Corrosion, Shedding, and Internal Short in Lead-Acid Batteries: Causes, Detection, and Prevention

Lead-acid batteries, widely used across industries for energy storage, face several common issues that can undermine their efficiency and shorten their lifespan. Among the most critical problems are corrosion, shedding of active materials, and internal shorts. Understanding these challenges is essential for maintaining battery performance and ensuring long-term reliability. In this detailed guide, we explore each of these issues and provide actionable solutions for preventing and addressing them.

Table of Contents

Understanding Battery Corrosion

Corrosion is one of the most frequent problems that affect lead-acid batteries, particularly around the terminals and connections. Left untreated, corrosion can lead to poor conductivity, increased resistance, and ultimately, battery failure.

Causes of Corrosion

Battery corrosion typically occurs due to the chemical reactions between the hydrogen gas emitted during the charging process and external factors such as moisture, air, and salt in the environment. When hydrogen gas combines with oxygen in the atmosphere, it forms a corrosive substance around the battery terminals, which appears as a white, blue, or greenish powder.

The electrolyte inside the battery can also contribute to corrosion if it leaks through cracks or spills during maintenance, exposing the terminals to acid.

Preventing Battery Corrosion

To prevent corrosion and ensure uninterrupted power delivery, it is essential to maintain the battery properly:

Regular Cleaning: Clean the battery terminals regularly using a wire brush or a specialized battery terminal cleaner. This will remove any corrosive buildup and improve the electrical connection between the terminals and the cables.
Protective Coating: After cleaning, apply a thin layer of battery terminal protector or dielectric grease to the terminals. This creates a barrier that prevents moisture and contaminants from triggering the corrosion process again.
Ensure Proper Ventilation: Batteries should be stored in well-ventilated areas to prevent hydrogen gas buildup, which can accelerate corrosion.
Inspect for Leaks: Periodically check for electrolyte leaks and ensure the battery case remains intact and sealed.

By following these preventive measures, battery users can minimize the impact of corrosion, prolonging both the battery’s lifespan and the reliability of power delivery.

Active Material Shedding in Lead-Acid Batteries

Another common problem with lead-acid batteries is the shedding of the active material from the battery plates, which leads to reduced capacity and overall performance degradation over time.

Causes of Active Material Shedding

The shedding process occurs naturally as lead-acid batteries age. The lead dioxide material in the positive plates slowly disintegrates and flakes off. This material falls to the bottom of the battery case and begins to accumulate. As more material sheds, the effective surface area of the plates diminishes, reducing the battery’s capacity to store and discharge energy efficiently.

Overcharging is a major cause of shedding. When a battery is overcharged, excessive current can cause the plates to heat up, leading to faster degradation of the active material. Deep discharges and frequent cycling can also accelerate shedding, especially when the battery is subjected to high loads or left discharged for long periods.

Preventing Active Material Shedding

To minimize active material shedding and ensure your lead-acid battery performs optimally, consider the following tips:

Avoid Overcharging: Use a smart charger or a charger with automatic cutoff to prevent overcharging. These chargers monitor the battery’s voltage and automatically stop the charging process when the battery reaches its optimal charge level.
Maintain Proper Charge Levels: Lead-acid batteries perform best when kept at a moderate state of charge. Avoid discharging the battery to extremely low levels and recharge it promptly after use.
Monitor Electrolyte Levels: Regularly check the electrolyte levels in flooded lead-acid batteries. If the electrolyte level is low, refill with distilled water to the recommended level, ensuring the battery stays in peak condition.
Use High-Quality Batteries: Invest in premium quality lead-acid batteries from reputable manufacturers. High-quality batteries often have enhanced plate designs that resist shedding and last longer in demanding conditions.

By following these best practices, users can reduce the rate of active material shedding, extending the battery’s operational lifespan and maintaining its energy storage capacity.

Internal Shorts: Causes, Detection, and Prevention

Internal shorts represent a more serious issue for lead-acid batteries, often leading to rapid self-discharge and severe performance loss. They occur when there is an unintended electrical connection within the battery, typically between the positive and negative plates.

Causes of Internal Shorts

Several factors contribute to the development of internal shorts in lead-acid batteries:

Plate-to-Plate Contact: Over time, the separation between the positive and negative plates can deteriorate, allowing them to make contact and create a short circuit. This is often the result of physical damage, deterioration of separators, or warping of the plates due to extreme heat or overcharging.
Metallic Whiskers: Tiny metallic particles, known as whiskers, can form inside the battery and bridge the gap between the plates, causing a short.
Shedded Material Accumulation: As mentioned earlier, active material that sheds from the plates can accumulate at the bottom of the battery case. If enough material builds up, it can form a conductive bridge between the plates, leading to an internal short.

Detecting Internal Shorts

Detecting internal shorts early is crucial for preventing extensive damage to the battery. Here are a few signs that may indicate the presence of an internal short:

Rapid Self-Discharge: If the battery discharges unusually fast, even when not in use, it could indicate an internal short. This self-discharge occurs because the internal short circuit is draining the battery’s energy continuously.
Increased Internal Resistance: Performing regular impedance tests or internal resistance tests can help detect shorts. A sudden rise in internal resistance is often a clear indicator that something is wrong inside the battery.
Drop in Capacity: A significant drop in the battery’s capacity, despite maintaining regular charge cycles, is another sign of an internal short. Capacity testing using specialized battery testers can reveal if the battery is underperforming due to an internal fault.

Preventing Internal Shorts

Preventing internal shorts involves maintaining good battery health and ensuring proper usage conditions:

Avoid Overcharging: Overcharging can damage the internal components of the battery, leading to plate warping or separator failure, both of which can cause internal shorts. Always use a regulated charger to prevent this.
Monitor Battery Health: Conduct regular testing to monitor the battery’s internal resistance and overall health. Regular testing helps identify internal issues early, allowing for timely intervention before significant damage occurs.
Handle with Care: Lead-acid batteries should be handled and stored carefully to prevent physical damage. Rough handling or exposure to excessive vibration can damage internal components and create conditions for shorts.
Replace Aging Batteries: As lead-acid batteries age, they become more prone to internal shorts. If the battery shows signs of excessive wear, such as persistent shedding or internal resistance spikes, it may be time to replace it.

Conclusion

Corrosion, shedding, and internal shorts are common problems that can significantly reduce the performance and lifespan of lead-acid batteries. However, with proper maintenance, regular testing, and preventive care, these issues can be minimized. Ensuring that your battery remains in optimal condition not only prolongs its useful life but also ensures reliable performance across various applications.

By implementing regular cleaning, monitoring charging practices, and performing periodic tests, we can effectively manage these common battery challenges and prevent costly damage or premature failure. Taking proactive measures will guarantee a longer, more efficient battery life and reduce the need for frequent replacements.