Sulfation refers to the accumulation of lead sulfate crystals on the surface and within the pores of the active material *on* the lead plates. If a battery is left unattended after sulfation begins, larger crystals can form on the plates, leading to a gradual decrease in battery capacity and, potentially, eventual failure.
Under normal circumstances, the formation of lead sulfate crystals is temporary, as they disperse during the charging process. However, problems arise when larger lead sulfate crystals become permanent.
Types of Lead-Acid Battery Sulfation
There are primarily two types of sulfation in lead-acid batteries: reversible (often referred to as soft sulfation) and permanent (known as hard sulfation). These terms are descriptive, reflecting the varying degrees of sulfation’s impact on the battery. If sulfation is detected early, it may be possible to reverse it. Still, this process should only be performed by qualified professionals as it may require overcharging and increasing the battery’s temperature. Research has also been conducted on reverse charging techniques for recovering sulfated lead-acid batteries, and these warrant further attention.
The voltage discharge curve is an indicator of whether sulfation is reversible. If a fully charged battery maintains a stable voltage curve *during* discharge, *reversal is more likely*.
Permanent sulfation occurs when a battery is left in a low state of charge for extended periods (weeks or months). At this stage, recovery or reversal of sulfation becomes less likely, leading to damage from permanent sulfation.
What Causes Battery Sulfation?
All lead-acid batteries inevitably experience some degree of sulfation throughout their lifespan; it’s a natural aspect of battery chemistry. However, sulfation tends to accelerate under certain conditions, such as when a battery is not fully charged, is stored at high temperatures, is left unused for extended periods, or is stored in a discharged state.
Battery sulfation is one of the most common causes of premature failure in lead-acid batteries. Starting batteries in applications like cars and power sports vehicles are particularly susceptible to sulfation. Additionally, off-grid renewable energy systems, such as wind and solar-powered, may suffer from sulfation due to their intermittent charging characteristics.
How to Detect a Sulfated Battery
If your battery is experiencing sulfation, you may notice a decrease in efficiency. One of the most obvious symptoms of sulfation is the battery’s inability to hold a charge effectively. This can cause it to discharge faster than expected or result in insufficient power reaching electronic devices (e.g., dim headlights, weak air conditioning, or slow starting). Externally, the battery may appear unchanged, so it is essential to use a multimeter to assess the battery’s static voltage. A voltage below 12.6 volts for an AGM battery or below 12.4 volts for a starting battery indicates a possible undercharge, potentially caused by sulfation.
Effects of a Sulfated Battery
Permanent battery sulfation can lead to a range of problems, including:
- Reduced starting/cranking power
- Significantly extended charging times
- Increased heat generation
- Shorter run times between charges or reduced runtime
- Noticeably reduced battery life
- Complete battery failure
How to Prevent Battery Sulfation
The most effective strategy for preventing permanent sulfation is to keep the battery fully charged and avoid prolonged periods of low charge.
To effectively maintain your Keheng’s lead-acid battery and prevent battery sulfation, you should adhere to the recommended storage guidelines and best charging practices.
To avoid sulfation during storage, ensure your battery voltage remains at least 12.4 volts and store it in an environment with temperatures not exceeding 75°F (24°C). Be aware that the battery’s self-discharge rate doubles with every 10°F (approximately 5.6°C) increase in temperature.
Even when storing new, fully charged Keheng’s lead-acid batteries, monitoring the voltage to prevent it from dropping below 12.4 volts is crucial. Regularly providing top-up charging, also known as maintenance charging, will help prevent the accumulation of sulfation.
Sulfation is the main reason why you should avoid storing Keheng’s lead-acid batteries in a discharged state. Once sulfation affects the lead plates, the damage is difficult to reverse. Therefore, taking care of your batteries from the outset is essential.