Li polymer battery. Lithium polymer rechargeable battery. Lithium Polymer Battery Charging Guidelines

What is the difference between a lithium-polymer battery and an ionic battery?

The overwhelming majority of residents of developed countries have mobile phones, tablets, and laptops. When you buy a gadget in a store, most likely, you don't even think about the type of battery in it. And this is not surprising. Technology is advancing rapidly, including in the battery industry. Not so long ago, Ni─Cd batteries were used in mobile electronics, which were then replaced by Ni─MH. Then came lithium ion, which quickly conquered the portable gadget market. And now they are being crowded out by lithium-polymer batteries. At some point, the user begins to think about what kind of rechargeable battery he has. What are its advantages and disadvantages? In this post, we will try to understand what is the difference between a lithium-polymer battery and a lithium-ion battery.

Work on creating batteries using lithium has been going on for a long time. But the first workable copies for household appliances appeared only in the 70s of the last century. But then these were imperfect models with metal lithium electrodes. And the operation of such batteries is problematic in terms of safety. There were many unresolved problems with the process of charging and discharging such batteries.

The fact is that lithium metal is very active and has a high electrochemical potential. Its use in batteries can significantly increase the energy density. Rechargeable batteries with metal Li electrodes, which were the first to be developed, have high voltage and large capacity. However, the constant operation of such a battery in a charge and discharge mode causes the lithium electrode to change.

This leads to the fact that the stability of operation is disturbed and there is a threat of ignition due to an uncontrolled reaction in the battery. The battery cell heats up quickly and when the temperature rises to the melting point of lithium, a violent reaction occurs with ignition. Related to this was the recall of the first lithium-type batteries in consumer electronics in the early 90s.

As a result, scientists began to develop battery based on Li ions. Due to the fact that it was necessary to abandon the use of metallic lithium, the energy density slightly decreased. But on the other hand, safety problems were solved during the operation of the battery. These new batteries are called lithium ion batteries.

The energy density of lithium ─ ion batteries is 2-3 times (depending on the materials used) higher than that of. When Li─Ion is discharged, the batteries show characteristics similar to Ni─Cd. The only thing in which they are inferior to them is work at ultra-high discharge currents (more than 10C). To date, many different modifications of lithium ion batteries have already been released.

They differ in the material used as the cathode, form factor, and in some other parameters. They are uniquely characterized by the design, which includes electrodes immersed in a liquid electrolyte containing lithium ions. This battery cell is enclosed in a sealed metal sheath (steel, aluminum). Lithium ion batteries have a printed circuit board called a controller to control the charging and discharging processes.

To make the picture of Li─Ion batteries complete, consider their advantages and disadvantages.

Li─Ion advantages

• Small self-discharge;
• High energy density and capacity compared to alkaline;
• One battery cell has a voltage of about 3.7 volts. For cadmium and metal hydride, this value is 1.2 volts. This greatly simplifies the design. Phones, for example, use batteries that have only one can;
• There is no memory effect, which means that maintenance of the battery is simplified.

Disadvantages of Li─Ion

• Controller required. This is a printed circuit board that monitors the voltage of the battery cell or cells, if there are several. The board also monitors the maximum discharge current, and in some cases, the can temperature. Safe operation of a lithium ion battery is impossible without a controller;
• The Li─Ion system degrades even during storage. That is, after a year, the capacity of the battery decreases significantly, even if it is not used. Batteries of other types (alkaline, lead-acid) also gradually degrade during storage, but this is less pronounced in them;
• The price of lithium ion is higher than cadmium or.

The capabilities of lithium ion technology have not been fully developed. Therefore, new batteries constantly appear, where certain problems of this type of battery are solved. For more information about what it is, read the article at the specified link.

Li─Pol battery

Due to safety problems during charging and discharging of Li─Ion batteries, further development of modifications of these batteries began. As a result, lithium-polymer batteries were developed. Their difference from ionic in the used electrolyte. It is worth saying that the first developments in this direction were carried out simultaneously with Li─Ion technology. Back in the last century, a dry electrolyte from a solid polymer was first used. In appearance, it looks like a plastic film. This polymer is non-conductive, but do not interfere with ion exchange, which involves the movement of charged atoms or groups of them. In addition to its electrolyte content, the polymer also acts as a porous separator between the electrodes.

The new design has improved safety and simplified battery manufacturing. And more importantly, lithium-polymer batteries can be produced in almost any shape and very thin (up to 1 millimeter). This allows various devices powered by Li─Pol rechargeable batteries to be made thin, compact and sleek. Some lithium-polymer batteries may even be sewn into clothing.

Naturally, there are also disadvantages. In particular, Li─Pol dry cell batteries have low electrical conductivity at room temperature. This is due to the fact that at this temperature their internal resistance is high, which prevents the discharge of the discharge current necessary for the operation of portable electronics.

If you heat a lithium-polymer battery to 60 degrees Celsius, then the conductivity increases. It is clear that this is not suitable for use in phones or tablets. However, dry polymer batteries have found their niche in the market. They are used as backup power supplies in high temperature conditions. There are options when heating elements are installed to provide the temperature required for normal battery operation.

Another important point should be clarified here. Surely everyone has seen that batteries marked Li─Pol have been used for a long time in smartphones, tablets and laptops. These are lithium-polymer hybrid batteries, so to speak. They are a cross between Li─Ion and dry polymer batteries. Manufacturers producing lithium-polymer batteries use a gel-like substance with lithium ions as an electrolyte.

So, almost all lithium-polymer batteries in modern mobile gadgets use a gel-like electrolyte. By design, they are a hybrid of ionic and polymer batteries. What is the difference between ionic and polymer batteries with a gel electrolyte? Their basic electrochemical parameters are approximately the same. The difference between such hybrid batteries is that they use a solid electrolyte instead of a porous separator. He, as mentioned above, also acts as a porous separator. A gelled electrolyte is used to increase the conductivity of ions.

Lithium-polymer batteries are becoming more and more popular in the market and are the future. At least in the segment of home appliances and consumer electronics. But while their implementation is not very active. Some market experts attribute this to the fact that too much money has been invested in the development of Li─Ion batteries. And investors just want to "recoup" the money invested. read the link.

The main types of batteries:

• Ni-Cd Nickel Cadmium Batteries
• Ni-MH Nickel Metal Hydride Batteries
• Li-Ion Lithium-ion batteries

Ni-Cd Nickel Cadmium Batteries

For cordless tools, nickel cadmium batteries are the de facto standard. Engineers are well aware of their advantages and disadvantages, in particular Ni-Cd Nickel-cadmium batteries contain cadmium, a heavy metal with increased toxicity.

Nickel-cadmium batteries have a so-called "memory effect", the essence of which boils down to the fact that when charging an incompletely discharged battery, its new discharge is possible only to the level from which it was charged. In other words, the battery "remembers" the level of residual charge from which it was fully charged.

So, when charging an incompletely discharged Ni-Cd battery, its capacity decreases.

There are several ways to combat this phenomenon. We will describe only the simplest and most reliable method.

When using cordless tools with Ni-Cd rechargeable batteries, a simple rule of thumb is to charge only fully discharged batteries.

Pros of Ni-Cd Nickel Cadmium Batteries

• Low Price Ni-Cd Nickel Cadmium Battery
• Ability to deliver the highest load current
• The ability to quickly charge the battery
• Keeping high battery capacity down to -20 ° C
• A large number of charge-discharge cycles. With proper operation, such batteries work perfectly and allow up to 1000 charge-discharge cycles or more.

Cons of Ni-Cd Nickel Cadmium Batteries

• Relatively high self-discharge level - Ni-Cd Nickel-cadmium battery loses about 8-10% of its capacity in the first day after full charge.
• During storage Ni-Cd Nickel-cadmium battery loses about 8-10% charge every month
• After long-term storage, the capacity of the Ni-Cd Nickel-Cadmium battery is restored after 5 discharge-charge cycles.
• To prolong the life of the Ni-Cd Nickel-Cadmium battery, it is recommended to completely discharge it every time to prevent the "memory effect"

Ni-MH Nickel Metal Hydride Batteries

These batteries are offered on the market as less toxic (compared to Ni-Cd Nickel-Cadmium batteries) and more environmentally friendly, both in production and disposal.

In practice, Ni-MH Nickel-Metal Hydride batteries do demonstrate a very large capacity with dimensions and weight somewhat smaller than that of standard Ni-Cd Nickel-Cadmium batteries.

Due to the almost complete rejection of the use of toxic heavy metals in the design of Ni-MH Nickel-metal hydride batteries, the latter, after use, can be disposed of quite safely and without environmental consequences.

Nickel-metal hydride batteries have a slightly reduced "memory effect". In practice, the "memory effect" is practically invisible due to the high self-discharge of these batteries.

When using Ni-MH Nickel-Metal Hydride batteries, it is advisable to partially discharge them during operation.

Store Ni-MH Ni-MH batteries in a charged state. In case of long (more than a month) interruptions in operation, the batteries must be recharged.

Pros of Ni-MH Nickel Metal Hydride Batteries

• Non-toxic batteries
• Less "memory effect"
• Good low temperature performance
• Higher capacity compared to Ni-Cd Nickel-cadmium batteries

Cons of Ni-MH Nickel Metal Hydride Batteries

• More expensive type of batteries
• Self-discharge is about 1.5 times higher than Ni-Cd Nickel-cadmium batteries
• After 200-300 discharge-charge cycles, the working capacity of Ni-MH Nickel-metal hydride batteries decreases slightly
• Ni-MH Ni-MH rechargeable batteries have a limited life

Li-Ion Lithium-ion batteries

The undoubted advantage of lithium-ion batteries is the almost imperceptible "memory effect".

Thanks to this remarkable property, the Li-Ion battery can be charged or recharged as needed, based on needs. For example, you can recharge an incompletely discharged lithium-ion battery before important, demanding or extended work.

Unfortunately these batteries are the most expensive rechargeable batteries. In addition, lithium-ion batteries have a limited life, independent of the number of discharge-charge cycles.

In summary, we can assume that lithium-ion batteries are best suited for cases of constant intensive use of cordless tools.

Pros of Li-Ion Lithium Ion Batteries

• There is no "memory effect" and therefore it becomes possible to charge and recharge the battery as needed
• High capacity Li-Ion Lithium-ion batteries
• Lightweight Li-Ion Lithium-ion batteries
• Record low self-discharge level - no more than 5% per month
• Fast charge capability for Li-Ion Li-ion batteries

Cons of Li-Ion Lithium Ion Batteries

• High Cost Li-Ion Lithium Ion Batteries
• Reduced operating time at temperatures below zero degrees Celsius
• Limited service life

Note

From the practice of using Li-Ion Lithium-ion batteries in phones, cameras, etc. it can be noted that these batteries serve on average from 4 to 6 years and withstand about 250-300 discharge-charge cycles during this time. At the same time, it was definitely noticed: more discharge-charge cycles - shorter service life of Li-Ion Li-ion batteries!

All these types of batteries have such an important parameter as capacity. The capacity of the battery shows how long it will be able to power the load connected to it. The radio's battery capacity is measured in milliampere-hours. This characteristic is usually indicated on the battery itself.

Let's take the Alpha 80 radio and its 2800 mAh battery as an example. With a cycle of 5/5/90, where 5% of the radio station's operating time for transmission, 5% for receiving, 90% of the time in standby mode, the operating time of the radio station will be at least 15 hours. The lower this parameter for the battery, the less it can work.

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) there are 2 types of batteries: li pol and li ion. Are there any significant differences between them? What are the advantages and disadvantages of each type? And which battery is better (in terms of capacity, safety, durability) than the other: li pol or li ion? To understand the nuances, you need to examine them "under a microscope", and this material will tell you about them in more detail.

What is a Li-ion Battery?

This is a kind of battery that has found its application in a wide variety of devices:, video cameras,.

The advantages of this unit:

• lack of a "memory effect" (with this effect, the battery seems to remember that in previous cycles the reserve of its capacity was not fully used and, when discharged, gives up current to this limit) - there is a possibility of regular small recharging;
• immediately ready for use - no need to discharge it after purchase, and then charge it;
• relatively slight "aging" with regular use - up to 20% in 365 days;
• high level of energy density (or, in other words, capacity).

In addition, according to user reviews, the advantages of the device include ease of maintenance and operation. The reserve of working cycles of this type of battery is from 1000.

The disadvantages of the battery include:

• if the shell is damaged, there is a danger of explosion;
• charging is difficult at subzero temperatures;
• Aging of the battery even when not in use.

To avoid all these shortcomings in the work of li ion, you need to adhere to simple recommendations: do not overheat the device, do not use it in severe frosts, keep it from shocks and falls.

What is a lithium polymer battery?

This is an improved version of the previous type of battery. Used in radio controlled gadgets, etc.

The choice of users in favor of buying this type is justified by the following advantages of the battery:

1. Can be made of any shape and thickness (up to 1 mm);
2. Increased level of safety (there is no liquid electrolyte, which means that the risk of ignition of the device is minimized)
3. Slight voltage drop during discharge (the battery remains operational longer, even if it is not recharged for a long time);
4. Slightly higher capacity compared to lithium-ion unit.

These batteries last longer, even if not charged for a long time.

The disadvantages of polymer devices include:

• "aging"; however, it is slower than li ion;
• rather high manufacturing cost.

Such devices can power longer and ensure the autonomous operation of devices.

Which is better: li-pol or li-ion?

This requires a comparison of the characteristics of two types:

Both options are great for smarts (for example, li ion is installed). And such types as lithium-titanium batteries, although they have more outstanding characteristics (one of them is 10,000 cycles up to 80% capacity), but due to their impressive weight, they are good only in stationary use.

As for the dilemma, which battery is better of the two described here: li ion or li pol, then buyers should remember that the first option is cheaper to manufacture, the second is distinguished by elegance and delicate shapes. In practice, even if you buy a powerful and capacious battery and do not follow the recommendations for use, it will fail regardless of its parameters. Therefore, you need to use the devices correctly so that all their internal components, including batteries, last as long as possible.

The growing consumer interest in mobile gadgets and high-tech portable technology in general forces manufacturers to improve their products in a variety of ways. At the same time, there are a number of general parameters, the work on which is being carried out in one direction. These include the method of energy supply. Just a few years ago, active market participants could observe the process of displacement of NiMH by more advanced elements of nickel-metal hydride origin. Today, new generations of batteries are competing with each other. The widespread lithium-ion technology is successfully replacing the lithium-polymer battery in some segments. The difference from the ionic in the new unit is not so noticeable for an ordinary user, but in some aspects it is significant. At the same time, as in the case of the competition between NiCd and NiMH elements, the replacement technology is far from flawless and in some respects is inferior to its analogue.

Li-ion battery device

The first models of serial lithium batteries began to appear in the early 1990s. However, cobalt and manganese were then used as the active electrolyte. In modern ones, it is not so much the substance that is important as the configuration of its placement in the block. Such batteries consist of electrodes which are separated by a pore separator. The mass of the separator, in turn, is impregnated with the electrolyte. As for the electrodes, they are represented by a cathode base on an aluminum foil and a copper anode. Inside the block, they are interconnected by current collector terminals. Servicing charge performs a positive charge on the lithium ion. This material is advantageous in that it has the ability to easily penetrate into the crystal lattices of other substances, forming chemical bonds. However, the positive qualities of such batteries are increasingly not enough for modern tasks, which led to the emergence of Li-pol cells, which have many features. In general, it is worth noting the similarity of lithium-ion power supplies with full-size helium batteries for cars. In both cases, the batteries are designed with physical usability in mind. In part, this direction of development was continued by polymer elements.

Lithium polymer battery device

The impetus for improving lithium batteries was the need to combat two disadvantages of existing Li-ion batteries. Firstly, they are unsafe to operate, and secondly, they are quite expensive in terms of price. The technologists decided to get rid of these disadvantages by changing the electrolyte. As a result, the impregnated porous separator was replaced by a polymer electrolyte. It should be noted that the polymer was previously used in electrical engineering as a plastic film that conducts current. In a modern battery, the thickness of the Li-pol cell reaches 1 mm, which also removes restrictions on the use of various shapes and sizes from developers. But the main thing is that there is no liquid electrolyte, which eliminates the risk of ignition. Now it's worth taking a closer look at the differences from lithium-ion cells.

What is the main difference from an ionic battery?

The fundamental difference lies in the rejection of helium and liquid electrolytes. For a more complete understanding of this difference, it is worth referring to modern car battery models. The need to replace the liquid electrolyte was driven, again, by safety concerns. But if, in the case of automobile batteries, progress stopped at the same porous electrolytes with impregnation, then lithium models received a full-fledged solid base. What is so good about a solid-state lithium polymer battery? The difference from the ionic one is that the active substance in the form of a plate in the contact zone with lithium prevents the formation of dendrites during cycling. This very factor excludes the possibility of explosions and fires of such batteries. This is only about the merits, but there are also weaknesses in the new batteries.

Lithium polymer battery life

On average, such batteries can withstand about 800-900 charge cycles. This indicator is modest against the background of modern analogues, but even this factor cannot be considered as a determining element resource. The fact is that such batteries are subject to intense aging, regardless of the nature of their operation. That is, even if the battery is not used at all, its resource will be reduced. It doesn't matter if it's a lithium-ion battery or a lithium-polymer cell. All lithium-based power supplies are characterized by this process. A significant loss in volume can be noticed within a year after the acquisition. After 2-3 years, some batteries fail altogether. But a lot depends on the manufacturer, since within the segment there are also differences in the quality of the battery. Similar problems are inherent in NiMH cells, which age when exposed to sharp temperature fluctuations.

disadvantages

In addition to problems with rapid aging, such batteries need additional protection system. This is due to the fact that internal stress in different areas can lead to burnout. Therefore, a special stabilization circuit is used to prevent overheating and overcharging. This system also has other disadvantages. The main one is the current limitation. But on the other hand, additional protective circuits make the lithium polymer battery safer. The difference from ionic in terms of cost also takes place. Polymer batteries are cheaper, but not much. Their price tag is also increasing due to the introduction of electronic protective circuits.

Operational features of gel modifications

In order to increase the electrical conductivity, the technologist still adds a gel-like electrolyte to the polymer elements. There is no talk of a complete transition to such substances, since this contradicts the concept of this technology. But in portable technology, it is often hybrid batteries that are used. Their peculiarity lies in their sensitivity to temperature. Manufacturers recommend using these battery models in environments between 60 ° C and 100 ° C. This requirement has also defined a special niche of application. Gel models can only be used in hot climates, not to mention the need to immerse themselves in a thermally insulated case. Nevertheless, the question of which battery to choose - Li-pol or Li-ion - is not so acute in enterprises. Where temperature is particularly important, combined solutions are often used. In such cases, polymer elements are usually used as backup.

Optimal charging method

Typical replenishment time for lithium batteries is on average 3 hours. Moreover, the unit remains cold during charging. The filling takes place in two stages. At the first, the voltage reaches its peak values, and this mode is maintained up to 70%. The remaining 30% are recruited already under normal stress conditions. Another question is also interesting - how to charge a lithium-polymer battery if it is necessary to maintain its full volume in a constant mode? In this case, the charging schedule should be followed. It is recommended to perform this procedure approximately every 500 hours of operation with a complete discharge.

Precautions

During operation, you should use only a charger of the appropriate characteristics, connecting it to a network with a stable voltage. It is also necessary to check the condition of the connectors so that the battery does not open. It is important to consider that, despite the high degree of safety, it is still a type of battery sensitive to overloads. The lithium polymer cell does not tolerate overcurrents, excessive cooling of the external environment and mechanical shock. However, according to all these indicators, polymer blocks are still more reliable than lithium-ion ones. Still, the main aspect of safety is the harmlessness of solid-state power supplies - provided, of course, that they are kept sealed.

Which battery is better - Li-pol or Li-ion?

This issue is largely determined by the operating conditions and the target of the energy supply. The main advantages of polymer devices are rather tangible for the manufacturers themselves, who can more freely use new technologies. The difference will be subtle to the user. For example, in the question of how to charge a lithium polymer battery, the owner will have to pay more attention to the quality of the power supply. In terms of charge time, these are identical elements. As for durability, the situation in this parameter is also ambiguous. The aging effect mainly characterizes polymer elements, but practice shows different examples. For example, there are reviews of lithium-ion cells that become unusable after a year of use. And polymer in some devices are operated for 6-7 years.

Conclusion

Around the batteries, there are still many myths and false judgments that relate to various nuances of operation. Conversely, some of the features of batteries are hushed up by manufacturers. As for the myths, one of them refutes the lithium polymer battery. The difference from the ionic analogue is that polymer models experience less internal stress. For this reason, charging sessions that have not yet run down batteries do not adversely affect the performance of the electrodes. If we talk about the facts hidden by manufacturers, then one of them concerns durability. As already mentioned, the battery life is characterized not only by a modest rate of charging cycles, but also by the inevitable loss of the useful volume of the battery.

Lithium polymer batteries appeared on the market not so long ago, but they already serve as a power source for many gadgets. These batteries are used in smartphones, tablets, laptops, children's toys and other equipment.

Batteries are gradually being improved, old mistakes and shortcomings are fixed. Still, lithium-polymer batteries fail, and sometimes they can explode. Below we will discuss how to avoid premature breakdowns, where to buy, as well as the features of this type of battery.

Li-Po batteries are a type of lithium battery. The development of polymer batteries was based on lithium-ion batteries. They use a liquid electrolyte, which causes some problems during operation.

The main goal of the specialists was to get rid of the old electrolyte, as it caused many difficulties.

In addition, several changes have been made to how the battery works.

To understand how lithium polymer batteries differ from others, you need to understand two main concepts:

1. An electrolyte is an acid solution that conducts an electrical current. Unlike conventional conductors, positively charged ions conduct current here.
2. A polymer is a substance that consists of a chain of repeating monomers (a group of molecules).

So what have scientists changed about lithium-ion batteries? First, the electrolyte became solid. Secondly, a polymer was used as an electrolyte. Hence the name of these batteries.

At the same time, the polymer is very thin, it looks like a film. The polymer now does not conduct current, but it retains the ability to conduct ions.

Thus, the scientists obtained an electrolyte and a separator in one piece of polymer.

Electrochemistry is developing rapidly today, new changes are constantly being made to the design of Li-Po. For example, rake electrolytes that contain lithium ions have recently been added to batteries.

Li-Po characteristics

The data below is constantly changing, as progress in electrochemistry does not stand still.

All characteristics are relevant only in 2019. In addition, it may vary depending on the battery and manufacturer.

Main characteristics:

1. Energy capacity - measured in mAh (milliamperes per hour). If you recall the school physics course, then ampere is the current strength. The clock, in this case, characterizes the time during which this battery maintains the required current. To understand the essence of the characteristics, let's take a regular 4000 mAh battery from a smartphone, for example. For one hour, such a battery produces a current of 4000 mA. If we take 4 hours, then the current strength will be approximately equal to 1000 mA, and so on.
2. The next characteristic is the number of discharges and charges, pay attention to it. This number determines how long the battery will last. Li-Po does not have that many cycles. The norm for these batteries is 400-500 cycles. When the battery has completed its 500 cycles, it can be thrown away. Ni-MH batteries have a minimum of 1000 cycles.
3. Input and output voltage. Input is the voltage that should be in the outlet. The output is the voltage that the battery produces. Most often, these two characteristics are equal, but there are exceptions.

Correct operation

Lithium polymer batteries are very delicate. There are many reasons why batteries fail.

Failure to follow the rules of operation leads to fire and complete malfunction.

Let's figure out how to use lithium polymer batteries to make them last longer.

Operating rules:

1. Do not overcharge the battery, that is, the voltage should not exceed 4.2 volts. Bloating may occur due to overcharging.
2. Short circuit.
3. Supply the battery with a current that exceeds the permissible rate.
4. Strong overheating (above 60 degrees).
5. Damage to the housing and leakage.
6. Keep lithium polymer batteries discharged.

For the first three reasons, a fire often occurs. To prevent this, use only serviceable chargers. The correct connector, which has short circuit protection, will save from a short circuit.

It is also necessary to control the current consumed by the device in which the lithium polymer battery is installed.

Overheating of the battery occurs due to the fact that the device itself, heating up, heats up the Li-Po battery.

If the battery temperature reaches 70 degrees, then the energy stored in the battery begins to turn into heat, thereby increasing the already high temperature. In this case, the battery begins to set fire to everything around. Especially smartphones with lithium polymer batteries and laptops suffer from this.

There is an opinion that Li-Po cannot be used at low temperatures. Despite the fact that the range in which the battery works normally is set from 0 to 50 degrees, you can still use it at subzero temperatures.

The main thing is not to freeze the battery.

Keep it warm, for example in your pocket. The internal heat of the battery will keep the battery from cooling down. Of course, in the cold, the recoil will be slightly lower than when using the battery in warmth.

What are the advantages and disadvantages of lithium polymer batteries

1. Polymer batteries have a large electrical capacity.
2. The thickness of the batteries reaches one millimeter.
3. The shape of the body can be any.
4. If the battery is discharged, then the voltage does not drop as much as in other batteries.
5. Li-Po has no memory effect. In short, the memory effect is the loss of significant battery capacity.
6. The battery can operate over a fairly wide temperature range (-20 to 40 degrees).

• if the ambient temperature is below -20 degrees, then the battery is quickly discharged;
• great value.

DIY battery assembly

To assemble the battery yourself, you need to buy batteries, or in common parlance - banks. To assemble, you need to be able to solder and understand the basic concepts of electronics.

To assemble the battery, all purchased banks must be connected in parallel. In order to determine the number of cans in a purchased battery, you need to look at the label. Not only the number of cans is written on it, but also the number of cans connected in series and in parallel.

Usually, the letter P indicates the number of cans connected in parallel, and the letter S indicates the number of cans connected in series. For example, the packaging says 3S2P. It stands for this: under the case there are 3 rows of batteries connected in series, in each row there are 2 banks.

If you use batteries that you bought separately, then before connecting them together, you should equalize the potentials on the brands.

If this is not done, then the banks will start charging each other, which will cause a current strength greater than 1C.

Also, before connecting, it is necessary to discharge all the banks so that the voltage is 3V, with a current of 0.1-0.2C. Especially all of the above applies to parallel connections. The voltage is measured with a digital voltmeter, otherwise inaccuracies may occur.

Many manufacturers do not balance banks in order to speed up and save on battery production, so balancing is best done by yourself.

In order to avoid imbalance of the battery in the future, in no case should new cells be added to the battery sequentially with the old ones.

Operation of cans with different capacities can lead to imbalance, even if the difference between the values \u200b\u200bis small. For example 1800 mAh and 2000 mAh. Different manufacturers have batteries with different voltages, and this leads to imbalance.

When all the batteries are purchased, you can start soldering the cells. Of course, you can come up with the layout of the elements on your own, but it is best to take a ready-made one.

In order not to overheat the outputs and the tightness of the can, we solder carefully, otherwise the battery will fail without even working.

You can purchase a special PCB printed circuit board, on which it will be more convenient to solder wires. It is soldered to every jar. This adds a small weight to the jar (about 1 gram), but it becomes much more convenient to solder, since fiberglass conducts heat poorly and it takes longer to heat.

For balancing, a special board is used, which contains load resistors, a circuit for control, as well as an LED that will light up if the voltage is higher than 4.2V.

If the voltage exceeds this value, then the board closes part of the current, which does not allow it to rise further. This board must be soldered to each bank.

Correct Li-Pol charging

Charging the battery is simple. All you need is a constant current source with a voltage of 4.2V. The current should be 1C, although many modern models can withstand as much as 5C.

A full charge of the battery takes 1–3 hours, depending on the model and its specifications.

Also, battery charging can be stopped when the current drops to 0.1C. Before the batteries go into the voltage stabilization mode, they gain 60–80% of the energy from the entire capacity, at a constant current of 1C.

Proper charging requires careful selection of the charger. The voltage that the charger gives out should be 0.01 per cell.

There are two types of charges on the market. The first is budget devices, ranging from $ 10 to $ 50, intended only for. The second one is universal chargers that are suitable for different equipment. Of course, they cost much more, from $ 80.

Cheap chargers do not have an indicator showing current, voltage, charging time. The number of cans and the required current are set using jumpers or by connecting the charger to different connectors on the device.

Plus a cheap option at a low price. The disadvantage of such charges is that they do not know how to accurately determine when to stop charging. All they can do is determine the moment of transition from current stabilization to voltage stabilization. But, as a rule, the battery at this moment is only 80% charged.

The second type of charger has more advantages than the first. They allow you to immediately know the voltage, current, charge that was "transferred" to the battery in the process.

Conclusion

Lithium polymer batteries have changed a lot over the past few years. Many people assume that the future of electrochemistry is behind them. Although fuel energy sources are actively appearing on the market.