Botswana Active Balancing Lithium Battery Pack

What is passive balancing in a battery management system?

Source: Monolithic Power Systems Most battery management systems (BMS) today include passive balancing to periodically bring all cells in series to a common SOC value. Passive balancing does this by connecting a resistor across each individual cell as necessary to dissipate energy and lower the SOC of the cell.

What is active balancing?

As an alternative to passive balancing, active balancing uses power conversion to redistribute charge among the cells in a battery pack. This enables a higher balancing current, lower heat generation, faster balancing time, higher energy efficiency, and longer operating range.

How does passive balancing work?

Passive balancing does this by connecting a resistor across each individual cell as necessary to dissipate energy and lower the SOC of the cell. As an alternative to passive balancing, active balancing uses power conversion to redistribute charge among the cells in a battery pack.

What is buck-boost active balancing?

Rather than moving charge to various locations along a battery stack or to a separate power rail, buck-boost active balancing moves charge to directly adjacent cells. This greatly simplifies the balancing circuitry and leverages the simultaneous operation of many balancers to distribute charge across the entire stack.

How does a 2-channel buck-boost active balancer work?

Compared to the two previous active balancers, a 2-channel buck-boost active balancer follows a simple process: In buck-balancing mode, the active balancer transfers energy from the upper cell (CU) to the lower cell (CL). In boost-balancing mode, the active balancer transfers energy from the CL to the CU.

What is the difference between active and passive balancing?

Passive balancing simply dissipates energy; active balancing, however, redistributes energy with a significant improvement in energy efficiency. Passive balancing is only practical during the charge cycle, since operation during discharge hastens energy depletion from the pack.