What are the main causes of lead-acid battery plate sulfation?
2 Answers
Reasons for battery plate sulfation: 1. The electrolyte level in the battery is too low, exposing the upper part of the plates to air, causing severe oxidation of the negative plate; 2. Insufficient initial charging or frequent undercharging, and failure to perform regular charging; 3. The electrolyte density in the battery is too high, making it difficult for lead sulfate to dissolve; 4. Frequent over-discharge or deep discharge with small current in lead-acid batteries, leading to massive generation of lead sulfate that penetrates deep into the plates; 5. The battery remains in a semi-discharged or discharged state for extended periods; 6. Impure electrolyte containing excessive organic matter and impurities, which not only promote battery self-discharge but also constitute the primary cause of plate sulfation.
Last time when I helped a friend check the battery of an old car, I found this issue is quite common. When a battery is used under prolonged low charge, white crystals gradually accumulate on the positive and negative terminals—this is sulfation. The primary cause is insufficient charging. For instance, I’ve encountered many car owners who frequently take short trips, so the alternator doesn’t have enough time to fully recharge the battery. Secondly, deep discharging also severely damages the battery, like when my friend forgot to turn off the headlights and drained the battery completely. Additionally, insufficient electrolyte levels exposing the plates to air can accelerate sulfation. I’ve noticed that high summer temperatures worsen this phenomenon, and vehicles left idle for long periods are more prone to this issue. To prevent it, I recommend using a charger to fully recharge the battery once a month and regularly checking the electrolyte level.
