Large-scale energy storage systems rely on numerous battery cells connected in series and parallel. However, inconsistencies in these batteries' capacity, resistance, and temperature can significantly impact overall performance. This article explores the problems caused by battery inconsistency and solutions to mitigate them.
Problems Caused by Battery Inconsistency:
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Reduced Usable Capacity:
- Series Inconsistency: The entire system's usable capacity is limited by the cell with the lowest capacity. As this cell reaches full charge or empty discharge, others are restricted, hindering overall capacity.
- Parallel Inconsistency: When battery clusters connect in parallel, voltage imbalances lead to circulating currents. This uneven current distribution causes some clusters to overcharge/discharge, reducing overall usable capacity and accelerating battery degradation.
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Shortened Battery Life:
- Temperature Inconsistency: Temperature variations within the system exacerbate internal resistance and capacity inconsistencies. This accelerates cell differentiation and shortens the overall lifespan of the energy storage system.
Solutions for Mitigating Battery Inconsistency:
- Active Balancing Technology: Real-time monitoring of individual cell voltage and temperature allows for active balancing to minimize inconsistencies in series-connected batteries. This can increase usable capacity by over 20% throughout the system's lifecycle.
- Separate Cluster Management: By managing the charging and discharging of each battery cluster independently and avoiding parallel DC connections, circulating current issues are eliminated, leading to improved usable capacity.
- Precise Temperature Control: Real-time temperature monitoring of individual cells combined with thermal design optimization ensures a maximum temperature difference of less than 5°C within the system. This minimizes temperature-induced cell differentiation and extends battery life.