Balanced principle of battery pack

　　Assuming that CELL1 is balanced during the battery pack discharge process, at this time the charger is disconnected, the transistor T2 and T3 are kept off, and the T1 is turned on. The circuit connection of the battery pack is shown in Figure 3, Figure 4 is its Davidin equivalent circuit. From the equivalent circuit, the CELL1 leaving circuit composed of a transistor T1 does not have the conclusions of absorbing the current from Cell2 and Cell3. Therefore, the transistor T1 only discharge Cell1. Similarly, T2 and T3 only discharge Cell2 and Cell3 respectively. On the other hand, Cell1's current is related to the load resistance. If the load resistance is higher than that of R1+T1, most discharge currents pass through the power transistor T1. However, if the load resistance is low, the partial discharge current will be loaded, which will reduce the balanced efficiency.

　　In order to reduce the discharge time, the power transistor's pipe resistance must be very small, and the R1 resistance must be as small as possible. The load resistance is usually related to the system and is difficult to control. It is recommended to choose a load resistance with the resistance value of R1+T1, so that most of the discharge current will pass through the power transistor instead of the load. Because the load current is minimal or no at all, the efficiency will be relatively high at the time of adjustment. Typical initialization adjustment time can be as long as 18 hours. As shown in Figure 5, if the battery balance is performed during the charging process, the current provided by the charger is lchaarge, and LCHARGE = 'Charge+LLOAD. The actual charging current of the battery is I'Charge, and the maximum value is obtained when the load resistance is opened. However, if the load resistance is connected during the charging phase, some charging currents will flow through the load. During the balance of Cell1, the size of 'charge = L1+12, 12, compared to the resistance of the power transistor T1 and resistance R1 relative to 11.

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