Car battery sulfation is a common issue that affects lead-acid batteries, which are widely used in vehicles. Sulfation occurs when a lead-acid battery is deprived of a full charge, leading to the formation of lead sulfate crystals on the battery plates. Over time, these crystals can build up and reduce the battery’s active material, which is responsible for its performance. This can result in longer charging times, excessive heat build-up, shorter running times between charges, dramatically shorter battery life, and even complete battery failure.
Understanding Sulfation: Reversible vs. Permanent
According to Battery University, sulfation can be reversible or permanent, depending on the stage of the battery’s life.
Reversible Sulfation
Reversible sulfation can often be corrected by applying an overcharge to an already fully charged battery. This is done by applying a regulated current of about 200mA, allowing the battery terminal voltage to rise to between 2.50 and 2.66V/cell (15 and 16V on a 12V mono block) for about 24 hours. Increasing the battery temperature to 50–60°C (122–140°F) during the corrective service further helps in dissolving the crystals.
Permanent Sulfation
Permanent sulfation occurs when a battery has been in a low state-of-charge for weeks or months. At this stage, no form of restoration seems possible, and the battery may need to be replaced.
Preventing Sulfation
To prevent sulfation, it is essential to keep the battery charged and avoid storage below 2.07V/cell or at a specific gravity level below 1.190. Avoiding deep discharges and keeping the electrolyte level above the tops of the plates are also crucial.
Battery Capacity and Formatting
When new, a deep-cycle battery may have a capacity of 70 percent or less. Formatting as part of field use will gradually increase the battery’s performance. A capacity check as part of acceptance is advisable to ensure that the battery is performing as expected.
Sulfation: The Leading Cause of Early Battery Failure
According to Crown Battery, sulfation is the number one cause of early battery failure in lead-acid batteries. Sulfation occurs when a battery is deprived of a full charge, and it builds up and remains on battery plates. When too much sulfation occurs, it can impede the chemical-to-electrical conversion and significantly impact battery performance.
Symptoms of Sulfation
When your battery has a buildup of sulfates, you may experience the following:
- Longer charging times
- Excessive heat build-up
- Shorter running times between charges
- Dramatically shorter battery life
- Complete battery failure
Proper Battery Storage to Prevent Sulfation
To prevent battery sulfation, proper battery storage is essential. When a battery is stored, even if it’s stored at a full charge, it must be charged enough to prevent it from dropping below 12.4 volts. Applying this maintenance charge will prevent sulfates from building up.
It’s also important to note that while a battery shouldn’t be stored in temperatures above 75 degrees, the rate of self-discharge doubles for every 10 degrees above room temperature.
Conclusion
In summary, car battery sulfation is a common issue that can significantly impact battery performance and lifespan. Proper charging and maintenance practices, such as avoiding deep discharges, keeping the electrolyte level above the tops of the plates, and storing the battery properly, can help prevent sulfation and extend the battery’s life.
References:
– Battery University: Acid Stratification and Surface Charge
– Battery University: Sulfation and How to Prevent It
– Crown Battery: Sulfation and Battery Maintenance
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