Introduction
Sulfation is the most common failure mode in lead-acid energy storage batteries. It becomes especially severe when the battery remains undercharged for extended periods. This article explains how sulfation forms and how to manage it effectively.
Keywords: sulfation repair, undercharged lead-acid battery, battery capacity loss, VRLA sulfation, AGM/GEL maintenance
What Is Sulfation?
Sulfation occurs when lead sulfate crystals accumulate on the battery plates. During normal charging, they dissolve back into the electrolyte. However, when charging is incomplete, these crystals harden and become difficult to remove.
Why Undercharging Accelerates Sulfation
- Low SOC allows crystals to grow rapidly
- Reduced electrolyte density slows chemical reactions
- Battery temperature rises during repeated shallow charging
Effects of Sulfation
- Low voltage under load
- Long charging time but low capacity
- Increased internal resistance
- Reduced cycle life
How to Repair Mild Sulfation
1. Equalization Charge
Best for flooded batteries; restores up to 20% lost capacity.
2. Slow, High-Voltage Absorption (AGM/GEL)
Use manufacturer specs to avoid dry-out.
3. Pulse Desulfation Technology
Helps remove surface-level sulfate buildup.
When the Battery Cannot Be Recovered
If plates are heavily corroded or crystals are fully hardened, replacement is the only option.
Conclusion
Sulfation is preventable with proper charging habits. Ensuring full recharge cycles is the most effective way to maintain long-term battery health.
