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How Lead Acid Batteries Work

How Lead Acid Batteries Work

There are several types of batteries, depending on their functioning and of the internal structure of the same, mainly, although in general terms we can make a distinction of two kinds of batteries. These are the lithium batteries and the lead acid batteries. Although lithium batteries come with a lot of advantages, they are still very expensive.

How Lead Acid Batteries Work

On the contrary, lead acid batteries are becoming more modern, which means that we can find them in different models depending on the use we are going to give them, such as deep cycle lead acid batteries, sealed lead acid batteries… Next, we analyze everything that has to do with lead acid batteries, their operation, the different types and the most common uses of this type of battery, as in the case of photovoltaic lead acid batteries.

What are lead acid batteries?

Lead acid batteries, whether they are deep cycle lead acid batteries or photovoltaic lead acid batteries, consist of two electrodes, one positive and one negative. When these are connected, they form a closed circuit —as in all batteries— through which the current circulates. The main difference in terms of composition and materials, with respect to lithium batteries, is that they use a electrolyte composed of a solution of sulfuric acid with distilled water. In lithium batteries, the electrolyte contains lithium salt, which gives rise to a different chemical reaction in each case. Each lead acid battery is made up of multiple pairs of electrodes located in separate compartments. These are called cells. These are immersed in the electrolyte solution, where the reaction takes place. The positive electrode of lead acid batteries is made up of a lead plate coated with lead(II) oxide and PbO2. The negative electrode, on the other hand, is coated with sponge lead.

What is the operation of lead acid batteries?

The operation of lead batteries is based on a chemical reaction that takes place between lead and sulfuric acid. This produces a potential difference between the battery terminals —in the metal terminals—, allowing us to obtain energy when we connect to an electrical circuit. If, on the other hand, we apply electricity to the battery, then the reaction is reversed, which gives us the option of storing the energy to be able to use it later – this gives rise to what is known as the lead acid battery cycle. , loading and unloading—.

In the case of photovoltaic lead acid batteries, the electricity with which the battery is charged —in isolated photovoltaic solar installations— comes from the solar panels, previously passing through the charge regulator. However, if the battery is completely discharged the process varies a bit. What happens is that the electrodes have “decomposed” because they have changed their nature. It is advisable that the batteries do not discharge completely. If we want to reverse this situation to have a lead acid battery, fully charged and working correctly, then we must proceed to charge it again. What we will achieve is that the current circulates in the opposite direction to the usual one and that it recomposes the electrodes.

Types of lead acid batteriesF

The different types of lead acid batteries can be classified depending on various criteria. These can be based on the type of lead acid plate used, the type of alloy, depending on the maintenance they require and the type of electrolytes. This interferes with the cycle of lead acid batteries, charge and discharge:

  • Lead Acid Plate Type: The most used are three. These are the flat pasted plates, the tubular plates and the planted plates.
  • alloy type: If the alloy is lead and antimony, if it is lead and selenium or if it is lead and calcium.
  • Maintenance: Lead-acid batteries generally require maintenance —when the antimony alloy is high— since during use they generate gasification —as is the case with valve-regulated lead-acid batteries (VRLA, Valve Regulated Lead Acid). Acid)—. These batteries are not completely sealed, in their structure they have rubber plugs that can be uncovered to release the pressure generated by the gases. Now, we can also find lead acid batteries —such as deep cycle lead acid batteries— that have low maintenance, these batteries have an alloy of lead and selenium. We can also find maintenance-free batteries —if the alloy is lead and calcium— or unattended —if they are completely closed—.
  • electrolyte type: In this case we find three types of electrolytes that are assembled in the battery and that vary depending on the state in which they are when the reaction occurs. These electrolytes can be liquid, gel or absorbed. In the case of absorbed electrolytes we find VRLA AGM (Absorbed Glass Mat) batteries. These batteries separate the positive and negative plates by means of an absorbent fiberglass base. The electrolyte is assembled in liquid form, but this is absorbed by the mentioned fiber. As in gel batteries, AGM batteries with absorbed electrolyte are not in danger of leaking if there is a break. These batteries can be installed lying down.

Uses of lead acid batteries

Knob acid batteries are currently the most widely used due to their performance, their different models —increasingly more sophisticated— and they are quite cheap. We can find knob acid batteries both in cars, as well as in different generators, photovoltaic solar panels, portable equipment, SAIS, small lighting devices, alarm systems and much more. The cycle of lead acid batteries, charge and discharge is very fast and effective.