Troubleshooting Common Lead-Acid Battery Failures: A Diagnostic Guide

Lead-acid batteries fail in predictable ways. Understanding which failure mode you are dealing with determines whether the battery can be salvaged.

Failure Mode 1: Sulfation

Symptoms: Capacity drops progressively. Charging voltage normal but current stays high. Low specific gravity after equalization. White coating on plates.

Causes: Chronic undercharging, PSOC operation, storage in discharged condition.

Recovery: Light sulfation — controlled desulfation at C/20 for 24 hours. Crystalline sulfation — no recovery possible.

Failure Mode 2: Grid Corrosion

Symptoms: Positive grid brittle and expanded. Dark brown/black positive plates. Reduced capacity despite full charge.

Causes: Chronic overcharging, high temperature, high float voltage.

Failure Mode 3: Active Material Shedding

Symptoms: Capacity loss with no sulfation. Brown sediment in bottom of cells.

Causes: Deep discharge cycling, vibration stress.

Failure Mode 4: Acid Stratification

Symptoms: High SG at bottom, low at top. Uneven cell performance.

Fix: Equalization charging.

Failure Mode 5: Thermal Runaway

Emergency: Battery temperature above 50C during charging. Case swelling. Disconnect immediately.

FAQ

Q: Can I recover a sulfated battery? A: Light sulfation: possibly. Crystalline sulfation: no — replace.

Q: Why do some cells fail while others are fine? A: Manufacturing variation, temperature differences, unequal connections.

Need help? Contact CHISEN’s technical team.

Email: sales@chisen.cn

www.chisen.cn

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