AGM batteries for particularly demanding cars and motorcycles. AGM batteries - what are they and how to properly maintain them? What is the difference between an agm battery and a regular one

Technology Description

Disassembled battery made using AGM technology

A classic lead-acid battery is a case divided into compartments by separators - microporous plastic. An electrolyte is poured into the compartments - a solution of sulfuric acid, and the plates are immersed in this solution, current flows between the positive and negative plates. AGM technology uses liquid electrolyte-impregnated porous fiberglass hull filler. The micropores of this material are not completely filled with electrolyte. Free volume is used for gas recombination.

Batteries manufactured using AGM technology are manufactured in a spiral or flat configuration. A series of products with a spiral block design is produced mainly in North America, and with a flat configuration of electrodes - in both North America and Europe. Spiral elements have a larger surface contact area, which makes it possible to deliver higher currents for a short time and charge faster. However, the downside is a reduction in the specific battery capacity (ratio of electric capacity and size) compared to the flat configuration. Both technologies are promising and can be used as OEM components for automakers. At the moment, the most common AGM car batteries with a flat block configuration. SpiraCell spiral blocks are patented by Johnson Controls for the Optima series and cannot be used without its permission, unlike flat blocks.

Advantages

The battery produced using AGM technology has a number of advantages over classic batteries obtained through this technology. In particular, resistance to vibration, the ability to install in any position and without the need for maintenance. Some manufacturers claim increased performance of such batteries or high starting current.

• Maintenance-free design.
• The design is hermetically sealed and valve-adjustable, preventing acid leakage and terminal corrosion.
• Safer operation: Properly charging batteries eliminates the possibility of gassing and the risk of explosion.
• The sealed design allows the battery to be installed in almost any position (however, upside down installation is not recommended).
• Confident operation at low temperatures (below −30*С).
• Increased vibration resistance increases service life.

Flaws

• From 1985 to this day, B-52 bombers and F-18 fighters have been equipped with AGM batteries.
• To charge batteries manufactured using AGM technology, it is advisable to use a special charger with appropriate charging parameters that are different from charging classic batteries with liquid electrolyte.
• At the moment, AGM car starter batteries are used as a power source for the Start-Stop system, which is equipped with a number of car models from leading manufacturers.
• Using AGM batteries, the first version of the tzero roadster was made. It was equipped with 28 batteries of this type. At the same time, the weight of the car was 1040 kg, and acceleration from 0 to 60 mph (96 km/h) was only 4.07 seconds. The cost of the car was $80,000. The new version is equipped with lithium batteries.

see also

• Autoelectrolyte

Notes

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Battery failure is one of those annoying malfunctions that can befall a motorist at the most inopportune moment. Anyone who has experienced this knows what it is. Are there reliable power supplies?

The date of birth of the first battery is considered to be 1860. Since then it has been constantly improved. Changed materials, dimensions, design. Years passed, and even the best of the classic lead-alkaline batteries (EFB) - ceased to meet the demands of the time. A unique and bold solution was required, both in the design and in the very principle of operation of the batteries. With its advent, AGM technology ( absorbent glass Matt- moisture-absorbing glass mats) owes to the engineers of the American company Gates Rubber Company. Almost fifty years ago, it was they who proposed an alternative to the classic liquid battery.

Design features or what is an AGM battery?

The essence of the discovery is the complete rejection of the liquid state of the electrolyte. It was replaced by a special woven material. In this case, a mixture of sulfuric acid and distilled water appears to be bound by the structure of the synthetic mats. It should be noted that the small pores of the material serve to hold electrolyte drops, and the large ones (capillary forces leave them free) to circulate vapors that have not had time to condense in the battery cavity.

Note that in batteries with AGM technology, only highly qualified lead (degree of chemical purity) is used. Another innovation is antimony and calcium additives, which significantly extend the service life of the plates.

For its time, this engineering solution and the results of its tests turned out to be so outstanding that the AGM technology battery was supplied exclusively for the needs of the army and military aviation for several years.

The difference between AGM and GEL batteries

Scientific progress does not stand still, and, apparently, that is why AGM technology once had a competitor - these are gel batteries. Their main difference from their predecessors is that the space between the lead plates is no longer filled with fiberglass, but with a frozen porous solution of sulfuric acid and silica gel. The latter acts as a thickener. It is in this structure of the mixture that the main advantages and advantages of gel batteries lie. Such a state of the environment effectively prevents the failure of the electrodes and, as a result, prevents the failure of the battery itself.

For reference

The destruction of lead plates is an inevitable result of the electrolysis reaction. And if so, then slowing down this process and preventing internal circuit closure is the main task that scientists have been working on since the invention of the battery. A significant disadvantage of gel batteries is their increased sensitivity to temperature. So already at 100-110 degrees, the mixture of acid and silica gel loses its working state. At the same time, the ability of the gel to retain vapors of sulfuric acid decreased. All this ultimately affects the rigidity of the structure as a whole.
Among AGM batteries there is an internal division into types. Approximately a third of their total number has a spiral laying of mats. This technical solution allows to maximize the area of ​​the chemical reaction, but at the same time dimensions and weight are sacrificed. In addition, the exclusive rights to the “spiral” in batteries are patented, which significantly affects their popularity. As for plate batteries, this type of battery is the leader among the preferences of motorists. We also note that the peak of their popularity is yet to come, and the number of companies that produce AGM batteries is expanding every day.

Overview of AGM batteries from different manufacturers: features, prices, differences

Today, AGM batteries can be found literally everywhere. They are used on conveyors to complete cars equipped with a start-stop system. They operate barriers, shutters and gates. Thanks to rechargeable batteries, neon advertising and road signs on highways glow at night. We add that the AGM technology is recognized as optimal in the batteries of power plants operating on such energy sources as the sun, wind and waves. Out of competition, the advantages of AGM turned out to be in uninterruptible power supplies for computers. Currently, almost all well-known world brands have given a significant part of their production volumes to AGM batteries. This is BOSCH, and Optima, and Tudor, and Medalist and others. Below are several popular AGM car battery models and their specifications for comparison.

brand	Country of origin	Capacity	Weight	Estimated price	Life time
		Ah	kg	rub.	years
Haze HZB12-28 AGM	China-UK	28	16	4300	5
VOSTOK SK-1255	Russia	55	16	6200	5
DEKA	USA	32	10	7000	7
TOPLA	Slovenia	60	15	9500	8
VARTA D52	Germany	60	16	10700	10

Table 1. Comparative overview of AGM batteries

It is gratifying that recently Russian-made batteries have become increasingly common in the ratings of giants in the use of AGM technology in batteries. In addition to markings indicating the type of battery, you can often see on battery cases: VRLA (Valve Regulated Lead Acid batteries) or SLA (Sealed Lead Acid batteries). These labels are required by international safety standards.
The first abbreviation is usually placed on batteries with a capacity of more than 30 Ah and indicates that the device is equipped with a safety valve. The second marking is placed on low-capacity AGM batteries (up to 30 Ah). The presence of the bypass is due to the inevitable release of hydrogen during recharging. When the value reaches 100 millibars, the valve opens and releases gas into the atmosphere, thereby relieving pressure to a safe level.

Pros and cons of technology

Note that AGM technology in batteries is far from ideal, as are the power supplies themselves. Therefore, along with indisputable advantages, they also have some disadvantages.

Advantages:

• This type of battery does not require maintenance. And this means that care for them is reduced to a minimum;
• Has a large starting current. So, in comparison with acid batteries, it is 50-75% higher, which is priceless when starting in the cold season;
• Not afraid of deep discharge. Even an average AGM battery must cope with at least two hundred full discharges (to zero), at least five hundred battery discharges to 50% and a thousand of those that reduce capacity by 20-30 percent;
• Transportation and operation in almost any position is allowed;
• The service life of AGM is from 5 to 12 years (subject to mandatory observance of the charging rules);
• Neutral to high ambient temperatures (for example, in the engine compartment of a car). This puts them in rank above all classic and most gel batteries.

Flaws

• Increased weight;
• The AGM battery is significantly more expensive than any of its competitors among lead-acid batteries;
• Specific chargers required;
• Requires care and attention when charging, as well as when operating on vehicles that are not equipped with a recharge relay.

Important! Batteries using AGM technology cannot be taken as a panacea for all possible ills. This type of battery is very vulnerable to overcharging. This means that if the car is not equipped with a device that excludes excess charge, you should refrain from buying such batteries.

Requirements for the charging process and chargers

As already mentioned, AGM and GEL batteries are quite resistant to maximum discharges. Excessive values ​​of current and voltage can cause much more damage to them. The optimal current for charging is the one whose value is 10% of that indicated on the battery itself. For example, an AGM battery with a capacity of 32 Ah should be charged with a current of 3.2 A. This means that the charger (ideally) must have the function of adjusting the current and voltage. For a more detailed consideration of the technology for bringing the battery into working condition, we describe the process point by point:

• We connect the charger and set the nominal voltage on it, and set the current strength to "0";
• We connect the wires according to the system: minuses - to minuses, and pluses - to pluses;
• We set the current value equal to 10% of that indicated on the battery;
• We observe the process. In its normal course, the voltage should increase, and the current strength should decrease. When the value of the latter drops to values ​​close to zero, the AGM battery will be charged.

Important! Charging an AGM battery with a higher current will significantly reduce the charging time, but may also harm the battery. Therefore, resorting to such a regime should be done only in exceptional cases!

Regarding the chargers themselves, we note that their choice on the Russian market is sufficient to choose the best option. You can choose a universal one - with current and voltage regulation, or you can get by with highly specialized ones, where the current strength is fixed (0.1A, 0.2A, 0.3A, and so on). The price range for "charging" is from 1500 to 12 thousand rubles.

One step away from choice

Solid experience, rich driving experience and excellent craftsmanship can be useless if your car suddenly finds itself without energy. That is why the desire of motorists to have the best battery in all respects looks quite natural. The closest to obtaining such a status today are batteries using AGM technology. Now, we hope you know what it is. In this article, we talked about the features, compared batteries from different manufacturers, asked the price and received some useful information. Years will pass, AGM and EFB technologies in car batteries will become history. They will be replaced by more advanced power sources. It will be later, but the car needs energy today and now. To do this, it is enough just to make a choice between economy and reliability, some inconvenience and certainty. And do not make a mistake in it - we hope this article will help you. Video

They are used in many industries, but transport equipment is closest to the mass consumer. And in the same area, the weak points of such batteries are most clearly manifested. Problems in the operation of batteries are caused by the nuances of ergonomics, maintenance and maintaining optimal reliability in different applications. At the same time, some of the shortcomings were minimized with the help of Absorbent Glass Mat (AGM) technology back in the 1970s. A new approach to organization, also associated with a change in the characteristics of the electrolyte, is still relevant today. Moreover, AGM technology has undergone many adjustments throughout its existence and today allows the development of batteries with fundamentally improved qualities. However, such batteries are not spared from the shortcomings.

General information about technology

The peculiarity of this technology is due to the principles of the content of the so-called bound electrolyte. So, if in classical batteries liquid electrochemical filling is used as an active substance, then in AGM systems a dense electrolyte is used. Accordingly, this gives at least increased protection against vibrations. In terms of household treatment with such blocks, many note the convenience and reliability. But these are not all the features that characterize AGM technology. The absorbed electrolyte, which is most often used in such batteries, has a considerable number of advantages in itself. In practice, its use is noted for its resistance to temperature and the ability to withstand a large number of charges. The implementation of the concept of a bound electrolyte requires a special arrangement of the body and internal filling.

Block design

The case is made of high-strength plastic, which houses a set of electrode plates. As a rule, the latter are made of lead, which makes such designs related to classical blocks. The main difference lies in the properties of the electrolyte, which is represented by an aqueous acid solution. This is a kind of acid that fills the space of the body to ensure subsequent reactions between the electrodes. Actually, the difference is due to the fact that the filling is not a liquid, but a solid state. Typically, manufacturers use a microporous material based on glass fiber to ensure this condition. It is impregnated with electrolyte and thus forms a tight bond between the internal components of the block. The filler also acts as a separator, preventing the solution from spreading. However, AGM technology may provide for other ways to tightly bind an electrochemical substance, but the essence of the method remains the same - to ensure the reliability of the content of the active element without losing the basic function of the battery.

Varieties of AGM batteries

Battery models of this type are made in flat or spiral forms. This refers to the device of the electrodes. Spiral components are characterized by extensive surface electrochemical contact, which in practice increases the ability to provide high currents for a short time. In addition, many motorists note the rapid replenishment of the energy potential. But, on the other hand, models with flat electrodes outperform spiral ones due to the balanced specific capacity of the battery. By the way, gel blocks and traditional lead-acid blocks differ in similar qualities. With AGM technology, a planar configuration is only optimized, allowing in an established format to provide the highest battery performance.

Similarities to GEL technology

This is a group of gel batteries, which are also being developed in accordance with the concept of a bound electrolyte. Only in this case, a different principle of providing viscous filling is used. For this, silica gel is used, which completely covers the entire space of the block. Like the AGM technology, the manufacturing technique of GEL batteries provides vibration resistance and reliability of the electrochemical filling as a whole. In this regard, the main advantage of gel batteries is the elimination of the risk of a short circuit. A tight fit to the electrodes does not allow them to collapse over time, and the electrolyte also effectively copes with its function, interacting through the pores of the filler.

According to experts, models of this type are capable of withstanding about 1200 charge cycles. allow you to replenish the charge 500-600 times. AGM technology achieves similar performance. The advantages and disadvantages of both designs are generally similar and lie in the features of the interaction of electrodes and electrolyte. But there is also a difference in operational nuances, which are noticeable only in practice.

Which is better - AGM or GEL?

To begin with, it is worth emphasizing that gel devices are more expensive than AGM models, although this does not indicate their obvious advantage. So, giving preference to designs with absorbed electrolyte is for those who want to be sure of the resistance of the filling to high-power discharges. In addition, such blocks benefit from the rapid replenishment of the energy reserve. At the same time, AGM and GEL technologies hold the charge approximately equally stably - at least if we compare models from the general price group. As for the advantages of gel cells, they perform better under high loads - for example, after a deep discharge or in the presence of external electrical interference. To this we can add the rigidity of the filler, which does not allow the physical destruction of the filling, while maintaining the integrity of the same electrode. Gel models in the latest versions are developed to strengthen the strength quality, but progress in this direction is hindered by the inevitable decrease in the electrical properties of the block.

Advantages of technology

If we compare the advantages of technology against the general background of batteries, then the absence of the need for maintenance will come to the fore. Further, we can emphasize the dignity that applies to all devices made according to the principle of a bound electrolyte. It is a sealed, valve regulated design that minimizes the risk of acid leakage. That is, it speaks of the reliability of the block in terms of physical handling, and of its environmental safety. This property, by the way, characterizes both expensive branded batteries and low-quality low-quality models. AGM technologies protect the internal filling as much as possible, which also contributes to an increase in the efficiency of electrochemical processes. Here again, you can return to a large number of charge cycles, fast energy replenishment and stable operation of the electrodes.

Flaws

Most of the disadvantages that this type of batteries have apply to all lead-acid devices. For example, this applies to the large weight, to the toxicity of lead oxide, as well as to restrictions on the organization of storage conditions. In particular, manufacturers do not recommend storing blocks in a discharged state. In addition, contrary to popular belief, experienced motorists note that in frosty conditions a decrease in performance is manifested. This refers to the voltage fluctuation, which is usually reduced. Also, many point to the impossibility of restoring the element after a deep discharge. This is another point on which AGM technology is inferior in reliability to GEL developments. However, subject to even the general rules for using such batteries, such troubles can be completely avoided.

Battery Rules

To prevent sulfation of batteries, it is recommended to always keep them optimally charged. As the capacity is lost, the working life of the active elements is also reduced. Also, short circuits in the terminals should not be allowed. Although AGM battery developers are working hard to improve the reliability and functional details of the case, it is important to observe the correct external connection. By the way, this is especially true for operations during which AGM batteries are repaired. Technologies for manufacturing new generation batteries also increase the mechanical strength of the case, but even taking this aspect into account, one should not rely too much on the durability of the plastic used for the shell. An opened AGM battery is no less dangerous than traditional lead-acid batteries.

Application areas of the technology

Of course, modern batteries with improved performance properties are used not only in cars. Products created on the basis of AGM technologies are used in power supply systems, public service stations, telecommunications, etc. The possibility of autonomous power supply is also in demand in medicine - to maintain equipment performance in emergency situations. But, since AGM technology in batteries does not exclude the use of heavy and toxic hazardous metals, manufacturers also impose restrictions on their operation.

Manufacturers

The domestic battery market is saturated with models of various types, including AGM cells. In particular, the initial segment represents products from Ventura, Optima, as well as some modifications from the Stinger line. However, the highest quality batteries with AGM technology, according to many motorists, are offered by Delta and Varta manufacturers. In addition, in the families of these companies, you can find different modifications of blocks for any request.

How much does an AGM battery cost?

Much depends on the technical characteristics, the quality of the materials used and the capacity, but on average prices vary from 10 to 20 thousand rubles. The cheapest batteries of this type cost about 5-6 thousand. If you buy a model for a car that is demanding on electrical engineering, then you can immediately turn to the segment from 20 thousand. This is how much high-quality and reliable AGM batteries cost. Technologies for organizing the content of an absorbent electrolyte at this price level are most beneficial, although they also do not exclude the disadvantages characteristic of the general class.

Conclusion

The emergence of breakthrough technologies in various areas often causes a stir in the market, but over time everything returns to its course and the consumer still prefers traditional products. This is due to the fact that the developers of new solutions in advertising focus on the merits, not always fully disclosing information about the shortcomings. So in this case, but experienced motorists and just specialists are well aware of both the pros and cons that AGM technology gives. Lead-acid batteries, even with a dense electrolyte, do not cease to be sensitive to voltage drops, require the same safety measures, and at the same time are not cheap. Nevertheless, in some cases this option will fully justify itself. AGM batteries meet the needs of those motorists who focus on the mechanical strength of the battery, its durability and performance. But you can save these qualities for many years only if you follow the rules for operating the battery.

AGM (Absorbent Glass Mat) lead batteries are a further improvement in battery technology, classic sulfuric acid batteries. Due to their advantages, they have taken a strong place among already known types of batteries.

AGM monobloc sealed battery

What is AGM lead battery

In traditional batteries, the electrolyte in the battery cell (bank) is contained in a liquid state. AGM batteries use special glass fiber material with high porosity instead of bulk fluid. The pore sizes in it are of the order of tenths of a micron. Such a liquid does not splash inside the cans during shocks and does not flow out when tilted. At the same time, ionic conductivity is ensured with low internal resistance, as in conventional batteries. Moreover, the internal resistance of AGM batteries is lower than that of conventional ones.

AGM technology batteries are used to start car engines, uninterruptible power supplies, communication equipment, emergency lighting, etc. Until recently, they were used in electric vehicles.

Section view of the element with filler

The fiberglass packing of the elements is not completely filled with electrolyte, leaving some space for the recombination of electrolysis gases. If the charge current slightly exceeds the passport values, these gases are released (hydrogen and oxygen during recharging) in an insignificant amount. However, this is enough to swell and break the case. Therefore, a safety valve is installed in the battery.

Such batteries are of the VRLA type (Valve-Regulated Lead-Acid - lead-acid with a protection valve). The valve releases excess gas and closes. Depending on the design of the battery case, the valve may be common to all compartments or each element has its own.

Gas release valve system

The location of the electrodes in the battery is usually flat. It is a stack of parallel plates separated by non-conductive separators. AGM battery can also be made with a cylindrical, more precisely, a spiral arrangement of electrodes. This doubles the maximum working pressure inside the element, which can, in this case, reach 2.7 kg/cm 2 . The spiral arrangement was patented in the USA and so far the owner has not sold a license to Europe or Asia, so it is almost impossible to find such batteries on the Russian market.

Despite this, batteries with a flat arrangement of electrodes have their advantages. They have a longer service life. The current given off by flat banks is lower than that of cylindrical ones, by about one and a half times. However, in this case, such a battery is capable of delivering a current of 500-900 amperes. (Compare with 200-300 A for a flooded starter battery.) The increased current delivered to the load is due to the lower polarization of the electrodes than that of bulk cans.

The phenomenon of polarization is that the electrodes are covered with tiny gas bubbles, because of this, the contact area with the electrolyte decreases and, naturally, the current decreases. Usually, polarization does not begin to appear immediately, but after a few seconds after applying a large load. So, if the engine “did not pick up”, then you have to wait a while.

In batteries made using AGM technology, the fibrous packing instantly absorbs gas bubbles. This happens due to capillary forces, it can be said that the filler “wipes” the plates from bubbles. Therefore, the high current output is significantly extended in time, compared with the purely liquid version of the element. This is the main feature of AGM batteries. It is hardly worth specifying how this affects when starting a car.

However, do not believe the claims about the wonderful properties of AGM in the winter. Low temperature acts on such batteries according to all the laws of physical chemistry and does not improve their properties in any way compared to classic banks.

Advantages and disadvantages

The benefits are:

• 1.5 times more current;
• work in an inclined position;
• acid does not leak
• no need to add electrolyte.

Disadvantages - the same as all lead batteries: heavy weight (about 30% heavier than conventional ones), relatively low capacity (compared to lithium), low environmental friendliness, like all lead batteries.

Batteries of various designs

How to choose?

When choosing an AGM battery, you need to proceed from the starting current that the starter requires from the buyer. Since an AGM battery is more expensive than a regular battery, it should be worth buying. If the car has a diesel engine, and it is stored in a garage at a temperature not lower than -20 ° C, then it is worth buying. Residents of warm regions, of course, will not hurt such a battery either, but you can do without it.

At start-up, the AGM takes on average no more than 1% of the charge, so this battery will be suitable for those who often have to turn off and start the engine.

Operating modes of AGM batteries

For proper operation, it is necessary to understand how to charge the battery. The battery can be in one of three states:

• storage;
• charge;
• discharge.

The state of charge is also divided into several stages, which is caused by the chemical features of the charge process:

• high current charge;
• charge with normal current;
• recharge;
• storage (when ZRU is connected).

When discharged, AGM cells are capable of delivering noticeably more ampere-hours than conventional batteries.

Important! AGM batteries must be charged with constant voltage, the upper limit of which is limited. Otherwise, at least the battery life will be greatly reduced. The voltage of the charger must be stabilized. During long-term storage, it is useful to constantly recharge the AGM battery with a special charger.

The reason for such precautions is that in the electrochemical series of voltages, lead is next to hydrogen, and +0.12 V over the specified voltage is sufficient, and hydrogen will begin to be released. This is especially evident towards the end of the charge. If, however, you simply “load it with a load” as the men in the garages do, then the excess hydrogen will simply tear the microporous packing. And the quality of the battery will drop sharply. Liquid battery “boiling” of the electrolyte does not threaten anything, but AGM is a completely different matter.

A conventional charger charges the battery by about 70%. For a full charge close to 90% of the nominal capacity, a 3-stage charge mode is used using specialized ZRU (float charger).

Graph of current and voltage when charging AGM

The figure shows the processes of charge (red line of the graph) and discharge (blue line). The symbol C20 means the battery discharge mode in hours: 20 hours. We can get the corresponding current by knowing the capacity of the battery. Let, for example, the battery capacity written on the label: 80 A / h. At C20, the current will be 80/20 = 4 A.

The charge in 3 stages begins with a stabilized current, a quarter of the nominal capacity. For a battery of 80 A / h, this is 20 A (no more than 28 A). The temperature should not exceed 35°C, otherwise the battery life will be shortened. The device monitors the voltage, and when it reaches 2.45 V per jar, it switches to voltage stabilization mode. The charge current gradually decreases. When it settles around 0.5 A, the device switches to storage mode (self-discharge compensation, float) and stabilizes the voltage at 2.3 V per jar.

Usually, motorists neglect the “subtleties”, and lose money on this, often buying new batteries.

AGM Battery Care

It is not entirely true that such batteries are maintenance-free because they are maintenance-free. Periodically, you need to remove the battery, recharge it if necessary, and thoroughly wipe the case, especially in those places where the terminals come out. Dirt, and the mandatory presence of moisture and salt there, leads to a significant self-discharge of the battery. In addition, when cleaning the body, you can notice a crack in the body in time and avoid getting acid on the body parts of the car.

In the 1970s of the last century, the company's specialists Gates Rubber developed a special technology for the production of lead-acid storage devices. She received the name AGM. Now such accumulators gain popularity among owners of various vehicles.

1 AGM devices - no liquid electrolyte needed

AGM battery (Absorbent Glass Mat) belongs to VRLA-class products. It differs from the lead devices familiar to us in that it is filled not with liquid, but with an absorbed special electrolyte. This gives batteries made using AGM technology special performance properties. Such batteries (batteries) are classified as maintenance-free. They have a sealed housing and built-in safety valves designed to remove excess gas formed during use of the device.

There are plates (negative and positive) inside the AGM batteries. Insulators are installed between them. They are made from highly porous paper or ultra-thin fiberglass material. Such fibers first began to be actively used in the mid-1980s in the United States. Then they were used to create energy sources (autonomous) for transport and emergency signaling, telecommunications systems.

The electrolyte in the described batteries is concentrated in porous plates and in a separator (this is how glass fiber gaskets are commonly called). The volume of the active substance is strictly dosed. All existing small pores are filled with electrolyte, leaving large ones free. The latter are necessary so that the gases released during battery operation can circulate inside the device. This process is controlled by a special recombination system. It does not allow the released oxygen and hydrogen to leave the battery until they are converted to water. The plates and gaskets in the body of the device are pressed against each other as tightly as possible. This is a prerequisite for the production technology of AGM devices.

Instead of plates, some manufacturers use spirals. Such elements are characterized by a larger contact area (surface) compared to plates. Due to this, they are able to charge faster and, if necessary, produce a current of greater power. In this case, the spirals have a small ratio of dimensions and capacitance (electric). This is bad. Since their specific electrical capacity is reduced. In Russia and European countries, car batteries with plates are more popular. But in the US, drivers prefer AGM devices with spiral elements.

2 Advantages of batteries - we will describe all the advantages

Compared to classic batteries, Absorbent Glass Mat devices are able to cope with high electrical loads without serious difficulties. This is of great importance. Lead batteries with liquid electrolyte have a relatively short service life precisely because of the inability to withstand serious loads from modern electronics - auto-refrigerators, navigators. In addition, AGM devices can be discharged up to 30–40% without worrying that this will lead to a noticeable decrease in their operating time. Any motorist knows that if you discharge a lead battery by half, its capacity will inevitably decrease (in relation to factory specifications) by 15–20%.

The next plus of AGM devices is increased resistance to shock and vibration. This is achieved by tightly pressing the gaskets and plates. In fact, no off-road can damage batteries produced using AGM technology, or reduce their lifespan. Vibration and shock resistance is especially important for trucks, SUVs and construction vehicles.

The low internal electrical resistance of the described batteries ensures their fast charging and efficient cold start of the motor. Moreover, during these processes, the battery emits a minimum of heat (no more than 4%, in conventional batteries this value is approximately 20%). It takes four times less time to charge an AGM than it takes to energize classic devices. But speed is not the most important advantage. It is important that the car engine during such an operation will consume much less fuel, since charging the batteries of the type in question does not strain the vehicle's generator.

AGM batteries are sealed. They don't need maintenance. Drivers do not have to regularly open the battery tanks, add distilled liquid to them, and constantly monitor the water level. Thanks to this, the described batteries quickly pay for themselves. Their cost is objectively high. But lower battery maintenance costs make AGM devices truly cost-effective.

Absorbent Glass Mat batteries function without problems at temperatures from +70 to -40 °C. There is no water (in free form) in them. Therefore, in products there is simply nothing to boil in extreme heat and freeze in cold weather.

The self-discharge of AGM batteries is minimal, for a month - no more than 3%, in practice even less. Experts say that such batteries can be used without additional recharging, even if they have lain in the garage for a whole year. By the way, they are allowed to be used in the supine position or in any other position. Leakage of the active substance is excluded in principle. Feel free to flip AGM batteries! And the last important plus of batteries is the possibility of their use in almost all modern cars.

3 Disadvantages of AGM batteries - the ideal is not yet achievable

Do not think that AGM batteries have only pluses in operation, the devices also have minuses. Here are their key disadvantages:

• batteries need to be charged using a special device;
• large mass (as with classic batteries);
• high susceptibility to overcharge voltage;
• a small number of discharge and charge cycles (maximum - 4000, inexpensive batteries can withstand no more than 1000-1500 cycles);
• discharges of less than 1.8 V must not be allowed (in this regard, AGMs are no different from conventional batteries);
• high cost (AGM devices are cheaper than classic ones, but more expensive than batteries produced using GEL technology).

Also note the toxicity of batteries. They use lead and acid. These compounds can hardly be called harmless to both human health and the environment.

4 Charging devices with electrolyte - which mode to use?

A special charger must be used to restore the AGM. Ideally, if it is equipped with an intelligent control system that can automatically control the process of charging the battery in the optimal (sparing) mode. There are not so many such devices now available. But there is a choice. Many experts advise purchasing charging systems Hyundai HY 1500 Expert, regardless of their considerable price.

If there is no desire or financial opportunity to spend money on smart devices, buy chargers with an indication of current and voltage. These characteristics when charging the battery must be monitored very carefully, otherwise there is a possibility of active gas formation and battery failure. It is recommended to charge the AGM in one of two ways:

1. main charge plus storage mode;
2. main charge plus accumulation plus storage.

Under the main understand the charge sufficient to restore the battery capacity to 80%. Storage is the operation in which the AGM device stabilizes its operating parameters at a voltage of 12 V. Storage is a cycle in which the current drawn by the battery from the charger is at a minimum.

The first mode involves charging at a current strength of not more than 30% of the battery capacity (voltage - 14.2–14.8 V), and then storage at a similar current, but with a voltage of up to 13.8 V (minimum - 13.2). The second scheme is more complicated, but also more reliable. Everything should go like this:

• we give the main charge from the special. devices with direct current and voltage (the values ​​\u200b\u200bare indicated above);
• when fully discharged, we use the accumulation mode: amperage from the electric capacity of the battery is about 10%, the voltage is standard;
• storage (the car has been in the garage for a long time): current strength - 5-10% of the battery capacity, voltage - 13.2-13.8.

Choose the mode that suits you and charge the AGM battery in accordance with our parameters.