How does a lithium battery work? Lithium batteries

Assessing the characteristics of a particular charger is difficult without understanding how an exemplary charge of a li-ion battery should actually proceed. Therefore, before moving directly to the diagrams, let's remember a little theory.

What are lithium batteries?

Depending on what material the positive electrode of a lithium battery is made of, there are several varieties:

• with lithium cobaltate cathode;
• with a cathode based on lithiated iron phosphate;
• based on nickel-cobalt-aluminium;
• based on nickel-cobalt-manganese.

All of these batteries have their own characteristics, but since these nuances are not of fundamental importance for the general consumer, they will not be considered in this article.

Also, all li-ion batteries are produced in various sizes and form factors. They can be either cased (for example, the popular 18650 today) or laminated or prismatic (gel-polymer batteries). The latter are hermetically sealed bags made of a special film, which contain electrodes and electrode mass.

The most common sizes of li-ion batteries are shown in the table below (all of them have a nominal voltage of 3.7 volts):

Internal electrochemical processes proceed in the same way and do not depend on the form factor and design of the battery, so everything said below applies equally to all lithium batteries.

How to properly charge lithium-ion batteries

Most the right way Lithium batteries are charged in two stages. This is the method Sony uses in all of its chargers. Despite a more complex charge controller, this ensures a more complete charge of li-ion batteries without reducing their service life.

Here we are talking about a two-stage charge profile for lithium batteries, abbreviated as CC/CV (constant current, constant voltage). There are also options with pulse and step currents, but they are not discussed in this article. More about charging pulse current can be read.

So, let's look at both stages of charging in more detail.

1. At the first stage A constant charging current must be ensured. The current value is 0.2-0.5C. For accelerated charging, it is allowed to increase the current to 0.5-1.0C (where C is the battery capacity).

For example, for a battery with a capacity of 3000 mAh, the nominal charge current at the first stage is 600-1500 mA, and the accelerated charge current can be in the range of 1.5-3A.

To ensure a constant charging current of a given value, the charger circuit must be able to increase the voltage at the battery terminals. In fact, at the first stage the charger works as a classic current stabilizer.

Important: If you plan to charge batteries with a built-in protection board (PCB), then when designing the charger circuit you need to make sure that the voltage idle speed circuits will never be able to exceed 6-7 volts. Otherwise, the protection board may be damaged.

At the moment when the voltage on the battery rises to 4.2 volts, the battery will gain approximately 70-80% of its capacity (the specific capacity value will depend on the charging current: with accelerated charging it will be a little less, with a nominal charge - a little more). This moment marks the end of the first stage of charging and serves as a signal for the transition to the second (and final) stage.

2. Second charge stage- this is the battery charge constant voltage, but with a gradually decreasing (falling) current.

At this stage, the charger maintains a voltage of 4.15-4.25 volts on the battery and controls the current value.

As the capacity increases, the charging current will decrease. As soon as its value decreases to 0.05-0.01C, the charging process is considered complete.

An important nuance of the operation of a proper charger is its complete shutdown from the battery after charging is completed. This is due to the fact that for lithium batteries it is extremely undesirable for them to remain under high voltage for a long time, which is usually provided by the charger (i.e. 4.18-4.24 volts). This leads to accelerated degradation chemical composition battery and, as a result, a decrease in its capacity. Long-term stay means tens of hours or more.

During the second stage of charging, the battery manages to gain approximately 0.1-0.15 more of its capacity. The total battery charge thus reaches 90-95%, which is an excellent indicator.

We looked at two main stages of charging. However, coverage of the issue of charging lithium batteries would be incomplete if another charging stage were not mentioned - the so-called. precharge.

Preliminary charge stage (precharge)- this stage is used only for deeply discharged batteries (below 2.5 V) to bring them to normal operating mode.

At this stage the charge is ensured DC reduced value until the battery voltage reaches 2.8 V.

The preliminary stage is necessary to prevent swelling and depressurization (or even explosion with fire) of damaged batteries that have, for example, an internal short circuit between the electrodes. If you immediately pass through such a battery high current charge, this will inevitably lead to its warming up, and then depending on your luck.

Another benefit of precharging is pre-heating the battery, which is important when charging at low ambient temperatures (in an unheated room during the cold season).

Intelligent charging must be able to monitor the voltage on the battery during the preliminary charging phase and, in case the voltage for a long time does not rise, conclude that the battery is faulty.

All stages of charging a lithium-ion battery (including the pre-charge stage) are schematically depicted in this graph:

Exceeding the rated charging voltage by 0.15V can reduce the battery life by half. Lowering the charge voltage by 0.1 volt reduces the capacity of a charged battery by about 10%, but significantly extends its service life. The voltage of a fully charged battery after removing it from the charger is 4.1-4.15 volts.

Let me summarize the above and outline the main points:

1. What current should I use to charge a li-ion battery (for example, 18650 or any other)?

The current will depend on how quickly you would like to charge it and can range from 0.2C to 1C.

For example, for a battery size 18650 with a capacity of 3400 mAh, the minimum charge current is 680 mA, and the maximum is 3400 mA.

2. How long does it take to charge, for example, the same 18650 batteries?

The charging time directly depends on the charging current and is calculated using the formula:

T = C / I charge.

For example, the charging time of our 3400 mAh battery with a current of 1A will be about 3.5 hours.

3. How to properly charge a lithium polymer battery?

All lithium batteries charge the same way. It doesn't matter whether it's lithium polymer or lithium ion. For us, consumers, there is no difference.

What is a protection board?

The protection board (or PCB - power control board) is designed to protect against short circuit, overcharging and overdischarging of the lithium battery. As a rule, overheating protection is also built into the protection modules.

For safety reasons, the use of lithium batteries in household appliances, if they do not have a built-in protection board. Therefore, in all batteries from cell phones There is always a PCB board. The battery output terminals are located directly on the board:

These boards use a six-legged charge controller on a specialized device (JW01, JW11, K091, G2J, G3J, S8210, S8261, NE57600 and other analogues). The task of this controller is to disconnect the battery from the load when the battery is completely discharged and disconnect the battery from charging when it reaches 4.25V.

Here, for example, is a diagram of the BP-6M battery protection board that was supplied with old Nokia phones:

If we talk about 18650, they can be produced either with or without a protection board. The protection module is located near the negative terminal of the battery.

The board increases the length of the battery by 2-3 mm.

Batteries without a PCB module are usually included in batteries that come with their own protection circuits.

Any battery with protection can easily turn into a battery without protection; you just need to gut it.

Today, the maximum capacity of the 18650 battery is 3400 mAh. Batteries with protection must have a corresponding designation on the case ("Protected").

Do not confuse the PCB board with the PCM module (PCM - power charge module). If the former serve only the purpose of protecting the battery, then the latter are designed to control the charging process - they limit the charge current at a given level, control the temperature and, in general, ensure the entire process. The PCM board is what we call a charge controller.

I hope now there are no questions left, how to charge an 18650 battery or any other lithium battery? Then let's move on to small selection ready-made circuit solutions for chargers (the same charge controllers).

Charging schemes for li-ion batteries

All circuits are suitable for charging any lithium battery; all that remains is to decide on the charging current and the element base.

LM317

Diagram of a simple charger based on the LM317 chip with a charge indicator:

The circuit is the simplest, the whole setup comes down to setting the output voltage to 4.2 volts using trimming resistor R8 (without a connected battery!) and setting the charging current by selecting resistors R4, R6. The power of resistor R1 is at least 1 Watt.

As soon as the LED goes out, the charging process can be considered completed (the charging current will never decrease to zero). It is not recommended to keep the battery on this charge for a long time after it is fully charged.

The lm317 microcircuit is widely used in various voltage and current stabilizers (depending on the connection circuit). It’s sold on every corner and costs just a penny (you can get 10 pieces for just 55 rubles).

LM317 comes in different housings:

Pin assignment (pinout):

Analogs of the LM317 chip are: GL317, SG31, SG317, UC317T, ECG1900, LM31MDT, SP900, KR142EN12, KR1157EN1 (the last two are domestically produced).

The charging current can be increased to 3A if you take LM350 instead of LM317. It will, however, be more expensive - 11 rubles/piece.

The printed circuit board and circuit assembly are shown below:

The old Soviet transistor KT361 can be replaced with a similar one pnp transistor(for example, KT3107, KT3108 or bourgeois 2N5086, 2SA733, BC308A). It can be removed altogether if the charge indicator is not needed.

Disadvantage of the circuit: the supply voltage must be in the range of 8-12V. This is due to the fact that for normal operation LM317 microcircuit, the difference between the battery voltage and the supply voltage must be at least 4.25 Volts. Thus, it will not be possible to power it from the USB port.

MAX1555 or MAX1551

MAX1551/MAX1555 are specialized chargers for Li+ batteries, capable of operating from USB or from a separate power adapter (for example, a phone charger).

The only difference between these microcircuits is that MAX1555 produces a signal to indicate the charging process, and MAX1551 produces a signal that the power is on. Those. 1555 is still preferable in most cases, so 1551 is now difficult to find on sale.

A detailed description of these microcircuits from the manufacturer is.

The maximum input voltage from the DC adapter is 7 V, when powered by USB - 6 V. When the supply voltage drops to 3.52 V, the microcircuit turns off and charging stops.

The microcircuit itself detects at which input the supply voltage is present and connects to it. If food is coming via the USB bus, the maximum charging current is limited to 100 mA - this allows you to plug the charger into the USB port of any computer without fear of burning the south bridge.

When powered by a separate power supply, the typical charging current is 280 mA.

The chips have built-in overheating protection. But even in this case, the circuit continues to operate, reducing the charge current by 17 mA for each degree above 110 ° C.

There is a pre-charge function (see above): as long as the battery voltage is below 3V, the microcircuit limits the charge current to 40 mA.

The microcircuit has 5 pins. Here typical diagram inclusions:

If there is a guarantee that the voltage at the output of your adapter cannot under any circumstances exceed 7 volts, then you can do without the 7805 stabilizer.

The USB charging option can be assembled, for example, on this one.

The microcircuit does not require either external diodes or external transistors. In general, of course, gorgeous little things! Only they are too small and inconvenient to solder. And they are also expensive ().

LP2951

The LP2951 stabilizer is manufactured by National Semiconductors (). It provides the implementation of a built-in current limiting function and allows you to generate a stable charge voltage level for a lithium-ion battery at the output of the circuit.

The charge voltage is 4.08 - 4.26 volts and is set by resistor R3 when the battery is disconnected. The voltage is kept very precisely.

The charge current is 150 - 300mA, this value is limited by the internal circuits of the LP2951 chip (depending on the manufacturer).

Use the diode with a small reverse current. For example, it can be any of the 1N400X series that you can purchase. The diode is used as a blocking diode to prevent reverse current from the battery into the LP2951 chip when the input voltage is turned off.

This charger produces a fairly low charging current, so any 18650 battery can charge overnight.

The microcircuit can be purchased both in a DIP package and in a SOIC package (costs about 10 rubles per piece).

MCP73831

The chip allows you to create the right chargers, and it’s also cheaper than the much-hyped MAX1555.

A typical connection diagram is taken from:

An important advantage of the circuit is the absence of low-resistance powerful resistors that limit the charge current. Here the current is set by a resistor connected to the 5th pin of the microcircuit. Its resistance should be in the range of 2-10 kOhm.

The assembled charger looks like this:

The microcircuit heats up quite well during operation, but this does not seem to bother it. It fulfills its function.

Here's another option printed circuit board With smd led and micro USB connector:

LTC4054 (STC4054)

Very simple circuit, great option! Allows charging with current up to 800 mA (see). True, it tends to get very hot, but in this case the built-in overheating protection reduces the current.

The circuit can be significantly simplified by throwing out one or even both LEDs with a transistor. Then it will look like this (you must admit, it couldn’t be simpler: a couple of resistors and one condenser):

One of the printed circuit board options is available at . The board is designed for elements of standard size 0805.

I=1000/R. You shouldn’t set a high current right away; first see how hot the microcircuit gets. For my purposes, I took a 2.7 kOhm resistor, and the charge current turned out to be about 360 mA.

It is unlikely that it will be possible to adapt a radiator to this microcircuit, and it is not a fact that it will be effective due to the high thermal resistance of the crystal-case junction. The manufacturer recommends making the heat sink “through the leads” - making the traces as thick as possible and leaving the foil under the chip body. In general, the more “earth” foil left, the better.

By the way, most of the heat is dissipated through the 3rd leg, so you can make this trace very wide and thick (fill it with excess solder).

The LTC4054 chip package may be labeled LTH7 or LTADY.

LTH7 differs from LTADY in that the first can lift a very low battery (on which the voltage is less than 2.9 volts), while the second cannot (you need to swing it separately).

The chip turned out to be very successful, so it has a bunch of analogues: STC4054, MCP73831, TB4054, QX4054, TP4054, SGM4054, ACE4054, LP4054, U4054, BL4054, WPM4054, IT4504, Y1880, PT6102, PT6181, 2, HX6001, LC6000, LN5060, CX9058, EC49016, CYT5026, Q7051. Before using any of the analogues, check the datasheets.

TP4056

The microcircuit is made in a SOP-8 housing (see), it has a metal heat sink on its belly that is not connected to contacts, which allows for more efficient heat removal. Allows you to charge the battery with a current of up to 1A (the current depends on the current-setting resistor).

The connection diagram requires the bare minimum of hanging elements:

The circuit implements the classical charging process - first charging with a constant current, then with a constant voltage and a falling current. Everything is scientific. If you look at charging step by step, you can distinguish several stages:

1. Monitoring the voltage of the connected battery (this happens all the time).
2. Precharge phase (if the battery is discharged below 2.9 V). Charge with a current of 1/10 from the one programmed by the resistor R prog (100 mA at R prog = 1.2 kOhm) to a level of 2.9 V.
3. Charging with a maximum constant current (1000 mA at R prog = 1.2 kOhm);
4. When the battery reaches 4.2 V, the voltage on the battery is fixed at this level. A gradual decrease in the charging current begins.
5. When the current reaches 1/10 of the one programmed by the resistor R prog (100 mA at R prog = 1.2 kOhm), the charger turns off.
6. After charging is complete, the controller continues monitoring the battery voltage (see point 1). The current consumed by the monitoring circuit is 2-3 µA. After the voltage drops to 4.0V, charging starts again. And so on in a circle.

The charge current (in amperes) is calculated by the formula I=1200/R prog. The permissible maximum is 1000 mA.

A real charging test with a 3400 mAh 18650 battery is shown in the graph:

The advantage of the microcircuit is that the charge current is set by just one resistor. Powerful low-resistance resistors are not required. Plus there is an indicator of the charging process, as well as an indication of the end of charging. When the battery is not connected, the indicator blinks every few seconds.

The supply voltage of the circuit should be within 4.5...8 volts. The closer to 4.5V, the better (so the chip heats up less).

The first leg is used to connect the temperature sensor built into the lithium-ion battery(usually the middle terminal of a cell phone battery). If the output voltage is below 45% or above 80% of the supply voltage, charging is suspended. If you don't need temperature control, just plant that foot on the ground.

Attention! This circuit has one significant drawback: the absence of a battery reverse polarity protection circuit. In this case, the controller is guaranteed to burn out due to exceeding the maximum current. In this case, the supply voltage of the circuit directly goes to the battery, which is very dangerous.

The signet is simple and can be done in an hour on your knee. If time is of the essence, you can order ready-made modules. Some manufacturers of ready-made modules add protection against overcurrent and overdischarge (for example, you can choose which board you need - with or without protection, and with which connector).

You can also find ready-made boards with a contact for the temperature sensor. Or even a charging module with several parallel TP4056 microcircuits to increase the charging current and with reverse polarity protection (example).

LTC1734

Also a very simple scheme. The charging current is set by resistor R prog (for example, if you install a 3 kOhm resistor, the current will be 500 mA).

Microcircuits are usually marked on the case: LTRG (they can often be found in old Samsung phones).

A transistor will do just fine any p-n-p, the main thing is that it is designed for a given charging current.

There is no charge indicator on the indicated diagram, but on the LTC1734 it is said that pin “4” (Prog) has two functions - setting the current and monitoring the end of the battery charge. For example, a circuit with control of the end of charge using the LT1716 comparator is shown.

Comparator LT1716 in this case can be replaced with a cheap LM358.

TL431 + transistor

It is probably difficult to come up with a circuit using more affordable components. The most difficult thing here is to find the TL431 reference voltage source. But they are so common that they are found almost everywhere (rarely does a power source do without this microcircuit).

Well, the TIP41 transistor can be replaced with any other one with a suitable collector current. Even the old Soviet KT819, KT805 (or less powerful KT815, KT817) will do.

Setting up the circuit comes down to setting the output voltage (without a battery!!!) using a trim resistor at 4.2 volts. Resistor R1 sets maximum value charging current.

This circuit fully implements the two-stage process of charging lithium batteries - first charging with direct current, then moving to the voltage stabilization phase and smoothly reducing the current to almost zero. The only drawback is the poor repeatability of the circuit (it is capricious in setup and demanding on the components used).

MCP73812

There is another undeservedly neglected microcircuit from Microchip - MCP73812 (see). Based on it, a very budget charging option is obtained (and inexpensive!). The whole body kit is just one resistor!

By the way, the microcircuit is made in a solder-friendly package - SOT23-5.

The only negative is that it gets very hot and there is no charge indication. It also somehow doesn’t work very reliably if you have a low-power power source (which causes a voltage drop).

In general, if the charge indication is not important for you, and a current of 500 mA suits you, then the MCP73812 is a very good option.

NCP1835

A fully integrated solution is offered - NCP1835B, providing high stability of the charging voltage (4.2 ±0.05 V).

Perhaps the only drawback of this microcircuit is its too miniature size (DFN-10 case, size 3x3 mm). Not everyone can provide high-quality soldering of such miniature elements.

From undeniable advantages I would like to note the following:

1. Minimum number of body parts.
2. Possibility of charging a completely discharged battery (precharge current 30 mA);
3. Determining the end of charging.
4. Programmable charging current - up to 1000 mA.
5. Charge and error indication (capable of detecting non-chargeable batteries and signaling this).
6. Protection against long-term charge (by changing the capacitance of the capacitor C t, you can set maximum time charge from 6.6 to 784 minutes).

The cost of the microcircuit is not exactly cheap, but also not so high (~$1) that you can refuse to use it. If you are comfortable with a soldering iron, I would recommend choosing this option.

More detailed description is located in .

Can I charge a lithium-ion battery without a controller?

Yes, you can. However, this will require close control of the charging current and voltage.

In general, it will not be possible to charge a battery, for example, our 18650, without a charger. You still need to somehow limit the maximum charge current, so at least the most primitive memory will still be required.

The simplest charger for any lithium battery is a resistor connected in series with the battery:

The resistance and power dissipation of the resistor depend on the voltage of the power source that will be used for charging.

As an example, let's calculate a resistor for a 5 Volt power supply. We will charge an 18650 battery with a capacity of 2400 mAh.

So, at the very beginning of charging, the voltage drop across the resistor will be:

U r = 5 - 2.8 = 2.2 Volts

Let's say our 5V power supply is rated for a maximum current of 1A. The circuit will consume the highest current at the very beginning of the charge, when the voltage on the battery is minimal and amounts to 2.7-2.8 Volts.

Attention: these calculations do not take into account the possibility that the battery may be very deeply discharged and the voltage on it may be much lower, even to zero.

Thus, the resistor resistance required to limit the current at the very beginning of the charge at 1 Ampere should be:

R = U / I = 2.2 / 1 = 2.2 Ohm

Resistor power dissipation:

P r = I 2 R = 1*1*2.2 = 2.2 W

At the very end of the battery charge, when the voltage on it approaches 4.2 V, the charge current will be:

I charge = (U ip - 4.2) / R = (5 - 4.2) / 2.2 = 0.3 A

That is, as we see, all values ​​do not go beyond the permissible limits for a given battery: the initial current does not exceed the maximum permissible charging current for a given battery (2.4 A), and the final current exceeds the current at which the battery no longer gains capacity ( 0.24 A).

The main disadvantage of such charging is the need to constantly monitor the voltage on the battery. And manually turn off the charge as soon as the voltage reaches 4.2 Volts. The fact is that lithium batteries tolerate even short-term overvoltage very poorly - the electrode masses begin to quickly degrade, which inevitably leads to loss of capacity. At the same time, all the prerequisites for overheating and depressurization are created.

If your battery has a built-in protection board, which was discussed just above, then everything becomes simpler. When a certain voltage is reached on the battery, the board itself will disconnect it from the charger. However, this charging method has significant disadvantages, which we discussed in.

The protection built into the battery will not allow it to be overcharged under any circumstances. All you have to do is control the charge current so that it does not exceed the permissible values ​​for a given battery (protection boards cannot limit the charge current, unfortunately).

Charging using a laboratory power supply

If you have a power supply with current protection (limitation), then you are saved! Such a power source is already a full-fledged charger that implements the correct charge profile, which we wrote about above (CC/CV).

Everything you need to do for li-ion charging- this is to set the power supply to 4.2 volts and set the desired current limit. And you can connect the battery.

At first, when the battery is still discharged, laboratory block power supply will operate in current protection mode (i.e. it will stabilize the output current at a given level). Then, when the voltage on the bank rises to the set 4.2V, the power supply will switch to voltage stabilization mode, and the current will begin to drop.

When the current drops to 0.05-0.1C, the battery can be considered fully charged.

As you can see, the laboratory power supply is an almost ideal charger! The only thing it can’t do automatically is make a decision to fully charge the battery and turn off. But this is a small thing that you shouldn’t even pay attention to.

How to charge lithium batteries?

And if we are talking about a disposable battery that is not intended for recharging, then the correct (and only correct) answer to this question is NO.

The fact is that any lithium battery (for example, the common CR2032 in the form of a flat tablet) is characterized by the presence of an internal passivating layer that covers the lithium anode. This layer prevents a chemical reaction between the anode and the electrolyte. And the supply of external current destroys the above protective layer, leading to damage to the battery.

By the way, if we talk about the non-rechargeable CR2032 battery, then the LIR2032, which is very similar to it, is already a full-fledged battery. It can and should be charged. Only its voltage is not 3, but 3.6V.

How to charge lithium batteries (be it a phone battery, 18650 or any other li-ion battery) was discussed at the beginning of the article.

Where to buy microchips?

You can, of course, buy it in Chipe-Dip, but it’s expensive there. That's why I always buy from one very secret store)) The most important thing is to choose the right seller, then the order will arrive quickly and for sure.

For your convenience, I have collected the most reliable sellers in one table, use it for your health:

Testing Features

The main difficulty in the experiments is the discrepancy between the declared capacity and the real one. All batteries have a capacity higher than stated, ranging from 0.1% to 5%, which introduces an additional element of unpredictability.

NCA and NMC batteries were most commonly used, but lithium cobalt and lithium phosphate batteries were also tested.

A few terms:
DoD - Depth of Discharge - depth of discharge.
SoC - State of Charge - charge level.

Using Batteries

Number of cycles

This curve is called the Wöhler curve. The main idea came from mechanics about the dependence of the number of stretches of a spring on the degree of stretching. The initial value of 3000 cycles at 100% battery discharge is a weighted average at 0.1C discharge. Some batteries show better results, some worse. At a current of 1C, the number of full cycles at 100% discharge drops from 3000 to 1000-1500, depending on the manufacturer.

Generally, this ratio, presented in the graphs, was confirmed by the results of experiments, because It is advisable to charge the battery whenever possible.

Calculation of superposition of cycles

According to the results of the experiments, the combined cycle showed results similar to the addition of complete equivalent cycles of two independent cycles. Those. The relative capacity of the battery in the combined cycle fell according to the sum of the discharges in the small and large cycles (the linearized graph is presented below).


The effect of large discharge cycles is more significant, which means that it is better to charge the battery at every opportunity.

Memory effect

Battery storage

Storage temperatures

Charge level

Main problems of the experimental results

Results of the experiments

Sources

Lithium-ion batteries are not as finicky as their nickel-metal hydride counterparts, but they still require some care. Sticking to five simple rules , you can not only extend life cycle lithium-ion batteries, but also increase the operating time of mobile devices without recharging.

Do not allow complete discharge. U lithium-ion batteries There is no so-called memory effect, so they can and, moreover, need to be charged without waiting for discharge to zero. Many manufacturers calculate the life of a lithium-ion battery by the number of full discharge cycles (up to 0%). For quality batteries This 400-600 cycles. To extend the life of your lithium-ion battery, charge your phone more often. Optimally, as soon as the battery charge drops below 10-20 percent, you can put the phone on charge. This will increase the number of discharge cycles to 1000-1100 .
Experts describe this process with such an indicator as Depth Of Discharge. If your phone is discharged to 20%, then the Depth of Discharge is 80%. The table below shows the dependence of the number of discharge cycles of a lithium-ion battery on the Depth of Discharge:

Discharge once every 3 months. Fully charging for a long time is just as harmful to lithium-ion batteries as constantly discharging to zero.
Due to the extremely unstable charging process (we often charge the phone as necessary, and wherever possible, from USB, from an outlet, from external battery etc.) experts recommend completely discharging the battery once every 3 months and then charging it to 100% and keeping it charged for 8-12 hours. This helps reset the so-called high and low battery flags. You can read more about this.

Store partially charged. The optimal condition for long-term storage of a lithium-ion battery is between 30 and 50 percent charge at 15°C. If you leave the battery fully charged, its capacity will decrease significantly over time. But the battery, which has been collecting dust on a shelf for a long time, discharged to zero, is most likely no longer alive - it’s time to send it for recycling.
The table below shows how much capacity remains in a lithium-ion battery depending on storage temperature and charge level when stored for 1 year.

Use the original charger. Few people know that the charger in most cases is built directly inside mobile devices, and the external network adapter It only lowers the voltage and rectifies the current of the household electrical network, that is, it does not directly affect the battery. Some gadgets, such as digital cameras, do not have a built-in charger, and therefore their lithium-ion batteries are inserted into an external “charger”. This is where using an external charger of questionable quality instead of the original one can negatively affect the performance of the battery.

Avoid overheating. Well, the worst enemy of lithium-ion batteries is high temperature - they cannot tolerate overheating at all. Therefore, do not allow mobile devices direct sun rays, and do not leave them in close proximity to heat sources such as electric heaters. Maximum permissible temperatures, in which it is possible to use lithium-ion batteries: from –40°C to +50°C

Also, you can look

Lithium batteries

Lithium or lithium-ion (Li-ion) batteries are mainly found in cell phones, laptops, and video cameras. The products are expensive, and so are the batteries, so you need to handle them even more competently than any other batteries. So what is the power of Li-Ion? There are probably even more rumors and myths here. Firstly, it begins to appear by itself, if only because sellers of equipment with Li-ion batteries do not give any special instructions, saying that the battery is “smart” and will do everything as it should. But not herself. After all, how many cases are there when owners of new laptops rendered the battery unusable within a month and then paid good prices for new battery. Of course, lithium batteries are expensive because they are packed with electronics, but, unfortunately, they do not save you from being a fool.

Overdischarge

As with nickel batteries, lithium batteries are also very susceptible to overcharging and overdischarging. But since these batteries are used in smart devices and come with their own chargers, their electronics do not allow overcharging - i.e. you don't have to be afraid of him. But overdischarge is more difficult to control, which is why it is the most typical cause premature failure of the battery. Of course, in expensive and complex devices, such as laptops, shutdown occurs before the voltage drops to a critical value. But precedents indicate that this emergency shutdown is better viewed as emergency measure, to which, if possible, it is better not to reach. This is the most important rule - avoid complete discharge, since low voltage may disable the emergency protection circuit. It happens that people “kill” their batteries when they get carried away by training. Training is a good thing, but for lithium batteries 2-3 full cycles are enough.

Lithium batteries have no memory effect, so they can be charged whenever you want, so it is better not to completely discharge the batteries after training. The recommended lower threshold is 5-10%. The critical lower threshold is 3%.

Many incomplete cycles or one complete

Lithium batteries have a service life of approximately 300 cycles. A full cycle is considered to be a cycle of full charge and complete (i.e. up to approximately 3% capacity) discharge, or vice versa. If you discharge the battery to 50% and then charge it, it will be 1/2 cycle, if to 75% and charge it will be 1/4 cycle, etc. So, for phones and laptops, the difference in benefits between full and incomplete cycles is different. It is persistently stated on the Internet that a lot of people charged their phones when they were not fully discharged (i.e., they recharged the phone every day) and eventually ruined them. At the same time, for laptops it is reliably known that full cycles wear out the battery faster than incomplete ones. The situation becomes clearer upon closer examination of the device. Li-ion batteries(see additional materials). It turns out that a lot depends on the controller. It is he who controls the charge current, monitors the condition of the battery, etc. So, in laptops the controller is located in the battery itself and is adjusted system utilities, for example calibration. In cell phones, the controller is located in the phone itself and cannot be easily adjusted. At least in lithium batteries and there is no memory effect, but there is a so-called “digital memory” effect. The fact is that the charge-discharge control electronics located in the battery itself operate independently of the device using the battery. Internal electronics monitor the voltage level of the element, interrupt the charge when the set maximum value is reached (taking into account the change in voltage due to the charging current and battery temperature), interrupt the discharge when a critical value is reached and report this “upstream” (a large range of products are produced for these purposes specialized chips). The battery monitoring system “at the top” calculates the charge level based on information about the moments of switching off the charge and discharge from the battery and the readings of the current measurement system. But if the operating conditions are such that complete discharge before hardware shutdown or fully charged does not occur, these calculations may not be entirely correct after several cycles - the battery capacity drops over time, and the readings of the current meter may not always correspond to reality. Typically, deviations do not exceed one percent for each cycle, unless serious changes occur during operation, associated, for example, with the failure of one of the battery cells. The monitoring system has the ability to “learn”, that is, recalculate the value of the full capacity of the battery, but for this it is necessary to perform at least one full charge-discharge cycle before the hardware circuits of the battery itself are triggered. So it turns out that with very frequent cycles the controller gets lost, and, therefore, incorrectly calculates the battery charge and carries out incorrect charging, causing the battery to deteriorate. Unlike a laptop, a phone cannot be recalibrated. All that remains in this case is to do a couple of full cycles to get the controller in order. I recommend, ideally, combining full and incomplete cycles, adhering to the “golden mean” principle. Personally, I did this with my cell phone - as a result, after 2 years of operation, the drop in capacity was no more than 40%, which is the norm. In part, time is also not kind to lithium batteries - they wear out over time, regardless of use; Their lifespan is short and it is reasonable to change batteries every 2-3 years.

Storage

When the battery is not in use, it is recommended to store it at 40% capacity in a cool place. The lower temperature limit for storage and operation is 00 C. In general, lithium batteries like to be charged, i.e. They are better to store and keep in a charged state, unlike nickel ones. But during long-term storage maximum charge still wears out the battery more, so the optimal state is considered to be 40% charge.

Battery resuscitation

In general, if the battery is dead, it is better to buy a new one; this is the most logical option, although it is expensive. I have not seen any reliable recipes for resuscitating batteries. There are real legends here, especially about laptops, that people have revived their ruined laptop battery and everything is fine with them. One of them sounds like this: “You need to completely discharge the battery, leave the laptop for a week; then fully charge the battery and also leave it for a week; in two months the capacity should be restored.”

For cell phones: combine full and incomplete cycles (in the “XZ” proportion).
For laptops: as few complete cycles as possible (after training).
For everyone: it is recommended to do 80% cycles; do not allow complete discharge (below 3%).

The first experiments to create lithium galvanic cells were recorded back in 1012. A truly working model was created in 1940, the first production copies (non-rechargeable!) appeared in the 70s, and the triumphant march of this type of battery began in the early 90s, when the Japanese company Sony was able to master their commercial production.

Currently, it is believed that this is one of the most promising areas for creating autonomous electrical sources energy despite their rather high (at current level) cost.

The main advantage of this type of battery is high energy density(about 100 W/hour per 1 kg of weight) and the ability to perform a large charging/discharging cycle.

Newly created batteries are also characterized by such an excellent indicator as a low self-discharge rate (only from 3 to 5% in the first month, with a subsequent decrease in this indicator). This allows for

And that's not all - compared to the widespread Ni-Cd, new scheme with the same dimensions, it provides three times greater performance with virtually no negative memory effect.

Negative characteristics

lithium ion batteries.

First of all, the high cost, the need to keep the battery in a charged state and the so-called “aging effect”, which manifests itself even when the galvanic cell has not been in use. The last unpleasant property manifests itself in a constant decrease in capacity, which after two years can lead to complete failure of the product.