Active cell balancing significantly contributes to the safety of electric vehicle (EV) batteries by preventing the cells from becoming overcharged or deeply discharged, both of which can lead to unsafe and unstable battery behaviors. Here’s how active balancing enhances EV battery safety:
Prevention of Overcharge and Deep Discharge
- Each cell in a battery pack can degrade at a different rate and may have slightly different states of charge (SoC), due to manufacturing variances, operating temperature differences, and other factors. Without balancing, some cells may become overcharged while others are undercharged, increasing the risk of thermal runaway or internal damage that could cause fires or failures.
- Active balancing redistributes charge among cells to maintain a uniform SoC, thus avoiding pushing any single cell beyond its safe operating limits.
Efficient Energy Redistribution During Charge and Discharge
- Unlike passive balancing, which wastes excess energy as heat and is mostly effective only during charging, active balancing transfers energy from higher-charged cells to lower-charged cells. This bidirectional energy transfer can occur both during charging and discharging cycles, extending the battery pack runtime and reducing thermal stresses.
- This reduction in heat generation lowers the thermal load on the battery system, which is a critical factor in preventing unsafe temperature spikes that can lead to battery failure or hazards.
Faster and More Effective Balancing
- Active balancing supports higher balancing currents (up to 6A) compared to passive balancing (around 0.25A), enabling faster balancing. Faster balancing ensures that cells remain well balanced even during rapid charge/discharge cycles typical in EV operation, maintaining safety margins effectively.
- The quicker equalization of cell voltages helps avoid the accumulation of charge imbalance that might otherwise lead to individual cells operating outside their safe range.
Improved Battery Lifetime and Reliability
- By maintaining balanced SoC, active balancing reduces uneven cell aging and degradation. Cells that age uniformly are less prone to developing faults that could compromise safety, such as internal shorts or capacity loss leading to overheating.
- It also helps avoid conditions that might cause cell swelling or other mechanical failures, adding an additional layer of safety.
In summary, active cell balancing contributes to EV battery safety by ensuring that all cells operate within their safe voltage and charge limits through efficient energy transfer, reducing heat generation, enabling fast and continuous balancing during operation, and promoting uniform cell aging. This prevents unstable and unsafe battery behaviors such as overcharging, overheating, and capacity loss, thereby enhancing overall battery safety and reliability in electric vehicles.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-active-cell-balancing-contribute-to-the-safety-of-ev-batteries/
