Charger for 3.7 volts batteries. MAX1555. USB charger for Li-Po battery. How to charge lithium-ion batteries

Publikovano 23.06.2012

The battery is a lithium-ion - the thing is not new and many of the ways to charge it. I will describe a practical example of a charm of a single-bounte (3.7V) Li-Po. battery using food USBconnector. Charging USB - this is the most convenient way for mobile devices and appliances.

But, before describing the charger scheme, consider the batteries themselves. Exist simple batteries, sort of such:

And batteries with a built-in charge controller. A controller is performed as a tiny board soldered to the battery conclusions. Please note that such batteries usually have contacts in the form of wires.

Indeed - this is logical: to supply the battery controller charge. Let slightly more expensive, but how much less hassle. But what lies under this title: "Charge controller"?

This is just a battery protection chip from overvoltage, excessive discharge and short circuit. The essence of its actions is simple - with extended voltages or current, the chip turns off the transistor key, disconnecting the battery from the chain. Sometimes there is a voltage of 0V at the output of such a battery. Do not be scared, it does not mean that the battery "died." Just the battery was discharged to the lower limit and the charge controller turned off it. It is enough to charge it.

How to charge such batteries? Answer: just like Li-Po. Battery without charge controller. Li-Po. Battery with charge controller is just a battery with additional protection. What battery is better - choose to you. But you must remember that Li-Po. The battery is afraid of excessive charge and excessive discharge. And if the problem with an excessive charge is solved by the charger, the probability of discharge the battery below the permissible limit is forced to apply Li-Po. Battery with charge controller.

Thus, we decided that both options Li-Po. Accumulators - and with charge controller and without it - require a special charger. What will happen if Li-Po. Battery stupid to stick to 5V power USB? You will be surprised, but the battery charges! Although the process of charging is not called normal, and with such charging the battery will not live for a long time. Moreover Li-Po. Battery with charge controller with full charge will turn off (protection will work). Although by this time the battery is pretty pretty, nothing terrible, may not happen. But without charge controller, the battery can end up life in a bright flash, and burn your computer, or where you get it there, along with the house / office / factory.

There is a cheap "Chinese" way to charge Li-Po. Battery (but only with charge controller!) Through a current-limiting resistor. And parallel to the resistor include the LED. The LED goes out with full charge. Those. When protecting protection. This method is used in children's Chinese toys, when moving / flying / floating toy is charged from the battery of the remote control unit. This method is suitable if your uncle works on the battery factory, and you have these batteries "well, they just went out" (c). We also reject it, although ... no: still reject. We are not Chinese and uncle on the rechargeable factory we have no! And we love the users of our devices, so, charge Li-Po. Battery We will be correct.

Simple battery llipo charging scheme:

For this we take a special chip and turn it on as indicated in. Please note that the microcircuit has two inputs - USB (3.7-6V) and DC (3.7-7V) To connect the DC power supply. Those. At least straightened.

I made a small test scarf for. The LED glows while the charge goes and goes well when charging the battery is completed. If the battery is not connected, the LED does not burn.

As a result, we have a miniature charger for Li-Po. batteries. Such a scheme can be built on the fee of your device and charge it from USB. In combination with Li-Po. Battery with charge controller Get a complete protection device Li-Po. Battery and correct charger. Long years of service Li-Po.!

Over-compact charging for lithium batteries as 1s (3.7V / 4.2B) and 2s (7.4 / 8.4B) - first of all, for all sorts of photo-video techniques and different lanterns that do not have their own built-in "carcass" Charging (as well as for charging additional batteries). The range of input voltages 5-18B (required so that at the input voltage is at least 1B higher than the voltage on the charging battery).

Charge current:

• for 3.7V - 0.75A
• for 7.4B - 1A

These charge currents are optimally universal (and most importantly, safe !!!) for the overwhelming majority of batteries of any photo-video cameras.

To assess the dimensions in the photo is a ruble coin :)

Waterproof performance. Protection against short circuit and crooked polarity (really works - I checked it yourself! :)

For "subjects" to battery contacts, customizable clamping contacts from the "Ketai frog" are used. There is an opportunity (with difficulty "subject" due to the battery design), change places plus and minus the contacts "Frog".

Well, naturally, there are always options to connect to the accumulator contacts "Alternatively", for example, by fixing the conductors using an elastic band or isol :)

For batteries with "very hit-up" contacts (and this, as a rule, Sony batteries) additionally attached the wiring detachable in order to slightly "upgrade" the original charger - to fall this connector to the output contacts of the original charging.

Switching between 3.7V and 7.4B is made by opening or closing the wiring (see photo). The condition is closed - 7.4V, open - 3.7V (this information is also "drawn" on the board, for forgetful :)

The output connector from the board (which is to the battery) is made by me compatible with the whole family of universal type charges imax (Dad connector of type Deans. , he is T-plug. ) - i.e. can be used at home (and in the car) imax (With the same "frog" and other contacts), and in purely hiking - for lightness and compactness, just take this scarf instead of Imax, the size of a little more ruble coin :)

Important note:

This charge charge has one feature (this is rather a "bug", but "Fich" - but you need to take into account) - she has a very slow the final part of the charging (CV - Constant Voltage). Roughly speaking, about 98% of the battery capacity charging is perfectly simply (within the framework of the indicated currents), but the final "impetitive" - \u200b\u200bsooooo slowly! Those. From the moment when the battery is already charged, and before the lighting of the LED indicator, signaling about the end of the charge, can take a very long time!

And in some cases (basically, it concerns the batteries of 7.4V from the photo-video), it is possible and not to wait for the lighting of the LED - as, for example, in the battery of my pentakovskaya mirror ... The fact is that in its battery there is a balancing board, "Balancing "Voltage up to 8.3V - while charging fee is waiting for an estimate of 8.4V :) And in the end, it does not wait for it ... :)

How to deal with it? Yes very easy!

First, you can simply estimate the charging time (and the charging current is known to us, the battery capacity is also written on it). For example, I charge the battery with a voltage of 7.4B (7.2V or 8.4B designations - it's all the same :) and a capacity of 1600mAh. Accordingly, with a charge current about 1a, the battery can be considered after an hour and a half.

Secondly, you can simply touch the throtsel on the charge charge (this is such a large square-round item on the board, the largest of all the details :) if it is warm to the touch, then active charging continues. But if its temperature differs little from the total temperature of the entire board (it is clearly not felt by the finger), it means that the active charging is over, and you can safely disconnect the battery.

Here the main thing is to remember the simple truth: a small underwear for lithium-ion batteries is not only not harmful, but everything is exactly the opposite, it is very useful to increase their service life !!! So do not be afraid lithium batteries Undertaking, we can only reload (fortunately, this charge charge does not allow this :)

Lithium battery (Li-Io, Li-Po) are the most popular currently rechargeable sources of electrical energy. A lithium battery has a rated voltage of 3.7 volts, it is indicated on the housing. However, a charged 100% battery has a voltage of 4.2 V, and the discharged "in zero" - 2.5 B, there is no point in discharge the battery below 3 V, first, it will deteriorate from this, secondly, in the interval from 3 to 2.5 In the battery gives just a couple of percent of energy. Thus, the working voltage range is accepted 3 - 4.2 volts. My selection of lithium batteries, you can see this selection and storage of lithium batteries.

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

With a serial connection, a voltage on all batteries is summed up, when the load is connected from each battery, a current equal to a total current in the circuit is in general the load resistance sets the discharge current. This you must remember from school. Now the most interesting, container. The assembly capacity with such a connection for a good equal to the battery capacity with the smallest container. Imagine that all batteries are charged 100%. See, the discharge current here is the same everywhere, and the first battery with the smallest capacity is first, it is at least logical. And as soon as it is discharged, it will be impossible to load this assembly. Yes, the remaining batteries are still charged. But if we continue to pull the current, then our weak battery will begin to be redesigned, and fails. That is, it is correct to assume that the tank of the connected assembly is equal to the tank of the very tight, or the most discharged battery. From here we conclude: it is necessary to collect a sequential battery at first of the same batteries on the capacity, and secondly, before assembly, they should all be charged the same, simply speaking by 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 turns off the entire battery from the load, this will be discussed below. Now it concerns charging such a battery. It is necessary to charge it with a voltage equal to the sum of maximum voltages on all batteries. For lithium it is 4.2 volts. That is, the battery of three is charged with a voltage of 12.6 V. See what happens if the batteries are not the same. The battery with the smallest capacity will be charged faster. But the rest are still not charged. And our poor battery will be fried and recharge until the rest are charged. Referee, I remind you, lithium also does not like very much and flies. To avoid this, remember the previous conclusion.

Let us turn to the parallel connection. The capacity of such a battery is equal to the sum of the containers of all batteries in it incoming. The discharge current for each cell is equal to the total current of the load shared by the number of cells. That is, the more Akumov in such an assembly, the greater the current it can give. But with a voltage there is an interesting thing. If we collect batteries that have different voltages, that is, roughly speaking charged to a different percentage, then after the connection they will begin to exchange energy until the voltage on all cells becomes the same. We conclude: Before assembling akuma, again, they must be charged the same, otherwise there will be big currents when the connection will be departed, and the discharged Akum will be spoiled, and most likely can even light up. In the process of discharge, the batteries also exchange energy, that is, if one of the cans has a lower capacity, the rest will not be able to discharge them faster themselves, that is, in a parallel assembly, you can use batteries with a different container. The only exception is to work at high currents. On the different batteries Under the load, the voltage is different in different ways, and the current will start running between the "strong" and "weak" akum, and we do not need it at all. And the same applies to charging. You can absolutely calmly charge different batteries in parallels, that is, the balancing is not needed, the assembly will balance itself.

In both cases considered, the charging current and discharge current must be observed. 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 specified in the datashet (TTX) battery. For example: laptop 18650 and batteries from smartphones can not be shipped with current exceeding 2 battery capacity in amperes (example: AKUM at 2500 mAh, it means that the maximum you need to take 2.5 * 2 \u003d 5 amps). But there are high-strength batteries, where the discharge current is explicitly specified in the characteristics.

Features of charging batteries by Chinese modules

Standard purchased charging and protective module for 20 rubles for lithium battery ( link to Aliexpress.)
(Positioned by the Seller as a module for one bank 18650) maybe it will charge any lithium battery, regardless of the form, size and container Prior to the correct voltage of 4.2 volts (voltage of a fully charged battery, under the string). Even if it is a huge lithium package for 8000mAh (of course it is about one cell by 3.6-3.7V). The module gives a charging current of 1 ampThis means that they can be charged without fears to charge any battery with a capacity of 2000mAh and higher (2Ah, which means the charging current - half the tank, 1a) and, accordingly, charging time in the clock will be equal to the battery capacity in amps (actually a little more, one and a half or two hour for every 1000mAh). By the way the battery can be connected to the load during the charge.

Important! If you want to charge a smaller capacity battery (for example, one old jar at a 900mAh or a tiny lithium bag at 230mAh), then the charging current 1a is a lot, it should be reduced. This is done by replacing the R3 resistor on the module according to the applied table. The resistor is optional to SMD, the most common one will suit. I remind you that the charging current should be half of the battery capacity (or less, not scary).

But if the seller says that this module for one bank is 18650, can they charge two banks? Or three? What if you need to assemble the capacious PowerBank from several batteries?
CAN! All lithium batteries can be connected in parallel (all the advantages to the advantages, all cons by cons) regardless of the tank. Speeded parallel batteries retain the operating voltage of 4.2V and their container is developing. Even if you take one jar at 3400mAh and the second to 900 - it turns out 4300. Batteries will work as one whole and discharge will be proportional to its container.
The voltage in the parallel assembly is always the same on all batteries! And no battery can physically be discharged in the assembly before others, the principle of reporting vessels works here. Those who claim the opposite and say that the batteries with a smaller capacity are discharged faster and die - confused with a consistent assembly, spit them into the face.
Important! Before connecting to each other, all batteries must have about the same voltage, so that equation currents are not flowed between them, they can be very large. Therefore, it is best before assembling simply charge each battery separately. Of course, the time for charging the entire assembly will increase, since you use the same module on 1a. But you can spararal the two modules by receiving the charging current to 2a (if your charger can give so much). To do this, it is necessary to connect with jumpers all similar terminals of the modules (except Out- and B +, they are duplicated on cards by other fives, and so will be connected). Or you can buy a module ( link to Aliexpress.), where chips are already in parallel. This module is able to charge a current of 3 amps.

Sorry for completely obvious things, but people are still confused, so you have to discuss the difference between the parallel and consistent compound.
Parallel Compound (all the advantages to the pros, all cons by cons) retains 4.2 volt battery voltage, but increases the container, folding all the containers together. All Power Banks use a parallel connection of several batteries. Such an assembly can still be charged from a USB and the voltage increases up to the output 5V.
Consistent The compound (each plus to minus 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 container remains the same. If three batteries are used for 2000mAh, the assembly capacity is 2000mAh.
Important! It is believed that for consistent assembly, it is necessary to use only the batteries of the same container. In fact, it is not. You can use different, but then the battery capacity will be determined by the smallest tank in the assembly. Fold 3000 + 3000 + 800 - get an assembly to 800mAh. Then the specialists begin to sway that the less capacious battery will be quickly discharged and die. And it does not matter! The main and truly sacred rule - for consistent assembly always and necessarily you need to use the BMS protection fee for the desired number of cans. It will determine the voltage on each cell and turn off the entire assembly if some kind of discharge is first. In the case of a bank for 800, it will also be discharged, bms will turn off the load from the battery, the discharge will stop and the residual charge of 2200mAh on the rest of the banks will not be valid - it is necessary to charge.

The BMS fee in contrast to the single charging module is not a sequential assembly charger. For charging need configured source of the desired voltage and current. About this gamever shot a video, so do not waste time, look at it, there is much thoroughly about it.

Is it possible to charge a consistent assembly by connecting multiple single charging modules?
In fact, with some assumptions - it is possible. For some homemakes, a scheme has proven to use single modules connected also in series, but for each module, a separate power supply is needed. If you charge 3s - take three telephone charging and connect each one to one module. When using one source - nutrition short circuit, nothing works. Such a system also works and how the assembly protection (but the moduli is able to give no more than 3 amps) or simply charge the assembly shipping, connecting the module to each battery to a complete charge.

Accumulator charge indicator

Also a pressing problem - at least approximately know how many percent of the charge remains on the battery so that it does not discharge in the most responsible moment.
For parallel assemblies by 4.2 volts, the most obvious solution will immediately purchase a ready-made PowerBank fee, which already has a display that displays the charge percentage. These percentages are not super-accurate, but still help. The issue price is approximately 150-200rub, all are presented on the website of the Gaiver. Even if you are collecting not Powerbank and something else, this fee is quite cheap and small to place it in the homemade. Plus it already has a battery protection and protection function.
There are ready-made miniature indicators on one or more cans, 90-100r
Well, the cheapest and folk method is to use the MT3608 increasing converter (30 rubles), configured by 5-5.1V. Actually, if you make Powerbank on any 5 volt transmitter, then you don't even need to buy anything. The revision is to install a red or green LED (other colors will operate on another output voltage, from 6V and above) through a current-limiting resistor 200-500 between the output plus terminal (it will be plus) and the input plus (for the LED it will turn out to be minus). You are not mistaken, between two pluses! The fact is that during the operation of the converter between the advantages, the difference of voltage is created, +4.2 and + 5V, the voltage is 0.8V. When the battery discharge, its voltage will fall, and the output from the converter is always stable, then the difference will increase. And at a voltage on a bank, 3.2-3,26VI, the difference will reach the necessary value to light the LED - it begins to show that it is time to charge.

How to measure the capacity of batteries?

We are already accustomed to the belief that Iamaks B6 needs for measurement, and it costs money and for most radio amateurs is excessive. But there is a way to measure the capacity of 1-2-3bachal batteries with sufficient accuracy and cheaply - a simple USB tester.

Assessment of the characteristics of a particular charger is difficult without an understanding of how the exemplary charge Li-ion battery should actually flow. Therefore, before proceeding directly to the schemes, let's remember the theory a little.

What are lithium batteries

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

• with cobeda of cobaltat lithium;
• with cathode based on lithium iron phosphate;
• based on nickel-cobalt aluminum;
• based on nickel-cobalt-manganese.

All these batteries have their own characteristics, but since for a wide consumer, these nuances have no fundamental importance, in this article they will not be considered.

All Li-Ion batteries are also produced in various sizes and form factors. They can be both in a housing design (for example, 18650 popular today) and in laminated or prismatic design (gel polymer batteries). The latter are hermetically sealed packages made of special films in which electrodes and electrode mass are located.

The most common sizes of Li-Ion batteries are shown in the table below (they all have a rated voltage of 3.7 volts):

Internal electrochemical processes proceed equally and do not depend on the form factor and the execution of the AKB, so everything that has been said is equally applied to all lithium batteries.

How to charge lithium-ion batteries

The most correct way of charge lithium batteries is charged in two stages. This method uses Sony in all its chargers. Despite the more complex charge controller, it provides a more complete charge of Li-Ion batteries, without reducing their service life.

Here we are talking about a two-step charge profile of lithium batteries, shortcutly referred to as CC / CV (Constant Current, Constant Voltage). There are still options with hypertices and speed currents, but in this article they are not considered. Read more about charging pulse current you can read.

So, consider both stages of charge.

1. At the first stage A constant charge current must be provided. The value of the current is 0.2-0.5c. For an accelerated charge, an increase in current is allowed to 0.5-1.0 ° C (where C is the battery capacity).

For example, for a battery with a capacity of 3000 m / h, the rated charge current at the first stage is 600-1500 mA, and the current charge current may lie within 1.5-3A.

To ensure permanent charging current of a given value, the charger diagram (memory) should be able to raise the voltage on the battery terminals. In fact, at the first stage, it works as a classic current stabilizer.

Important: If you plan to charge batteries with a built-in protection board (PCB), then when designing a memory scheme you need to make sure that the voltage idle move Schemes can never exceed 6-7 volts. Otherwise, the protection board may fail.

At a time when the voltage on the battery rises to the value of 4.2 volts, the battery drops approximately 70-80% of its capacitance (the specific value of the capacity will depend on the charge current: with an accelerated charge it will be slightly smaller, at a nominal one - a little more). This moment is the end of the first stage of the charge and serves as a signal to move to the second (and last) stage.

2. The second stage of charge - This is the battery charge constant tensionBut gradually declining (falling) current.

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

As the tank set, the charging current will decrease. As soon as its value decreases to 0.05-0.01С, the charge process is considered to be completed.

An important nuance of the proper charger is its complete shutdown from the battery after the end of charging. This is due to the fact that for lithium batteries is extremely undesirable to their long-term detection under increased voltage, which usually provides memory (i.e. 4.18-4.24 volts). This leads to accelerated degradation of the chemical composition of the battery and, as a result, reducing its capacity. Under long finding is meant tens of hours or more.

During the second stage of charge, the battery has time to score more than about 0.1-0.15 of its capacitance. The overall charge of the battery thus reaches 90-95%, which is an excellent indicator.

We looked at the two main stages of charge. However, the coverage of the charge of lithium batteries would be incomplete if another charge stage was not mentioned - so-called. Prepare.

Preliminary Charge Stage (Prepare) - This stage is used only for deeply discharged batteries (below 2.5 V) to output them to normal operational mode.

At this stage, the charge is ensured dC reduced values \u200b\u200buntil the voltage on the battery reaches 2.8 V.

The preliminary stage is necessary to prevent intimidation and depressurization (or even an explosion with fire) damaged batteries having, for example, internal short circuit between the electrodes. If through such a battery immediately skip a high charge current, it will inevitably lead to healing it, and then how lucky.

Another benefit of the prerequisite is pre-warming the battery, which is relevant when charging at low ambient temperatures (in the unheated room during the cold season).

Intelligent charging should be able to control the voltage on the battery during the preliminary stage of the charge and, if the voltage does not rise long time, make an output of the battery malfunction.

All stages of charge lithium-ion battery (including the prerequisite stage) are schematically depicted on this schedule:

Excess of the nominal charging voltage by 0.15V can reduce battery life twice. A decrease in the charge voltage by 0.1 volts reduces the capacity of the charged battery by about 10%, but significantly extends its service life. The voltage of the fully charged battery after removing it from the charger is 4.1-4.15 volts.

Summarize the above, we denote the basic theses:

1. What is the current to charge the Li-Ion battery (for example, 18650 or any other)?

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

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

2. How much time needs to be charged, for example, the same accumulatory batteries 18650?

The charge time directly depends on the charge current and is calculated by the formula:

T \u003d C / I ZA.

For example, the charge time of our accumulator with a capacity of 3400 mA / h current in 1a will be about 3.5 hours.

3. How to charge a lithium-polymer battery correctly?

Any lithium batteries charge the same. It does not matter, lithium-polymer he or lithium-ion. For us, consumers, there is no difference.

What is the protection board?

The protection board (or PCB - POWER Control Board) is designed to protect against short circuit, reloading and redevelopment of a lithium battery. As a rule, overheating protection is also built into the protection modules.

In order to comply with safety, the use of lithium batteries in household appliances is prohibited if the protection fee is not built into them. Therefore, in all batteries from cell phones there is always a PCB fee. Output terminals of the battery are placed right on the board:

These boards use a six-legged charge controller on a specialized microme (JW01, JW11, K091, G2J, G3J, S8210, S8261, NE57600, etc. Analogs). The task of this controller is to disconnect the battery from the load when the battery is fully discharged and shutting down the battery from charging upon reaching 4.25V.

Here, for example, a BP-6M battery protection circuit, which supplied old Nokiev phone phones:

If we talk about 18650, they can be released as a protection fee so without it. The protection module is located in the area of \u200b\u200bthe minus battery terminal.

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

Batteries without a PCB module are usually included in batteries completed with their own protection schemes.

Any battery with protection is easily turning into a battery without protection, just just jump it.

To date, the maximum capacity of the accumulator 18650 is 3400 mA / h. Batteries with protection necessarily have a corresponding designation on the housing ("Protected").

Do not confuse PCB fee with PCM module (PCM - Power Charge Module). If the first serve only the targets for protecting the battery, then the second are designed to control the charge process - 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 the charge controller.

I hope now there are no questions left, how to charge a 18650 battery or any other lithium? Then we turn to a small selection of ready-made schematic solutions of chargers (those most charge controllers).

Battery Li-Ion Charge Schemes

All schemes are suitable for charging any lithium battery, it remains only to determine the charging current and an element base.

LM317.

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

The simplest scheme, the entire setting is reduced to the installation of the output voltage of 4.2 volts using the R8 stroke resistor (without a connected battery!) And the charge current installation by selecting resistors R4, R6. The power of the resistor R1 is at least 1 watt.

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

The LM317 microcircuit is widely used in various voltage and current stabilizers (depending on the inclusion circuit). Sold on every corner and stands at all a penny (you can take 10 pcs. Total for only 55 rubles).

LM317 happens in different buildings:

Purpose of conclusions (Cocolevka):

Analogues of the LM317 chip are: GL317, SG31, SG317, UC317T, ECG1900, LM31MDT, SP900, KR142EN12, KR1157EN1 (last two - domestic production).

Charging current can be increased to 3A if instead of LM317 take LM350. She, however, will be more expensive - 11 rubles / pcs.

The printed circuit board and the collection scheme are shown below:

The old Soviet transistor Kt361 can be replaced by similar P-N-P Transistor (for example, KT3107, CT3108 or Bourgeois 2N5086, 2SA733, BC308A). It can be removed at all if the charge indicator is not needed.

Lack of scheme: supply voltage must be within 8-12V. This is due to the fact that for normal operation of the LM317 chip, the difference between the battery voltage and the supply voltage should be at least 4.25 volts. Thus, the USB port will not be powered.

MAX1555 or MAX1551

MAX1551 / MAX1555 - specialized chargers for Li + batteries that can work from USB or from a separate power adapter (for example, a charger from the phone).

The only difference between these chips - max1555 gives a signal for the charge indicator, and MAX1551 is the signal that power is enabled. Those. 1555 In most cases, it is still preferable, so 1551 is already difficult to find on sale.

Detailed description of these chips from the manufacturer.

The maximum input voltage from the DC adapter is 7 V, when powered by USB - 6 V. When a supply voltage is reduced to 3.52 V, the chip is disconnected and the charge stops.

The microcircuit itself detects at what input is the supply voltage and connects to it. If the power goes according to the USB bus, the maximum charge current is limited to 100 mA - it allows you to push the charger to the USB port of any computer without fear of burning the southern bridge.

When powered from a separate power supply, the typical value of the charging current is 280 mA.

In the microcircuits are built-in overheating protection. But even in this case, the scheme continues to operate, reducing the charge current by 17 mA per degree above 110 ° C.

There is a pre-charge function (see above): until the voltage on the battery is below 3V, the chip limits the charge current at 40 mA.

The microcircuit has 5 conclusions. Here is a typical inclusion scheme:

If there is a guarantee that at the output of your adapter, the voltage must not be able to exceed 7 volts, then you can do without a 7805 stabilizer.

USB charging option can be collected, for example, on such.

The chip does not need external diodes, nor in external transistors. In general, of course, gorgeous microhi! Only they are small too, to solder uncomfortable. And still cost ().

LP2951.

The LP2951 stabilizer is made by National Semiconductors (). It provides the implementation of the built-in current limit function and allows you to form a stable level of charge voltage level of a lithium-ion battery at the output scheme.

The value of the charge voltage is 4.08 - 4.26 volts and is set to the R3 resistor when the battery is disconnected. Voltage is very accurate.

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

Diode apply with low reverse current. For example, it can be any of the 1N400X series, which will be able to purchase. The diode is used as blocking, to prevent the return current from the battery in the LP2951 chip when the input voltage is disconnected.

This charging gives a rather low charging current, so that any battery 18650 can charge all night.

The chip can be bought both in the DIP-housing and in the SOIC housing (cost of about 10 rubles for the face).

MCP73831

The chip allows you to create the right chargers, besides it is cheaper than the promoted MAX1555.

Typical inclusion scheme taken from:

An important advantage of the scheme is the absence of low-level powerful resistors that limit the charge current. Here the current is set by the resistor connected to the 5th conclusion of the chip. Its resistance must lie in the range of 2-10 com.

Charging assembly looks like this:

The microcircuit in the process of work is well heated so much, but it does not seem to her. Performs your function.

Here is another option pCB With SMD LED and micro USB connector:

LTC4054 (STC4054)

Highly simple schemeAn excellent option! Allows you to charge up to 800 mA (see). True, it has a property very much, but in this case the built-in overheating protection reduces the current.

You can easily simplify the scheme by throwing out one or even both LEDs with a transistor. Then she will look like this (you see, it's easier to nowhere: a pair of resistors and one Conder):

One of the printed circuit board options is available by software. The board is calculated under the elements of the size of 0805.

I \u003d 1000 / R. Immediately a large current is not worth it, first look at how much the microcircuit will be warm. I took the resistor for my goals at 2.7 com, while the charge current turned out about 360 mA.

The radiator to this chip is unlikely to be able to adapt, and not the fact that it will be effective due to the high thermal resistance of the transition of the crystal-housing. The manufacturer recommends making the heat sink "through the conclusions" - to make as thick paths as possible and leave the foil under the chip body. And in general, the more "earth" foil will be left, the better.

By the way, most of The heat is given through the 3rd leg, so you can make this track very wide and thick (pour it with an overpressure of solder).

The LTC4054 chip body may have LTH7 or Ltady marking.

LTH7 from Ltady is distinguished by the fact that the first can raise a strongly sitting battery (on which the voltage is less than 2.9 volts), and the second - no (you need to split separately).

The chip came out very successful, so it has a bunch of analogues: STC4054, MCP73831, TB4054, QX4054, TP4054, SGM4054, ACE4054, LP4054, U4054, BL4054, WPM4054, IT4504, Y1880, PT6102, PT6181, VS6102, HX6001, LC6000, LN5060, CX9058, EC49016, CYT5026, Q7051. Before using any of the analogues, check on datasheets.

TP4056.

The microcircuit is made in the SOP-8 case (see), has a metal heat generator on a belly, which allows you to more effectively remove heat. Allows you to charge the battery to 1a (depends on the current resistor).

The connection scheme requires the minimum of attachments:

The scheme implements the classic charge process - first the charge of a constant current, then a constant voltage and a falling current. Everything is scientifically. If you disassemble charging in steps, you can select several stages:

1. Control of the voltage of the connected battery (this happens constantly).
2. Prerequisite phase (if the battery is discharged below 2.9 V). 1/10 charge from the R PROG programmed by the resistor (100ma at R Prog \u003d 1.2 com) to 2.9 V.
3. Charging with the maximum current of a constant value (1000mA at R Prog \u003d 1.2 com);
4. When it is reached on the battery 4.2 V, the battery voltage is fixed at this level. The smooth decrease in the charging current begins.
5. When the current 1/10 is reached from the R PROG programmed by the resistor (100ma at R Prog \u003d 1.2kom), the charger is turned off.
6. After the charging is completed, the controller continues to monitor the battery voltage (see clause 1). Current consumed by a monitoring scheme 2-3 μA. After the voltage drop to 4.0V, the charging is turned on again. And so in a circle.

Charge current (in amperes) is calculated by the formula I \u003d 1200 / R Prog. The maximum permissible is 1000 mA.

The real charge charge with a battery 18650 by 3400 mA / h is shown in the graph:

The advantage of the chip is that the charge current is given by only one resistor. Most powerful low-level resistors are required. Plus there is an indicator of the charge process, as well as an indication of the end of charging. With an unscheduled battery, the indicator blinks with a frequency once a few seconds.

The supply voltage of the diagram must lie within 4.5 ... 8 volts. The closer to 4.5V, the better (so the chip is heated less).

The first foot is used to connect the temperature sensor built into the lithium-ion battery (usually this is the middle output of the cell phone battery). If the voltage output is below 45% or above 80% of the supply voltage, the charging is suspended. If you do not need control control, just put this leg to the ground.

Attention! This scheme has one significant disadvantage: the lack of a battery reversal protection scheme. In this case, the controller is guaranteed to focus due to exceeding the maximum current. At the same time, the supply voltage of the circuit directly falls on the battery, which is very dangerous.

Printing is simple, it is done per hour on the knee. If the time is tolerate, you can order ready-made modules. Some manufacturers of ready-made modules add protection against overload and overloading (, for example, you can choose which fee you need - with or without protection, and with what connector).

You can also find ready-made boards with an derived contact for the temperature sensor. Or even a charging module with several TP4056 chicircles for increasing the charging current and with a stir protection (example).

LTC1734.

Also a very simple scheme. The charge current is set by the R PROG resistor (for example, if you put a resistor by 3 kΩ, the current will be 500 mA).

Chips usually have labeling on the housing: ltrg (they can often be found in old phones from Samsung).

The transistor is suitable at all any P-N-PThe main thing is that it is designed for a given charging current.

The charge indicator on the specified scheme is not, but in LTC1734 it is said that the output "4" (PROG) has two functions - the current installation and control of the battery charge. The example shows a scheme with charge end control using the LT1716 comparator.

The LT1716 comparator in this case can be replaced by cheap LM358.

TL431 + transistor

Probably it is difficult to come up with a scheme from more affordable components. It is 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, as a source of nutrition costs without this chip).

Well, the TIP41 transistor can be replaced with any other with a suitable collector current. Even old Soviet CT819, CT805 (or less powerful KT815, KT817) are suitable.

The scheme setting is reduced to the output voltage setting (without battery !!!) using a stroke resistor at 4.2 volts. Resistor R1 sets the maximum charging current value.

This scheme fully implements a two-step process of charge lithium batteries - first charging a direct current, then the transition to the voltage stabilization phase and the smooth decrease in the current almost to zero. The only drawback is the poor repeatability of the circuit (the caprication in the setting and demanding to the components used).

MCP73812.

There is one more undeservedly deprived of the microcircuit from Microchip - MCP73812 (see). At its base it turns out very a budget option Charging (and inexpensive!). All body kit is just one resistor!

By the way, the chip is performed in a package convenient for soldering - SOT23-5.

The only minus is greatly heated and there is no charge indication. She is still somehow working very well if you have a low-power supply source (which gives stress drawdown).

In general, if the charge indication is not important for you, and the current of 500 mA suits you, then the MSR73812 is a very good option.

NCP1835

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

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

From indisputable benefits I would like to note the following:

1. The minimum number of body parts.
2. The possibility of charging a fully discharged battery (overhead of the current of 30mA);
3. Determining the end of charging.
4. Programmable charging current - up to 1000 mA.
5. Indication of charge and errors (able to detect unloadable batteries and signal it).
6. Protection against a long charge (changing the capacitor capacitor with T, you can set the maximum charge time from 6.6 to 784 minutes).

The cost of the chip is not so kopeck, but not so big (~ $ 1) to abandon its use. If you are friends with a soldering iron, I would recommend to stop your choice on this option.

More detailed description is in.

Is it possible to charge a lithium-ion battery without a controller?

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

In general, to charge the battery, for example, our 18650 will not work at all without a charger. All the same, it is necessary to somehow limit the maximum charge current, so at least the most primitive memory, but still it will be necessary.

The simplest charger for any lithium battery is a resistor enabled sequentially with the battery:

The resistance and power of the scattering of the resistor depend on the power supply voltage to be used for charging.

Let's calculate the resistor for the power supply of 5 volts. We will charge the 18650 battery, with a capacity of 2400 mA / h.

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

U r \u003d 5 - 2.8 \u003d 2.2 volts

Suppose our 5-volt power supply is calculated for maximum current 1A. The biggest current scheme will consume at the very beginning of the charge, when the voltage on the battery is minimal and is 2.7-2.8 volts.

ATTENTION: These calculations are not taken into account the likelihood that the battery can be very deeply discharged and the voltage on it can be much lower, right up to zero.

Thus, the resistance of the resistor necessary to limit the current at the very beginning of the charge at the level of 1 amp should be:

R \u003d u / i \u003d 2.2 / 1 \u003d 2.2 ohms

Resistor dispersion capacity:

P r \u003d i 2 r \u003d 1 * 1 * 2.2 \u003d 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 \u003d (U IP - 4.2) / R \u003d (5 - 4.2) / 2.2 \u003d 0.3 A

Those., As we see, all values \u200b\u200bdo not go beyond permissible for this battery: the initial current does not exceed the maximum allowable charge current for a given battery (2.4 a), and the final current exceeds the current at which the battery is already stopped recruiting the container ( 0.24 a).

The most important drawback of such charging is to constantly monitor the voltage on the battery. And manually disable the charge as soon as the voltage reaches 4.2 volts. The fact is that lithium batteries are very poorly carrying even short-term overvoltage - the electrode masses begin to degrade rapidly, which inevitably leads to loss of tank. At the same time, all prerequisites for overheating and depressurization are created.

If the protection fee is built into your battery, about which it was slightly higher, then everything is simplified. Upon reaching a certain battery voltage, the board itself turns it off from the charger. However, this method of charging has the essential minuses that we told in.

Protection embedded in the battery will not allow it to recharge under any circumstances. All you have to do is to control the charge current so that it does not exceed the permissible values \u200b\u200bfor this battery (the protection fees do not know how to limit the charge current, unfortunately).

Charging with the Laboratory Power Supply

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

All you need to be done to charge Li-Ion is to set 4.2 volts on the power supply and set the desired current limit. And you can connect the battery.

First, when the battery is still discharged, laboratory block Power will work in current protection mode (i.e., it will stabilize the output current at a given level). Then, when the tension on the bank rises to the 4.2V installed, the power supply will switch to the voltage stabilization mode, and the current will start falling.

When the current falls to 0.05-0.1c, the battery can be fully charged.

As you can see, laboratory BP is a practically perfect charger! The only thing he does not know how to do automatically, is to make a decision to complete the battery charging and turn off. But this is a trifle, which is not even worth paying attention.

How to charge lithium batteries?

And if we are talking about a disposable battery that is not intended for recharging, the correct (and the only right) answer to this question is in any way.

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, which is covered with a lithium anode. This layer prevents the chemical reaction of an anode with an electrolyte. A third-party feed destroys the above protective layer, leading to a damage of the battery.

By the way, if we talk about an unloadable CR2032 battery, that is, the LIR2032 very similar to it is already a full battery. Its can be charged. Only she does not voltage 3, but 3.6V.

About the same way to charge lithium batteries (whether there is a phone battery, 18650 or any other Li-Ion battery) was discussed at the beginning of the article.

Today, one of the most popular battery formats for various electronic devices is 18650. It requires the proper circulation during operation. The durability and functionality of this power supply depends on this.

How to charge the battery 18650, you should consider in detail. This will help to understand the advice of specialists.

general characteristics

Today, many sizes are used and one of the most popular is a battery of type 18650. It has a cylindrical shape. Externally, such a battery resembles finger batteries. Only the presented view is slightly more in size than the usual devices.

In the course of operation, necessarily the question of how to charge the battery 18650. This is a simple procedure. However, refer to it with full responsibility. The durability of the use of the battery depends on the correctness of the charging.

The batteries of the presented type are used today to power laptops, as well as electronic cigarettes. This made presented sizes popular. Also, such batteries are installed in flashlights and laser pointers. Most often, the devices presented are produced by lithium-ion type. This type of batteries proved its effectiveness and simplicity during operation.

Features

Considering how to charge the 18650 battery for a flashlight, electronic cigarette and other devices, it is necessary to describe the principle of its operation. The presented sizes are produced in the category of lithium-ion batteries. It has minor dimensions. The height is only 65 mm, and the diameter is 18 mm.

Inside the device there are metal electrodes, between which lithium ions circulate. This allows you to produce an electric current to feed the technique. With a low or high charge on one of the electrodes, more ions are formed. They grow on the material by changing its volume and characteristics.

In order for the battery to work for a long time and fully, it is necessary to prevent the appearance of a deep or too high charge. Otherwise, the device will quickly fail. Depending on the nominal battery rates, special types of charging devices are used.

Battery protection

Today, the presented varieties of batteries are available complied with a special controller or have a manganese. Previously, there were batteries without protection. How to charge the battery 18650 correctly in this case, it was necessary to know for your own security.

The fact is that the device in which there was no special protection could be very overheated with an incorrect or too long charging. In this case, a short circuit could occur and even ignition or today the use of such structures has sunk in the fly.

All lithium-ion type batteries have protection against such negative phenomena in their design. The special controller is most often applied. It monitors the battery capacity. If necessary, it simply turns off the battery. In some types of structures, a manganese is included. It significantly affects chemical reactions inside. Therefore, such batteries controller is not needed.

Features of charging

Many buyers are interested in how to charge the 18650 Li-ion battery (3.7V). You need to familiarize yourself with the features of this process. He is quite simple. Modern manufacturers make special devices that control the battery charging.

Lithium-ion batteries have practically no memory effect. This provides a number of rules when charging and operating batteries. The effect of memory is the gradual decrease in the battery capacity with an incomplete discharge. This property was characteristic of nickel-cadmium batteries. They needed to discharge completely.

On the contrary, do not tolerate deep discharge. They need to be charged to 80% and discharge up to 14-20%. In such conditions, the device will serve as long as possible and productive. The presence of special boards in the design allows you to simplify this process. When the capacity level drops to a critical value (most often up to 2.4 V), the device turns off the battery from the consumer.

Holding charging

Many buyers of various electrical engineering are interested in how to charge the 18650 Li-Ion battery (3.7V, 6800mAh). This process is carried out using a special device. It starts charging at a voltage of 0.05 V, and finishes at the maximum level 4.2 V. Above this value, the battery is not necessary.

You can charge the batteries of 18650 current 0.5-1a. What he is more, the faster the process passes. However, more smooth current is preferable. It is better not to speed up the charging process if the battery does not need to be used urgently.

The procedure takes no more than 3 hours. After that, the device will turn off the battery. This prevents its overheating and failure. Available for charging devices that cannot control the flow of this process are presented. In this case, the user must follow its execution. Experts recommend purchasing devices that themselves manage the process. This is a secure method.

Parameters

Batteries with different capacity indicators are available. This affects the duration of the work and the process of charging. Low capacity has a battery 1100-2600 mAh. The most popular in this category are Ultrafire products. This manufacturer manufactures high-quality lights. Therefore, consumers have reasonably the question arises on how to charge the battery 18650 Ultrafire.

In this case, it should be noted that the devices with a capacity of up to 2600 mAh need to be charged with a current of 1.3-2.6 A. This process is carried out in several stages. At the beginning of charging, the battery enters the current, which is 0.2-1 from the size of the battery capacity. At this point, the voltage is maintained at about 4.1 B. This stage lasts about an hour.

During the second stage, the voltage is held at a constant level. For some manufacturers of charging, this procedure can be carried out using AC. It should also be taken into account that in the presence of a graphite electrode in the battery design, it cannot be charged with a current more than 4.1 V.

Varieties of chargers

There is a simple technique, how to charge the battery for this you need to buy a specific type of device. On sale presented big choice Charger for batteries of this type. The simplest and inexpensive is the device for one battery. The current level in it can reach 1 A.

Instruments in which several batteries can be placed immediately. Most often, such designs are equipped with an indicator. Some models can also be used for other varieties of lithium-ion type batteries. Their planting sockets have the appropriate design. Such devices differ acceptable cost and high functionality.

Also available universal chargers are presented. They can charge batteries not only lithium-ion type, but also other varieties. Such aggregates need to be properly configured before conducting the procedure.

Homemade instrument

Some users have a question about how to charge the 18650 battery in emergency situationWhen there is no special device at hand. In this case, it can be done independently. An old charger is suitable on the phone (for example, "Nokia").

It is necessary to remove the shell of the wire and disconnect the wires minus (black) and plus (red). With the help of plasticine, you can attach the bare contacts to the battery. It is necessary to observe the appropriate polarity. Next, the device includes network.

Such charging can last about an hour. This will be enough enough to ensure that the battery can provide the right work of the technique.

Specialists recommend responsibly referring to the charging process and its durability depends on it. Discharge the battery completely and charge it up to 100%. It is better to limit the charging process to a level of 90%. However, periodically (once every three months) can be fully discharged and complete battery charging. This is necessary to calibrate the controller.

You can store a battery long enough. For this you need to charge by 50%. In such a state, it can be about a month. At the same time, it should not be too hot or too cold. The ideal conditions are considered to hold temperatures at 15 ºС.

Having considered how to charge the battery 18650, you can maintain and operate the battery correctly. In this case, its use will be significantly longer.