Why Cell Balancing is Necessary
in Lithium Battery Packs?

Author: Polinovel    |    April 27, 2022


A lithium-ion battery pack is designed using multiple battery cells in series to meet the voltage requirements of various applications. It is crucial to develop electronic features to balance the cell voltages continually. That is not only for the battery pack’s performance but also for optimal life cycles.

Over Voltage Protection

The duration and life of lithium batteries will be reduced

When the lithium battery is overcharged and overdischarged, the life and use time of the battery will also be reduced, and the best state of lithium ion is in the middle state of power. This is due to unbalance charging of the battery.

Battery performance Degraded

Battery unbalance charge or discharging would reduce charging time and usage time.This is cause of battery is not durable.

Thermal runaway

Lithium batteries affect each other when charging and discharging because the batteries are connected in series. Once a battery is in a bad state, other batteries will also be affected. Thermal runaway is also very easy.

Battery damage

Although we can’t see battery internal structure.But with the longer use, the instability of the battery also manifested. There may be a sudden fire one day.

Benefits of Cell Balancing

Extend battery working time and life

Delaying battery operating time and life is what everyone who buys a battery wishes for. The reason why people buy lithium-ion batteries is to make their lives easier. However, improper use of the battery, such as overcharging and discharging, also frequently occurs. In this way, it is easy to cause the battery to be unbalanced, thereby affecting the service life of the battery. Therefore, the balance of the battery is so important.

Reduce the cost of replacing new lithium batteries

In daily life, people choose lithium-ion batteries because of their long service life and high safety performance. But the disadvantage is that the price of lithium batteries is more expensive than other batteries. If you want to save replacement costs, battery balance is critical. Because if the balance is not maintained, then the battery life and safety performance will also be reduced.

Improve battery safety

The battery remains in a balanced state, which improves its safety. When the battery is in an unbalanced state, it often leads to an increase in internal resistance, which increases the occurrence of accidents.

Passive and Active Cell Balancing

Passive cell balance

If you want to reduce costs, then passive equalization is a good choice. You can turn off the charging switch at the right time,until the battery pack is charged. This also ensures the safety and service life of the battery. Another method is to install a shunt resistor from cell to cell, which can discharge the excess voltage to balance itself.

Active cell balance

Active balancing techniques are more complex than passive balancing techniques. During the charging and discharging process, the charge of the battery needs to be redistributed, thereby increasing the overall charge. The benefits of active equalization are time savings and reduced battery heat.


Lithium-ion batteries are generally stable. But if used improperly, there will be many problems, such as overcharge, overdischarge, thermal runaway, etc. These factors also cause the SOC of each battery to be unbalanced, which affects the service life and safety of the battery. If you want a better experience, you need to actively balance the battery or passively balance the battery.

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