Progress is moving forward, and lithium batteries are increasingly replacing the traditionally used NiCd (nickel-cadmium) and NiMh (nickel-metal hydride) batteries.
With a comparable weight of one element, lithium has a higher capacity, in addition, the element voltage is three times higher - 3.6 V per element, instead of 1.2 V.
Price lithium batteries began to approach conventional alkaline batteries, the weight and size are much smaller, and besides, they can and should be charged. The manufacturer says they can withstand 300-600 cycles.
There are different sizes and choosing the right one is not difficult.
The self-discharge is so low that they sit for years and remain charged, i.e. The device remains operational when needed.

"C" stands for Capacity

A designation like “xC” is often found. This is simply a convenient designation of the charge or discharge current of the battery with shares of its capacity. Derived from English word"Capacity" (capacity, capacity).
When they talk about charging with a current of 2C, or 0.1C, they usually mean that the current should be (2 × battery capacity)/h or (0.1 × battery capacity)/h, respectively.
For example, a battery with a capacity of 720 mAh, for which the charge current is 0.5 C, must be charged with a current of 0.5 × 720 mAh / h = 360 mA, this also applies to discharge.

You can do something simple or not so simple yourself Charger, depending on your experience and capabilities.

Circuit diagram of a simple LM317 charger

Rice. 5.

The application circuit provides fairly accurate voltage stabilization, which is set by potentiometer R2.
Current stabilization is not as critical as voltage stabilization, so it is enough to stabilize the current using a shunt resistor Rx and an NPN transistor (VT1).

The required charging current for a particular lithium-ion (Li-Ion) and lithium-polymer (Li-Pol) battery is selected by changing the Rx resistance.
The resistance Rx approximately corresponds to the following ratio: 0.95/Imax.
The value of resistor Rx indicated in the diagram corresponds to a current of 200 mA, this is an approximate value, it also depends on the transistor.

It is necessary to provide a radiator depending on the charging current and input voltage.
The input voltage must be at least 3 Volts higher than the battery voltage for normal operation of the stabilizer, which for one can is 7-9 V.

Circuit diagram of a simple charger on LTC4054

Rice. 6.

You can remove the LTC4054 charge controller from an old cell phone, for example, Samsung (C100, C110, X100, E700, E800, E820, P100, P510).

Rice. 7. This small 5-legged chip is labeled "LTH7" or "LTADY"

I won’t go into the smallest details of working with the microcircuit; everything is in the datasheet. I will describe only the most necessary features.
Charge current up to 800 mA.
The optimal supply voltage is from 4.3 to 6 Volts.
Charge indication.
Output short circuit protection.
Overheating protection (reduction of charge current at temperatures above 120°).
Does not charge the battery when its voltage is below 2.9 V.

The charge current is set by a resistor between the fifth terminal of the microcircuit and ground according to the formula

I=1000/R,
where I is the charge current in Amperes, R is the resistor resistance in Ohms.

Lithium battery low indicator

Here simple circuit, which lights up the LED when the battery is low and its residual voltage is close to critical.

Rice. 8.

Any low-power transistors. The LED ignition voltage is selected by a divider from resistors R2 and R3. It is better to connect the circuit after the protection unit so that the LED does not drain the battery completely.

The nuance of durability

The manufacturer usually claims 300 cycles, but if you charge lithium just 0.1 Volt less, to 4.10 V, then the number of cycles increases to 600 or even more.

Operation and Precautions

It's safe to say that lithium polymer batteries the most “delicate” batteries in existence, that is, they require mandatory compliance with several simple but mandatory rules, failure to comply with which can lead to troubles.
1. Charge to a voltage exceeding 4.20 Volts per jar is not allowed.
2. Not allowed short circuit battery
3. Discharge with currents that exceed the load capacity or heat the battery above 60°C is not allowed. 4. A discharge below a voltage of 3.00 Volts per jar is harmful.
5. Heating the battery above 60°C is harmful. 6. Depressurization of the battery is harmful.
7. Storage in a discharged state is harmful.

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

From the experience of many years of use, I can say that the capacity of batteries changes little, but the internal resistance increases and the battery begins to work less time at high current consumption - it seems that the capacity has dropped.
For this reason, I usually install a larger container, as the dimensions of the device allow, and even old cans that are ten years old work quite well.

For not very high currents, old cell phone batteries are suitable.

You can get a lot of perfectly working 18650 batteries out of an old laptop battery.

Where do I use lithium batteries?

I converted my screwdriver and electric screwdriver to lithium a long time ago. I don't use these tools regularly. Now, even after a year of non-use, they work without recharging!

I put small batteries in children's toys, watches, etc., where 2-3 “button” cells were installed from the factory. Where exactly 3V is needed, I add one diode in series and it works just right.

I put it in LED flashlights.

Instead of the expensive and low-capacity Krona 9V, I installed 2 cans in the tester and forgot all the problems and extra costs.

In general, I put it wherever I can, instead of batteries.

Where do I buy lithium and related utilities

For sale. At the same link you will find charging modules and other useful items for DIYers.

The Chinese usually lie about the capacity and it is smaller than what is written.

Honest Sanyo 18650

Batteries for mobile devices- charging methods

The old lady bought a car, drove it some distance, and suddenly the engine stopped. The called technical support service stated that the gas had run out. A perplexed old woman is suing: during the sale, no one explained to her that the car still needs to be filled with gasoline...

So, the batteries need to be charged. This is their significant difference from batteries. But before we talk about chargers, let's briefly look at the basic methods of charging the most common types of batteries.

A few words about terminology. Battery capacity is usually designated by the letter “C” (capacity). When they talk about a discharge equal to 1/10 C, this means a discharge with a current equal to a tenth of the nominal capacity of the battery. So, for example, for a battery with a capacity of 1000 mAh this will be a discharge current of 1000/10 = 100 mA. In theory, a 1000 mAh battery can deliver 1000 mA for one hour, 100 mA for 10 hours, or 10 mA for 100 hours. In practice, at high discharge current values ​​the rated capacity is never reached, and at low currents it is exceeded.

Similarly, when charging batteries, a value of 1/10 C means charging with a current numerically equal to a tenth of the declared battery capacity.

Charging methods for NiCd and NiMH batteries

Existing methods can be divided into 4 main groups:

• slow charge- direct current charge of 0.1 C or 0.2 C for approximately 15 or 6-8 hours, respectively.
• fast charge- charge with direct current equal to 1/3 C for about 3-5 hours.
• accelerated or delta V charge- a charge with an initial charge current equal to the nominal capacity of the battery, at which the voltage on the battery is constantly measured and the charge ends after the battery is fully charged. Charging time is approximately an hour and a half.
• reverse charge- pulse charging method, in which short discharge pulses are distributed between long charging pulses.

Let me make a reservation right away: this division is quite arbitrary and depends on the battery manufacturer. The approach to the issue of charging batteries is something like this: the company is developing Various types batteries for various applications and sets for each type recommendations and requirements for the most favorable charging methods. As a result, the same appearance(size) batteries (single cells) may require different charging methods. This approach can be illustrated by the materials posted on and.

Slow charging method

With this method, several options are possible: charging with semi-constant current and charging with constant current.

When charging with semi-constant current, the initial current value is set to approximately 1/10 C. As charging continues, this value decreases.

Charging time is approximately 15-16 hours. In practice, the method is implemented by charging through a current-setting resistor from a constant voltage source (see for NiCd batteries). A slow charge of 1/10 C is usually safe for any battery.

When charging with constant current, a current value of 1/10 C is maintained throughout the entire charging time. (Fig.1)

Figure 1. Slow charging method for NiCd and NiMH batteries

During charging, the voltage across the battery cell increases.

Upon reaching full charge and when recharging, the voltage begins to decrease.

Reducing the charging time by 2-2.5 times is possible by increasing the current to 0.2 C, but it is necessary to limit the charging time to 6-8 hours.

Fast charge method

A type of slow charge is the fast charge method, which uses a charge current ranging from 0.3 to 1.0 C. But this can cause the battery to overheat, especially at charge currents close to 1 C. To avoid overheating and determine when the battery has finished charging , a thermal fuse and a temperature sensor are built into the latter.

If you measure the voltage at the battery terminals during direct current charging, you will notice that the voltage first slowly increases, and at the point of full charge it will decrease briefly. The magnitude of the decrease is small, approximately 15-30 mV per element for NiCd and 5-10 for NiMH, but is clearly pronounced. This small drop in voltage is taken as the criterion for stopping the charge. In addition, the delta V charging method is almost always accompanied by a temperature measurement, which provides an additional criterion for assessing the state of charge of the battery (and to be sure, chargers for large high-capacity batteries usually also have safety timers).

Figure 2. Delta V charging method for NiCd and NiMH batteries

Figure 2 shows a charge graph with a current of 1 C. After achieving a full charge, the charging current is reduced to 1/30 ... 1/50 C to compensate for the phenomenon of battery self-discharge.

Exist electronic circuits, designed specifically to implement the delta V charge method. For example MAX712 and MAX713. Implementing charging using this method is more difficult and expensive than others, but gives highly reproducible results. At the same time, it should be noted that in a battery with at least one bad element from a chain connected in series, the delta V charge method may not work and lead to the destruction of the remaining elements.

NiMH batteries have specific charging problems. Their delta V value is very small and is more difficult to detect than in the case of NiCd batteries. Therefore, NiMH cell phone batteries have temperature sensors as a backup to detect when they are fully charged.

Another problem with charging with this method is that when used in cars, electrical interference masks the delta V detection and phones mostly control charge based on temperature.

This can damage the battery since the phone is always connected in the car and the engine starts and stops repeatedly. Each time the ignition is turned off for a few minutes and then turned back on, a new charge cycle is initiated.

The Cadex 7000 [ , ] and CASP/2000L(H) battery analyzers use reverse pulse charging methods, in which short discharge pulses are distributed among long charging pulses. It is believed that this charging method improves the recombination of gases generated during the charging process and allows charging with a higher current in less time. In addition, the active surface area of ​​the battery's working substance is restored, thereby eliminating the “memory effect”.

Figure 3 schematically shows the time diagram of the reverse method of charging NiCd and NiMH batteries, implemented in the Cadex 7000 analyzer. Number 1 indicates the load (discharge) pulse, and number 2 indicates the charging pulse.

Figure 3. Reverse charging method for NiCd and NiMH batteries

The magnitude of the reverse load pulse is determined as a percentage of the charge current in the range from 5 to 12%. Optimal value 9%.

Charging method for lithium-ion (Li-ion) batteries

For charge Li-ion batteries use the “constant voltage / D.C.", the essence of which is to limit the voltage on the battery. In this way it is similar to the lead acid (SLA) battery charging method. The main differences are that for Li-ion batteries there is a higher voltage per cell (nominal cell voltage 3.6 V versus 2 V for SLA), a tighter tolerance for this voltage (±0.05 V) and the absence of slow recharging the end of a full charge.

• maximum charge voltage 4.2 or 4.1 volts depending on the battery model;
• end of discharge voltage 3.0 volts;
• recommended charge current is 0.7 C, discharge (load) current is 1 C or less;
• if the battery voltage is less than 2.9 volts, then the recommended charge current is 0.1 C;
• deep discharge may damage the battery (i.e. general rule — Li-ion batteries they like to be in a charged state rather than in a discharged state, and they can be charged at any time without waiting for a discharge);
• As the battery voltage approaches its maximum value, the charging current decreases. The end of the discharge should occur when the charging current decreases to (0.1 ... 0.07) C, depending on the battery model. After charging is complete, the charging current stops completely.
• temperature range when charging is from 0 to 45 degrees Celsius, when discharging from minus 10 to 60 degrees Celsius.

The above data may differ in one direction or another for batteries from other manufacturers.

While SLA batteries allow some flexibility in setting the charge stop voltage, for Li-ion batteries manufacturers are very strict in choosing this voltage. The charge termination voltage threshold for Li-ion batteries is 4.10 V or 4.20 V, installation tolerance for both types is ±0.05 V per cell. For newly developed Li-ion batteries, other values ​​of this voltage will likely be determined. Therefore, chargers for them must be adapted to the required charging voltage.

A higher voltage threshold also ensures higher value capacitance, therefore it is in the manufacturer's interest to select the highest possible voltage threshold without compromising safety. However, this threshold is affected by the temperature of the battery and is set low enough to allow elevated temperatures during charging.

In chargers and battery analyzers that allow you to change the value of this voltage threshold, it correct installation must be observed when servicing any Li-ion type batteries. However, most manufacturers do not indicate the type of Li-ion battery and the end-of-charge voltage. And, if the voltage is set incorrectly, then the battery with more high voltage

will give a lower capacity value, and a battery with a lower one will be slightly overcharged. At moderate temperatures there is no damage to batteries.

This is, as a rule, the reason that a battery charged, for example, in a “native” phone, lasts less or longer than the same battery charged in a desktop charger from an unknown manufacturer.

The increase in battery temperature during charging is insignificant (from 2 to 8 degrees depending on the type and manufacturer) Consumer intervention in any Li-ion charger

The device is not recommended.

Slow recharging at the end of the charge, characteristic of nickel-based batteries, is not used because the Li-ion battery does not tolerate overcharging. Slow charging can cause lithium metallization and lead to cell destruction. Instead, a short-term charge can be applied from time to time to compensate for the small self-discharge of the battery due to the small current consumption of the protective device. Li-ion batteries contain several built-in protection devices: a fuse, a thermal fuse and an internal, which turns off the battery at the lower and upper points of the discharge and charge voltage.

Precautionary measures: Never try to charge lithium batteries! Attempting to charge these batteries may cause an explosion and fire, which will release toxic substances and may cause equipment damage.

Security measures: If the lithium-ion battery ruptures, leaks electrolyte and gets on your skin or eyes, immediately rinse these areas with running water. If electrolyte gets into your eyes, rinse them with running water for 15 minutes and consult a doctor.

When writing this article, materials were used kindly provided by Mr. Isidor Buchmann, founder and head of the Canadian company Cadex Electronics Inc. [—Batteries for mobile devices and laptop computers.

Battery analyzers.

Batteries for mobile devices. Device and main parameters.

Batteries for mobile devices - condition assessment.

Batteries for mobile devices - types, comparative characteristics. In modern household appliances , both for “high technology” and for simple devices

, use lithium-ion, which are distinguished by their simplicity and low cost of production. In addition, one cannot fail to note the good performance characteristics. It is important to understand how to properly charge li-ion batteries, because if this is done incorrectly, the device will not hold a charge for a long time and will soon simply fail. There are several rules that should definitely be taken into account in order for your phone or other device to work longer.

How to charge a li-ion battery? Often modern technology has a device that does not allow the charge to pass to critical levels. If the gadget has a lithium-ion battery, then it should be charged when the battery indicators are 10-20%. In this case, the number of complete charging cycles increases from 600 times to 1700. Another important point – when it is indicated that the charge has reached 100%, do not disconnect the device from the network for another couple of hours. Speaking about how to charge a new li-ion battery, it is worth saying that to increase the service life technical device

, it is recommended to alternate between full and partial charging. If a USB port is used for charging, then the process should take longer.

1. It is recommended to completely discharge the gadget once every three months. Such prevention will prevent the maximum and minimum charge marks from being knocked down. A complete discharge causes the minimum charge value to be reset to zero, and then charging should be carried out for 8-12 hours, this will also reset the maximum value. Thanks to such manipulations, the battery will work better.
2. If the battery will not be used for some time, then it is better to store it with a small amount of charge of 30-50%. It is best if the temperature is approximately 15 degrees. Thanks to this, the battery will be stored without degrading its capabilities. If the battery is fully charged, then most of the capacity may be wasted. After storage, a discharged battery will only need to be thrown away.
3. Talking about how to charge li-ion battery, it is worth replacing that it is important to use only the original device, since the external adapter plays the role of a rectifier and voltage stabilizer. If it is not there, then the battery should be removed and charged using an external device.
4. For lithium-ion batteries, elevated temperatures are detrimental. That is why it is recommended to store the device away from direct sunlight and various heat sources. The permissible temperature range is from -40 to +50 degrees.

Many people today use so-called “frogs” for charging, produced by Chinese manufacturers. You can find messages that such the devices simply caught fire during operation. That is why, before using such universal charger, it is important to reconcile acceptable values which are indicated on the packaging. Pay special attention to the maximum capacity, which is used to judge whether charging will take place or not.

What current should I use to charge a li-ion battery?

In most devices, the nominal voltage on the cell is 3.6 V, so the recommended charge current should be 0.7 C, and the discharge current should not be more than 0.1 C. If the battery operates at a voltage less than 2.9 V, then the current should be 0.1 C.

Modern devices like mobile phones, laptops, tablets, etc. operate from an autonomous power source, which is often a li-ion battery.

The widespread use of this particular type of battery is explained by the simplicity and low cost of its production, as well as excellent performance characteristics and a large supply of discharge-charge cycles. And in order to extend the life of the device and battery, you need to know how to charge a li-ion battery correctly and what mistakes you should not make.

Rules for charging li-ion batteries

For the convenience of users, most batteries are equipped with a special controller that will prevent the charge from going beyond critical levels. So, when the lower discharge limit is reached, the circuit simply stops supplying the device with voltage, and when the maximum permissible charge level is exceeded, the incoming current is turned off.

So, how to properly charge li-ion batteries: you need to recharge the device when the charge level reaches at least 10-20%, and after reaching 100% charge, you need to leave the battery on recharging for another 1.5-2 hours, because In fact, the charge level at this moment will be 70-80%.

Approximately once every 3 months it is necessary to carry out a preventive discharge of the battery. To do this, you need to “land” the battery, and then recharge the completely discharged li-ion battery for 8-12 hours. This will help reset the battery threshold flags. However, frequent discharge to zero is harmful for li-ion batteries.

What current should I use to charge li-ion batteries?

Users often have questions about what current to charge the li-ion battery of a smartphone or other device. This type of battery is charged using the constant voltage/constant current method. The nominal voltage per cell is 3.6 V, and it does not Supports slow recharging after full charging.

The recommended charge current for such batteries is on average 0.7 C, and the discharge current is 0.1 C. If the battery voltage is below 2.9 V, the recommended charge current is 0.1 C. A deep discharge can lead to bad consequences, including battery damage.

You can charge li-ion batteries when you reach any discharge level, without waiting for critical values. During recharging, as the voltage approaches maximum, the charging current decreases. At the end of the charge, the charging current stops completely.

IN given time Li-ion batteries and Li-pol (lithium polymer) batteries are widely used.

The difference between them is the electrolyte. In the first option, helium is used as it, in the second - a polymer saturated with a solution containing lithium. Today, thanks to the popularity of cars with electric motors, there is an urgent question of finding the ideal type of li ion battery that is optimal for such vehicles.

It consists, like other batteries, of an anode (porous carbon) and a cathode (lithium), a separator separating them and a conductor - electrolyte. The discharge process is accompanied by the transition of “anode” ions to the cathode through a separator and electrolyte. Their direction is reversed during charging (picture below).

Ions circulate during the process of discharging and charging the cell between oppositely charged electrodes.

Ion batteries have a cathode made of different metals, which is their main difference. Manufacturers use different materials for electrodes to improve the characteristics of batteries.

But it happens that an improvement in some characteristics leads to a sharp deterioration in others. For example, by optimizing the capacity needed to increase travel time, you can increase power, safety, reduce the negative impact on environment. At the same time, you can reduce the load current, increase the cost or size of the battery.

Get acquainted with the main parameters of different types lithium batteries(lithium-manganese, lithium-cobalt, lithium-phosphate and nickel-manganese-cobalt) can be found in the table:

Rules for electric transport users

The capacity of such batteries practically does not decrease during long-term storage. Li-ion batteries are discharged by only 23% if stored at a temperature of 60 degrees for 15 years. It is thanks to these properties that they are widely used in electric transport technologies.

Lithium-ion batteries that have a full-fledged control system built into the body are suitable for electric transport.

For this reason, during operation, users forget about the basic rules that can extend their service life:

• The battery must be fully charged immediately after purchasing it in the store, since the electrodes are charged by 50% during the production process. Therefore, the available capacity will decrease, i.e. operating time if there is no initial charge;
• the battery should not be allowed to completely discharge in order to preserve its resource;
• The battery must be charged after each trip, even if there is still some charge left;
• Do not heat batteries, as high temperatures contribute to the aging process. In order to make maximum use of the resource, operation must be carried out at the optimal temperature, which is 20-25 degrees. Therefore, the battery cannot be stored near a heat source;
• In cold weather, it is recommended to wrap the battery in a plastic bag with a vacuum seal to store it at 3-4 degrees, i.e. in an unheated room. The charge must be at least 50% of the full charge;
• after the battery has been used at subzero temperatures, it cannot be charged without keeping it at room temperature for some time, i.e. it needs to be warmed up;
• The battery must be charged using the charger supplied in the kit.

There are several subtypes of PU of these batteries - lithium - LiFePO4 (iron - phosphate), using an iron phosphate cathode. Their characteristics allow us to talk about batteries as the pinnacle of technology used for the production of batteries.

Their main advantages are:

• the number of charge-discharge cycles, which reaches 5000 until the capacity decreases by 20%;
• long service life;
• no “memory effect”;
• wide temperature Range with unchanged performance characteristics (300-700 degrees Celsius);
• chemical and thermal stability, increasing safety.

Most widely used batteries

Among the many, the most common are li ion batteries of size 18650, produced by five companies: LG, Sony, Panasonic, Samsung, Sanyo, whose factories are located in Japan, China, Malaysia and South Korea. It was planned that 18650 li ion batteries would be used in laptops. However, thanks to their successful format, they are used in radio-controlled models, electric cars, flashlights, etc.

Like any quality product, such batteries have many counterfeits, therefore, in order to extend the life of the device, you need to purchase only batteries from well-known brands.

Protected and unprotected lithium-ion batteries

It is also important for lithium batteries whether they are protected or not. The operating range of the former is 4.2-2.5V (used in devices designed to work with lithium-ion sources): LED lights, low-power household appliances, etc.

Power tools, bicycles with electric motors, laptops, video and photographic equipment use unprotected batteries controlled by a controller.

What you need to know about lithium-ion batteries?

First of all, the restrictions that must be observed during operation:

• recharge voltage (maximum) cannot be higher than 4.35V;
• its minimum value cannot fall below 2.3 V;
• The discharge current should not exceed more than twice the capacitance value. If the value of the latter is 2200 mAh, the maximum current value is 4400 mA.

Functions performed by the controller

Why do you need a li ion battery charge controller? It performs several functions:

• supplies a current that compensates for self-discharge. Its value is less than maximum current charge, but more than the self-discharge current;
• implements an efficient charge/discharge cycle algorithm for a specific battery;
• compensates for the difference in energy flows when simultaneous charging and providing energy to the consumer. For example, when charging and powering a laptop;
• Measures the temperature when overheating or hypothermia, preventing damage to the battery.

A li ion battery charge controller is manufactured either in the form of a microcircuit built into the battery or as a separate device.

To charge the batteries, it is better to use the standard charger for 18650 li-ion batteries, supplied in the kit. A charger for 18650 lithium batteries usually has a charge level indicator. More often it is an LED that shows when the charge is in progress and when it is finished.

On more advanced devices, you can track on the display the time remaining until the end of the charge and the current voltage. For an 18650 battery with a capacity of 2200mA, the charging time is 2 hours.

But, it is important to know what current to charge a 18650 li ion battery. It should be half the nominal capacity, i.e., if it is 2000 mAh, then the optimal current is 1A. By charging the battery with high current, its degradation quickly occurs. If using low current, it will take longer.

Video: How to charge a Li ion battery charger with your own hands

Diagram of a device for charging batteries

It looks like this:

The circuit is distinguished by its reliability and repeatability, and the included parts are inexpensive and easily accessible. To increase the service life of the battery, proper charging of li-ion batteries is required: towards the end of charging, the voltage should decrease.

After its completion, i.e. When the current reaches zero, charging of the li-ion battery should stop. The circuit given above satisfies these requirements: a discharged battery connected to the charger (VD3 lights up) uses a current of 300 mA.

The ongoing process is indicated by the burning LED VD1. The current gradually decreasing to 30 mA indicates that the battery is charging. The end of the process is signaled by the VD2 LED lighting up.

Used in the circuit operational amplifier LM358N (you can replace it with an analogue of KR1040UD1 or KR574UD2, which differs in the location of the pins), as well as transistor VT1 S8550 9 LEDs of yellow, red and green colors (1.5V).

Is it possible to revive a battery?

After a couple of years of active use, batteries catastrophically lose capacity, creating problems when using your favorite device. Is it possible and how to restore a li ion battery while the user is looking for a replacement?

Restoring a li ion battery is possible temporarily in several ways.

If the battery is swollen, i.e. no longer holds a charge, which means gases have accumulated inside.

Then proceed as follows:

• the battery case is carefully disconnected from the sensor;
• separate the electronic sensor;
• they find a cap with control electronics under it and carefully pierce it with a needle;
• then, find a heavy flat object, larger in area than the area of ​​the battery, which will be used as a press (do not use a vice or similar devices);
• Place the battery on a horizontal plane and press down with a press, remembering that the battery can be damaged by applying excessive force. If it is not enough, the result may not be achieved. This is the most crucial moment;
• All that remains is to drop epoxy resin onto the hole and solder the sensor.

There are other ways, which you can read about on the Internet.

You can select a charger on the website http://18650.in.ua/chargers/.

Video: Li-ion batteries, tips for using li-ion batteries