Lithium polymer batteries represent an improved design of the world renowned lithium-ion batteries. It is planned that these devices will soon completely displace nickel-metal-hydride and nickel-cadmium devices from the market. accumulators... Lithium polymer cells are increasingly being used in a wide variety of electronic devices as a power source. With the same weight in terms of energy capacity, they are several times superior to nickel-metal-hydride and nickel-cadmium designs.

Potentially, lithium-polymer cells will cost less than lithium-ion batteries. However, at the moment they are still quite expensive. At the moment, only a few large firms are engaged in their production. They are similar in design to lithium-ion cells, but they use a helium electrolyte. As a result, they are released by a low discharge current, significant energy density, and a significant number of charge and discharge cycles. Their shape can be very different, and they themselves are distinguished by their light weight and compactness.

Kinds

At the moment, lithium-polymer batteries can be of several types, which differ in the structure of the electrolyte:

• Elements having gel-like homogeneous electrolyte , which is created by the introduction into the composition of polymer lithium salts.
• Elements having dry polymer electrolyte ... This type is made on the basis of polyethylene oxide using a variety of lithium salts.
• Having polymer matrix electrolyte having a microporous structure. It contains non-aqueous components of lithium salts.

Due to the fact that a liquid electrolyte is used in a polymer cell, their operational safety is an order of magnitude higher. In addition, they can be manufactured in various shapes and configurations.

Some lithium polymer cells are made of metallic polymer. However, at low temperatures, the parameters of such batteries are significantly reduced due to polymer crystallization.

There are developments in polymer batteries where a metal anode is used. Some companies have managed to obtain a significant expansion of the operating temperature range and current density. These types of batteries can be used in various household appliances and electronics.

At the same time, different manufacturers use different electrode materials, electrolyte structure and assembly technology. As a result, the manufactured batteries can have completely different parameters. But all companies producing such batteries note that the stability of the functioning of lithium-polymer batteries ensures the uniformity of the electrolyte from the polymer. This, in turn, depends on the number of components, as well as the polymerization temperature.

There are already versions of batteries that are only 1 millimeter thick. This allows manufacturers to produce very compact mobile devices.

Also, lithium polymer batteries that are commercially available are divided into:

• Regular.
• Fast-discharge.

Device

Lithium polymer batteries work on the principle of moving a number of polymer elements into semiconducting substances, provided that electrolyte ions are included in them. As a result, there is a significant increase in conductivity. According to the device, these batteries are emitted by an electrolytic composition.

The essence of polymer technology is that the electrolyte is applied to a plastic film. It does not allow electricity to be conducted, but it makes it possible to exchange ions. In other words, the polymer electrolyte replaces the conventional porous separator impregnated with liquid electrolyte. Thanks to the dry polymer structure, it is possible to ensure a minimum cell thickness of about 1 mm, safety of use and ease of production. Thanks to this design, developers have the opportunity to integrate such batteries into shoes, clothing, miniature equipment and other devices.

But a dry polymer battery has disadvantages in the form of a decrease in the conductivity and internal resistance of polymers, which is unacceptable for a number of powerful mobile devices. To make the small polymer battery more advanced, a certain percentage of gel cells are added to the electrolyte. Most of the commercial batteries currently used in cell phones are polymer-gel hybrids. Hybrid batteries are by far the most popular.

Operating principle

Lithium-polymer batteries have a principle of action similar to lithium-ion cells, that is, they operate on the reversibility of a chemical reaction. Here, the anode is a material made of carbon, where lithium ions are embedded. Oxides of vanadium, manganese or cobalt are used in the cathode. The operation of such a battery is based on the ability of polymers to pass into a semiconducting state due to the inclusion of electrolytic ions in them.

Lithium salts are still used here as the chemical base of the electrolyte. However, they are located in a corresponding polymer spacer that is located between the cathode and anode. Thanks to this, lithium polymer batteries can be made in any arbitrary shape. They can be placed in various inaccessible places, which opens up new possibilities for electronics manufacturers.

Application

Lithium polymer batteries are increasingly being used. Such batteries can significantly increase the operating time of the device while reducing the weight of the battery. Thanks to this, it is possible to obtain an energy carrier that will be several times larger in capacity. Even better performance will be achieved with fast discharge batteries. Therefore, such batteries become an excellent option for radio-controlled models of airplanes and helicopters, including other radio-controlled devices.

Application Li-Pol rechargeable batteries makes it possible to reduce the weight of the battery and increase the period of operation of the devices. Lithium polymer batteries have proven their worth in small helicopters such as the Piccolo. Such devices are capable of flying on such batteries for 30 minutes or more. These elements are a good option for small flying structures.

Typical lithium polymer batteries are used as power supplies that are required for electronic devices that draw relatively little current. These can be laptops, smartphones, and so on. Fast-discharge batteries are used in devices where high current consumption is required. Similar batteries are used in modern, portable power tools and radio-controlled devices.

Limitations of use

These batteries will be widely used in the automotive industry in the future. Today they are used to create new technologies and test electric vehicles. However, there are certain limitations that prevent the use of these batteries everywhere.

• Lithium polymer batteries require a special charging mode. In principle, it is not difficult, but the usual cannot be used for this. This is due to the fact that they are distinguished by a fire hazard during the over-discharge period. To combat this phenomenon, all such batteries have an electronic system that prevents over-discharge and overheating.
• If the lithium polymer battery is misused, it may cause a fire.
• A lithium polymer battery should not be used immediately after charging. First, it should be cooled to ambient temperature. Otherwise, the battery may be damaged.
• Inadmissible short circuit.
• Depressurization of the battery is not allowed.
• Battery discharge below 3 volts.
• Do not heat above 60 degrees.
• Batteries should not be exposed to microwaves or pressure. This can lead to the appearance of smoke, fire and more serious consequences.
• It is necessary to protect the battery from damage and shock. Strong mechanical stress can lead to disruption of the internal structure.

However, these disadvantages do not prevent their use in a wide variety of areas. In the future, all these shortcomings will be leveled by the introduction of new technologies and developments.

The advantages of lithium polymer batteries

• Quite high energy density.
• Small self-discharge parameter.
• There is no memory effect.
• Lithium polymer batteries are somewhat superior to lithium counterparts in battery capacity and duration of use.
• Manufacturing batteries with a thickness of only one millimeter.
• Applications in a fairly wide temperature range: from minus 20 to plus 40 degrees Celsius.
• The ability to shape the battery into different shapes.
• Small voltage drop during discharge.

Technological progress is a machine that rolls without stopping! More and more problems of our modern world serve as fuel for this machine. Remember, not so long ago nickel-cadmium (NiCd) batteries were in use, they were replaced by nickel-metal hydride (NiMH). But today they are trying to take the place of lithium-ion (Li-ion) batteries. What is the difference between Li-pol and Li-ion? What are the advantages of lithium polymer over lithium-ion batteries? Let's try to figure it out.

When we buy a phone or tablet, few people ask themselves the question - what is the battery inside? Only later, faced with the problem of the rapid discharge of the gadget, we begin to examine in more detail the "internal" of our device.

It became known about lithium batteries in 1912, then the first experiments began, but they did not find wide application. And only in the 70s, after six decades, these charging elements took their place in almost all household devices. We would like to emphasize that so far the conversation is only about batteries, not accumulators.

Lithium is the lightest metal, provides the highest energy density and has significant electrochemical potential. Batteries, which are based on lithium metal electrodes, have a large capacity and high voltage. In the 80s, as a result of numerous studies, it turned out that the cyclic operation of lithium batteries (charge / discharge process) leads to the ignition of the chargers, and after them the gadgets themselves. So, in 1991, several thousand phones were recalled in Japan due to the threat of fire. Because of these dangerous properties of lithium, scientists have turned all their efforts to non-metallic lithium batteries based on lithium ions. And after a while, a safer version of the charger was created, which was named lithium-ion (Li-ion).

Today, a lithium-ion battery is found in almost all mobile devices, it has a large number of varieties, has a lot of positive qualities, but also disadvantages, which we will talk about in more detail.

The advantages of lithium-ion batteries:

High energy density and, as a result, high capacity

Low self-discharge

Single cell high voltage. This simplifies construction - often the battery consists of only one cell. Many manufacturers today use such a single-cell battery in cell phones (remember Nokia)

Low maintenance (operating costs)

No memory effect requiring periodic discharge cycles to restore capacity.

Flaws:

The battery requires a built-in protection circuit (which leads to an additional increase in its cost), which limits the maximum voltage on each battery cell during charging and protects the cell voltage from being too low during discharge

The battery is susceptible to aging, even when not in use and just lying on the shelf. The aging process is common in most Li-ion batteries. For obvious reasons, manufacturers are silent about this problem. A slight decrease in capacity becomes noticeable after a year, regardless of whether the battery was in use or not. After two or three years, it often becomes unusable.

Higher cost compared to NiCd batteries.

Lithium-ion batteries are constantly being improved, the technology is improving. And everyone would be good with this battery, if not for the safety problems during its use and the high price. All these reasons became the basis for the creation lithium polymer batteries (Li-pol or Li-polymer)... The most obvious and most basic difference between Li-pol and Li-ion Is the type of electrolyte used. The use of solid polymer electrolyte significantly reduces the cost of the process of creating a battery and makes it safer, as well as allows you to create thinner chargers. Why hasn't the lithium polymer battery completely supplanted its predecessor? One of the possible versions, which are expressed by experts - investors who have invested large sums in the development and mass introduction of Li-ion batteries, are trying to return their investments.

Let's summarize. Generally speaking, the lithium polymer battery is a more advanced version of the lithium-ion battery. Judge for yourself:

Advantages of Li-pol and Li-ion batteries

In summary, we can say that, thanks to modern technology, we have two types of reliable external batteries. With the development of mobile technologies, with the advent of smartphones, tablets and many other digital gadgets, with the creation of energy-intensive applications, users are faced with the problem of "dead battery". Of course, both Li-ion and Li-Pol batteries immediately found their way into external chargers.

This is the perfect solution for modern life. The most important thing when choosing a powerbank is not to run into scammers (for more details on how to distinguish a fake from the original, we wrote , and how to understand on the store website with 100% certainty that they will sell you a fake in it -

Progress is moving forward, and to replace the traditionally used NiCd (nickel-cadmium) and NiMh (nickel-metal hydride), we have the opportunity to use lithium batteries. With a comparable weight of one cell, they have a higher capacity compared to NiCd and NiMH, in addition, their cell voltage is three times higher - 3.6V / cell instead of 1.2V. So for most models, a 2 or 3 cell battery is sufficient.

Among lithium batteries, there are two main types - lithium-ion (Li-Ion) and lithium-polymer (LiPo, Li-Po or Li-Pol). The difference between the two is the type of electrolyte used. In the case of LiIon, it is a gel electrolyte; in the case of LiPo, it is a special polymer saturated with a lithium-containing solution. But for use in power plants of models, lithium-polymer batteries are most widely used, so in the future we will talk about them. However, the strict division here is very arbitrary, since both types differ mainly in the electrolyte used, and everything that will be said about lithium-polymer batteries almost fully applies to lithium-ion batteries (charge, discharge, operating features, safety ). From a practical point of view, we are only concerned with the fact that lithium polymer batteries currently provide higher discharge currents. Therefore, on the model market, they are mainly offered as an energy source for power plants.

Main characteristics

Lithium-polymer batteries with the same weight surpass NiCd by 4-5 times in energy capacity, NiMH by 3-4 times. The number of working cycles is 500-600, at discharge currents of 2C up to a loss of capacity of 20% (for comparison - for NiCd - 1000 cycles, for NiMH - 500). Generally speaking, there are still very few data on the number of working cycles, and their characteristics given in this case should be treated critically. In addition, the technology of their manufacture is being improved, and it is possible that at the moment the figures for this type of battery are already different. Just like all batteries, lithium batteries are subject to aging. After 2 years, the battery loses about 20% of its capacity.

From the whole variety of power lithium-polymer batteries available on the market, two main groups can be distinguished - high-discharge (Hi discharge) and conventional. They differ among themselves by the maximum discharge current - it is indicated either in amperes, or in units of battery capacity, denoted by the letter "C". For example, if the discharge current is 3C, and the battery capacity is 1 Ah, then the current will be 3 A.

The maximum discharge current of conventional batteries, as a rule, does not exceed 3C, some manufacturers indicate 5C. Fast-discharge batteries allow a discharge current of up to 8-10C. Such batteries are somewhat heavier than their low-current counterparts (by about 20%), and in the name they have the letters HD or HC after the capacity numbers, for example, KKM1500 is a regular 1500 mAh battery, and KKM1500HD is a fast-discharge one. I would like to immediately make a small comment for those who like to experiment. In household appliances, fast-discharge batteries are not used. Therefore, if you get an idea to get a cheap battery from a cell phone or video camera, then it is difficult to count on a good result. Most likely, such a battery will die very quickly due to a violation of the intended operating modes.

Applications and cost

The use of lithium-polymer batteries allows you to solve two important problems - to increase the operating time of the motor and to reduce the weight of the battery.

When replacing the 8.4 V NiMH 650 mAh battery with two conventional, non-fast-discharge lithium batteries with a capacity of 2 A * h, we get a battery 3 times larger, 11 g lighter and with a slightly lower voltage (7.2 volts)! And if you use fast-discharge batteries, then large airplanes can fly, not yielding to the internal combustion engine in terms of power-to-weight ratio. In confirmation of this, the American on the electric plane took 7th place in the world championship in aerobatic models F3A. Moreover, it was not a small buzzbox, but a normal two-meter plane, like the rest of the participants who had models with internal combustion engines!

Lithium-polymer batteries have proven themselves very well in small helicopters such as the Piccolo or Hummingbird - for example, even with a standard brushed motor, the flight time on two 1Ah banks is more than 25 minutes! And when replacing the motor with a brushless motor - more than 45 minutes!

And, of course, lithium batteries are simply irreplaceable when it comes to indoor airplanes weighing 4-20 g. In this area, NiCd cannot be compared to them - there are simply no such batteries (for example, the weight of a 45 mAh can is 1 g, 150 mAh is 3.2 d), which, with such a low weight, would give the necessary power - even if only for 1 minute!

The only area where lithium-polymer batteries are so far inferior to Ni-Cd is the area of ​​super-high (40-50C) discharge currents. But progress is going forward, and maybe in a couple of years we will hear about new successes in this area - after all, 2 years ago, no one heard about fast-discharge lithium batteries either ...

For example, here are the main characteristics of Kokam LiPo batteries:

Name	Capacity, mAh	Dimensions, mm	Weight, g	Maximum current
Kokam 145	145	27.5x20.4x4.3	3.5	0.7A, 5C
Kokam 340SHC	340	52x33x2.8	9	7A, 20C
Kokam 1020	1020	61x33x5.5	20.5	3A, 3C
Kokam 1500HC	1500	76x40x6.5	35	12A, 8C
Kokam 1575	1575	74x41x5.5	32	7A, 5C

For price in terms of capacity, lithium polymer batteries cost about the same as NiMH batteries.

Manufacturers

Currently, there are several manufacturers of lithium polymer batteries. The leader in the number of produced batteries and one of the first in quality is Kokam. Also known are Thunder Power, I-Rate, E-Tec, and Tanic (presumably, this is the second name of Thunder Power, or it is one of the Thunder Power sellers under its own name). You can view the Kokam types at www.fmadirect.com, batteries from different manufacturers are offered at www.b-p-p.com and www.lightflightrc.com.

There is also Platinum Polymer, offered at www.batteriesamerica.com, presumably another name for I-Rate.

The range of battery capacity is very wide - from 50 to 3000mAh. To obtain large capacities, parallel connection of batteries is used.

All batteries are flat in shape. As a rule, their thickness is more than 3 times less than the shortest side, and conclusions are made from the short side in the form of flat plates.

I-Rate, as far as I know, does not make fast-discharge batteries yet, and their batteries have one feature: one of the electrodes is aluminum, and it is problematic to solder it. This makes them inconvenient when assembling the battery yourself.

E-Tec batteries are something in between, they are not declared as fast-discharge, but their discharge current is higher than that of conventional ones - 5-7C.

The leaders in popularity are Kokam and Thunder Power, with Kokam mainly used in light and medium models, and Thunder Power in medium, large and giant (over 10 kg!). Obviously, this is due to the price and the presence in the range of powerful assemblies - up to 30 volts and 8Ah capacity. Then there are Tanic and E-tec, but there are few mentions about the I-rate. For some reason, Platinum Polymer is popular only in America, and it is used almost exclusively on slow slowflyers.

Charging lithium polymer batteries

The batteries are charged according to a fairly simple algorithm - charging from a constant voltage source of 4.20 volts / cell with a current limitation of 1C. The charge is considered complete when the current drops to 0.1-0.2C. After switching to the voltage stabilization mode at a current of 1C, the battery gains approximately 70-80% of its capacity. It takes about 2 hours to fully charge. Quite strict requirements are imposed on the charger for the accuracy of maintaining the voltage at the end of the charge - not worse than 0.01 V / can.

Of the chargers on the market, the main types can be distinguished - simple, not "computer" chargers, in the $ 10-40 price category, intended only for lithium batteries, and universal - in the $ 120-400 price category, designed for various types of batteries, including for LiPo and Li-Ion.

The first ones, as a rule, have only LED indication of the charge, the number of cans and the current in them are set by jumpers. The advantage of such chargers is their low price. The main drawback is that some of them do not know how to correctly show the end of the charge. They show only the moment of transition from the current stabilization mode to the voltage stabilization mode, which is approximately 70-80% of the capacity. For the complete end of the charge, you still need to wait 30-40 minutes.

The second group of chargers has much wider capabilities, as a rule, they all show the voltage, current and capacity (mAh) that the battery "took" during the charging process, which allows you to more accurately determine how much the battery is charged.

When using a charger, the most important thing is to correctly set the required number of cans in the battery and the charge current on the charger. The charge current is usually 1C.

Operation and Precautions

It is safe to say that lithium-polymer batteries are the most "delicate" batteries out of the existing ones, that is, they require compulsory observance of several simple, but mandatory rules, due to non-observance of which either a fire occurs or the battery "dies".

Let's list them in decreasing order of danger:

1. Charge to voltages in excess of 4.20 volts / cell.
2. Battery short circuit.
3. Discharge by currents exceeding the load capacity or heating the battery above 60 ° C.
4. Discharge below voltage 3.00 volts / cell.
5. Battery heating above 60 ° C.
6. Depressurization of the battery.
7. Discharged storage.

Failure to comply with the first three points leads to a fire, all others - to a complete or partial loss of capacity.

From all that has been said, the following conclusions can be drawn:

To avoid a fire, you need to have a normal charger and correctly set the number of charged cans on it. It is also necessary to use connectors that exclude the possibility of a short circuit of the battery (because of this, my friend's table on which the batteries were charged and the curtain were burnt) and control the current consumed by the motor at "full throttle". In addition, it is not recommended to close the batteries on all sides from the air flow on the model, and if this is not possible, then special cooling channels should be provided.

In cases where the current consumed by the motor is more than 2C, and the battery on the model is closed on all sides, after 5-6 minutes of operation of the motor, stop it, and then remove and touch the battery - is it too hot? The fact is that after heating above a certain temperature (about 70 degrees), a "chain reaction" begins in the battery, converting the stored energy into heat, the battery literally spreads, setting fire to everything that can burn.

If you close an almost discharged battery, then there will be no fire, it will quietly and peacefully die due to overdischarge ... Hence follows the second important rule: watch the voltage at the end of the battery discharge and be sure to disconnect the battery after work!

Some speed controllers (especially Jeti sinning with this) do not stop current consumption after turning off the standard switch. What made the Czechs make such a strange decision - I don't know. But the fact remains that almost all models of controllers for Jetti brushless motors (including the new "Advanced" series), which have a BEC, that is, a power stabilizer for the receiver and machines from the mains supply, do not provide a complete de-energization of the circuit with a standard switch. Only the receiver and servos are turned off, and the controller continues to consume a current of about 20 mA. This is especially dangerous, since it is not visible that the power is on, the cars are standing, the motor is silent ... And if you forget about the connected battery for a day or so, it turns out that you can say goodbye to it - he does not like deep discharge lithium.

Of course, it should be remembered that the engine controller must be able to work with lithium batteries, that is, have an adjustable engine shutdown voltage. And we must not forget to program the controller for the required number of cans. However, now there is a new generation of controllers that automatically determine the number of connected cans.

Depressurization is another reason for the failure of lithium batteries, since air should not get inside the cell. This can happen if the outer protective bag is damaged (the battery is sealed in a bag like a heat shrink tube), as a result of shock or damage with a sharp object, or when the battery terminal is overheated during soldering. Conclusion - do not drop from a great height and solder carefully.

Storage of batteries, judging by the recommendations of the manufacturers, should be carried out in a charged state of 50-70%, preferably in a cool place, at temperatures no higher than 20 ° C. Storage in a discharged state negatively affects the service life - as with all batteries, lithium polymer has a small self-discharge.

Battery assembly

To obtain batteries with a high current output or large capacity, parallel connection of batteries is used. If you buy a ready-made battery, then by marking you can find out how many cans there are in it and how they are connected. The letter P (parallel) after the number denotes the number of banks connected in parallel, and S (serial) denotes in series. For example, "Kokam 1500 3S2P" denotes a battery connected in series from 3 pairs of batteries, and each pair is formed by 2 parallel-connected batteries with a capacity of 1500mAh. That is, the battery capacity will be 3000mAh (when connected in parallel, the capacity increases), and the voltage - 3.7 * 3 = 11.1V ..

If you buy batteries separately, then before connecting them to the battery, you need to equalize their potentials. This is especially true for the parallel connection option, since in this case one bank will start charging another, and the charging current may exceed the 1C value. It is advisable to discharge all purchased cans before connecting to 3 volts with a current of 0.1C - 0.2C. The voltage must be monitored with a digital voltmeter with an accuracy of at least 0.5%. This will ensure reliable battery performance in the future.

Potential equalization (balancing) is also desirable to be carried out even on already assembled branded batteries before their first charge, since many companies that assemble cells into a battery do not balance them before assembly.

Due to the drop in capacity as a result of operation, in no case should new banks be added sequentially to the old ones - the battery will be unbalanced at the same time.

Of course, it is also impossible to connect batteries of different, even close capacities, such as 1800 and 2000 mAh into a battery, as well as to use batteries from different manufacturers in one battery, since different internal resistance will lead to an imbalance in the battery. Care should be taken when soldering, overheating of the leads should not be allowed - this can break the sealing and permanently kill the battery that has not yet had time to fly. Some types of Kokam batteries come with pieces of printed circuit board already soldered to the leads for easy wiring. At the same time, extra weight is added - about 1 g per element, but it is possible to heat the places for soldering wires much longer - fiberglass conducts heat poorly. The wires with connectors should be fixed to the battery case, at least with tape, so as not to accidentally tear off the lead to the root.

Application nuances

So, let us emphasize once again the most important points associated with the use of lithium polymer batteries.

• Use a normal charger.
• Use connectors that will not short-circuit the battery.
• Do not exceed the permissible discharge currents.
• Monitor the battery temperature when there is no cooling.
• Do not discharge the battery below the voltage of 3 V / cell (remember to disconnect the battery after the flight!).
• Do not subject the battery to shock.

Here are some more useful examples that follow from what was said above, but are not obvious at first glance.

When using commutator motors, avoid situations where the motor is stuck (for example, the model is on the ground) and the transmitter is on full throttle. At the same time, the current is too high, and we run the risk of blowing up the battery (if the motor or regulator does not burn out earlier). This issue has been discussed several times in the RC Groups forums. Most ESCs for brushed motors turn off the motor when the signal from the transmitter is lost, and if your ESC knows how to do this, I would advise turning off the transmitter if the model has fallen, for example, into the grass far from you - there is less risk of hitting the throttle stick when searching for a model. on the strap of the transmitter and not notice it.

During the long operation of the battery, its cells become unbalanced due to the initial small spread of capacities - some banks “age” earlier than others and lose their capacity faster. With more cans in the battery, the process is faster.

Hence the following rule follows - sometimes it is necessary to control the capacity of each battery cell separately. To do this, you can measure its voltage at the end of the charge. How often? It is still difficult to establish exactly this - too little operating experience has been accumulated. As a rule, it is recommended, after about 40-50 cycles after the start of operation, once every 10-20 cycles, to check the voltage of the battery cells during charging to identify "bad cells".

It is not recommended to "drop to zero" the battery by running the motor until it stops rotating at all. Such treatment will not harm a new battery, but for a slightly unbalanced one it is an extra risk to discharge the "worst bank" below 3 volts, because of which it will lose its capacity even more.

When the capacities differ by more than 20%, such a battery cannot be fully charged without special measures!

For automatic balancing of battery cells during charging, so-called balancers are used. This is a small board connected to each bank, containing pull-up resistors, a control circuit, and an LED indicating that the voltage across that bank has reached 4.17 - 4.19 volts. When the voltage on a separate element of the 4.17 volt threshold is exceeded, the balancer closes part of the current "to itself", preventing the voltage from exceeding the critical threshold. By the simultaneous ignition of the LEDs, you can see which banks have a smaller capacity - the LED on their balancer will light up first. One important additional requirement is imposed on the balancers - the current consumed by them from the battery in the "standby" mode must be small, usually 5-10 μA.

It should be added that the balancer does not save from overdischarge of some cells in an unbalanced battery, it serves only to protect against damage to cells during charging and as a means of indicating "bad" cells in the battery. The above applies to batteries composed of 3 or more cells; for 2-cell batteries, balancers, as a rule, are not used.

There is an opinion that lithium polymer batteries cannot be operated at subzero temperatures. Indeed, the technical characteristics of the batteries indicate the operating range of 0-50 ° C (at 0 ° C, 80% of the capacity is retained). But nevertheless, it is possible to fly on them at temperatures around -10 ...- 15 ° С. The fact is that you do not need to freeze the battery before the flight - put it in your pocket, where it is warm. And in flight, the internal heat generation in the battery is at the moment a useful property, not allowing the battery to freeze. Of course, the battery performance will be slightly lower than at normal temperatures.

Conclusion

Given the pace at which technological progress in the field of electrochemistry is moving, it can be assumed that the future belongs to lithium-polymer batteries - if fuel cells do not catch up. As the demand for batteries increases and the volume of their production increases, the price will inevitably fall, and then lithium will finally become as ubiquitous as NiMH. In the West, this time has already come half a year, at least in America. The popularity of electrolytes with lithium polymer batteries is growing. I would like to hope that brushless motors and controllers for them will also become cheaper, but in this area the progress of price reductions is moving less rapidly. After all, just two years ago, a question was asked in the forum - "Does anyone really fly on a brushless?" And then there was no mention of lithium batteries at all ...

In general, we will wait and see.

How do I charge and properly operate a lithium-polymer battery?

More and more lithium-polymer batteries are used in modern gadgets. This type of battery has been around recently. Their design and the materials used are gradually being improved. Li─Pol batteries can be found in tablets, some models of smartphones and laptops. They are also widely used in toys and radio controlled models. Quite a few questions come to us about how to charge such batteries. This has already been mentioned in some articles. Since this topic is in great demand, we decided to put it in a separate note.

How to properly charge and operate Li─Pol batteries?

Now directly about how to charge lithium-polymer batteries and their correct operation. First you need to understand that a lithium-polymer battery must have a voltage within certain limits for its entire service life. These limits are in most cases from 2.7 to 4.2 volts. These values ​​correspond to the minimum charge and the maximum.

It is also worth understanding that the capacity of a battery is the amount of stored energy that it gives up when it is completely discharged from a 100% charge. Often these batteries have an upper voltage threshold limited to 4.1 V. This decreases the capacity slightly, but increases the battery life. Indeed, for Li─Pol batteries, borderline states (full charge and discharge) are harmful. This is due to the fact that in this state, lithium ions are maximally incorporated into the crystal lattice of the cathode or anode. Being in such borderline states is not even long time negatively affects its service life.

So, you can achieve the maximum service life of a lithium-polymer battery by maintaining its charge level at 40-60 percent. Often rechargeable batteries on the market have approximately this charge level. These limits can be controlled by the user himself, and the minimum and maximum battery charge is controlled by a special board. It is called a charge-discharge controller.

Users can be advised to charge the battery without waiting for a full discharge. Also, do not charge it "to the eyeballs". At 80% charge, it is quite possible to disconnect it from the adapter. It only remains to add that in electronics (tablets, laptops, smartphones), the operation of the controller board is often supplemented by a power circuit in the device itself.

What do users need to keep in mind when charging a battery?

For the user, you can name a number of simple rules when using Li─Pol batteries:

• Don't let your battery run down to a minimum. It is especially not recommended to wait until the phone, tablet, etc. disconnect. If this happens, immediately put the battery on charge;
• Don't be afraid to do frequent recharges. That is, use the power outlet whenever you need it. If the lithium battery is not fully charged, frequent charging will not harm it. You can, for example, use a laptop to charge your phone. To do this, simply plug it into a USB port. You can also replenish the battery charge a little from the cigarette lighter in the car, if there is an appropriate adapter. And it's okay if you don't fully charge the battery. On the contrary, it is the best mode for Li─Pol batteries;
• Battery overcharging may occur even during normal controller operation. The reason for this may be a rise in temperature. For example, the battery is fully charged and the controller has disconnected the battery from charging. If you keep charging your device, it may become slightly warm. Accordingly, the battery will also heat up. Along with the temperature, the battery charge also rises. And this does not contribute to the increase in the service life of the lithium -polymer battery;
• Ideally, the Li─Pol battery should be charged at 50 percent. This is difficult in real life. But maintaining the charge in the range of 30-80 percent is quite realistic.

Without normal battery life, all meaning in a mobile device is lost. The user is tied to the power grid and cannot be connected while moving. At Magazin-Detaley.RU you can buy a lithium-polymer battery and solve problems with a quick discharge of the device.

How to order a lithium polymer battery at Magazin-Detaley.RU

Do you want to quickly buy Li-Pol batteries and not wait for spare parts to be delivered? Please contact our store. We are suppliers of leading service centers and parts stores, and we are preferred by retail buyers from all over the country.

Our company has been engaged in sales for several years and cooperates directly with equipment manufacturers. We specialize in the supply of high quality original spare parts. This guarantees the customer the uninterrupted operation of the battery.

Also here you will find Li-Ion batteries for laptops, smartphones, phones and tablets.

Our company strives to simplify the ordering procedure as much as possible. To buy a polymer lithium-ion battery, a client does not need to waste time and come to our office. All questions will be quickly resolved through the website, email or phone.

You can find out the exact cost of parts on our website. Store managers are constantly updating the assortment, information on cost and balances.

The Magazin-Detaley.RU company cooperates with legal entities and individuals. You can pay for your order through popular services and payment systems without leaving your home.

Delivery of lithium polymer batteries for smartphones is carried out through courier services, transport companies or the Russian Post. Also, the goods can be picked up at a convenient time by yourself from our warehouse.