The battery is exactly what is found on absolutely all modern vehicles. The main purpose of this node has always been and is today to supply electricity to electronic devices machines, if they need one, bypassing the generator. In general, the first batteries appeared several hundred years ago. Starting in the 1800s, the design and technical development of rechargeable batteries led to the creation of one of the most famous types of assembly in the world - the lead-acid battery. Taking into account the demand for such batteries for motorists, our resource decided to consider them in more detail.

The history of the appearance of such batteries

The first to create and design a really working lead-acid battery was a French scientist - Gaston Plante. This person was seriously interested in creating batteries that were universal at that time, since he had not only scientific interest, but also partly financial. According to historical reports, battery manufacturers, of which there were few at that time, offered a lot of money to Gaston Plante for creating a new type of battery and convenient charging for it.

As a result, the French scientist partially managed to achieve his goal. To be more precise, Plante created a battery design using lead electrodes and a 10% sulfuric acid solution. Despite the innovativeness of the acid battery in those years, it had a significant drawback - the need to go through a huge number of “charge-discharge” cycles to charge the battery “to full”. By the way, the number of these cycles was so large that it could take several years to fully accommodate the electricity in the battery. This was largely due to the design of lead electrodes and separators used in batteries, as a result of which the next few decades the minds of the "battery business" struggled with this particular defect in batteries.

So, in the period from 1880-1900, scientists such as Faure and Volkmar designed an almost ideal lead-acid battery design among all types. The essence of such a battery was to use not solid lead plates, but only its oxide, combined with antimony and deposited on special plates. Later, Sellon patented the most successful type of design for this battery, introducing a metal grid smeared with oxides of lead and antimony into it, which as a result:

• increased the capacity of the batteries several times;
• increased commercial interest on the part of companies in the battery;
• and, in general, made some evolutionary leap in the battery business.

Note that since the beginning of 1890 lead acid batteries went into serial production and began to be widely used everywhere.

In the 1970s, batteries were sealed due to the replacement of standard acidic electrolytes in them with improved gases and gels. As a result, the battery became somewhat sealed. However, it was not possible to achieve complete sealing, since, in any case, when charging and discharging the battery, some gases are formed that are important to release from the inside of the battery for its own good. Since then, sealed lead-acid batteries have been used on a huge scale and have remained virtually unchanged, with the exception of minor improvements in the electrolytes and electrodes used in their design.

Lead Acid Battery Device

In its own way general design lead-acid batteries have been unchanged for more than 110 years. IN general view The battery consists of the following elements:

• plastic or rubber housing in the form of a prism;
• a metal grid with an appropriate lead coating and subdivisions for positive, negative electrodes;
• gas release valve;
• areas for filling with electrolyte, otherwise - separators;
• interdimensional areas filled with mastic;
• lid.

All elements as stationary lead acid battery, and non-stationary batteries of this type are a sealed complex. Partially-complete sealing is available for most modern batteries, because it has systems for removing excessively pressurizing gases. Full sealing is structurally provided only in high batteries using a special design of electrodes, which makes it possible not to add electrolyte at all during operation and not to remove exhaust gases. In any case, that batteries with partially-complete sealing, that with completely complete insulation, it is customary to call sealed lead-acid batteries, therefore, in this regard, between different types There are no differences in batteries.

Types of batteries and how they work

It was already mentioned earlier that lead-acid batteries are divided into different types. Regardless of the type of their organization, they work on the principle of electrolytic chemical reactions. These are based on the interaction of lead (or other metal), lead oxide (with antimony) and sulfuric acid (or other electrolyte). It is this type of interaction in acid batteries was recognized as the best, since during acid hydrolysis, other combinations of interactions of substances lead either to a low battery life (with the addition of calcium), or to excessive “boiling” inside the part (in the absence of antimony), or to insufficient power (when using only lead plates) .

To date, there are three main types of lead-acid batteries, to be exact:

1. Lead-acid batteries 6V. They are built on the principle of using 6 elements, that is, the battery is internally divided into 6 blocks working together, each of which is in general case produces about 2.1 volts of voltage, which ultimately gives 12.6 volts per whole battery. On this moment 6V lead-acid batteries are the most used in the automotive industry, as they are of the highest quality from all sides of their work;
2. Hybrid batteries. These "beasts" are a mixture where one electrode (often positive) with lead-antimony oxide is used, and the other (usually negative) with lead-calcium. Such batteries, due to the use of calcium in their design, are less durable;
3. Gel lead acid batteries. Slightly different from the design of the types of batteries described above, as they have a gel-like electrolyte, which allows them to be used in any position. By characteristics gel batteries are similar to conventional lead-antioxidant batteries and are already actively conquering the auto industry market in their segment.

As practice shows, the most successful designs lead acid batteries- this is a standard one with the presence of antimony on the electrode grid and a relatively young gel one. As for hybrid ones, due to their peculiarities of demand on the market, they still do not have, therefore they are practically not sold and you can meet them extremely rarely.

Operating rules

Compared to other types of batteries, lead-acid batteries are less whimsical to use. General requirements batteries are subject to special organizations and directly from their manufacturer. By the way, the requirements are different for stationary and non-stationary batteries. For the first types of batteries, they are as follows:

• Inspection and inspection - weekly by specialized personnel;
• Maintenance - at least once a year;
• Capital restoration - at least once every 3 years, and only if possible;
• Reliable fastening of the battery during operation on special stands;
• Mandatory availability of lighting in the storage area;
• Painting the surface on which the battery stands in acid-resistant paint;
• Maintaining the electrolyte in the battery separators at the proper level (checking / topping up monthly);
• Availability of chargers and compliance with charging rules;
• The rated voltage in the network is 5% higher than the batteries charged in it;
• Avoid storing the battery in a discharged state for more than 12 hours;
• Storage temperature from -20 to +45 degrees Celsius, for 50% charged batteries - from -20 to +30. Uncharged batteries must not be stored.

In the case of non-stationary lead-acid batteries, storage conditions consist only in their timely recharging, electrolyte control (if necessary) and using the battery strictly for its intended purpose.

Charging Rules

Charging any battery is exactly the procedure that should be carried out in the only correct mode. Otherwise, a couple of incorrect battery charging operations will either make it a low-power current source or completely “kill” the part. Knowing this feature of batteries, their owners often ask two questions:

1. How to properly charge the battery?
2. Which Charger for lead-acid equipment is best to use?

Regarding the second question, we can unequivocally say that it is permissible to charge the battery with any equipment, the main thing is that it is in good working order. And about how to charge a lead-acid battery, let's talk in more detail. In general, the correct charging order is as follows:

1. The battery is placed in a place specially equipped for charging: the surface is painted in anti-acid paint, there are no open sources of water and fire, access to the territory is limited;
2. After that, the battery is connected to the charger in accordance with all standards;
3. Then, the charging mode is set on the charging equipment, subject to two basic conditions:
   • the voltage is constant and equal to about 2.35-2.45 volts;
   • the current at the beginning of the charge is the highest, towards the end it gradually and noticeably decreases.

The direct process of charging the battery in standard mode lasts about 3-6 hours, except for cases using cheap and weak equipment, as well as when restoring charging a “killed” battery.

Battery Recovery

At the end of today's material, let's pay attention to the process of restoring lead-acid batteries. It is generally accepted that at deep discharge given type batteries either completely “dead” or hold a very weak charge. In fact, the situation is different.

According to numerous studies, lead-acid batteries are capable of not losing nominal capacity even after 2-4 full discharges. To do this, it is enough to competently carry out the procedure for their restoration. How to restore this battery? In the following order:

1. The battery is placed in a specially prepared place with an air temperature of about 5-35 degrees Celsius;
2. The battery and charger are connected;
3. The latter includes indicators such as:
   • voltage - 2.45 Volts;
   • current strength - 0.05 SA.
4. There is a cyclic charge with small interruptions of the order of 2-3 times;
5. The battery has been restored.

Note that not in every situation such a procedure ends in success, but if the rules for restoring the battery are followed and the battery itself is made of high-quality materials, then there is no doubt about the success of the event.

On this, perhaps, the most important information on lead-acid batteries came to an end. We hope that today's material was useful for you and gave answers to your questions.

If you have any questions - leave them in the comments below the article. We or our visitors will be happy to answer them.

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The mechanism of the battery

Batteries are chemical current sources with a reversible process: they can give energy by converting chemical energy into electrical energy, or store energy by converting electrical energy into chemical energy. Thus, the battery is alternately discharged, giving off electrical energy, then charging from some appropriate source. direct current.

Batteries, depending on the electrolyte used in them, are divided into acid and alkaline. In addition, batteries differ, depending on the material of the electrodes. Only lead, cadmium-nickel, iron-nickel and silver-zinc batteries are widely used.

The capacity of the battery is determined by the amount of electricity q p that it can give when discharged into the powered circuit.

This amount of electricity is measured not in coulombs, but in larger units - ampere-hours (ah). 1 Ah = 3600 cells But to charge the battery, a greater amount of electricity q 3 is required than is given off during discharge. The ratio q p: q 3 \u003d n e is called the return of the battery in terms of capacity.

The voltage required to charge the battery is much higher than the voltage at the battery terminals at which it gives a continuous discharge current.

An important characteristic of a battery is its average charging and discharging voltages.

It is clear that due to a series of energy losses, the battery gives off a much smaller amount of energy W p during discharge than it receives when charging. The ratio W p: W 3 \u003d n is the coefficient useful action or battery power output.

Finally, a very important value for characterizing a battery is its specific energy, i.e., the amount of energy given off during discharge per 1 kg of battery weight. It is especially important that the specific energy be as high as possible for non-stationary batteries installed, for example, on aircraft. In such cases, it is usually more important than efficiency and return on capacity.

It should be borne in mind that with a slow discharge, the process in the battery proceeds evenly throughout the entire mass of the plates, due to which, with a long-term discharge with a low current, the battery capacity is greater than with a short-term discharge. high current. With a fast discharge, the process in the mass of the plates lags behind the process on their surface, which causes internal currents and a decrease in recoil.

The battery voltage changes significantly during discharge. It is desirable that it be as permanent as possible. The calculations usually indicate the average discharge voltage U p. But to charge the battery, you need a current source that gives much more charging voltage U s (by 25-40%). Otherwise, the battery cannot be fully charged.

If the voltage of one battery cell is not enough for a given installation, then the required number of battery cells is connected in series. Of course, only batteries designed for the same discharge current can be connected in series.

If the discharge current of one element is insufficient, then apply parallel connection multiple identical elements.

Of the acid batteries, only lead batteries are of practical importance. In them, lead dioxide Pb0 2 serves as an active substance on the positive electrode, spongy lead Pb on the negative electrode. The positive plates are brown, the negative ones are grey, the electrolyte is a solution of sulfuric acid H 2 S0 4 with a specific gravity of 1.18-1.29.

The chemical process of discharging and charging a lead battery is relatively complex. Basically, it comes down to the reduction of lead at the positive electrode and the oxidation of spongy lead at the negative electrode into sulfuric acid oxide. In this case, water is formed and, consequently, the density of the electrolyte decreases. When discharging, the battery voltage first drops rapidly to 1.95 V, and then slowly drops to 1.8 V. After that, it is necessary to stop discharging.

With further discharge, an irreversible process of formation of crystalline lead sulfate PbS 4 takes place. The latter covers the plates with a white coating. It has a high resistivity and is almost insoluble in the electrolyte. A layer of lead sulfate increases the internal resistance of the active mass of the plates. This process is called plate sulfation.

When the battery is charged, the process goes in the opposite direction: metallic lead is reduced at the negative electrode, and lead is oxidized at the positive electrode to Pb0 2 dioxide. The S0 4 ion passes into the electrolyte, so the density of sulfuric acid increases during charging, and therefore the specific gravity of the electrolyte also increases. A special hydrometer is used to measure the specific gravity of the electrolyte. According to his testimony, you can roughly judge to what extent the battery is charged. The average discharge voltage of a lead battery is 1.98V, and the average charge voltage is 2.4V.

The internal resistance r B n of lead batteries, due to the small distance between the plates and the large area of ​​​​their contact with the electrolyte, is very small: about thousandths of an ohm for stationary batteries and hundredths for small portable batteries.

Due to the low internal resistance and relatively high voltage, the efficiency of these batteries reaches 70-80%, and the return is 0.85-0.95%.

However, due to the low internal resistance in lead batteries during short circuits, currents are very great strength, which leads to warping and disintegration of the plates.

Of the alkaline batteries, cadmium-nickel, iron-nickel and silver-zinc are currently widely used. In all these batteries, the electrolyte is alkali - about a two percent solution of caustic potassium KOH or caustic soda NaOH. During charging and discharging, this electrolyte undergoes almost no changes. Therefore, the battery capacity does not depend on its quantity. This makes it possible to minimize the amount of electrolyte in all alkaline batteries and thus significantly lighten them.

The cores of the positive and negative plates of these batteries are made of nickel-plated steel frames with packages for the active mass. Thanks to this design, the active mass is firmly held in the plates and does not fall out during shocks.

In a cadmium-nickel KN battery, the active substance of the positive electrode is nickel oxides mixed with graphite to increase electrical conductivity; the active substance of the negative electrode is spongy metallic cadmium Cd. During the discharge, a part of the active oxygen contained in nickel oxides is consumed on the positive electrode, and metallic cadmium is oxidized on the negative electrode. When charging, the positive electrode is enriched with oxygen back: nickel oxide hydrate Ni (OH) 2 turns into nickel oxide hydrate Ni (OH) 3. At the negative electrode, cadmium oxide hydrate is reduced to pure cadmium. Approximately, the process in this battery can be expressed by the chemical formula:

2Ni (OH) 3 + 2KOH + Cd? ? 2Ni (OH) 2 + 2KOH + Cd (OH) 2.

As the formula shows, a particle (OH) 2 is released from the electrolyte during the discharge on the negative plate and the same particle passes into the electrolyte on the positive plate. When charging, the process goes in the opposite direction, but in both cases, the electrolyte does not change.

The device of the iron-nickel battery differs only in that in it the cadmium in the negative plates is replaced by a fine powder of iron (Fe). The chemical process of this battery can be followed from the equation above for a cadmium-nickel battery by replacing Cd with Fe.

The use of iron instead of cadmium reduces the cost of the battery, makes it more mechanically durable and increases its service life. But on the other hand, for an iron-nickel battery, with approximately the same discharge voltage, the charging voltage is 0.2 V higher, as a result of which the efficiency of this battery is lower than that of a cadmium-nickel battery. Then a very important disadvantage of the iron-nickel battery is the relatively fast self-discharge. The cadmium-nickel battery has a low self-discharge and is therefore preferred when the battery must be charged for a long time, for example, to power radio installations. The average discharge voltage of both these batteries is 1.2 V.

The hermetically sealed vessels of the alkaline batteries described above are made of nickel-plated steel sheet. The bolts through which the plates of the accumulators are connected to the external target are passed through holes in the lid of the vessel, the bolt to which the negative plates are connected being carefully insulated from the steel case; but the bolt connected to the positive plates is not isolated from the housing.

The internal resistance of alkaline batteries is much greater than that of acid batteries, which makes them more resistant to short circuits. But for the same reason, the efficiency of alkaline batteries (about 45%) is much lower than that of acid batteries, their specific energy and capacity return (0.65) are also significantly lower. Since the state of the electrolyte in alkaline batteries does not change during operation, then determine their degree of charge by outward signs it is forbidden. As a result, the charge has to be monitored based on their capacitance and voltage. When charging, you need to tell the battery the amount of electricity It \u003d q is much larger than its capacity, about 1.5 times. For example, it is desirable to charge a battery with a capacity of 100 Ah with a current of 10 A for 15 hours.

Silver-zinc batteries are the latest among modern batteries. The electrolyte in them is an aqueous solution of caustic potassium KOH with a specific gravity of 1.4, with the active substance of the positive electrode (silver oxide Ag 2 0) and the negative electrode (zinc Zn). The electrodes are made in the form of porous plates and are separated from each other by a film partition.

When the battery is discharged, silver oxide is reduced to metallic silver, and metallic zinc is oxidized to zinc oxide ZnO. The reverse process occurs when the battery is charged. The basic chemical reaction is expressed by the formula

AgsO + KOH + Zn ? ? 2Ag + KOH + ZnO.

http://website/www.youtube.com/watch?v=0jbnDTRtywE
The stable discharge voltage is about 1.5 V. At low discharge currents, this voltage remains almost unchanged for about 75-80% of the battery life. Then it drops rather quickly, and at a voltage of 1 V, the discharge should be stopped.

The internal resistance of silver-zinc batteries is significantly less than other alkaline batteries. With equal capacity, the former are much lighter. They work satisfactorily both at low (-50°C) and high (+ 75°C) temperatures. Finally, they allow large discharge currents. For example, some types of such batteries can be heated with a current short circuit within one minute.

The above is just basic battery information. In practical work with batteries, especially with lead batteries, it is necessary to carefully follow the relevant factory instructions. Violation of them causes the rapid destruction of batteries.

Lead-acid battery is one of the most common types of batteries, used as a source of electricity for a car, motorcycle, moped, or in case of need to create spare power supplies.

The first model of a lead-acid battery was created in the middle of the 19th century by the scientist Gaston Plante. Then its design meant two lead plates, a glass flask with sulfuric acid and an ordinary canvas as a separator. This device had a low charge capacity and was not widely used. But the idea was appreciated by other scientists and began to experiment with the composition of the electrodes. As a result, the lattice structure made of an alloy with the addition of antimony turned out to be the most successful. The invention of DC generators solved the problem of a suitable power source, and lead-acid rechargeable batteries have finally become widespread.

At the end of the twentieth century, their design became more complicated, appeared, in the electrodes of which calcium was added. This innovation has significantly reduced water consumption. Ideally, batteries of this type are able to work without replenishing the amount of water in the electrolyte for the entire service life. By the way, if necessary, you can try to restore a device that has lost its functionality using the principle of operation of acid batteries.

By design features modern batteries are divided into three types:

1. with liquid electrolyte. They can be either serviced or unattended. An electrolyte is a mixture of sulfuric acid and water in liquid form. In the version requiring maintenance, the plates are made of lead with the addition of antimony and arsenic. These batteries have a high water consumption, which makes maintenance of the battery not a very easy task. After replacing antimony with calcium in the composition of the alloy of the negative plate, the so-called hybrid batteries appeared, which are more convenient to use than their predecessors. And, finally, with the addition of calcium to both plates, an era of devices began that did not require restoration of the amount of water for the entire service life. Despite the perfection of the design, they have one drawback - they do not tolerate an almost complete discharge, especially in conditions of negative temperature.
2. Gel batteries. In these designs, the electrolyte is in a condensed state due to the addition of silicon. The advantage of this design is that the battery becomes completely sealed. The gas released in the course of chemical reactions finds a place for itself in the pores of the gel, and during the reverse reactions, it again joins the sulfuric acid solution. But these are very capricious batteries. They require strict observance of operating conditions, are sensitive to temperature changes, cope with high loads worse than their liquid counterparts. But they do well with strong discharge, really do not require additional service. Gel batteries are more often used as a stationary backup power source and are rarely installed on vehicles.
3. AGM batteries. This is the most modern look batteries, combining all the advantages of the previous options. The electrolyte remains liquid, but circulates in a porous structure made of the finest glass fibers. Two types of pores - large and small - ensure the free movement of gas before the reverse reaction starts. The design of the device is such that the battery can work even if its shell is slightly damaged. They are not afraid of cold, deep discharge, vibrations. The only vulnerability of such a device is sensitivity to voltage drops. This problem can be solved by controlling the operation of the generator and using a reliable memory.

Capacitance and voltage

Any one has two main parameters: capacitance and voltage. Capacity determines the amount of energy that a battery can deliver at operating voltage, measured in amp-hours. It depends on the area of ​​the lead plates involved in chemical reactions. When the battery wears out, its capacity decreases due to natural losses in the size of the plates.

Voltage is the amount of electrical current supplied by a battery. It is measured in volts and depends on the density of the electrolyte. Both parameters must be controlled, since the performance of the device depends on them.

A voltmeter is used to measure voltage, the correct readings are from 11 to 13 volts (6 volt batteries were previously produced, now they are considered obsolete).

To measure capacitance, there are several methods:

• « » - voltage measurement at reference load. The battery must be fully charged.
• special indicator, capable of sending a signal that determines the area of ​​lead plates and converting it into numbers. Does not require special conditions of use.
• At home, you can connect a powerful automotive halogen lamp and measure the voltage at this time. Ate for 2 minutes, it keeps at a level of ~ 11 volts, and the light of the lamp is even and strong - everything is in order.

Operation and restoration

Depending on the type of battery used, its operating conditions will vary greatly. the only common feature- all of them need to be charged in time. So, a serviced battery requires adding water to the battery, which can be dangerous - the acid heats the water, and boiling water can significantly burn the car owner.

Design maintenance-free batteries does not imply the possibility of replenishing the water supply in them. But, even if you make small changes in the design, getting burned with boiling water will still be problematic. For batteries of this type, it is important not to allow large voltage fluctuations. This is true for both car and motorcycle batteries. But the sealed case reduces the device's recovery options.

How ? Often, a decrease in battery capacity or voltage is due to the fact that some areas of the electrolyte are too compacted. With repeated small charging, these areas are liquefied, and the potential of the device is restored. There are several recipes for a repair solution that slightly improves the condition of the device. Unfortunately, its use is somewhat difficult on batteries with a sealed case, since it will be problematic to drain this solution from it.

Whichever battery is installed on vehicle, it is important to follow the instructions for its use, charge it in time and, if necessary, replenish the supply of water in the electrolyte. Then the battery will last as long as possible.

Operating principle. battery called chemical source current, which is able to accumulate (accumulate) electrical energy in itself and, as necessary, give it to an external circuit. The accumulation of electrical energy in the battery occurs when current is passed through it from

foreign source (Fig. 158, a). This process, called battery charge, is accompanied by the conversion of electrical energy into chemical energy, as a result of which the battery itself becomes a source of current. When the battery is discharged (Fig. 158, b), the reverse transformation of chemical energy into electrical energy occurs. The battery has a big advantage over the galvanic cell. If the element is discharged, then it becomes completely unusable; battery or. after the discharge, it can be re-charged and will serve as a source of electrical energy. Depending on the type of electrolyte, batteries are divided into acid and alkaline.

On locomotives and electric trains, the most widely used alkaline batteries, which have significantly longer term services than acid. Acid batteries TN-450 are used only on diesel locomotives, they have a capacity of 450 A * h, a rated voltage of 2.2 V. The battery 32 TN-450 consists of 32 batteries connected in series; the letter T means that the battery is installed on the locomotive, the letter H - the type of positive plates (spread).

Device. In an acid battery, the electrodes are lead plates coated with so-called active masses, which interact with the electrolyte during electrochemical reactions during charging and discharging. The active mass of the positive electrode (anode) is lead peroxide PbO 2, and the active mass of the negative electrode (cathode) is pure (spongy) lead Pb. The electrolyte is a 25-34% aqueous solution of sulfuric acid.

The accumulator plates may be of surface or spread type construction. Plates of surface type are cast from lead; their surface, on which electrochemical reactions occur, is increased due to the presence of ribs, grooves, etc. They are used in stationary batteries and some batteries in passenger cars.

In the batteries of diesel locomotives, spread-type plates are used (Fig. 159, a). Such plates have a core made of an alloy of lead with antimony, in which a number of cells filled with paste are arranged.

After filling with paste, the cells of the plates are covered with lead sheets with a large number of holes. These sheets prevent the active mass from falling out of the plates and at the same time do not interfere with electrolyte access to it.

The starting material for the manufacture of paste for positive plates is lead powder Pb, and for negative ones, powder, lead peroxide PbO 2, which are kneaded on aqueous solution sulfuric acid. The structure of active masses in such plates is porous; due to this, not only surface, but also deep-lying layers of battery electrodes participate in electrochemical reactions.

To increase the porosity and reduce the shrinkage of the active mass, graphite, carbon black, silicon, glass powder, barium sulfate and other inert materials are added to the paste, called expanders. They do not take part in electrochemical reactions, but make it difficult for particles of lead and its oxides to stick together (sintering), and thereby prevent a decrease in porosity.

Spread plates have a large surface of contact with the electrolyte and are well impregnated with it, which helps to reduce the mass and size of the battery and allows you to receive high currents during discharge.

In the manufacture of batteries, the plates are subjected to special charge-discharge cycles. This process is called battery molding. As a result of molding, the paste of positive plates is electrochemically converted into lead peroxide (dioxide) PbO 2 and acquires a brown color. The paste of negative plates during molding turns into pure lead Pb, which has a porous structure and is therefore called spongy; the negative plates turn grey.

Some batteries use shell-type positive plates. In them, each positive plate is enclosed in a special shell (case) made of ebonite or fiberglass. The shell reliably keeps the active mass of the plate from shedding during shaking and shocks; to communicate the active mass of the plates with electrolyte in the shell, horizontal cuts are made with a width of about 0725 mm.

To prevent the plates from closing with foreign objects (a probe for measuring the electrolyte level, an electrolyte filling device, etc.), the plates in some batteries are covered with a PVC mesh.

To increase the capacity, several positive and negative plates are installed in each battery; plates of the same name are connected in parallel into common blocks, to which output pins are welded. Blocks of positive and negative plates are usually installed in an ebonite battery vessel (Fig. 159, b) so that between each two

plates of one polarity were placed plates of another polarity. Negative plates are placed along the edges of the battery, since positive plates are prone to warping when installed along the edges. The plates are separated from one another by separators made of microporous ebonite, PVC, glass felt or other insulating material. Separators prevent the possibility of a short circuit between the plates when they are warped.

The plates are installed in the battery vessel so that there is some free space between their lower part and the bottom of the vessel. Lead sediment (sludge) accumulates in this space, which is formed due to the falling off of the spent active mass of the plates during operation.

Discharge and charge. When the battery is discharged (Fig. 160, a), positive H 2 + ions and negative ions of the acid residue
S0 4 -, into which the molecules of sulfuric acid H 2 S0 4 of electrolyte 3 decompose, are directed respectively to the positive
1 and negative 2 electrodes and enter into electrochemical reactions with their active masses. Between the electrodes there is
a potential difference of about 2 V, which ensures the passage of electric current when the external circuit is closed. As a result
electrochemical reactions that occur during the interaction of hydrogen ions with lead peroxide PbO 2 positive
electrode and ions of sulfate residue S0 4 - with lead Pb of the negative electrode, lead sulfate PbSO 4 (lead sulfate) is formed, into which the surface layers of the active mass of both electrodes are converted. At the same time, during these reactions, a certain amount of water is formed, so the concentration of sulfuric acid decreases, i.e., the density of the electrolyte decreases.

The battery can theoretically be discharged until the active masses of the electrodes are completely converted into lead sulfate and the electrolyte is depleted. However, in practice, the discharge is stopped much earlier. The lead sulphate formed during the discharge is a white salt, poorly soluble in the electrolyte and having a low electrical conductivity. Therefore, the discharge is not carried out to the end, but only until the moment when about 35% of the active mass passes into lead sulfate. In this case, the resulting lead sulfate is evenly distributed in the form of tiny crystals in the remaining active mass, which still retains sufficient electrical conductivity to provide a voltage between the electrodes of 1.7-1.8 V.

A discharged battery is charged, that is, it is connected to a current source with a voltage greater than the battery voltage. When charged (Fig. 160, b), positive hydrogen ions move to negative electrode 2, and the negative ions of the sulfuric acid residue S0 4 - to the positive electrode 1 and enter into chemical interaction with lead sulfate PbS0 4 covering both electrodes. In the process of emerging electrochemical reactions, lead sulfate PbS0 4 dissolves and active masses form again on the electrodes: lead peroxide PbO 2 on the positive electrode and spongy lead Pb on the negative. At the same time, the concentration of sulfuric acid increases, i.e., the density of the electrolyte increases.

Electrochemical reactions during battery discharge and charge can be expressed by the equation

PbO 2 + Pb + 2H 2 SO 4? 2PbSO 4 + 2H 2 O

Reading this equation from left to right, we get the discharge process, from right to left - the charge process.

The rated discharge current is numerically equal to 0.1C NOM, the maximum when starting the diesel engine (starter mode) is approximately 3C NOM, the charging current is 0.2 C NOM, where C NOM is the rated capacity.

A fully charged battery has d.s. about 2.2 V. The voltage at its terminals is approximately the same, since the internal resistance of the battery is very small. When discharging, the battery voltage drops quite quickly to 2 V, and then slowly drops to 1.8-1.7 V (Fig. 161), at this voltage, the discharge is stopped in order to avoid damaging the battery. If a discharged battery is left idle for some time, then its voltage is restored again to an average value of 2 V. This phenomenon is called "rest" of the battery. When such a “rested” battery is loaded, the voltage drops rapidly, so measurement of battery voltage without load does not give a correct judgment about the degree of discharge.

When charging, the battery voltage quickly rises to 2.2 V, and then slowly rises to 2.3 V, and finally rises again quite quickly to 2.6-2.7 V. At 2.4 V, gas bubbles begin to form, forming by the decomposition of water into hydrogen and oxygen. At 2.5 V, both electrodes emit a strong jet of gas, and at 2.6-2.7 V, the battery begins to boil, as it were, which is a sign of the end of the charge. When the battery is disconnected from the source charging current its voltage quickly drops to 2.2 V.

Battery care. Acid batteries quickly lose capacity or even become completely unusable when

incorrect operation. Self-discharge occurs in them, as a result of which they lose their capacity (approximately 0.5-0.7% per day). To compensate for self-discharge, non-working batteries must be periodically recharged. When the electrolyte is contaminated, as well as the covers of the batteries, their terminals and inter-cell connections, an increased self-discharge occurs, which quickly depletes the battery.

The battery must always be kept clean, and the terminals must be covered with a thin layer of technical vaseline to protect against oxidation. Periodically it is necessary to check the electrolyte level and the degree of charge of the batteries. Batteries must be recharged periodically. Storage of uncharged batteries is unacceptable. In case of improper use of batteries (discharge below 1.8-1.7 V, systematic undercharging, improper charging, long-term storage uncharged battery, lowering the electrolyte level, excessive electrolyte density) their plates are damaged, called sulfation. This phenomenon consists in the transition of fine-crystalline lead sulfate, which covers the plates during discharge, into insoluble coarse-grained chemical compounds, which, when charged, do not turn into lead peroxide PbO 2 and lead Pb. In this case, the battery becomes unusable.

Batteries play an important role in our lives, and many everyday things are now simply unthinkable without them. We depend on good and reliable operation batteries, therefore, in order for them to work stably, you need to know what properties they have and how to handle them. This article discusses the characteristics of different types of batteries, such as specific energy, service life, load characteristics, need for maintenance, self-discharge rate, etc.

Lead acid batteries

One of the oldest battery systems. This inexpensive, reliable and overload-tolerant battery; but it has a low specific energy and a limited lifetime. Lead acid battery is used in road transport, V wheelchairs, in emergency lighting systems and in uninterruptible power supplies (UPS).

Nickel-cadmium (NiCd) batteries

It is also one of the oldest and well studied battery systems. These power supplies are used where long life, high discharge current, extreme temperatures and low cost. Because of NiCd battery s cause significant harm to the environment, they are replaced by other types of systems. Main applications: power tools, walkie-talkies, air transport, UPS. In Europe, it was forbidden to sell consumer products with these types of batteries, but in Russia they can be purchased.

Nickel Metal Hydride (NiMH) Batteries

In fact, they are a replacement for nickel-cadmium; has a higher specific energy and less toxic metals. NiMH batteries are used in medical equipment, hybrid cars, in rocket and space technology, in industry.

Lithium-ion (Li‑ion) batteries

The most promising type of battery systems; used in portable consumer products as well as electric vehicles. Li-ion batteries are sensitive to overvoltage when charging and, to ensure safety, a protective circuit is added to them, but not always. These types of batteries are more expensive than those described above.

The family of lithium-ion systems can be divided into three main types of batteries depending on the cathode material - these are lithium cobalt, lithium manganese spinel and lithium ferrophosphate. The characteristics of these lithium-ion systems are given below.

Lithium cobalt or lithium cobalt oxide (LiCoO2)

It has a high specific energy, tolerates moderate loads and has a short service life. It is used in cell phones, laptops, digital cameras and other gadgets.

Lithium manganese spinel or lithium manganese (LiMn2O4)

Tolerates high charge and discharge current, but has low specific energy and short service life; used in power tools, medical equipment and electrical power units.

Lithium ferrophosphate (LiFePO4)

Similar to lithium-manganese; nominal voltage 3.3V/cell; more durable, but more high speed self-discharge than other lithium-ion systems.

There are many other types of lithium-ion batteries, some of which will be described later on this site. The popular lithium-polymer battery type is missing here. While Li-Ion systems get their name from the cathode material, Li-Po systems get their name from their architecture. Lithium-metal batteries are also not mentioned here. This type of current source still needs to be developed, but, most likely, they will soon have an unusually high energy density and good power density.

Table 1 - Comparative characteristics of the four most commonly used types of battery systems, indicating average parameters

1 The internal resistance of batteries depends on milliamp-hours (mAh), wiring, and number of cells. Li-ion battery protection circuit adds about 100 mΩ

2 The element size is 18650. The element size and design determines the internal resistance.

3 The life cycle of batteries that undergo regular maintenance.

4 The life cycle depends on the magnitude of the discharge. Smaller discharge increases the service life.

5 The most high speed self-discharge immediately after charging. The NiCd battery loses 10% of its charge during the first 24 hours, then the charge loss rate decreases to 10% every 30 days. Heat increases self-discharge.

6 The protective circuit typically consumes 3% of the stored energy per month.

7 The traditional voltage of 1.25 is more commonly used; 1.2 V.

8 Low internal resistance reduces voltage drop under load and lithium-ion batteries often labeled with a value greater than 3.6V/cell. Elements marked 3.7V and 3.8V are fully compatible with 3.6V.

9 Able to withstand big momentum load current, but need time to recover.

10 Do not regularly charge lithium-ion batteries at temperatures below freezing.

11 Maintenance such as balancing or recharging to prevent sulfation.

12 For most types of lithium-ion systems, cutoff occurs if the voltage is less than 2.20V and greater than 4.30V, other voltages apply for lithium ferrophosphate batteries.

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