Correct charging of lithium-ion batteries of smartphones. How to extend the life cycle of lithium-ion (Li-ion) batteries

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If you are interested in how to charge a lithium-ion battery, then you have come to the right place.

Modern mobile devices require an independent power source.

Moreover, this is true for both “ high technology» like smartphones and laptops, and for more simple devices, say, electric drills or multimeters.

There are many different types of batteries. But for portable equipment Li-Ion is most often used.

The relative ease of production and low cost led to such wide distribution.

Excellent performance characteristics, plus low self-discharge and a large reserve of charge-discharge cycles, also contributed to this.

Important! For greater convenience, most of these batteries are equipped with a special monitoring device that prevents the charge from crossing critical levels.

During a critical discharge, this circuit simply stops supplying voltage to the device, and when it exceeds permissible level charge switches off the incoming current.

A phone or tablet with a lithium-ion battery should be charged when the battery level is 10–20%.

Moreover, after reaching the nominal 100%, charging should last another one and a half to two hours.

This is necessary because the battery will actually be charged to 70–80%.

Advice! Approximately once every three months it is necessary to carry out preventive discharge.

When charging from a laptop or desktop computer it must be taken into account that USB port unable to provide sufficiently high voltage, therefore the process will take longer.

Alternating cycles of full and incomplete (80–90%) charging will extend the life of the device.

Despite such a smart architecture and general unpretentiousness, following some rules for using batteries will help extend their life.

To prevent the device’s battery from “suffering”, it is enough to adhere to simple recommendations.

Rule 1. No need to completely discharge the battery

Modern lithium-ion batteries do not have a “memory effect”. Therefore, it is better to charge them before the moment of complete discharge comes.

Some manufacturers measure the service life of their batteries by the number of charge cycles from zero.

The highest quality products can withstand up to 600 such cycles. When charging the battery with 10–20% remaining, the number of cycles increases to 1700.

Rule 2. Complete discharge still needs to be done once every three months.

With unstable and irregular charging, the average maximum and minimum charge levels in the previously mentioned controller are lost.

This leads to the device receiving incorrect information about the amount of charge.

Preventive discharge will help prevent this. When the battery is completely discharged, minimum value charge in the control circuit (controller) will be reset to zero.

After this, you need to charge the battery to capacity, keeping it connected to the network for eight to twelve hours.

This will update maximum value. After such a cycle, the battery operation will be more stable.

Rule 3: An unused battery should be stored with a small amount of charge.

Before storage, it is better to charge the battery by 30–50% and store it at a temperature of 15 0 C. In such conditions, the battery can be stored for quite a long time without much damage.

A fully charged battery will lose a significant portion of its capacity during storage.

And completely discharged ones after long-term storage will only have to be sent for recycling.

Rule 4. Charging must be done only with original devices

It is noteworthy that directly Charger built into the design of a mobile device (phone, tablet, etc.).

In this case, the external adapter acts as a rectifier and voltage stabilizer.

Cameras and video cameras are not equipped similar device. That is why their batteries must be removed and charged during external device.

The use of third-party “charging” can negatively affect their condition.

Rule 5. Overheating is detrimental to Li-Ion batteries

High temperatures have an extremely negative impact on the design of batteries. Low ones are also destructive, but to a much lesser extent.

This must be remembered when operating lithium ion batteries.

The battery must be protected from direct sunlight and used at a distance from heat sources.

The permissible temperature range is between -40 0 C and +50 0 C.

Rule 6. Charging batteries using a “frog”

Using uncertified chargers is unsafe. In particular, the common "frogs" made in China often ignite during charging.

Before using such a universal charger, you must check the maximum instructions on the package. acceptable values.

So, attention must be paid to the maximum capacity.

If the limit is less than the battery capacity, then at best it will not be fully charged.

When the battery is connected, the corresponding indicator on the frog body should light up.

If this does not happen, it means the charge is critically low or the battery is faulty.

When the charger is connected to the network, the connection indicator should light up.

Another diode is responsible for achieving maximum charge, which is activated under appropriate conditions.

How to charge and maintain a lithium ion battery: 6 simple rules

The first lithium-based battery appeared in 1991. But only against the backdrop of popularization mobile phones Li-ion devices have also gained wide popularity. On this moment lithium batteries used wherever required autonomous support operation of electronic or technical device. Batteries provide energy household appliances, power tools, gadgets and various equipment. Due to the low self-discharge threshold, the ability to replenish energy without waiting for the power supply to be completely consumed and the rich resource of Li-ion batteries, they are able to support the operation of devices that require high power.

Lithium battery design

According to the design, Li-ion batteries are produced in prismatic and cylindrical designs. Prismatic batteries are made by stacking rectangular plates on top of each other. Such models provide for more dense packaging compared to cylindrical counterparts, but it is necessary to provide more intense compressive forces against the electrodes. The cylindrical device of a lithium battery is a package with electrodes and a separator, rolled up and enclosed in a metal frame connected to the negative electrode. The positive electrode of the battery is connected to the cover via a special insulator. By the way, the roll assembly principle is also used in some versions of prismatic models in the form of an elliptical spiral. This design combines the advantages of both types of lithium batteries.

Why shouldn’t it be brought to “zero”?

Experts do not recommend using batteries until the energy is completely spent. Lithium devices do not have the memory effect that other types of batteries have. In practice, this means that you need to charge the battery before its level drops to zero. By the way, the number of cycles by which lithium batteries are charged is an indicator of the durability of power sources - manufacturers indicate this figure in the labeling.

For example, for quality models the number of cycles can be 600. In order to increase the service life of the Li-ion battery, it is worth charging the device regularly. The optimal level at which you should start charging is 15%. This measure can increase the number of cycles to 1,100.

How is charging done?

Lithium batteries are charged according to a mixed scheme, that is, first from a direct current of 1C to an average voltage of 4.2 V, and then at a constant voltage level. The primary stage lasts about 40 minutes, and the second - longer. It is worth noting that only modern lithium batteries can be charged at voltages up to 4.2 V. Industrial and military battery models have a longer service life than standard models, as a result of which the threshold for the end of their charge has been pushed back to 3.90 V.

How long does it take to charge?

The process of charging a lithium cell with a 1C current usually takes 2.5 hours. The Li-ion battery fully replenishes energy when its voltage level corresponds to the same cutoff indicators. At the same time, the current should decrease by approximately 3% relative to the initial charge. There is an opinion that lithium batteries charge faster when the current increases. In reality, this is not the case, however, the increased charging current contributes to an increase in voltage, while recharging from the end of the first stage requires more time.

In some types of devices, charging lithium batteries takes less than 1 hour. The reduction in time is due to the fact that the second stage of the cycle is absent and the battery can be used immediately after the completion of the first stage. But there is one caveat: the battery does not completely replenish its energy reserve - it is only 70%.

It would seem, what is the point of such a charging scheme? This approach is beneficial if multiple cycles are required. fast charging. For example, a screwdriver with a lithium battery will require 30 minutes for each operation, after which you can charge the current battery and continue working with a spare one (power tools are usually equipped with two batteries).

Why do you need to overcharge the battery?

It is recommended to start charging before the energy is reduced to zero, however, once a month it is still worth completely discharging. After this, you should use the original charger for lithium batteries in order to replenish the energy 100%. The need for this procedure is due to the characteristics of Li-ion batteries. Experienced users of devices powered by lithium cells may have noticed that the indication of the remaining charge is not always correct. For example, the tablet screen displays that the device is only 50% discharged - in fact, only 10 minutes of active work can drain the battery.

To prevent such inconsistencies, lithium batteries should be completely discharged. As a result, the device will be able to more accurately calculate the capabilities of the power source and reliably display information on the display.

Reducing power consumption during charging

Although the power consumption of mobile devices and other gadgets that require lithium batteries is incomparable in terms of energy consumption with powerful household appliances, some simple tips will help not only save on electricity, but also extend the life of the devices:

Using the capabilities of the device’s software to minimize power consumption.
Disable functions that work unnecessarily. For example, the Internet, various networks and Bluetooth - according to statistics, their combined work can reduce work time devices.
Optimize the device settings - dim the backlight, turn off unnecessary notifications and sound effects will extend the operation of the gadget by 10-15 minutes. This is not much, but in critical situations it will not be superfluous.

Rules for preserving lithium batteries

Durability is one of strengths Li-ion batteries. Thus, the annual reduction in volume as a result of self-discharge is no more than 10%. Despite this, chemical and structural methods for protecting batteries from overheating should be taken into account during operation. If modern lithium batteries have protection against improper charging, temperature effects still pose a danger to them. Therefore, it is recommended to reduce any unnecessary heating of the batteries. However, manufacturers are also working in this direction. The use of cathode elements, in particular, will increase the thermal safety of lithium power supplies.

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. Lithium-ion batteries do not have the so-called memory effect, so they can and, moreover, need to be charged without waiting for them to 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. Full charge over a long period of time is just as harmful to lithium-ion batteries as continuous discharge 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 heat– they cannot tolerate overheating at all. Therefore, do not expose your mobile devices to direct sunlight or place them near 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

From this article you will understand how to properly charge a Li-Ion (lithium-ion) battery, as well as learn its proper operation and maintenance. This kind of knowledge will extend the life of your battery.

The lithium-ion battery has become so widespread due to its ease of production, low cost and a large number charge-discharge cycles. But to appreciate these benefits, it is necessary to use the Li-Ion battery correctly.

Operating instructions vary depending on the type of battery. For example, Ni-MH and Ni-Cd batteries must be completely discharged before charging. Otherwise, the elements become larger and the battery volume decreases. However, the rule “bought a phone - discharge it to zero, and then charge it and repeat the cycle several times” is not universal and does not apply to Li-Ion.

Therefore, before applying the recommendations below, take a look at your battery. It should say that it is lithium-ion (Li-Ion). Only in this case, use the following operating rules.

Do not discharge the battery to zero too often.

It will still not be possible to completely discharge the battery. The protection board turns off the device when a certain minimum is reached. Complete discharge is only possible if you disassemble the battery and remove the protective board. Li-Ion and Li-Pol batteries do not tolerate frequent complete discharge. That's why they are sold 2/3 charged.

Place the device to charge when the battery has 10-20% remaining

A message like “Please connect the charger” appears when the charge reaches 10-20% for a reason. Follow the manufacturers' recommendations and connect the charger.

But you don’t have to wait for such a fall. If you can charge your phone or laptop, do it. Regular charging is not a panacea, but the more often you charge your Li-Ion, the longer it will last.

Calibrate your battery periodically

Calibration implies complete discharge and subsequent charging of the device. There is no contradiction with the first rule: calibration must be done approximately once every three months.

Calibration does not directly extend battery life, but only helps the controller correctly determine the battery capacity. If the controller determines the amount of charge incorrectly, the device will have to be charged more often. Charge-discharge cycles are wasted and the battery fails faster.

Use original charger

Originality in the context of the problem under consideration is needed to protect yourself from using low-quality products. If you are sure that specifications third party device correspond to the characteristics of the original charger, then no problems will arise.

Try not to use "frogs"

If possible, avoid charging batteries using a frog. The use of uncertified devices is unsafe; there are cases when “frogs” ignite during charging.

Lithium batteries (Li-Io, Li-Po) are the most popular rechargeable sources at the moment electrical energy. The lithium battery has a nominal voltage of 3.7 Volts, which is indicated on the case. However, a 100% charged battery has a voltage of 4.2 V, and a discharged one “to zero” has a voltage of 2.5 V. There is no point in discharging the battery below 3 V, firstly, it will deteriorate, and secondly, in the range from 3 to 2.5 It only supplies a couple of percent of energy to the battery. Thus, the operating voltage range is 3 – 4.2 Volts. You can watch my selection of tips for using and storing lithium batteries in this video

There are two options for connecting batteries, series and parallel.

At serial connection the voltage on all batteries is summed up when a load is connected from each battery current is flowing, equal total current in a chain, in general resistance load sets the discharge current. You should remember this from school. Now comes the fun part, capacity. The capacity of the assembly with this connection is fairly equal to the capacity of the battery with the smallest capacity. Let's imagine that all batteries are 100% charged. Look, the discharge current is the same everywhere, and the battery with the smallest capacity will be discharged first, this is at least logical. And as soon as it is discharged, it will no longer be possible to load this assembly. Yes, the remaining batteries are still charged. But if we continue to remove the current, then our weak battery will begin to overdischarge and fail. That is, it is correct to assume that the capacity of a series-connected assembly is equal to the capacity of the smallest or most discharged battery. From here we conclude: to assemble a series battery, firstly, you need to use batteries of equal capacity, and secondly, before assembly, they all must be charged equally, in other words, 100%. There is such a thing called BMS (Battery Monitoring System), it can monitor each battery in the battery, and as soon as one of them is discharged, it disconnects the entire battery from the load, this will be discussed below. Now as for charging such a battery. It needs to be charged with a voltage equal to the amount maximum stress on all batteries. For lithium it is 4.2 volts. That is, we charge a battery of three with a voltage of 12.6 V. See what happens if the batteries are not the same. The battery with the smallest capacity will charge the fastest. But the rest have not yet charged. And our poor battery will fry and recharge until the rest are charged. Let me remind you that lithium also does not like overdischarge very much and deteriorates. To avoid this, recall the previous conclusion.

Let's move on to parallel connection. The capacity of such a battery is equal to the sum of the capacities of all batteries included in it. The discharge current for each cell is equal to the total load current divided by the number of cells. That is, the more Akum in such an assembly, the more current it can deliver. But what happens with tension? interesting thing. If we collect batteries that have different voltage, that is, roughly speaking, charged to different percentages, then after connection they will begin to exchange energy until the voltage on all cells becomes the same. We conclude: before assembling, the batteries must again be charged equally, otherwise, when connected, large currents will flow, and the discharged battery will be damaged, and most likely may even catch fire. During the discharge process, the batteries also exchange energy, that is, if one of the cans has a lower capacity, the others will not allow it to discharge faster than themselves, that is, in a parallel assembly you can use batteries with different capacities. The only exception is when working high currents. On different batteries under load, the voltage drops differently, and current will start flowing between the “strong” and “weak” batteries, and we don’t need this at all. And the same goes for charging. You can absolutely safely charge batteries of different capacities in parallel, that is, balancing is not needed, the assembly will balance itself.

In both cases considered, the charging current and discharge current must be observed. The charging current for Li-Io should not exceed half the battery capacity in amperes (1000 mah battery - charge 0.5 A, 2 Ah battery, charge 1 A). The maximum discharge current is usually indicated in the datasheet (TTX) of the battery. For example: 18650 laptops and smartphone batteries cannot be loaded with a current exceeding 2 battery capacities in Amperes (example: a 2500 mah battery, which means the maximum you need to take from it is 2.5 * 2 = 5 Amps). But there are high-current batteries, where the discharge current is clearly indicated in the characteristics.

Features of charging batteries using Chinese modules

Standard purchased charging and protection module for 20 rubles for lithium battery ( link to Aliexpress)
(positioned by the seller as a module for one 18650 can) can and will charge any lithium battery, regardless of shape, size and capacity to the correct voltage of 4.2 volts (the voltage of a fully charged battery, to capacity). Even if it's a huge 8000mah lithium pack (of course we're talking about about one cell at 3.6-3.7v). The module gives charging current 1 ampere, this means that they can safely charge any battery with a capacity of 2000mAh and above (2Ah, which means the charging current is half the capacity, 1A) and, accordingly, the charging time in hours will be equal to the battery capacity in amperes (in fact, a little more, one and a half to two hours for every 1000mah). By the way, the battery can be connected to the load while charging.

Important! If you want to charge a smaller capacity battery (for example, one old 900mAh can or a tiny 230mAh lithium pack), then the charging current of 1A is too much and should be reduced. This is done by replacing resistor R3 on the module according to the attached table. The resistor is not necessarily smd, the most ordinary one will do. Let me remind you that the charging current should be half the battery capacity (or less, no big deal).

But if the seller says that this module is for one 18650 can, can it charge two cans? Or three? What if you need to assemble a capacious power bank from several batteries?
CAN! All lithium batteries can be connected in parallel (all pluses to pluses, all minuses to minuses) REGARDLESS OF CAPACITY. Batteries soldered in parallel maintain an operating voltage of 4.2v and their capacity is added up. Even if you take one can at 3400mah and the second at 900, you will get 4300. The batteries will work as one unit and will discharge in proportion to their capacity.
The voltage in a PARALLEL assembly is ALWAYS THE SAME ON ALL BATTERIES! And not a single battery can physically discharge in the assembly before the others; the principle of communicating vessels works here. Those who claim the opposite and say that batteries with a lower capacity will discharge faster and die are confused with SERIAL assembly, spit in their faces.
Important! Before connecting to each other, all batteries must have approximately the same voltage, so that at the time of soldering, equalizing currents do not flow between them; they can be very large. Therefore, it is best to simply charge each battery separately before assembly. Of course, the charging time of the entire assembly will increase, since you are using the same 1A module. But you can parallel two modules, obtaining a charging current of up to 2A (if your charger can provide that much). To do this, you need to connect all similar terminals of the modules with jumpers (except for Out- and B+, they are duplicated on the boards with other nickels and will already be connected anyway). Or you can buy a module ( link to Aliexpress), on which the microcircuits are already in parallel. This module is capable of charging with a current of 3 Amps.

Sorry for the obvious stuff, but people still get confused, so we'll have to discuss the difference between parallel and serial connections.
PARALLEL connection (all pluses to pluses, all minuses to minuses) maintains the battery voltage of 4.2 volts, but increases the capacity by adding all the capacities together. Applies to all power banks parallel connection several batteries. Such an assembly can still be charged from USB and the voltage is raised to an output of 5v by a boost converter.
CONSISTENT connection (each plus to minus of the subsequent battery) gives a multiple increase in the voltage of one charged bank 4.2V (2s - 8.4V, 3s - 12.6V and so on), but the capacity remains the same. If three 2000mah batteries are used, then the assembly capacity is 2000mah.
Important! It is believed that for sequential assembly it is strictly necessary to use only batteries of the same capacity. Actually this is not true. You can use different ones, but then the battery capacity will be determined by the SMALLEST capacity in the assembly. Add 3000+3000+800 and you get an 800mah assembly. Then the specialists begin to crow, which then is less capacious battery will discharge faster and die. But it doesn’t matter! The main and truly sacred rule is that for sequential assembly it is always necessary to use a BMS protection board for the required number of cans. It will detect the voltage on each cell and turn off the entire assembly if one discharges first. In the case of an 800 bank, it will discharge, the BMS will disconnect the load from the battery, the discharge will stop and the residual charge of 2200mah on the remaining banks will no longer matter - you need to charge.

The BMS board, unlike a single charging module, IS NOT A sequential charger. Needed for charging configured source of the required voltage and current. Guyver made a video about this, so don’t waste your time, watch it, it’s about this in as much detail as possible.

Is it possible to charge a daisy chain assembly by connecting several single charging modules?
In fact, under certain assumptions, it is possible. For some homemade products, a scheme using single modules, also connected in series, has proven itself, but EACH module needs its own SEPARATE POWER SOURCE. If you charge 3s, take three phone chargers and connect each to one module. When using one source - short circuit on nutrition, nothing works. This system also works as protection for the assembly (but the modules are capable of delivering no more than 3 amperes). Or, simply charge the assembly one by one, connecting the module to each battery until fully charged.

Battery charge indicator

Another pressing problem is to at least know approximately how much charge remains on the battery so that it does not run out at the most crucial moment.
For parallel 4.2-volt assemblies, the most obvious solution would be to immediately purchase a ready-made power bank board, which already has a display showing charge percentages. These percentages aren't super accurate, but they still help. The issue price is approximately 150-200 rubles, all are presented on the Guyver website. Even if you are not building a power bank but something else, this board is quite cheap and small to fit into a homemade product. Plus, it already has the function of charging and protecting batteries.
There are ready-made miniature indicators for one or several cans, 90-100 rubles
Well, the cheapest and folk method is to use a boost converter MT3608 (30 rubles), configured to 5-5.1v. Actually, if you make a power bank using any 5-volt converter, then you don’t even need to buy anything additional. The modification consists of installing a red or green LED (other colors will work at a different output voltage, from 6V and higher) through a 200-500 ohm current-limiting resistor between the output positive terminal (this will be a plus) and the input positive terminal (for an LED this will be a minus). You read that right, between two pluses! The fact is that when the converter operates, a voltage difference is created between the pluses; +4.2 and +5V give each other a voltage of 0.8V. When the battery is discharged, its voltage will drop, but the output from the converter is always stable, which means the difference will increase. And when the voltage on the bank is 3.2-3.4V, the difference will reach the required value to light the LED - it begins to show that it is time to charge.

How to measure battery capacity?

We are already accustomed to the idea that for measurements you need an Imax b6, but it costs money and is redundant for most radio amateurs. But there is a way to measure the capacity of a 1-2-3 can battery with sufficient accuracy and cheaply - a simple USB tester.