Introduction
Capacity loss is one of the most frequently reported issues by users of lead-acid energy storage batteries. While some degradation is natural, accelerated capacity loss usually indicates improper system design or operation.
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Understanding Battery Capacity in Energy Storage
Battery capacity represents the amount of energy that can be stored and released under specific conditions. In real-world applications, usable capacity is affected by:
- Discharge rate
- Temperature
- Battery age
- Depth of discharge (DOD)
Major Causes of Capacity Loss
1. Excessive Depth of Discharge
Repeated deep discharges below 50% DOD accelerate:
- Plate shedding
- Active material loss
- Grid corrosion
2. Chronic Undercharging
Undercharging prevents full chemical conversion, leading to sulfation and reduced capacity.
3. Acid Stratification
In flooded batteries, electrolyte density becomes uneven, causing:
- Bottom plate corrosion
- Uneven current distribution
How to Slow Capacity Degradation
- Limit DOD to ≤50%
- Perform regular equalization charging
- Ensure sufficient charging current
- Maintain stable operating temperatures
- Perform annual capacity testing
Conclusion
With correct operating parameters and maintenance, capacity degradation can be controlled and predicted.
