Almost all modern electronic gadgets are equipped with lithium-polymer batteries. They are widely used on flying radio-controlled models, quadrocopters, helicopters and airplanes. Lithium polymer batteries have many advantages, including high energy density, low self-discharge and the absence of the so-called "memory effect".

As a result, for models with Li Pol power units, there is practically no worthy alternative to the battery. It is to be expected that they will be used more and more widely, especially in areas such as unmanned aircrafts, electric vehicles, etc.

Despite all the advantages, LiPol batteries have a reputation for being capricious, dangerous and short-lived power sources. In fact, these shortcomings are somewhat exaggerated. If used correctly, problems will be minimized.

Charging Rules

In order for the power supply to work without problems, it is necessary to properly charge LiPo batteries. Otherwise, there is a high risk of damage and even spontaneous combustion. Consider how to properly charge a lithium polymer battery to avoid possible problems:

• Charging a LiPo battery with any charger will not work, this requires special chargers. This is due to the features of the two-phase charging process.

• Li Pol batteries are charged in two phases (CC-CV method). At the first stage, the voltage on all battery banks increases. By the end of the phase, it reaches 4.2 volts. In fact, at this point, Li Pol batteries are charging up to 95%. Then the second phase begins. To prevent overcharging, which is detrimental to a lithium polymer battery, the current is reduced. If the voltage exceeds 4.25 volts, the risk of spontaneous combustion increases.
• It is not recommended to allow the power supply to be completely discharged, about 10-20% should remain in it before recharging, otherwise it will quickly fail.
• It is important to ensure that the voltage does not fall below 3 volts on each bank. With such a decrease in voltage indicators, there is a high risk that the battery may swell. In this case, a swollen LiPo battery will lose more than 50% of its capacity. If a LiPo battery is swollen, all that remains is to throw it away - the loss of capacity is irreversible.

The fact that lithium polymer power supplies swell is one of the serious problems their operation. All banks should be charged and discharged evenly. At the same time, the charger for lithium polymer batteries monitors only the total voltage, but with a large variation in indicators, the likelihood that the LiPo battery is swollen increases significantly. It also leads to overcharging of individual cans, increasing the risk of spontaneous combustion.

To solve this problem, charging Li Pol batteries must be performed using a balancer that is able to monitor the voltage on each bank, or a charger with a built-in balancer. Do not charge the timer charger. If the current is insufficient, the charger will turn off without fully charging it. The charge current should not exceed 1C and be less than 0.5C. You also need to remember that the larger the capacity of the LiPo battery, the longer it will take to charge.

Exploitation

In order to extend the life of Li Pol devices, or at least not shorten it, proper battery operation is also important. When we charge the power supply, we must not allow it to heat up above 60 degrees. If heating does occur, the battery must be allowed to cool before being used. Also, you can not put an overheated drive on charge.

Do not store a fully discharged battery. Be sure to charge it. The most optimal indicators are 60%. In general, if these simple rules are observed, there are no problems with the use of lithium polymer batteries.

Progress is moving forward, and replacing 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 larger capacitance 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 battery of two or three cells is enough.

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

Main characteristics

Lithium-polymer batteries with the same weight are 4-5 times more energy efficient than NiCd, NiMH 3-4 times. The number of operating cycles is 500-600, at discharge currents of 2C up to a capacity loss of 20% (for comparison, NiCd has 1000 cycles, NiMH has 500). Generally speaking, there is still very little data on the number of operating cycles, and to those given in this case their characteristics must be taken critically. In addition, the technology of their manufacture is improving, and it is possible that in this moment The numbers 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 commercially available power lithium-polymer batteries, two main groups can be distinguished - fast-discharge (Hi discharge) and conventional ones. They differ among themselves in the maximum discharge current - it is indicated either in amperes or in units of battery capacity, denoted by the beech "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 they have the letters HD or HC in the name after the capacity numbers, for example, the KKM1500 is a regular 1500 mAh battery, and the KKM1500HD is a fast-discharge battery. I would like to immediately make a small remark for fans of experiments. IN household appliances fast-discharging batteries are not used. Therefore, if you are visited by the idea to get a cheap battery from a cell phone or camcorder, then good result it's hard to calculate. Most likely, such a battery will die very quickly due to violation of the provided operating modes.

Applications and cost

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

When replacing the 8.4 V NiMH 650 mAh battery with two conventional, non-fast-discharging 2 Ah lithium batteries, we get a battery 3 times larger in capacity, 11 g lighter and with a slightly lower voltage (7.2 volts)! And if you use fast-discharging batteries, then large planes can fly, not inferior in terms of power to the internal combustion engine. In confirmation of this, the 7th place in the world championship in aerobatic models F3A was taken by an American on an electric plane. Moreover, it was not a small buzzer, but a normal two-meter aircraft, 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 cans is more than 25 minutes! And when replacing the motor with a brushless one - more than 45 minutes!

And, of course, lithium batteries are simply indispensable when we are talking about indoor planes weighing 4-20 g. In this area, NiCd cannot compare with them - there are simply no such batteries (for example, the weight of a 45 mAh can is 1 g, 150 mAh is 3.2 g), which, with such a small weight, would provide the necessary power - even for 1 minute!

The only area where so far lithium-polymer batteries are inferior to Ni-Cd is the area of ​​\u200b\u200bsuperhigh (40-50C) discharge currents. But progress is moving 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-discharging lithium batteries either ...

Here, for example, 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
Kocam 1020	1020	61x33x5.5	20.5	3A, 3C
Kokam 1500HC	1500	76x40x6.5	35	12A, 8C
1575	1575	74x41x5.5	32	7A, 5C

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

Manufacturers

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

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

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

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

I-Rate, as far as I know, does not yet make fast-discharge batteries, and their batteries have one feature: one of their electrodes is aluminum, and it is problematic to solder it. This makes them uncomfortable self assembly batteries.

E-Tec batteries are something in between, they are not claimed to be fast-discharging, but their discharge current is higher than that of conventional batteries - 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 with a capacity. Next come Tanic and E-tec, but there is little mention of I-rate. For some reason, Platinum Polymer is popular only in America, and it is used almost exclusively on slow flyers.

Charging Lithium Polymer Batteries

The batteries are charged according to a fairly simple algorithm - a charge from a constant voltage source of 4.20 volts / cell with a current limit 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. The charger is subject to fairly stringent requirements for the accuracy of maintaining the voltage at the end of the charge - no worse than 0.01 V / bank.

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

The first, as a rule, have only an LED charge indication, the number of cans and the current in them are set by jumpers. The advantage of such chargers is their low price. Main disadvantage- 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 complete completion You still have to wait 30-40 minutes for a charge.

The second group of chargers has much wider possibilities, as a rule, they all show the voltage, current and capacity (mAh) that the battery “accepted” during the charge, which allows you to more accurately determine how charged the battery is.

When using the 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 “gentle” batteries in existence, that is, they require mandatory compliance with several simple, but binding rules, due to non-observance of which either a fire occurs or the battery “dies”.

We list them in descending order of danger:

1. Charge up to a voltage greater than 4.20 volts/cell.
2. Short circuit of the battery.
3. Discharge with currents exceeding the load capacity or heating the battery above 60 ° C.
4. Discharge below 3.00 volts/cell.
5. Battery heating above 60°C.
6. Battery depressurization.
7. Storage in a discharged state.

Failure to comply with the first three points leads to a fire, all the rest - 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 must 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 burned the table on which the batteries were charging, and the curtain) and control the current consumed by the motor at "full throttle". In addition, it is not recommended to close the batteries on all sides of the model from the air flow, and if this is not possible, then special channels for cooling 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 running the motor, stop it, and then pull out and touch the battery - is it not too hot. The fact is that after heating above a certain temperature (about 70 degrees), a “chain reaction” begins in the battery, turning the energy stored by it 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 die quietly and peacefully 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 (Jeti is especially guilty of this) do not stop current consumption after turning off the standard switch. What made the Czechs make such a strange decision - I do not know. But the fact remains that almost all models of controllers for Jetti brushless motors (including new series"Advanced"), in which there is a BEC, that is, a power supply stabilizer for the receiver and machines from power 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 two, it turns out that you can say goodbye to it - it does not like deep discharge lithium.

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

Depressurization is another reason for the failure of lithium batteries, since air must not enter the cell. This can happen if the outer protective bag is damaged (the battery is sealed in a bag similar to heat shrink tubing), as a result of being hit or damaged by a sharp object, or if severe overheating battery terminal when soldering. Conclusion - do not drop from a great height and solder carefully.

Storage of batteries, judging by the recommendations of manufacturers, should be carried out in a 50-70% charged state, preferably in a cool place, at temperatures not higher than 20 ° C. Storage in a discharged state negatively affects the service life - like all batteries, lithium-polymer ones have a small self-discharge.

Battery assembly

To obtain batteries with high current output or high capacity, batteries are connected in parallel. If you buy a ready-made battery, then by marking you can find out how many cans are in it and how they are connected. The letter P (parallel) after the number indicates the number of cans connected in parallel, and S (serial) - in series. For example, "Kokam 1500 3S2P" means a battery connected in series of 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 \u003d 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 1C. It is advisable to discharge all purchased banks before connecting to 3 volts with a current of 0.1C - 0.2C. The voltage must be controlled with a digital voltmeter with an accuracy of at least 0.5%. This will ensure reliable battery performance in the future.

It is also desirable to carry out potential equalization (balancing) even on already assembled branded batteries before their first charge, since many companies that assemble elements 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 in this case.

Of course, it is also impossible to combine batteries of different, even similar capacities into a battery - for example, 1800 and 2000 mAh, and also use batteries from different manufacturers in one battery, since different internal resistance will lead to battery imbalance. When soldering, be careful not to overheat the leads - this can break the seal and permanently kill the battery that has not yet had time to fly. Some types of Kokam batteries come with pieces already soldered on. printed circuit board to the conclusions, for the convenience of unsoldering wires. This adds excess weight- about 1g per element, but it is possible to heat places for soldering wires much longer - fiberglass does not conduct heat well. Wires with connectors should be fixed on the battery case, at least with adhesive tape, so as not to accidentally tear off the terminal at the root.

Nuances of application

So, let's emphasize once again the most important points related to the use of lithium-polymer batteries.

• Use a normal charger.
• Use connectors that exclude the possibility of shorting the battery.
• Do not exceed admissible currents discharge.
• Monitor the temperature of the battery in the absence of cooling.
• Do not discharge the battery below 3V/cell (don't forget 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 earlier, but are not obvious at first glance.

When using collector motors, it is necessary to avoid situations when the motor is stalled (for example, the model is on the ground), and the transmitter is at full throttle. The current is too high, and we risk blowing up the battery (if the motor or regulator does not burn out first). This issue has been discussed many 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 can do this, I would advise you to turn off the transmitter if the model has fallen, for example, into the grass far from you - there is less risk of hitting the dangling throttle when searching for the model on the transmitter belt and not notice it.

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

This implies the following rule - 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 this precisely - too little operating experience has been accumulated. As a rule, it is recommended that approximately 40-50 cycles after the start of operation, once every 10-20 cycles, check the voltage of the battery cells during charging to identify "bad cans".

It is not recommended to “zero out” the battery by driving the motor until it stops spinning at all. New battery such treatment will not hurt, but for a slightly unbalanced one, this is an extra risk of discharging the “worst bank” below 3 volts, because of which it will lose 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 (balancer) are used. This is a small board connected to each bank containing terminating resistors, a control circuit and an LED indicating that the voltage on this bank has reached a level of 4.17 - 4.19 volts. When the voltage on a separate element exceeds the threshold of 4.17 volts, the balancer closes part of the current "on itself", preventing the voltage from exceeding the critical threshold. By the simultaneous ignition of the LEDs, you can see which banks have a lower capacity - on their balancer, the LED will light up first. One important additional requirement is imposed on balancers - the current they consume from the battery in the "standby" mode must be small, usually it is 5-10 μA.

It should be added that the balancer does not save from overdischarging some cans in an unbalanced battery, it only serves to protect against damage to the 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 low temperatures. Indeed, the technical specifications for the batteries indicate an operating range of 0-50 ° C (at 0 ° C, 80% of the capacity is retained). But nevertheless, it is possible to fly them at temperatures around -10 ... -15 ° С. The fact is that it is not necessary 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 turns out to be a useful property at the moment, preventing the battery from freezing. Of course, the output of the battery will be somewhat lower than at normal temperature.

Conclusion

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

In general, wait and see.

Portable chargers have become an integral part of modern life. The quality of batteries is the main condition for their performance, efficiency and safety. Manufacturers of chargers use two types of batteries in their construction - lithium-ion and lithium-polymer. For the average consumer unfamiliar with the features different types, it often becomes a problem to choose one or another type of battery.

What is the difference between these varieties, which one will be more correct to choose - all these questions require detailed knowledge about each type. In this article, we will reveal the features of lithium-ion and lithium-polymer batteries, introduce them to their technical properties, charging methods, and service life.

Differences between lithium-ion and lithium-polymer batteries

Models of batteries produced by different technologies perform the same function of energy supply. The design features of each type affect the reported power, durability of operation, and the degree of protection against explosion. It cannot be said unequivocally that more modern

the type of battery is better than the outdated one. Both technologies have practical advantages and disadvantages. Models Li-pol and Li-ion have similar schemes of work, but differ in configuration and technical parameters.

To understand which is better - Li-polymer or Li-ion, let's take a closer look at each type separately. Compare the types of batteries and make a choice in the direction of one or another type should be based on the following indicators:

• price;
• weight-to-capacity ratio;
• safety;
• intended use in a device for a specific purpose;
• temperature regime operation.

When choosing one of the two types, consider the scope and financial possibilities.

Lithium-ion batteries: features and specifications

Initially, lithium-based models were produced using manganese and cobalt as the main element (active electrolyte). Modern lithium-ion batteries have undergone design changes. Their productivity does not depend on the substance used, but on the order in which the elements are placed in the block. The components of a modern Li-Ion battery are electrodes and a separator. Materials - aluminum and copper (copper anodes and aluminum foil as a cathode base).

Special current collector terminals provide an internal connection between the anode and cathode, and the electrolyte impregnation of the separator mass sets favorable environment for charge maintenance. The positive charges of lithium ions start chemical reactions, form bonds and provide energy output. The principle of operation of a lithium-ion-based power supply resembles the operation of a full-size gel battery.

Lithium polymer batteries

Since lithium-ion models do not cope with many modern tasks, they gradually began to be replaced by polymer elements. Li-ion batteries did not have a high level of safety and were quite expensive. To eliminate these shortcomings and operational problems, to make the batteries more efficient, the developers decided to change the electrolyte. Instead of impregnating a porous separator, polymer electrolytes were used in the battery design.

The lithium-polymer cell has a thickness of 1 mm, which allows you to make the size of the battery compact. The replacement of liquid electrolytes with polymer films eliminated high risk ignite the battery and make it safe. The comparison table below will help you visually determine how Li-ion differs from Li-Pol.

Specifications	Li-ion	Li-Pol
Energy intensity		low, the number of charge and discharge cycles is less
Size	small selection	high choice, independence from the standard cell format
	slightly heavier
		almost twice as high for the same size
Life time	about the same	about the same
Risk of explosion and fire	higher	built-in protection against leakage of electrolytes and overcharges
Charging time
	up to 0.1% monthly	less active

The design of lithium polymer battery devices completely eliminates the presence of an electrolyte in the form of a liquid or gel. You can clearly imagine the difference in technologies when considering the principle of operation of modern automotive power supplies. Safety interests have led to the exclusion of liquid electrolytes from everyday practice. But until recently, impregnated porous structures were used in automotive batteries.

The introduction of polymer-lithium elements already assumed a solid-state basis. A characteristic difference from lithium-ion batteries is the process of contact action of the plate active substance with lithium and preventing the formation of dendrites during cycling. It is this feature that protects the battery cells from fire or explosion.

Life time

Both lithium-ion and lithium-polymer batteries are subject to intense aging. They provide about nine hundred full charge cycles, after which they become unusable. It does not matter how active the operation of the device was. If the battery has not been used at all for a long time, a reduction in life will still occur.

Already after a year, the capacities become significantly reduced in resource, and after two or three years it can be stated that the battery has completely failed. This is a common disadvantage of lithium batteries, and it is worth choosing a more durable model only depending on the manufacturer's reputation and reviews on specific models.

Additional protection

If we consider the question of what is the difference between Li-ion and Li-Pol batteries, you should pay attention to the built-in protective systems. Lithium-Polymer models require the use of additional features internal protection. They are characterized by cases of burnout due to overheating of the elements. Such consequences are caused by the internal stress of various working areas.

In order to protect the device from unauthorized overcharging, from overheating of parts and burnout, a special stabilizing system and a current limiting mechanism are used in the design. This increases the safety of lithium-polymer models, but significantly increases the cost of the battery through the use of protective elements.

Part of the design involves electrolytic components in a gel formation. Combination batteries are used in many portable devices. They are extremely sensitive to temperature changes and require strict adherence to operating rules. The polymer-based battery can be used in devices with heating in the range of 60-100 degrees.

Producers conclude inner part in a housing with heat-insulating properties - it is convenient to use such batteries in hot climates. In conditions where the temperature regime does not meet the requirements of operation, elements with a polymer component are used as backup.

Features of battery charging

It takes at least three hours of charging to recharge the lithium polymer battery. In this case, the block does not heat up. There are two stages of filling. The first proceeds until the peak mode is set, which is maintained until the charge reaches 70%. Under normal voltage mode, a residual charge of 30% is gained. Recharging must be carried out according to a strict schedule, waiting for complete discharge and carrying out the procedure every 500 hours of using the device. This mode maintains a constant filling volume.

It is necessary to connect the battery only to a stable working power supply, without voltage drops and interference. Use only appropriate chargers that match the characteristics stated in the description. An important point: during the charging process, all connectors must be connected correctly, opening must not be allowed. Li-Pol elements are extremely sensitive to all kinds of overloads, exceeded current rates, mechanical shocks and hypothermia. The tightness of solid elements should be monitored.

Li-ion cells are charged in much the same way as polymer ones, but are more sensitive and less reliable in terms of safety. The charging time for both types is approximately the same, but the polymer element is "capricious" to the quality of the power supply point.

The better lithium-ion battery

Lithium-ion batteries are more familiar to the consumer, they have a number of operational advantages:

• the price is lower than the lithium-polymer battery;
• standardized sizes allow you not to make mistakes when choosing a model;
• widespread scope.

Powerful lithium batteries are effectively used for devices that require short-term high current consumption. The temperature regime, like that of polymer-based devices, has key value during operation.

An ordinary user does not feel a tangible difference, but, from the point of view of the rationality of the scope, this type of battery is convenient in chargers for the following equipment:

• battery tools (screwdrivers, saws, grinders);
• laptops;
• Cell phones;
• electric vehicles;
• domestic robots;
• wheelchairs.

Before choosing the optimal type of charging, you need to know exactly what device it will be used for. This is especially important if you plan to universally use and service several portable devices at once.

Lithium-polymer batteries are rationally used where important factors are weight and temperature. They are "afraid" of frost and are not very convenient for portable tools and gadgets. Therefore, the main area of ​​\u200b\u200buse:

• quadrocopters;
• airsoft guns;
• toys;
• CCTV Cameras.

Choosing suitable type charger, pay attention to the scope, cost and safety level. Read user reviews about products from different manufacturers and make a choice.

Features of lithium-polymer batteries and rules for their operation

The lithium polymer battery is a modified version of the lithium ion battery. The main difference lies in the use of a polymeric material that acts as an electrolyte. Conductive inclusions with lithium compounds are added to this polymer. Such batteries have been actively developed in recent years and are used in mobile phones, tablets, laptops, radio-controlled models and other equipment. Although lithium batteries are unable to provide high discharge currents, some special varieties polymer batteries can deliver a current that is much higher than their capacity. Since lithium-polymer batteries are rapidly spreading on the market, you need to have an understanding of their design, operating rules and safety precautions when handling them. This will be discussed in our today's material.

The advantage of replacing a liquid organic electrolyte with a polymer one is to increase the safety of battery operation. This is very important for lithium type batteries. It is the safe use of commercial purposes hindered their development from the very beginning. In addition, the polymer electrolyte gives much more freedom in choosing the shape of the battery.

The Li─Pol battery device was based on the process of transition of a number of polymers to a semiconductor state when electrolyte ions are introduced into them. In this case, the conductivity increases several times. The researchers were mainly engaged in the selection of a polymer electrolyte for batteries with lithium metal and Li─Ion models. In theory, it is allowed to increase the energy density of polymer batteries by several times compared to lithium ion ones. To date, there are several groups of Li─Pol batteries that differ in the composition of the electrolyte:

• With a gel-like homogeneous electrolyte. It is obtained as a result of the introduction of lithium salts into the polymer structure;
• With dry polymer electrolyte. This type is made on the basis of polyethylene oxide with various lithium salts;
• Electrolyte in the form of a microporous polymer matrix in which non-aqueous solutions of lithium salts are adsorbed.

If we compare the polymer and liquid electrolyte, then it is worth noting the lower ionic conductivity of the former. It decreases significantly at low temperatures. So one problem was to find a composition for an electrolyte with high conductivity. And the second important task was in expanding the operating temperature range of polymer batteries. Models of lithium-polymer batteries used in modern technology, according to their characteristics are not inferior to Li─Ion.

Since there is no liquid electrolyte in the polymer battery, their operational safety is much higher. In addition, they can be performed in almost any shape and configuration.

The containers of some models, in which the can itself is located, are made of metallized polymer. Due to the crystallization of the polymer electrolyte, the parameters of these batteries are significantly reduced at low temperatures.

There are developments of polymer batteries with a metal anode. Scientists have been able to high density current and a significant expansion of the operating temperature range. These types of batteries can also be used in various portable electronics and home appliances. Many leading companies are already producing such batteries.

Moreover, different manufacturers may differ in the materials of the electrodes, the composition of the electrolyte and the assembly technology itself. For this reason, the parameters of these batteries are very different. However, all manufacturers agree that the stability of Li─Pol is strongly influenced by the homogeneity of the polymer electrolyte. And it depends on the polymerization temperature and the ratio of components.

Now there are already many experiments that prove more high level the safety of polymer batteries compared to ion batteries. This applies to overcharging, accelerated discharge, vibration, compression, short circuit, puncture of lithium-polymer batteries. So, this type of batteries has the best development prospects. Below are the test results for safe operation Li-Pol batteries.

Type of tests
Type of tests	Battery with gel-polymer electrolyte	Wet battery
Needle puncture	There were no changes	Explosion, smoke, electrolyte leakage, temperature increase up to 250°С
Heating up to 200°C	There were no changes	Explosion, electrolyte leakage
Short circuit current	There were no changes	Electrolyte leakage, temperature increase by 100°C
Recharge (600%)	Bloating	Explosion, electrolyte leakage, temperature rise by 100°C

There are examples of lithium-polymer batteries that are 1 millimeter thick. These models allow designers mobile devices create very compact equipment. This opens up new possibilities for downsizing. electronic devices. To reduce the internal resistance of Li-Pol batteries, a gel electrolyte is added. Batteries used in mobile phones use this type of electrolyte. They combine the features of polymer and ion batteries.

What is the difference between Li─Ion and Li─Pol batteries. They belong to and are close in their electrical characteristics. But polymer models use a solid electrolyte. The gel component is introduced into the electrolyte to reduce the internal resistance of the battery and stimulate ion exchange processes.

In terms of their energy intensity, lithium-polymer rechargeable batteries have a specific energy intensity 4-5 times higher and 3-4 times higher. Both of these types belong to . The comparison is made with them, since basically lithium batteries have replaced alkaline batteries in mobile electronics.

Li─Pol batteries have a resource of 500─600 charge-discharge cycles (at a discharge current of 2C). According to this indicator, they lose to cadmium ones (1 thousand cycles) and approximately correspond to metal hydride ones. The production technology and design are constantly being improved and in the future, perhaps, the characteristics will improve. It is also worth noting that in 1-2 years, a polymer battery loses about 20% of its capacity. According to this parameter, they correspond to ion batteries.

It should be noted that there are 2 major categories of polymer batteries for commercial use. These are normal and fast-discharge. The latter are often called Hi discharge. The difference between these groups lies in the maximum allowable discharge current. It may be indicated in absolute value or a multiple of the nominal capacity.

For example, 3S. For conventional batteries, the maximum discharge current is not more than 3÷5C. Fast-discharge models have a maximum discharge current of 8─10C. The mass of quick-discharge batteries is approximately 20 percent higher than that of standard models. The marking of such batteries contains the symbols HC or HD.

KKM2500 stands for 2500 mAh regular model, while KKM2000HD stands for 2000 mAh fast discharge battery. Fast-discharge models are not used in home appliances and consumer electronics. battery from cell phones and tablets cannot withstand high discharge currents, and therefore are equipped with protection against such operating modes.

The areas of application of lithium-polymer batteries stem from the tasks that were set during their development. This is an increase in the operating time of the device and a decrease in its weight. Standard Li─Pol models work in different electronics with low current consumption. These are laptops, smartphones, e-readers, tablets.

Models that provide for a quick discharge are also called "power". They are used in those devices where high current consumption is required. The most well-known scope of "power" batteries is radio-controlled models. This market is the most attractive for manufacturers of polymer batteries. In the field of operation of devices with very high discharge currents (up to 50 C), lithium-polymer batteries lose out to alkaline ones. Perhaps in the future, lithium models will overcome this limitation. For the price, they roughly correspond to nickel-metal hydride.

Operation of Lithium Polymer Batteries

Safety

Lithium-type batteries in general, and polymer batteries in particular, require rather delicate handling during operation. What you need to remember when using Li─Pol batteries:

• Excessive battery charge is harmful (above 4.2 volts per battery cell);
• Short circuit must not be allowed;
• It is unacceptable to discharge by currents that lead to heating of the battery by more than 60 degrees Celsius;
• It is impossible to depressurize the battery;
• Do not discharge the battery below 3 volts;
• Heating above 60 degrees is unacceptable;
• Discharged storage is not allowed.

If these rules are not followed, it can lead to a fire at worst, and a significant loss of capacity at best.

In this regard, several recommendations can be made safe use lithium-polymer batteries. First you need to purchase a high-quality charger and set the correct settings on it. In addition, it is recommended to use connectors that do not allow short circuit. Be sure to control the current drawn by the device.

It is also worth noting that it is necessary to observe the temperature regime and prevent overheating of the polymer battery. This is the weak point of all lithium-type batteries. If the battery heats up to 70 degrees, then a spontaneous reaction begins in it, which turns energy into heat. As a result, ignition, and sometimes an explosion. If it is possible to control the voltage of the battery, then it should be especially closely monitored at the end of the discharge.

Another reason for the failure of lithium batteries is depressurization. Under no circumstances should air enter the interior of the polymer battery. Initially, the case is sealed and should not be subjected to shock, drop. If you are soldering leads, then you need to do this very carefully.

Before storing a polymer battery, it is recommended to charge it halfway. Store the battery in a cool place out of direct sunlight. Like all rechargeable batteries, lithium-polymer batteries have a self-discharge, but it is less than that of lead or alkaline.

The polymer battery is an upgraded version of the lithium battery. A special gel is used as a filler for a lithium polymer battery, which has certain characteristics.

In order to decide whether to use li pol advanced batteries, you need to study certain information, take into account the advantages and disadvantages.

The performance of the equipment, portable device or installation depends largely on how well the power supply is selected. So, a lithium-ion or lithium-ion polymer battery is used to complete portable chargers. To do right choice, you need to know what the difference is. It is obligatory to take into account the pros and cons of power sources.

An interesting video about lithium polymer batteries.

Li-ion batteries

The demonstration of the first ion batteries took place in the last century. Then the developers presented models in which the electrodes were prepared from metallic lithium. They were different low level safety, long life. Therefore, metallic lithium was replaced by li ions.

The upgraded lithium-ion battery has the following advantages:

• Increased capacity, electrolyte density.
• Possibility of operation at higher voltage.
• Easy maintenance due to no memory effect.
• Minimum self-discharge.

The duration of operation of an ion battery also depends on whether the disadvantages are taken into account:

• Constant monitoring of voltage, current and temperature levels is required. This requires a special controller. This is what distinguishes ionic batteries from polymer ones.
• gradual decrease in capacity.
• A proven protective circuit, a controller with the necessary components must be introduced into the composition. Such work requires certain materials, tools. The procedure for manufacturing a protective circuit takes certain time. All this leads to an increase in the cost of li ion po batteries by 1.5–2 times.

Lithium polymer batteries

The development of a high-quality lithium polymer battery was started due to the fact that the safety level of ion power sources was not high. As a result, manufacturers received acb, which have special advantages, unlike li.

Instead of the standard electrolytic composition, a dry polymer electrolyte is used, presented in the form of a film. It does not conduct current, does not interfere with the exchange of charged particles. Unlike an ionic power source, a porous separator is not introduced into the polymer battery device.

Due to the fact that this design is used, the safety level of li pol household batteries is higher. After all, the likelihood of ignition is reduced to zero.

The polymer electrolyte lends itself well to processing. Therefore, manufacturers easily create a li ion polymer battery of the required shape, optimal configuration. Therefore, such power supplies are used in phones, laptops, portable equipment, and camcorders.

Unfortunately, lithium-ion polymer batteries are notable for their low electrical conductivity. Its level rises only when heated. But such an effect is not always acceptable. For example, battery heating is not allowed if there is no cooling system.

The resistance level of li ion polymer batteries is high, so it is quite difficult to obtain the required current value. Because of this, modern devices cannot be equipped with such power sources.

But the above problems are inherent only in those li ion poly power sources in which the electrolyte is presented in a dry form.

Upgraded lithium polymer batteries

The problem associated with the lack of electrical conductivity was solved by introducing certain components into the electrolyte. Now they produce polymer batteries, the electrolyte in which is presented in the form of a gel. Such power supplies are called lithium ion polymer batteries. They equip the best mobile phones, chargers and portable devices.

Rechargeable polymer batteries are found everywhere, no matter what technique is presented.

Fundamental differences

What to choose: li ion or li polymer battery? Both designs have similar characteristics and parameters. The difference lies in the presence of a solid electrolyte in li ion pol batteries.

The upgraded ion polymer battery does not come with a porous separator. It is distinguished by an increased capacity, a long period of operation, and increased electrical conductivity.

When deciding which battery is best for a phone, manufacturers take into account design features, as well as the difference between pol and li types. At the same time, most often they use ion li polymer batteries, which have all the advantages.

Features of using lithium batteries

The use of li ion and li ion pol follows a similar principle. To prevent problems you need:

• Maintain a voltage of 4.2–2.7 V during the entire period of operation. These indicators correspond to the maximum and minimum charge.
• Consideration of voltage limits introduced by manufacturers. For careful control, the use of proven schemes is allowed.
• The service life of batteries charged up to 45–46% pol or li is the longest.
• The introduction of controllers into the composition of ionic polymer batteries helps to maintain an acceptable voltage level.

Charging Rules for Lithium Polymer Batteries

To increase the operating time of the battery without additional recharging, you need to take into account the rules for using the charger.

1. Invalid full discharge. Polymer batteries do not have a memory effect. Therefore, the use of the charger is permissible even with a small discharge. To extend the life of the li ion po, the battery needs to be charged more frequently. In this case, you need to use the "native" charger.
2. It is harmful to use a battery that is fully charged all the time. Therefore, with a certain frequency, the power supply must be discharged to zero. Due to the instability of charging, the use of various circuits and devices. With periodic discharge, the probability of the formation of lower, upper thresholds is excluded.
3. Non-operated li ion po power supplies are stored at a temperature of 15-20 degrees. The charge level should be 40%. A fully charged power supply should not be stored. After all, this is fraught with loss of capacity, deterioration in performance.
4. Lithium-ion polymer batteries are charged using original chargers. Some mobile phones are equipped with built-in chargers. An external adapter is supplied separately to help stabilize the voltage. Part of the equipment is not equipped with such devices. Therefore, the battery is removed for charging.
5. Polymer batteries must not be overheated. Even an excess of 1-2 degrees adversely affects the state of the power source. Negative influence provide and low temperatures. Therefore, you need to use the battery only in the permissible mode.
6. It is forbidden to operate power sources in the immediate vicinity of heaters. The battery must not be exposed to direct sunlight. After all, all this helps to reduce the period of use.
7. It is not safe to use chargers that have not been certified. So how do you charge the battery? The best way out is to use proven and certified chargers that are recommended by manufacturers.
8. All connectors used must match in size. This is the only way to eliminate the possibility of shorting the battery.
9. The temperature of the power supply must be continuously monitored. This is especially important if no cooling system is available.
10. Mechanical loads are prohibited. This can provoke the formation of microcracks and other damage.

Video about the restoration of lithium-polymer batteries.

Before use universal charger necessary:

• Compare technical parameters.
• Check capacity readings. When using limited chargers, it will be difficult to charge the power supply.
• Make sure the charger is working. After all, Chinese products may have defects.

If necessary, you can check old battery how it will charge.

Storage and disposal of polymer batteries

The period of operation of whether ion polymer batteries depends on the observance of storage rules.

1. Primary power sources do not require special storage conditions. Just follow the manufacturer's recommendations.
2. The battery removed from the device is placed on a dry surface. At the same time, it is necessary to minimize the likelihood of sunlight hitting the surface of the power source.
3. The likelihood of freezing increases if the battery is in a discharged state. Therefore, premises with the required conditions are selected for storage.
4. It is necessary to store polymer batteries with a small charge (40–50%).
5. Lithium polymer batteries, whose voltage is constantly decreasing, should not be operated and stored. Such devices must be recycled.
6. After long-term storage the power source must be examined. Damaged or swollen batteries should be replaced.

The electrochemical system of polymer batteries is harmless. After all, the preparation took into account environmental standards and requirements. But the disposal of failed devices is mandatory. Such actions contribute to the preservation of the environment. Failed sources are transferred to the appropriate organizations in the prescribed manner.

Modernized lithium polymer batteries are gradually replacing traditional power sources. And this is due to considerable capabilities, technical characteristics and an increased level of security.

Video about lithium polymer batteries