prevent from overcharging/over discharging/overcurrent/overvolt
Active: Energy transfer ,Dynamic transfering high volt from high cells to lower one ,volt of each cell controlled and balanced
There are 6 methods to extend battery lifespan,
1. Add a parallel equalizing circuit to each single cell of the battery pack to achieve the function 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. Timing, sequencing, and independent detection and uniform charging of the single batteries in the battery pack.
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 in the battery pack is in a normal working state.
4. Using the time-sharing principle, through the control and switching of switch components,
extra current flows into the battery with 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 object of balance to restore the same voltage of each battery.
As shown in Figure 2, during equalizing charging, the capacitor is alternately connected to two adjacent batteries through the control switch,
accepts the charging of the high-voltage battery, and then discharges to the low-voltage battery until the voltages of the two batteries tend to be consistent.
This kind of equalization method better solves the problem of battery voltage imbalance, but this method is mainly used in occasions with a small number of batteries.
6. The entire system is controlled by a single-chip microcomputer, and the single battery has an independent set of modules.
The module manages the charging of each single battery separately according to the set procedure, and automatically disconnects after charging. is relatively simple,
but it will greatly increase the cost when the number of single cells is large, and it is also not conducive to the reduction of system volume.