Reviving a Sulfated Battery: Causes, Prevention, and Recovery Methods
Deep cycle batteries, particularly lead-acid batteries, are prone to sulfation. Sulfation occurs when lead sulfate crystals form on the surface and inside the pores of the battery's positive and negative plates. During a normal discharge process, soft lead sulfate crystals are produced. When the battery remains discharged or undercharged for an extended period, these soft crystals can re-crystallize into hard crystals that cannot be converted during subsequent recharging, leading to permanent sulfation. This process accounts for approximately 85% of deep cycle lead-acid battery failures. In this article, we will discuss the causes of sulfation, how to prevent it, and recovery methods for sulfated batteries.
PRO TIP
The best way to prevent sulfation is by keeping a lead-acid battery fully charged, as lead sulfate does not form in a fully charged battery. Here are three ways to accomplish this:
How Can I Tell If My Battery Has Permanent Sulfating?
Several signs indicate that a battery has permanent sulfation, including:
Wet Standard (Sb/Sb) or wet Low Maintenance (Sb/Ca) batteries not recharged for over three months, especially in warm or hot storage areas (Six months for wet Maintenance-Free (Ca/Ca) or one year for VRLA AGM or Gel Cell)
The ammeter does not drop to within 2% (C/50) of the ampere-hour (AH) capacity of the battery within twice the capacity divided by the charging rate in hours, and the battery is warm or hot while charging. For instance, if you have a 50 AH battery and a ten amp charger, the battery should be fully charged within 10 hours (2 x 50 AH/10 amps = 10 hours)
The temperature compensated absorption charging voltage is correct, but the battery is excessively gassing
Poor performance
The battery will not take or "hold" a charge
How Do I Prevent Permanent Sulfation?
The best way to prevent sulfation is by keeping a lead-acid battery fully charged, as lead sulfate does not form in a fully charged battery. Here are three ways to accomplish this:
Use a charger that can deliver a continuous "float" charge at the battery manufacturer's recommended float or maintenance voltage for a fully charged battery. Based on the battery type, charging can best be accomplished with a microprocessor-controlled, three-stage (for AGM or Gel Cell batteries) or four-stage (for wet batteries) "smart" charger or voltage-regulated float charger to "float" or maintain a fully charged battery. A cheap, unregulated "trickle" charger or manual two-stage charger can overcharge a battery and destroy it.
Periodically recharge the battery when the State-of-Charge drops to 80% or below. Maintaining a high State-of-Charge (SoC) tends to prevent irreversible sulfation. The recharge frequency depends on the parasitic load, temperature, the battery's condition, and plate formulation (battery type). Note that temperature matters, as lower temperatures slow down electrochemical reactions and higher temperatures speed them up. A battery stored at 95° F (35° C) will self-discharge twice as fast than one stored at 75° F (23.9° C).
Use a regulated solar panel or wind or water generator designed to float charge the battery. This is a popular solution when AC power is unavailable for charging.
How Do I Recover Sulfated Batteries?
Have you ever had a lead-acid battery that just won't take a charge? If so, the culprit could be permanent sulfation. Sulfation occurs when lead sulfate crystals form on the plates of a lead-acid battery, which reduces the battery's capacity and ability to be recharged. If left untreated, permanent sulfation can account for approximately 85% of deep cycle lead-acid battery failures. Fortunately, there are ways to recover sulfated batteries and give them a new lease on life.
Light Sulfation The first method to try is for light sulfation. Check the electrolyte levels and apply a constant current at 2% of the battery's RC or 1% of the AH capacity rating for 48 to 120 hours at 14.4 VDC or more, depending on the electrolyte temperature. This can often reverse light sulfation and restore the battery's capacity.
Deep Sulfation For deep sulfation, you can try a technique called desulfation. This involves pulsing a high-voltage, low-current charge into the battery. There are devices on the market specifically designed for this purpose, such as a desulfator or a pulse charger. This technique can take several weeks to see results, so patience is key.
Chemical Treatment Another option is to use a chemical treatment. There are various chemical solutions on the market designed to dissolve the lead sulfate crystals that cause sulfation. These solutions are typically added to the electrolyte and left to sit for a period of time before the battery is recharged. However, it's important to note that not all chemical treatments are effective, and some can even damage the battery further.
It's worth noting that not all sulfated batteries can be recovered. If the sulfation is too severe, the battery may need to be replaced. Additionally, prevention is always the best course of action. Keeping your lead-acid battery fully charged and avoiding leaving it in a discharged state for extended periods of time can help prevent sulfation from occurring in the first place.
In conclusion, sulfation is a common problem that can plague lead-acid batteries, but there are options for recovering them. From light sulfation to chemical treatments, there are different methods available, but results may vary. Remember to always prioritize prevention by keeping your batteries charged and maintained properly.
FAQ’s
What causes battery sulfation?
Battery sulfation is typically caused by prolonged disuse or a deep discharge of the battery, which causes sulfate crystals to form on the battery plates.
Can a sulfated battery be recharged?
In some cases, a sulfated battery can be recharged using a desulfator or a high-voltage pulse charger. However, if the battery has been severely damaged, it may not be recoverable.
2. How do I know if my battery is sulfated?
If your battery is sulfated, it may exhibit symptoms such as reduced performance, shorter run time, and difficulty holding a charge. You can also test the specific gravity of the battery's electrolyte to determine if it is sulfated.
3. How can I prevent battery sulfation?
To prevent battery sulfation, it's important to keep your battery fully charged when not in use and to avoid deep discharges. You can also use a battery maintainer or trickle charger to keep the battery charged when not in use.
4.How often should I check my battery for sulfation?
It's a good idea to check your battery for sulfation at least once a year, particularly if you use the battery infrequently. If you notice reduced performance or other symptoms of sulfation, you should check the battery more frequently.