Nowadays, every family has a large number of electronic devices in use. Phones, smartphones, flashlights, tablets, toys for children of all ages and many other household appliances need to be powered by portable power sources: batteries or accumulators.

Power supplies are designed to last for a long time, but can quickly fail due to carelessness. In order to make the most of the manufacturer's resource embedded in them, we recommend that you familiarize yourself with the features of the operation of batteries of various designs, the rules for their charging and safe handling.

The most impatient readers can go straight to the charging rules recommended by the factory. They are listed at the end. However, a consistent reading of the material will allow you to better understand their features and apply them correctly in practice.

How a battery works and works

The entire wide range of battery products works according to a single principle of converting the energy of chemical processes into electrical energy. For its flow, a special design has been created.

Battery design principles

A sealed vessel, called a jar, is filled with electrolyte. Two separate plates of different metals, called electrodes, are placed in it. They form a difference in electrical potentials, which is capable of doing useful work.

To increase the power of energy, banks with plates are made larger or connected in parallel chains. To raise output voltage they are connected in series. Such structures are called batteries.

Classification

According to the types of electrolyte, batteries are divided into:

• liquid;
• gel.

By design features liquid batteries are divided into:

• acid;
• alkaline;
• saline.

Constructions acid batteries are used relatively rarely. They can be found in budget models of flashlights, where they work in conjunction with a charger.

Alkaline type batteries are usually oversized. Previously, they were used for lighting in portable lanterns, but now such designs are not convenient for work and have ceased to be used.

AT mobile devices for home use, popular battery models:

• lead acid (Pb+H 2 SO 4);
• nickel-cadmium (Ni-Cd);
• nickel-zinc (Ni-Zn);
• nickel metal hydride (Ni-Mh);
• lithium-ion (Li-ion);
• lithium polymer (Li-Pol)

Design features of various models

A typical device of a battery of batteries, consisting of separate cans with a set of positive and negative plates inserted into them, the sequence of their arrangement can be observed on the example of an acid battery.

Designs of cylindrical or "finger" models are presented as a cutaway view for a lithium-ion battery with explanatory inscriptions for each layer.

Appearance of batteries

The dimensions and shape of the current sources are designed for their convenient location in the sockets of mobile devices, reliable power supply to consumers, and the possibility of fast charging.

Batteries can be cylindrical or tablet shaped, as shown in the photo for common nickel-cadmium devices, which are assembled into blocks with special jumpers.

When, according to the operating conditions, it is preferable to receive power from a single unit, then a common housing is created. Separate finger elements are built into it, which, due to their parallel and series connection, provide output characteristics for current and voltage.

This principle is laid down in the creation of a battery for a laptop.

For small-sized mobile devices, batteries are created in the form of a small parallelepiped with rounded edges. On one of the end sides, brass pads are mounted on it, which ensure the creation of an electrical contact for the source and current consumers.

The principle of converting chemical energy into electrical energy of interest to us is explained by the picture.

A redox chemical reaction occurs between two adjacent substances with selected properties. It is accompanied by the release of electrons and ions, which, as you know, form an electric current when moving.

In order for moving charges to create electrical potentials, and not just release heat into the environment when an oxidizing agent is mixed with a reducing agent, it is necessary to create conditions for this.

These purposes are:

• an anode (positive charge) that carries out an oxidative reaction;
• cathode reducing substance;
• an electrolyte that conducts current during the dissociation of the working medium into cations and anions.

The anode and cathode are placed in distant vessels, which are connected by a salt bridge. Anions and cations move along it, creating an internal battery circuit. The external circuit is formed by connecting the consumer to the input, for example, a voltmeter or other load.

At the anode and cathode, there is a constant transition of electrons and ions to the electrolyte and vice versa. In the inner chain goes the movement of charges through the salt bridge, and in the external current flows from the anode to the cathode.

This principle is basic for charging and discharging all models of chemical current sources.

How does a nickel cadmium battery work?

There are only two types of work:

1. discharge;
2. charge.

It is possible to single out another storage mode, but it is more correct to attribute it to the category that they try to limit as much as possible, although it cannot be completely avoided.

Discharge cycle

The energy accumulated on the electrodes, when a load is connected to them, creates an electric current in the external circuit.

The anode in a nickel-cadmium battery is nickel oxides with inclusions of graphite particles, which reduce the overall electrical resistance. Sponge cadmium is used as the cathode.

During the discharge, active oxygen molecules are released from the composition of nickel oxides, which enter the electrolyte and further onto cadmium, oxidizing it.

charge cycle

It is customary to carry out with the load removed. Then you can use less power charger.

The polarity of the terminals of the charger and the battery must match, and the external power must exceed the internal one. Then, under the influence of an external source, a current is formed inside the battery bank with a direction opposite to the discharge.

It reorients the course of chemical processes in the container of the can, enriches the anode with oxygen and restores cadmium at the cathode.

How Lithium Ion Battery Works

A carbon anode and a cathode made of metal oxides containing lithium, for example, the composition of LiMn 2 O 4 , are immersed in an organic electrolyte.

Positively charged Li+ ions move in it. In this case, lithium itself does not go into a metallic state, but an exchange of its ions between the electrode plates is created. For this reason, batteries are called lithium-ion.

charge cycle

Lithium ions are withdrawn (deintercalation process) from the cathode containing lithium and are introduced into the anode (intercalation).

Discharge cycle

The movement of ions goes in the opposite direction to the charge, and the electrons from the anode move to the cathode and form an electric current.

If we compare the principles of operation of a battery of any design, then we can observe the general pattern of movement of ions between electrodes along the internal circuit and electrons along the external circuit when creating charge and discharge circuits.

Battery performance

Working voltage

Its value is determined on open terminals with a voltmeter at optimal charge. In the course of work, it gradually decreases.

Battery capacity

A characteristic showing the amount of current in milliamps or amperes that a battery can deliver in a period of time expressed in hours.

Power

A parameter that takes into account the ability of the battery to do work per unit of time.

How mobile device battery charger works

Now all expensive electronic devices are supplied with their own power and charging devices.

To restore the performance of batteries used individually, separate charging device. They are accompanied by instructions and tables indicating the recommended duration of the technological cycle.

Such models usually give out a stabilized voltage to the battery terminals, in which, when charging, the electrical resistance gradually changes, affecting the amount of current flowing. Therefore, such recommendations are of an average nature.

Current forms generated by chargers

To charge batteries, not only direct currents can be used, but also many other types that solve specific problems.

To ensure their flow, various electronic circuits are created that output voltage of the appropriate type to the battery terminals.

Schematic diagrams of chargers

In view of their diversity, we give some typical solutions as an example.

Scheme for creating direct currents

The voltage is reduced by the transformer. Its harmonics are rectified by a diode bridge and the ripples are smoothed out by a high-capacity capacitor.

The output of the battery receives a constant current.

Scheme for creating pulsating currents

Removing the capacitor from the previous chain, we get voltage ripples at the battery terminals, which form currents of a similar shape.

Scheme for creating pulsating currents with a gap

Replacing the diode bridge with a single diode, we obtain ripple currents of increased frequency by a factor of two.

Service chargers

Due to the complexity of the internal electrical circuit various additional functions for chargers are being created.

In all calculations of the magnitude of the charging current Iz in amperes, the empirical ratio is taken as the base value, measured as a percentage of the value of capacitance C, expressed in ampere-hours.

However, for certain models, the manufacturer may indicate the charging current immediately in numerical terms in amperes, which does not comply with this rule. It is clear that he has serious reasons for this.

Lead acid batteries

It is customary to use currents for charging that are 10% or 0.1 of the capacity C. They are recorded as 1C.

For these batteries, the voltage on a single cell should not exceed 2.3 V, which should be taken into account when charging the battery so as not to exceed the critical value.

The increase in the capacity of acid batteries after reaching 90% of the nominal value is exponential. Therefore, further charging is performed with reduced currents with voltage control on the banks, which increases the duration of the process.

Lead-acid batteries require a periodic control training cycle with a full discharge and charge.

Alkaline batteries

For them, it is customary to maintain the charge current at a level of 25% of the capacity or 0.25C.

Nickel-cadmium battery models

The optimal temperature for charging, as well as for operation, is within + 10 ÷ 30 ° C. With it, oxygen absorption at the cathode is better.

Cylindrical accumulators are mounted by tightly winding electrodes into a roll. This allows you to effectively charge them with currents in a wide range of 0.1÷1C. The standard mode provides for currents of 0.1C and a time of 16 hours. On each element, the voltage rises from one to 1.35 V.

If an overcharge control system is built into the charger, then increased currents of a constant form of 0.2 ÷ 0.3C are used. This allows you to reduce the charging time to 6 or 3 hours. We even allow overcharging within 120 ÷ 140%.

A characteristic drawback of nickel-cadmium batteries is the “memory” effect or reversible loss of capacity, which manifests itself when the charge technology is violated, or rather, after the start of recharging a battery with an incomplete capacity.

The battery “remembers” the limit of the remaining reserve and, upon subsequent discharge to the load, reduces its resource when it is reached. This feature is taken into account during operation, and for storage of Ni-Cd batteries, they are transferred to full discharge mode.

Nickel-metal hydride battery models

They were created to replace nickel-cadmium batteries, are devoid of the memory effect, and have a high capacity. But, when preparing for work after a month or more of storage, a full discharge cycle is required, followed by charging. By performing 3÷5 such cycles, you can increase the working capacity.

To store these batteries, their capacity is transferred to 40% of the nominal value.

Charging is carried out according to the 0.1C technology for nickel-cadmium batteries, but with temperature control. Its excess of more than 50 ° C is unacceptable. Strong heating occurs at the end of the cycle, when the flow of chemical reactions slows down.

For these reasons, specialized chargers with built-in temperature sensors are being created for nickel-metal hydride batteries.

Nickel-zinc battery models

The voltage of one bank is 1.6 V. The strength of the charging current is 0.25C. Charging time 12 hours. There is no memory effect. The recommended limit for achieving capacity when charging is 90% of the nominal.

You can not heat more than 40 ° C. Limited resource - three times shorter than that of nickel-cadmium batteries.

Lithium-ion battery models

Optimum charging is carried out with direct current in two stages with a value of:

1. 0.2÷1С with voltage 4÷4.2 V during the first 40 minutes;
2. maintaining a constant voltage on the bank of 4.2 V until the end of the cycle.

Allowable charging current 1C for 2÷3 hours.

The resource of lithium-ion batteries is reduced:

• charging voltage greater than 4.2 V;
• overcharge accompanying the accumulation of lithium at the cathode and the release of oxygen at the anode.

As a result, there is a rapid release of thermal energy, an increase in pressure in the housing, and depressurization.

In order to improve safety during operation, manufacturers of these batteries apply one or more protective measures during charging:

• charging current shutdown circuit when the temperature in the case reaches 90 ° C;
• overpressure sensor;
• charging voltage control system.

Since the lithium-ion battery works and is charged inside expensive electronic devices, it should be charged carefully, using only specialized chargers.

Charging features by depth of discharge

Features of charging by temperature

The correct choice of these parameters can significantly extend the service life of lithium-ion batteries.

Lithium polymer battery models

They are subject to all operating rules designed for lithium-ion models. But, since they do not have a liquid electrolyte, but use a gel-like one, when recharging or overheating, an explosion of the case is excluded, which can only swell.

Understanding the principles of how the battery and charging for mobile devices works will help extend the life of your gadgets, operate them reliably and safely.

To consolidate the material, we suggest watching the video of the owner Admiral134 "How to properly use lithium-ion batteries."

It is now convenient for you to ask a question in the comments and send this material to your friends on the social network.

Batteries

When purchasing a mobile phone, a person, as a rule, least of all thinks about its uptime. And if he thinks about it, he connects it primarily with the unreliability of microcircuits, radio elements and mechanical damage. Studies show that the first place in terms of failures is occupied by batteries. Currently, nickel cadmium (NiCd), nickel metal hydride (NiMH), lithium ion (Li-Ion) and lithium polymer (Li-Polymer) batteries are used in mobile phones. Consider the characteristics of batteries.

Battery capacity

Battery capacity - maximum amount electricity that can be obtained from one full charge. It is denoted by the Latin letter C and is expressed in ampere-hours (Ah) or milliamp-hours (mAh). So, for example, a 720 mAh battery is capable of delivering a current of 720 mA to the load for one hour or 360 mA for two hours. In this case, of course, the discharge current should not exceed a certain maximum force for a particular type of battery, otherwise its plates will quickly fail.

Battery internal resistance

The smaller it is, the more current the battery can supply to the load. This is a very important feature. In receive mode, the mobile phone consumes a small amount of current. However, during a conversation, the current increases dramatically. In this case, batteries with different internal resistance behave differently. Nickel-cadmium, having the lowest internal resistance, easily give the required current. Nickel-metal hydride batteries have the highest resistance, so they have a voltage drop that can lead to crashes or your phone will signal that the battery is low. Since mobile phones consume more or less stable current during operation, lithium-ion or lithium-polymer batteries are used to power them. Nickel-metal hydride is used to power devices that consume a stable current.

Energy Density of a Charged Battery

It is measured in watt-hours per kilogram of battery mass (it is also found in a liter of volume). Here, lithium-ion and lithium-polymer batteries (110 ... 160 W / kg) are in the lead, batteries 100 ... 130 W / kg are noticeably inferior to them. Nickel-metal hydride batteries have this indicator 60 ... 120, nickel-cadmium - 45 ... 80 W x h / kg. It follows from the foregoing that lithium-polymer and lithium-ion batteries have the smallest dimensions and weight with the same capacity, and nickel-metal hydride batteries are somewhat larger. And lithium-polymer batteries can be molded into almost any shape.

Battery charge time

This is a rather important characteristic, because during intensive use, batteries mobile phones I have to recharge almost every day. It varies from 1 hour for nickel-cadmium batteries (if necessary, they can be charged in 15 minutes) and 2 ... 4 hours for nickel-metal hydride, lithium-ion and lithium-polymer batteries.

Rated voltage of one element

For nickel-cadmium and nickel-metal hydride batteries, the nominal voltage is 1.25 V, for lithium-ion and lithium-polymer batteries - 3.6 V. Moreover, for the first two types, the voltage during the discharge process is almost stable, while for Lithium-ion batteries during the discharge process, it linearly decreases from 4.2 to 2.8 V.

Battery self-discharge

Self-discharge is a decrease in the charge of a battery that is charged but not connected to an energy consumer during storage. For nickel-cadmium batteries, this is one of the weaknesses. Their charge loss reaches 10% on the first day after charging, and then 10% per month. Approximately the same figure for nickel-metal hydride batteries. Lithium-ion and lithium-polymer batteries are beyond competition in this indicator. Their self-discharge does not exceed 2 - 5% per month, which occurs mainly due to the presence of control circuits inside the batteries. However, the limited "life" of these batteries does not allow you to fully use this positive quality.

Life time

This is one of the most important characteristics of batteries, which for some reason the user thinks about last. For batteries with different chemistry, it is defined differently. For some batteries, the total number of charge-discharge cycles is critical, while for others, the total time of their operation is critical.
Nickel-cadmium batteries can withstand more than 1500 charge-discharge cycles, and experience shows that after recovery they can work the same amount. With proper periodic maintenance, nickel-cadmium batteries last from 5 to 10 or more years, until the mechanical wear of their case and internal contacts.
Nickel-metal hydride batteries can withstand about 500 charge-discharge cycles and their service life rarely exceeds two years, even with very careful maintenance.
Lithium-ion batteries can be charged and discharged 500 to 1000 times. But it is difficult to completely choose this number of cycles because of the short service life - no more than two years (according to manufacturers). In practice, lithium-ion batteries lose their performance after a year.
Lithium polymer batteries have 300 to 500 charge-discharge cycles and rarely last more than a year. In addition, the service life also depends on the degree of discharge - with partial discharges it is longer than with full discharges.
Nickel-cadmium batteries have the shortest charge time, allow the highest load current and have the lowest cost-life ratio, but at the same time they are the most critical to accurate compliance with the requirements for proper operation.

Comparative characteristics of batteries

memory effect

This is a well-known problem with nickel-cadmium and nickel-metal hydride batteries. The memory effect consists in a partial (temporary) loss of battery capacity if it is charged until it is completely discharged. The battery, as it were, remembers the start point of the next recharging cycle and, when discharging, actively gives away only the capacity received during the last recharging. In other words, an incompletely discharged battery remembers its previous capacity and, being fully charged again, when discharged, it gives only the charge that it gave in the previous discharge cycle. It manifests itself in the fact that the voltage in the circuit of a loaded and seemingly normally charged battery suddenly, ahead of time, drops. The memory effect is really manifested in the fact that in Everyday life users rarely wait until batteries are completely discharged before putting them on charge.
The physical essence of the memory effect is that when the battery is not completely discharged, the particles of the working substance of the battery are enlarged, respectively. total area contact of the working substance with the electrolyte is reduced. As a result, in just a few months, the capacity of a nickel-cadmium or nickel-metal hydride battery can be reduced several times.
Therefore, periodic maintenance is very important for these types of batteries, which consists of completely discharging and then fully charging the battery. This process is called battery training. Nickel-cadmium batteries require a monthly workout, nickel-metal hydride - once every two to three months.
With a noticeable decrease in the capacity of nickel-cadmium and nickel-metal hydride batteries, they are subjected to a recovery procedure. It consists in a very deep discharge of the battery, crushing large particles of the working substance into smaller ones. For this, there is special equipment, for example, the C7000 battery analyzer from the Canadian company CADEX. Lithium-ion and lithium-polymer batteries do not have a memory effect.

Device

Each battery has two electrodes - positive and negative. A separating layer is placed between the electrodes, which prevents opposite electrodes inside the battery from touching each other. The space between the electrodes is filled with an electrolyte (acidic or alkaline). The electrodes can be made as alternating plates.
At first, the batteries had plugs that made it possible to bleed the gases released during charging and change the electrolyte. Later, the developers came up with the idea of ​​making electrodes of different sizes, which allowed all the released gas to be absorbed by the unreacted part inside the battery. And this made it possible to produce batteries in a sealed case.
Many battery cases have built-in electronics that prevent deep discharge, overcharging, or high temperatures.

Battery charge

To date, there are three main methods of charging batteries:
- normal or slow charge;
- fast charge;
- speed charge.

Disconnecting the battery at the end of the charge is done using:
- temperature control;
- charge voltage control;
- charge voltage drop control;
- current control at the end of the charge;
- timer.

Normal or slow charge. This method, although rare, is used to charge nickel-cadmium and nickel-metal hydride batteries. It is cheap, but leads to crystallization of the battery cells, which reduces the capacity and service life. This method cannot be used to charge lithium-ion and lithium polymer batteries, since irreversible changes in the internal structure of the batteries occur.
The charger is a constant voltage source, in the output circuit of which a current-setting resistor is connected in series. The charging current of batteries is usually expressed numerically in parts of the battery capacity C. The normal charge current is approximately 0.1C. Thus, with a battery capacity of 720 mA / h, the value of 0.1 C will be 72 mA.

Fast charge. It is used only for charging nickel-cadmium batteries with a current of 0.5C. The end of the charge is determined by the achievement of a voltage on the battery of a certain value.

Speed ​​charge. It is characterized by a charging current of 1C and includes all ways to turn off the battery at the end of the charge.
To charge nickel-cadmium and nickel-metal hydride batteries, a method is used to control the end of the charge by a sharp slight decrease in the voltage on the battery. It is called a negative delta V charge. Its value is 10 ... 30 mV per element.
The temperature control method uses the fact that at the end of the charge, the battery is heated more intensively, and the end of the charge can be controlled by the rate of temperature change. When charging nickel-cadmium and nickel-metal hydride batteries, the end of the charge is determined if the temperature change reaches 1°C/min. The absolute overheating threshold is considered to be 60 °C.
Overcharging has a disastrous effect on the battery, especially if, at the end of the charge, it is forcibly disconnected and then reconnected to the charger. With each such operation, a high-speed charge cycle is initiated at its high initial current. Frequently connecting devices with nickel-cadmium and nickel-metal hydride batteries to external power sources will significantly reduce the life of the batteries.
Lithium-ion battery chargers are able to detect the state of charge of the battery.
A feature of the charge of lithium-ion and lithium-polymer batteries is the limitation of the charge voltage. These batteries can currently be charged up to 4.20 V. The tolerance is 0.05 V.
When charging lithium-ion and lithium-polymer batteries with a current of 1C, the charge time is 2-3 hours. During the charging process, they do not heat up. The battery reaches a state of full charge when the voltage on it reaches 4.20 V + 0.05 V, and the current decreases significantly and is approximately 3% of the initial charge current.

Sometimes it is necessary to charge completely discharged batteries. In the phone, such a charge is carried out automatically. What if there is no charger?

In the absence of a special charger, the batteries can be charged using a power source with adjustable output voltage and a maximum operating current of 2A and current and voltage control devices as follows.

Batteries for mobile devices

Device and basic parameters

Cellular phones and portable computers, radio stations and cordless telephones, sources uninterruptible power supply, film cameras and photo cameras, powerful hand tools, medical devices, various production equipment - this is not a complete list of devices, the normal operation of which directly depends on the condition of the batteries. In this regard, knowledge of the characteristics, features and operating conditions various types batteries is of particular importance and is the key to the trouble-free operation of mobile devices and portable equipment.

If you are curious and have some skills in damaging toys acquired as a child, then you have probably already got acquainted with the internal structure of your used battery. What is there inside? (I do not advise you to disassemble, this is due to the risk of physical damage). Actually, nothing special. Round or prismatic "batteries", which are in bulk in the nearest store, and at a much lower price. However, the first impression is deceptive. Before you are not just batteries, but accumulators. And they differ from batteries in that they allow (due to the reversibility of the reactions occurring in them) multiple discharge-charge cycles. This is their advantage over batteries, but on the other hand, the “headache” that they bring in case of loss of performance. And if everything is simple with the first ones: I bought it, inserted it, ran out, threw it away and bought new ones, then with batteries the situation is more complicated. For them, the sequence of actions is different: bought; prepared for work; use, following the rules of operation; and only when it is already completely unbearable - you buy a new one.

So, in order not to be excruciatingly painful for wasted money, below is information for the curious and inquisitive on the topic: what you need to know about batteries for mobile phones and laptops.

Device

Any battery, as a rule, consists of several single cells connected in series to increase the value of the generated voltage and packed in a common case. With the design of a single battery cell, such as nickel-metal hydride, with electrochemical reactions taking place inside it, and other useful information (on English language) can be found on the Panasonic website by downloading the pdf file Overview information on NiMH Batteries in PDF Format - 137KB .

In addition to single cells, nickel-based batteries contain a thermal fuse and a temperature sensor inside (the latter may be absent in NiCd batteries). A thermal fuse ensures safety at high charge currents, and the temperature sensor output is processed by the charger. Depending on the temperature value, a “competent” charger provides different battery charge modes: fast, slow, and switching from one to another.

Lithium-ion batteries, in addition to a thermal fuse and a temperature sensor, contain a special control integrated circuit and control keys. All this together is designed to protect the consumer from physical damage in the event of a violation of the electrical modes of operation of the battery.

BASIC BATTERY PARAMETERS

Let it be known to you that a battery, as an electrical device, is characterized by the following main parameters: the type of electrochemical system, voltage, electrical capacity, internal resistance, self-discharge current and service life. Moreover, depending on the scope of application, one parameter, then another, comes to the fore. For example, a cell phone battery should be evaluated based on the totality of its three main characteristics: real capacity, internal resistance, and self-discharge current, while a home radiotelephone battery with a range of up to 100 meters should be evaluated only by capacity and self-discharge. When underestimating or ignoring any parameter or exaggerating the importance of one of them (usually capacity), you can find yourself in a situation "with a broken trough".

Voltage. The battery voltage is determined by the device for which it is intended to power. If the required voltage value is not provided by one element, then the battery is assembled from several elements connected in series. For example, cell phones of various models use batteries with a voltage of 3.6 V (1 Li-ion cell or 3 NiCd or 3 NiMH cells), 4.8 V (only 3 NiCd or 3 NiMH cells), 6 V (only 5 NiCd or 5 NiMH cells), 7.2 V (2 Li-ion cells). Thus, if the phone uses 4 NiMH batteries with a total voltage of 4.8 V (as, for example, in some of the latest Ericsson models), then Li-ion batteries cannot be used in it. The battery voltage is not constant during operation. It is maximum immediately after the end of the charge, and then decreases during operation or storage. In the end, it decreases to such an extent that the cell phone does not turn on or automatically turns off. When assessing the condition of the battery, its voltage must be measured under the load for which it is designed.

Electrical capacitance. Rated electric capacity is the amount of energy that the battery should theoretically have in a charged state. This parameter is similar to the capacity of any vessel, for example, a glass. So, 200 ml of water can be poured into a standard faceted glass (up to the rim), and only a certain amount of energy can be pumped into a specific battery. But this amount of energy (capacity) is determined not at the moment of pumping (filling), but during the reverse process - discharging (pouring energy) of the battery with direct current for a measured period of time until the specified threshold voltage is reached. The capacity is measured respectively in ampere-hours (A hour) or milliamp hours (mAh) and is indicated by the letter "C". The capacity value is indicated on the battery label or encoded in its type designation. The actual value of the capacity of a new battery at the time of its commissioning ranges from 80 to 110% of the nominal value and depends on: the manufacturer, storage conditions and period, and commissioning technology. Theoretically, a battery, for example, with a nominal capacity of 1000 mAh can deliver a current of 1000 mA for one hour, 100 mA for 10 hours, or 10 mA for 100 hours. In practice, at a high value of the discharge current, the rated capacity is not reached, and at a low current, it is exceeded.

During use, the capacity of the battery decreases. The rate of decline depends on the type of electrochemical system, service technology in operation, the chargers used, conditions and age of operation. Using the same analogy with a glass, we can say that the amount of water poured into a glass will decrease if you pour water with a large amount of mechanical impurities, and drain the settled one. Then sediment will gradually accumulate in the glass, reducing its useful capacity. In a battery, a similar “deposit” is formed during charge / discharge cycles.

Internal resistance. The internal resistance of a battery (current source resistance) determines its ability to supply a large current to the load. This dependence obeys Ohm's law (remember the school physics course). With a low value of internal resistance, the battery is able to deliver a greater peak current to the load (without a significant decrease in the voltage at its terminals), and hence a greater peak power. While a high resistance value leads to a sharp decrease in voltage at the battery terminals when sharp increase load current. Such a collapse (decrease) in tension characterizes “weakness” externally. good battery, because the stored energy cannot be fully delivered to the load.

In other words, all of the above about the internal resistance of the battery can be illustrated as follows. Imagine that you need to water in an hour garden plot from the tank (battery) that you previously filled with water. In the normal state of affairs, you connect a hose to the drain tap, turn the tap fully on and water the area for an hour until the water in the tank runs out. Now suppose that the drain valve at your tank is stuck, you can only open it a little bit and the water oozes out of it only in a thin stream. It seems that there is water in the tank (the battery is charged), but it is impossible to water normally. The tap in this case plays the role of internal resistance for the tank. If the jet from the tap is large, then the internal resistance of the tank is small, if it is small, the internal resistance of the tank is large.

What do we have in practice? A cell phone in standby mode consumes a small current from the battery and the capacity of its battery is enough to power the phone. As soon as an incoming call arrives or you start making an outgoing call, the phone needs ten times more energy to operate normally in transfer mode, so you need to increase the capacity of the tap. If the tap is normal, then it will let this increased energy flow through itself, if it is jammed, then it is not, and the phone turns off. This is especially true for cell phones of NMT, AMPS standards, trunk and conventional radios, and portable computers.

The internal resistance of the battery depends on the type of its electrochemical system, capacity, the number of cells in the battery, connected in series, and increases towards the end of the service life.

self-discharge. The phenomenon of self-discharge, to a greater or lesser extent, is characteristic of all types of batteries and consists in the loss of their capacity after they have been fully charged. For a quantitative assessment of self-discharge, it is convenient to use the value of the capacity lost by them over a certain time, expressed as a percentage of the value obtained immediately after charging. As a rule, a time interval equal to one day and one month is taken as a time interval. So, for example, for serviceable NiCd batteries, a self-discharge of up to 10% is considered acceptable during the first 24 hours after the end of the charge, for NiMH - a little more, and for Li-ion it is negligible and is estimated for a month. It should be noted that the self-discharge of batteries is maximum in the first 24 hours after charging, and then significantly decreases.

The self-discharge of batteries depends on the quality of the materials used, technological process manufacture, type and design of the battery. It rises sharply with increasing ambient temperature, damage to the internal separator of the battery due to improper maintenance and due to the aging process.

Service life (life) of the battery. It is customary to evaluate it by the number of charge / discharge cycles that the battery can withstand during operation without a significant deterioration in its main parameters: capacity, self-discharge and internal resistance. The service life depends on many factors: charging methods, depth of discharge, maintenance or lack of maintenance procedures, temperature and the electrochemical nature of the battery. In addition, it is determined by the time elapsed since the date of manufacture, especially for Li-ion batteries. A battery is generally considered to have failed when its capacity falls below 80% of its nominal value.

For a more detailed and professional acquaintance with batteries, you can recommend the Panasonic website, which provides detailed reference data and analytical materials about NiCd, NiMH, Li-ion batteries produced by this company (in English). Unfortunately, the firm did not give permission for the translation and publication of this information in Russian, citing the lack of its representation in Russia in this area and the impossibility of evaluating the translated materials. But the information posted there is of some interest to both developers of battery-powered equipment and users, so the following is a short list of issues covered there:

• appearance;
• internal organization;
• electrochemical reactions occurring inside the battery;
• peculiarities;
• five main characteristics: charging, discharging, number of charge / discharge cycles, storage (self-discharge), safety with graphs and explanations;
• charge methods;
• packaging of cells in batteries;
• precautions when designing devices with batteries.

When writing the article, materials were used kindly provided by Mr. Isidor Buchmann, founder and head of the Canadian company Cadex Electronics Inc. .

More detailed information in Russian about batteries for mobile communications equipment, computers and other portable devices, tips on operation and maintenance are given in

LINKS

1. Cadex Electronics Inc. , Vancouver, BC , Canada is a developer and manufacturer of battery chargers, analyzers and battery maintenance systems (in English).
2. Batteries for mobile devices and portable computers. Battery analyzers (in Russian).
3. manufactured by Panasonic (in English).

Gone are the days when batteries for cell phones were assembled similarly to car batteries, only in miniature. Only 20 years ago, a cell phone battery was made up of parts, as it were, repeating the entire complex of devices of a larger brother. The figure shows a section of one of these elements.

Science and practice work together to advance technological progress. In 1991, lithium-ion batteries appeared, in which the cathode material of the electrodes is applied to aluminum foil, and the anode material to copper.

Lithium ions, under the influence electric current, are introduced into the crystal lattice of graphite and form chemical bonds with carbon molecules. When these bonds are broken, energy is released, which is converted into an electric current at the poles of the battery.

AT last years lithium-polymer batteries appeared.

The diagram shows how simple such a cell phone battery is.

Phone battery banks

Battery cans are soft plastic bags filled with a solution of lithium in a polymer, similar in consistency to sour cream. To control the state of the battery, a controller is connected to the banks. It is arranged in the form of an electronic board and can limit the connection of a charger that does not match the parameters, and the cell phone battery will not charge, no matter how hard we try. Instead of the usual 2 contacts, a connector is used in the battery device to connect to the cell phone board - a multi-pole connection.

How the phone battery works and how it works

The process of accumulating and discharging energy of such direct current sources is similar to lithium-ion batteries, but their production is much cheaper, although in some characteristics they lose to their predecessors.

The basic safety precautions to be observed when using small telephone batteries are no different from the operational safety precautions for acidic or alkaline DC power supplies found in automobiles. Charging with overvoltage, leading to overheating or short circuiting of the battery cells, may cause a fire. And from a small spark, as you know, a big flame flares up.

That is why a battery controller is installed on each battery, which turns off charging when a certain value is reached and turns off the phone when the discharge reaches a critical point.

All batteries used in mobile devices have contacts on the edge. They are used for the charging process. The article deals with the questions: what each of the contacts is responsible for and how the power of three-pin batteries differs from four-pin batteries. It is considered what function they perform, how they help to function better.

Maintenance

Why 3 contacts on a phone battery

Depending on the power scheme, a certain number of connectors are created. Two, three or four. Which on the left and right are + and -, which determines the positive, negative power pin. The third, middle contact, is present on the battery as a transmission source service information, which includes: state of charge, temperature, and other useful data.

The sensor built into the battery is responsible for the temperature. For charge control controller. The sensor monitors the temperature during the charging process. It transmits information about the charge as a percentage, turns it off in case of overcharging or overdischarging. The process allows you to extend the service life, which allows you not to spend money on a new battery. Actual question for owners who have a non-removable battery.

In "fancy" smartphones, the third contact transmits information about technical specifications: serial number, information about the phone, about the manufacturer and so on.

Important! It is li-ion batteries for mobile devices that are equipped with a third connector, for the reasons described above.

Why 4 contacts on a phone battery

If on three-pin batteries the third (middle) output is responsible for temperature control, recharging, transfer of service information, then the fourth output may take over some of the functions of the third contact, as on similar phones.

Important! In this case, it is impossible to answer exactly what the third connector is specifically responsible for, and what the fourth is for. Charger manufacturers do not advertise this issue.

On mobile devices, pin 4 can play the role of protection when it is not inserted into the "native" device. There will be no charging process, because the information transmitted through this contact will not correspond to that used in the "real" device. For example, you have a Samsung phone. And you can't find a battery of the same brand for it. Look for an analog that fits. Perhaps it has a similar battery layout, like a licensed brand battery.

After reading the article, it becomes clear that the third and fourth contact on the battery of a mobile device plays an important role. Helps prevent overcharging and overdischarging. Resets information to the processor. Extends the life of the phone, which is important in everyday life, when it is even uncomfortable to go out without a smartphone. Performance is completely dependent on the charge, so it is so important to know what all the connectors on the battery are used for. It comes in handy when you need to deal with charging another device.