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Battery Sulfation

Lead sulfate (PbSO4) is created at both the positive and negative electrode plates during a discharge. In principle, during the charging period, 100% of the lead sulfate transforms to the positive plate (lead dioxide), the negative plate (lead) and sulfuric acid. However, in real life, when PbSO4 (lead sulfate) is left in the battery for a period of time, it crystallizes and becomes a hard sulfate that coats the surface of the electrode plates. This phenomenon is called sulfation. Because hard lead sulfate is a non-conductive material, when it coats the electrode plates, it causes a reduction in the area needed for the electro- chemical reactions. It also reduces the batteries’ active materials needed to maintain a high capacity.

  • Lead sulfate covers surface of electrode plates limiting the area for electro-chemical reaction.
  • Lead sulfate is also made of useful component materials that are needed for maintaining a high capacity.
  • Lead sulfate that exists when a battery is not fully charged crystallizes to become a hard lead sulfate when left in a battery for a period of time. (2~3 days is said to be enough.)

In theory, there are three types of lead sulfate. One is soft lead sulfate that decomposes with a regular charge. The second is hard lead sulfate that only decomposes during an equalization charge (controlled over-charge done in industrial battery maintenance). The last is a very hard lead sulfate that fails to decompose even equalization charging.

*Notes to help understand batteries*

The worst sulfated battery can be created by just leaving a battery unattended for a long period of time. A battery is like a bucket with a tiny hole. Electricity leaks little by little through what is called “natural discharge”. It may take three to six months to drain a battery completely, and sulfation created in this process is quite possibly the worst kind.

  • For deep cycle batteries used in Renewable Energy, Marine and RV applications, sulfation buildup is a real problem because these batteries are not regularly charged to their full capacity. Conditioning the battery with Nanopulser makes good sense to maximize the life span of these batteries. (Nanopulser works on flooded, gel and AGM batteries.) — IT IS COMMON SENSE TO CONDITION BATTERIES WITH NANOPULSER.
    (In general, the average life of a car battery is approximately 48 months. The average life of a marine cranking battery in recreational marine use is only 22 months.)
  • An automobile starter battery is constantly charged while the automobile is running leading one to beleive that there might not be a sulfation problem, but in reality, automobile batteries sulfate. There are many conditions for car batteries to become sulfated. If a car is not in use and the battery is naturally discharged, the battery sulfates. Also, in regular starter usage, it takes about 4% of the battery capacity to start a car. If a car is taken on many short trips requiring the engine to be started many times without getting fully recharged, the battery sulfates. If a car is equipped with many electrical devices, it is more likely that the battery will sulfate. Then, when hard lead sulfate crystals form, charging via the alternator would not be sufficient to decompose the hard sulfation crystals completely. The starter battery begins to loose capacity. Nanopulser will help decompose the hard sulfation crystals so your car battery will last for its maximum life with a constant high capacity.
  • In the case of industrial batteries, such as a forklift batteries, where the recommendation is to perform equalization charges* every 4 to 6 cycles, Nanopulser will help ensure the batteries last their maximum possible lifespan. As a case study, in a warehouse situation, a 12 year old battery was conditioned with Nanopulser and the result was a rise in specific gravity (SG). It rose from 1.205 to 1.232 SG in 6 weeks. (This battery was a high acid-concentration battery and the SG specification at full charge was 1.310. The SG specification at full charge for common batteries is 1.280. Also, when crystallized lead sulfate grows to a large size on the plates, it precipitates from the plates when it is large enough and accumulates at the bottom of the battery case. When this accumulation touches the plates, it shorts out the battery.) The treatment with Nanopulser decomposed the hard lead sulfate on the plates that equalization charging could not dissolve. This 12 year old battery did not recover completely. We concluded that lead sulfate crystals already precipitated at the bottom of the battery case may not decompose. However, the increase in SG shows the desulfation effect of the lead sulfate on the plates. Also, in other cases, 4 ~ 6 year old batteries recovered SG up to 1.283. The best way to use Nanopulser in material handling is to install it on a brand new battery and avoid hard sulfation buildup from the very beginning even in a situation where batteries are well maintained. And of course, Nanopulser is highly recommended for those who tend to leave batteries discharged for a period of time**.

* Equalization charge is a controlled over-charge to equalize the specific gravity among all of the cells. It is a controlled high-voltage charge lasting for a duration of 5 to 7 hours. During this charge, the battery gases out hydrogen and oxygen and creates heat. By performing this charge it is possible to damamge the battery plates by excessive gassing and heat. The benefit of an equalization charge is removal of some sulfation buildup and correction the stratification of the acid density by stirring the electrolyte using the rising gas bubbles. Stirring is necessary to avoid high acid concentrations that can corrode the lower portion of the plate faster than the upper portion where the acid density is lower.

** In industrial usage batteries the recommendation is to avoid discharging batteries no more than 80% of their capacity and then charing them to 100% immediately after the disachrge. If drained lower than 80%, a quantity of lead sulfate will be created more than desired. Also, hard lead sulfate will start forming within 2 days if batteries are left discharged. To avoid sulfation buildup, the battery must be charged back to 100% right after discharge. Equalization charge should take care of the hard sulfation, but there will be some sulfation left over that the equalization charging misses.

Sulfation is a crystallized lead sulfate (PbSO4) which coats the electrode plates and eventually causes premature battery failure.

Sulfated electrode plate (picture on the left)

White sulfation (hard lead sulfate, the crystallized PbSO4) is covering the electrode plate. Lead sulfate is a non-conductive material. Coating an electrode plate with this non-conductive material causes a reduction in the surface area which is needed for the electro-chemical reactions. Sulfation also causes loss of component materials of the battery.

Condition of a new electrode plate (picture on the right)

The surface of new electrode plate is spongy. This porous condition increases the surface area for the electro-chemical reaction. When an electrode plate is new and not coated by hard lead sulafte buildup, it has more area for electro-chemical reactions and more component materials to produce electricity.


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