LiFePO4 battery packs ( or any lithium battery packs) have a circuit board with either a balance circuit, protective circuit module (PCM), or battery management circuit (BMS) board that monitor the battery and its cells (read this blog for more information about smart lithium circuit protection).
This is often referred to as the "barrel effect"—the idea that the overall capacity is limited by the weakest link. To optimize the performance and safety of your LiFePO4 battery pack, balancing is not just recommended—it's necessary. There are two primary methods for balancing LiFePO4 batteries: top balancing and bottom balancing.
Why is balancing cells in a LiFePO4 battery important?
Why Balancing Cells in a LiFePO4 Battery Is Critical (And How to Do It Right!) LiFePO4 batteries, or lithium iron phosphate batteries, are known for their reliability and safety. They are widely used in electric vehicles, solar power systems, and energy storage solutions. A key...
In LiFePO4 batteries, as soon as the cell with the lowest voltage hits the discharge voltage cut off designated by the BMS or PCM, it will shut down the entire battery. If the cells were unbalanced during discharge, this may mean that some cells have unused energy and that the battery isn't truly “empty”.
What happens if LiFePO4 cells are not balanced when charging?
Likewise, if the cells aren't balanced when charging, charging will be interrupted as soon as the cell with the highest voltage reaches the cut-off voltage and not all the LiFePO4 cells will be fully charged, and the battery won't be either.
Even small batteries benefit from balancing to ensure safety and maximize their lifespan. A key factor in ensuring their longevity and efficiency is cell balancing—the process of equalizing the voltage levels of individual cells in a battery pack. Imbalanced cells can lead to reduced performance, shorter lifespan, and even safety risks.
Because lithium-ion batteries incorporate a BMS which protects the cells from unsafe voltage, current and temperature, the battery will not enter these conditions. Due to these hard stops in the BMS, performance will suffer and overall effective pack capacity will be reduced corresponding to the level of imbalance if nothing is done.