The first working lead-acid batteries were invented in 1859 by the French scientist Gaston Plante. Their design was made of sheet lead electrodes separated by sheet separators, which were coiled and placed in a vessel with a 10% sulfuric acid solution.
Lead-acid batteries, a brief description, design features, application, main advantages and disadvantages.
The disadvantage of the first lead-acid batteries was their low capacity. Initially, a large number of charge-discharge cycles were performed to increase it. To achieve significant results, it took up to two years of such training. The reason for the lack was obvious – the design of the plates. Therefore, further improvement of the design of lead-acid batteries was aimed at improving the design of the plates and separators used in them.
In 1880, K. Fore proposed a technology for manufacturing plated electrodes by applying lead oxides to plates. This design of the electrodes allowed to significantly increase the battery capacity. And in 1881, E. Volkmar proposed the use of a spread grid as electrodes. In the same year, the scientist Sellon was granted a patent for the technology of manufacturing lattices from an alloy of lead and antimony.
Initially, the practical use of lead-acid batteries was difficult due to the lack of chargers. For the charge, the primary elements of the Bunsen construction were used. That is, the chemical current source was charged from another chemical source – batteries of galvanic cells. The situation has changed dramatically with the advent of inexpensive DC generators.
Development and practical use of lead-acid batteries.
It was lead acid batteries that were the first in the world of rechargeable batteries to find commercial use. By 1890, serial production was mastered in many industrialized countries. In 1900, the German company Varta released the first starter lead-acid batteries for cars.
In the 70s of the last, XX century, maintenance-free lead-acid batteries were created that can work in any position. The liquid electrolyte in them was replaced with a gel or absorbed (absorbed) separator electrolyte, the batteries were sealed, and safe valves were installed to drain the gases released during charge or discharge.
New plate designs based on copper-calcium alloys coated with lead oxide and based on titanium, aluminum and copper gratings were developed. The active substances of the battery are concentrated in the electrolyte and positive and negative electrodes, and the combination of these substances is called the electrochemical system.
In lead-acid batteries, the electrolyte is a solution of sulfuric acid, the active substance of the positive plates is lead dioxide, and the negative plates are lead.
Division of lead-acid batteries into groups according to the operating mode and manufacturing technology.
In order to make it easier to understand the variety of lead-acid batteries, you should be aware of their division into groups according to the mode of their operation and manufacturing technology. This will help to understand how to choose the right battery for solving specific problems. How to choose the modes of charge and discharge, what external factors and how will affect its operation during operation.
According to the operating mode, lead-acid batteries are divided into three groups:
1. Lead-acid batteries for buffer operation.
When the battery is running in a buffer with a main voltage source, such as a mains power supply. Moreover, its main purpose is a backup power source. Battery discharge periods are short compared to charge periods. Most of the time it is constantly recharged..
Lead-acid batteries work in buffer mode:
Backup power of base stations of mobile communication and automatic telephone exchange.
Network Switches of Internet Providers.
Uninterruptible power supplies for personal computers and servers (UPS).
2. Lead-acid batteries for cyclic operation.
This mode is characterized by their discharge for some time and subsequent charge. The cyclic operating mode of rechargeable batteries is used much less often than the buffer one. An example of this mode can be called the work of electric vehicles and devices with autonomous power. During the working day, the traction batteries or batteries are discharged, and after its completion, these lead-acid batteries are charged.
3. Lead-acid batteries for mixed operation.
For example, car batteries.
By design, lead-acid batteries can be divided into:
Liquid Electrolyte Batteries – Serviced and Unattended.
Adjustable valve batteries (VRLA – Valve Regulated Lead Acid batteries) – with wet separators and gel electrolyte.
In various technical literature you can find such names of batteries as SLA – Sealed Lead Acid batteries – sealed lead-acid batteries related to VRLA batteries. Although this is not entirely true. Absolutely sealed batteries do not exist for the reason that all of them use valves to reduce internal pressure.
Very often, emphasizing this, instead of the term “sealed batteries” they use the term “sealed batteries”. There is also a name Gelcell Is a brand name for gel batteries. Starter batteries are sometimes abbreviated as SLI, what stands for Start, Light, Ignition – start, lighting, ignition.
Generations of Lead Acid Batteries.
Lead-acid batteries are still the most reliable, durable and low maintenance chemical current sources. Three generations of lead-acid batteries are currently being produced and actively operated:
1. First-generation lead-acid batteries with liquid electrolyte, open or closed.
These are lead-acid batteries with liquid electrolyte, open or closed, having a capacity of 36 to 5328 Ah and a service life of 10 to 20 years or more. Open-type lead-acid batteries have no caps, and the electrolyte comes in direct contact with open air. The main costs during their operation are maintenance costs associated with the need for frequent refilling of distilled water, and the costs of maintaining well-ventilated rooms in which they are installed.
Closed-type lead-acid batteries have special plugs that provide a delay in sulfuric acid aerosols. Stoppers for pouring electrolyte and adding water during operation are unscrewed. Closed batteries can be maintenance free. From the manufacturer they are supplied filled and charged, and during the service life there is no need to top up water, because the design of the plugs of such batteries ensures the retention of its vapor in the form of condensate.
In addition to being used as stationary, closed-type lead-acid batteries are the main type of batteries used in starter and traction vehicles.
2. Lead-acid batteries of the second generation, gel.
They are sealed gel batteries. Instead of liquid electrolyte, they use a gel-like jelly obtained by mixing a solution of sulfuric acid with a thickener (usually it is silicon dioxide – silica gel). The technology for the production of gel batteries is called GEL. Gel batteries do not need maintenance during the entire life cycle, they must not be opened.
For their recharging, it is necessary to use chargers that ensure the instability of the charge voltage is not worse than ± 1% to prevent excessive gas evolution. Such lead acid batteries are critical to ambient temperature..
3. Lead-acid batteries of the third generation assembled by AGM technology.
These are sealed batteries with absorbed electrolyte separators. Often called AGM technology batteries.. AGM – Absorbed in Glass Mat, i.e., technology in which the electrolyte is absorbed in fiberglass separators placed between the electrodes. Such a separator is a porous system in which capillary forces hold electrolyte.
In this case, the amount of electrolyte is dosed so that small pores are filled, while large ones remain free for free circulation of the released gases. By their properties, AGM batteries are similar to gel batteries, except that the gas generation in them is much less, and the ambient temperature has a smaller effect on their operation. As with gel batteries, they require chargers that provide a charge voltage instability of at least ± 1%.
Features of the design of lead-acid batteries.
The terminals of automotive batteries have a standard cone shape. The terminals of the batteries for other purposes can have a different design.
The design of rechargeable batteries of various companies that produce them may have its own characteristics. For example, the special design of separators or gratings or the use of specific additives in the manufacture of plates. Often, when designating the type of battery, its marking is indicated, which is determined by the design of the positive plates.
Symbols applied to the case of lead-acid batteries.
Location of jumpers 6 and 12 volt lead-acid batteries in accordance with DIN standards.
Features of the production of lead-acid batteries.
In the manufacture of lead-acid batteries, chemical additives are used. For example, antimony is added to lead (the share in the alloy is 1-10%), which provides a more durable electrical contact of the active material with the grating, prevents it from shedding, which allows to increase the battery life.
In addition to lead-antimony, lead-calcium alloys are also used, which make the plates lighter and stronger while maintaining high electrical and mechanical characteristics. The correct selection of metals, chemicals and additives helps to achieve a compromise and balance between high energy density, long shelf life, extended life and safe operation.
Most types of lead-acid batteries have prismatic cells. Therefore, rectangular cases for them are made of plastic. Although some types of VRLA batteries are made on the basis of cylindrical cells, while retaining all the advantages of the latter. They provide higher stability of the cells, a greater discharge current, better temperature stability compared to batteries assembled from prismatic cells.
The voltage on the lead-acid battery cell is 2.2 V. Among all types of batteries, lead-acid batteries have the lowest energy density. They lack a “memory effect.” Their long charge will not cause a battery failure.
The ability to maintain charge on these batteries is the best of all types of batteries. If nickel-cadmium batteries lose 40% of their stored energy within three months, lead-acid batteries lose 40% of their energy in just one year. They are inexpensive, but their operating costs are higher than those of the same nickel-cadmium batteries..
Features of charge and discharge of lead-acid batteries.
The lead-acid batteries charge time is 8-16 hours. They should always be stored in a charged state, since storage in an uncharged state will lead to sulfation of the plates – the reason for the loss of capacity, and in the long run and the fact that the battery will subsequently not be charged at all.
Unlike nickel-cadmium, lead-acid batteries do not like deep charge / discharge cycles. Full discharge can cause deformation of the plates, and each cycle of the battery charge / discharge subsequently leads to a decrease in its capacity.
Such losses are relatively small, while the battery is operating under normal conditions, but even the only case of overloading it and, as a result, deep discharge will lead to a loss of its capacity by about 80%. To prevent such cases, it is recommended to use high capacity batteries.
Depending on the depth of discharge and operating temperature, the life or service life of a lead-acid battery can be from 1 year to 20 years or more. In addition, to a large extent, the service life is determined by the design of battery cells.
The optimum operating temperature of lead-acid batteries is 25 degrees, and its increase by every 10 degrees reduces the battery life by half. For example, a VRLA battery at a temperature of 25 degrees can work for 10 years, and at a temperature of 33 degrees – only 5 years. Well, at a temperature of 42 degrees – only 1 year.
Advantages of lead acid batteries:
Cheapness and simplicity of production. At the cost of 1 Wh of energy, these batteries are the cheapest.
Proven, reliable and well-understood service technology.
Small self-discharge. Lowest compared to other types of batteries.
Low maintenance requirements. There is no “memory effect”, no electrolyte topping up is required.
Permissible high discharge currents.
Disadvantages of lead acid batteries:
Discharged storage not allowed.
Low energy density. The heavy weight of the batteries limits their use in stationary and moving objects.
Only a limited number of full discharge cycles are permissible..
Acidic electrolyte and lead are harmful to the environment.
Incorrect charge may cause overheating.
Lead-acid batteries have such a low energy density compared to other types of batteries that it makes it inappropriate to use them as power sources for portable devices. Although examples of their use in portable electronic equipment are. In addition, at low temperatures, their capacity is significantly reduced.
Based on the book Battery.