What is battery cell balancing?

Battery cell balancing brings an out-of-balance battery pack back into balance and actively works to keep it balanced. Cell balancing allows for all the energy in a battery pack to be used and reduces the wear and degradation on the battery pack, maximizing battery lifespan. How long does it take to balance cells?

How to balance a battery pack correctly?

needs two key things to balance a battery pack correctly: balancing circuitry and balancing algorithms. While a few methods exist to implement balancing circuitry, they all rely on balancing algorithms to know which cells to balance and when. So far, we have been assuming that the BMS knows the SoC and the amount of energy in each series cell.

Do out-of-balance batteries cost you money?

Out-of-balance batteries cost you money in the short and long term. When an out-of-balance battery is charged or discharged, it delivers less than the nameplate capacity, leaving revenue on the table in every cycle.

How does battery balancing work?

The solution is battery balancing, or moving energy between cells to level them at the same SoC. In the above example, balancing would raise the cell at 90% SoC to match the other cells at 100% SoC. Thus, the previously locked-away energy is recovered, returning the pack to its nameplate capacity.

How does a battery balancing algorithm work?

In these algorithms, the BMS attempts to balance only when cell voltages are nearly maximized at 100% SoC or nearly minimized at 0% SoC. As a result, in typical usage patterns where batteries are usually not charged to 100% or discharged to 0%, the cell balancing algorithm rarely has an opportunity to balance during regular operations.

What happens if a battery pack is out of balance?

A battery pack is out of balance when any property or state of those cells differs. Imbalanced cells lock away otherwise usable energy and increase battery degradation. Batteries that are out of balance cannot be fully charged or fully discharged, and the imbalance causes cells to wear and degrade at accelerated rates.