Charging of lithium-ion batteries diagram. Li-ion and Li-polymer batteries in our designs. How to properly charge lithium-ion batteries

I liked the small microcircuits for simple chargers. I bought them from our local offline store, but as luck would have it, they ran out there, they took a long time to be transported from somewhere else. Looking at this situation, I decided to order them in small bulk, since the microcircuits are quite good and I liked the way they work.
Description and comparison under the cut.

It was not in vain that I wrote about comparison in the title, since during the journey the dog could have grown up. Microphones appeared in the store, I bought several pieces and decided to compare them.
The review will not have a lot of text, but quite a lot of photographs.

But I’ll start, as always, with how it came to me.
It came complete with other various parts, the mikruhi themselves were packed in a bag with a latch and a sticker with the name.

This chip is a charger chip for lithium batteries with a charge end voltage of 4.2 Volts.
It can charge batteries with a current of up to 800mA.
The current value is set by changing the value of the external resistor.
It also supports the charging function with a small current if the battery is very discharged (voltage lower than 2.9 Volts).
When charging to a voltage of 4.2 Volts and the charging current drops below 1/10 of the set value, the microcircuit turns off the charge. If the voltage drops to 4.05 Volts, it will again go into charging mode.
There is also an output for connecting an indication LED.
More information can be found in, this microcircuit has a much cheaper one.
Moreover, it is cheaper here, on Ali it’s the other way around.
Actually, for comparison, I bought an analogue.

But imagine my surprise when the LTC and STC microcircuits turned out to be completely identical in appearance, both were labeled LTC4054.

Well, maybe it’s even more interesting.
As everyone understands, it’s not that easy to check a microcircuit; it also needs a harness from other radio components, preferably a board, etc.
And just then a friend asked me to repair (although in this context it would be more likely to remake) a charger for 18650 batteries.
The original one burned out, and the charging current was too low.

In general, for testing we must first assemble what we will test on.

I drew the board from the datasheet, even without a diagram, but I’ll give the diagram here for convenience.

Well, the actual printed circuit board. There are no diodes VD1 and VD2 on the board; they were added after everything.

All this was printed out and transferred to a piece of textolite.
To save money, I made another board using scraps; a review with its participation will follow later.

Well, the printed circuit board was actually made and the necessary parts were selected.

And I will remake such a charger, it is probably very well known to readers.

Inside it is a very complex circuit consisting of a connector, an LED, a resistor and specially trained wires that allow you to equalize the charge on the batteries.
Just kidding, the charger is located in a block that is plugged into an outlet, but here there are simply 2 batteries connected in parallel and an LED constantly connected to the batteries.
We'll return to our original charger later.

I soldered the scarf, picked out the original board with contacts, soldered the contacts themselves with the springs, they will still be useful.

I drilled a couple of new holes, in the middle there will be an LED indicating the device is turned on, in the sides - the charging process.

I soldered contacts with springs, as well as LEDs, into the new board.
It is convenient to first insert the LEDs into the board, then carefully install the board in its original place, and only after that solder it, then they will stand evenly and equally.

The board is installed in place, the power cable is soldered.
The printed circuit board itself was developed for three power supply options.
2 options with a MiniUSB connector, but in installation options on different sides of the board and under the cable.
In this case, at first I didn’t know how long the cable would be needed, so I soldered a short one.
I also soldered the wires going to the positive contacts of the batteries.
Now they go through separate wires, one for each battery.

Here's how it turned out from above.

Well, now let's move on to testing

On the left side of the board I installed the mikruha bought on Ali, on the right I bought it offline.
Accordingly, they will be positioned mirrored on top.

First, mikruha with Ali.
Charge current.

Now purchased offline.

Short circuit current.
Likewise, first with Ali.

Now from offline.

It was noticed that at 4.8 Volts the charge current is 600 mA, at 5 Volts it drops to 500, but this was checked after warming up, maybe this is how the overheating protection works, I haven’t figured it out yet, but the microcircuits behave approximately the same.

Well, now a little about the charging process and finalizing the rework (yes, even this happens).
From the very beginning I was thinking of just setting the LED to indicate the on state.
Everything seems simple and obvious.
But as always, I wanted more.
I decided that it would be better if it was extinguished during the charging process.
I soldered a couple of diodes (vd1 and vd2 on the diagram), but got a small bummer, the LED indicating the charging mode shines even when there is no battery.
Or rather, it doesn’t shine, but flickers quickly, I added a 47 µF capacitor in parallel to the battery terminals, after which it began to flash very briefly, almost imperceptibly.
This is exactly the hysteresis of switching on re-charging if the voltage drops below 4.05 Volts.
In general, after this modification everything was fine.
The battery is charging, the red light is on, the green light is not on, and the LED does not light up where there is no battery.

The battery is fully charged.

When turned off, the microcircuit does not pass voltage to the power connector, and is not afraid of shorting this connector; therefore, it does not discharge the battery to its LED.

Not without measuring the temperature.
I got just over 62 degrees after 15 minutes of charging.

Well, this is what a fully finished device looks like.
External changes are minimal, unlike internal ones. A friend had a 5/Volt 2 Ampere power supply, and it was quite good.
The device provides a charge current of 600 mA per channel, the channels are independent.

Well, this is what the original charger looked like. A friend wanted to ask me to raise him charging current. It couldn’t stand even its own, where else to raise it, slag.

Resume.
In my opinion, for a chip that costs 7 cents it's very good.
The microcircuits are fully functional and are no different from those purchased offline.
I am very pleased, now I have a supply of mikrukhs and don’t have to wait for them to be in the store (they recently went out of sale again).

Of the minuses - This is not a ready-made device, so you will have to etch, solder, etc., but there is a plus: you can make a board for a specific application, rather than using what you have.

Well, in the end, getting a working product made by yourself is cheaper than ready-made boards, and even under your specific conditions.
I almost forgot, datasheet, diagram and trace -

Li-ion batteries of the 18650 type of various capacities are now very widespread. With their acquisition, the problem of charging arises and must comply with the technical requirements for the charging process. Here are some of these requirements:
- charging with stable current;
- voltage stabilization mode;
- indication of the end of charging;
- not exceeding the permissible temperature during battery charging.

We present to your attention a Li-ion battery charger circuit that is easy to manufacture and set up and has proven itself in operation.

The circuit is a current and voltage stabilizer. Until the voltage on the battery during charging reaches the level Ustabil.=(R7/R5+1)*Uref (Uref-reference voltage TL431=2.5V), TL431 is in the closed state, and the circuit works as a current stabilizer. Ist.=0.6/R2 (0.6 is the opening voltage of the KT816V transistor). As soon as the voltage on the battery reaches Ustabil., the circuit goes into voltage stabilization mode. For a Li-ion battery, this value is 4.2V. When the battery voltage reaches 4.2V, the yellow LED starts to light up, indicating that the battery is 80-90% charged. The charging current decreases to 7...8mA. Leave the battery in this state for 10-15 hours until it reaches its full capacity.

A little about the purpose of the circuit elements.
LED1 - blue, lights up when the battery (AC) is installed in the charging box and the charger power is not connected. When the voltage across the battery is less than 3V, LED1 does not light up.
LED2 - yellow. Serves to indicate the end of the battery charging process. When an uncharged AK is placed in the box, LED2 does not light up. If it lights up, then this indicates that a charged AK is inserted into the box (with the charger power not connected).
R2 - limits the charging current of the AK.
R5, R7 - serve to set the voltage to 4.2V on the contacts of the charging box before installing the battery in it (any one can be used).

All charger parts, except the transistor, are installed on the printed circuit board on the side of the printed conductors:

Board option for those who are not lazy to drill holes in fiberglass:

The transistor is equipped with a small heatsink. During charging, the transistor heats up to 40°C. Resistor R2 also heats up, so it is better to install two 10 Ohm resistors in parallel to reduce heating.
Power supply voltage for charging one battery is approximately 5V DC. If it is necessary to charge several batteries at once, the power supply voltage is selected so that it is 4.2V on each unit. The power of the power supply is selected from the charging current for each battery. Can be used pulse source nutrition. The dimensions of the charger will be smaller.
The process of setting up the charger is simple. Without inserting the battery, we supply power to the circuit. Both LEDs should light up. Next, we measure the voltage at the contacts of the charging box. If it is 4.2V, you are in luck and the setup is almost complete. If the voltage is more or less than 4.2V, turn off the power, instead of resistor R5 or R7, solder in a variable multi-turn resistor 10k and precisely set the voltage to 4.2V on the contacts of the box. Having measured the value of the resulting resistance of the adjustable resistor, we select the same constant and solder it into the circuit. Once again, check the voltage at the contacts of the charging box. We check the amount of charging current with an ammeter at the contacts of the charging box without inserting the battery. By selecting the value of resistor R2, you can set the desired charging current. We don’t get carried away with high currents; the battery may heat up, which is absolutely unacceptable. Overheating causes the capacity of Li-ion batteries to decrease and not be restored.
It is best to charge batteries one at a time. If you need to charge several batteries simultaneously, you can connect the blocks in series according to this scheme.

In this scheme, each battery is charged separately. The voltage at the end of charging on each battery will be 4.2V, and the charging current will be 0.5A. When charging, for example, seven batteries simultaneously, the power source voltage should be 4.2V*7=29.5V. The power of the power source is determined by the charging current of 0.5A for each battery, i.e. approximately 40W.

Photo of the finished device.

Almost all modern lithium- ion batteries excellent energy consumption, as well as high compact dimensions. It is with their help that you can power devices high power with the greatest efficiency. And for this it is absolutely not necessary to buy a ready-made charger in a store, because there is a more budget-friendly option that radio amateurs will especially like - to assemble a charger for lithium-ion batteries with your own hands.

Precautions: overcharging is prohibited

It is extremely important to remember one thing before starting to assemble the battery: simple thing- Lithium batteries must not be recharged. They have very strict requirements for the charging mode and operation, so they cannot be charged to a voltage greater than 4.2 V. It is even better to be guided by information about the safe threshold for each individual can. By the way, even a lower threshold may be indicated there, which is considered acceptable for this instance.

It’s even better if you’re going to do your own lithium battery charging, check the materials and equipment used several times. If you have doubts about the accuracy of your voltmeter readings or the origin of the cans, as well as the maximum permissible power of their charge, it is better to set the threshold even lower. The optimal range will be within 4.1–4.15 V. In this case, charging batteries that do not have a built-in protection board will be safe for you.

Otherwise, there is a high probability of strong heating and swelling of the cans, copious discharge gas with a sharp unpleasant odor and even their subsequent explosion. Check everything several times before proceeding with assembly and charging.

How to assemble a lithium charger DIY batteries

One of the simplest, if not the simplest, option for creating a charger. It involves the use of the LM317 chip. It is cheap and widely available, plus it is equipped with a charge indicator.

The setup comes down to setting the output voltage to 4.2 Volts using trimming resistor R8. Just be sure to not have the battery connected. The charging current is also set by selecting resistors R4 and R6. The recommended power of resistor R1 should be at least 1 Watt.

When the LED on the circuit goes out, this signals the completion of the battery charging process. In this case, the charging current will never decrease to zero.

Microcircuits of the LM317 type, like its analogues, are very widely used in all kinds of current and voltage stabilizers. At the same time, you can buy them at any radio market, and they will cost mere pennies.

The disadvantage of the circuit can be considered the supply voltage, which must be from 8 to 12 V. This is due to the fact that for the normal functioning of the microcircuit, a difference between the voltage on the automatic transmission and the supply voltage is required to be at least 4.25 V, that is, power the device using the USB port it won't work.

The sequence for collecting lithium battery charging with your own hands is as follows:

1. select a suitable case;
2. attach the power supply (5 V) and the elements of the specified circuit to it (necessarily in the correct order);
3. take brass and cut out two strips from it, attach them to the sockets;
4. using a nut, set the distance between the contacts and the battery that you are going to connect;
5. attach the switch if you want to later be able to change the polarity on the sockets (if not, leave everything as is).

But if the task is to assemble a charger designed to work with 18650 batteries, then you should immediately move on to more complex circuits, or buy a ready-made device. Without the appropriate technical skills, it will not be possible to assemble the unit. Sometimes it’s really easier to spend a little more money, but take a factory charger with the necessary parameters and protection.

How to assemble a charger for lithium-ion batteries with your own hands?

Since Li-Ion batteries sensitive to sudden voltage during charging; branded batteries have special microcircuits built into them. They provide voltage control and do not allow the permissible limits to be exceeded. Therefore, in order to assemble a charger for 18650 lithium batteries with your own hands, you need a more complex circuit than the one discussed above.

This version of the battery will be much more difficult to create than the previous one, and at home it is only possible if you have certain skills and relevant experience. In theory, you can get a charger whose characteristics are in no way inferior to branded batteries. But in practice this is not always the case.

Have you assembled a charger at home from scrap materials? Tell us about your results in the comments.

Many people probably have a problem with charging a Li-Ion battery without a controller; I had this situation. I received a dead laptop, and there were 4 SANYO UR18650A cans in the battery that were alive.
I decided to replace it with an LED flashlight, instead of three AAA batteries. The question arose about charging them.
After rummaging around on the Internet, I found a bunch of diagrams, but details are a little tight in our city.
I tried charging from a cell phone charger, the problem is in charge control, you need to constantly monitor the heating, it just starts to heat up, you need to disconnect from charging, otherwise the battery will be damaged in the best case, otherwise you can start a fire.
I decided to do it myself. I bought a bed for the battery in the store. I bought a charger at a flea market. To make it easier to track the end of the charge, it is advisable to find one with a two-color LED that signals the end of the charge. It switches from red to green when charging is complete.
But you can also use a regular one. The charger can be replaced with a USB cable and charged from a computer or charger with a USB output.
My charger is only for batteries without a controller. I took the controller from an old cell phone battery. It ensures that the battery is not overcharged above a voltage of 4.2 V, or discharged below 2...3 V. Also, the protection circuit saves from short circuits by disconnecting the bank itself from the consumer at the moment short circuit.
It contains the DW01 chip and an assembly of two SM8502A MOSFET transistors (M1, M2). There are also other markings, but the circuits are similar to this one and work similarly.

Cell phone battery charge controller.

Installed in laptops, cell phones and other household appliances. They are called the energy source from which all electronics operate. During operation, they require charging from special devices to ensure the operation of electrical equipment. Is it possible to use homemade batteries for charging? We will consider a report on this question below.

First time purchase mobile phone, many people wonder how to charge it for the first time. There is an opinion that for good and long-term operation, you should completely discharge and charge the device 3 times. But modern technologies refute this statement. The process of completely discharging li ion harms the device, which is why buying cell phone, we often see equipment charged at 2/3 of its capacity.

To avoid damage, do not allow it to completely discharge. The more lithium ions are on the electrode, the shorter the service life and the faster the li ion block wears out.

Let's look at some rules for charging li ion for long-term use.

1. Keep track of the charge percentage. Complete discharge can lead to malfunction, even complete failure.
2. Lithium energy storage devices require more high voltage per element, recharging according to the “constant current/constant voltage” principle.
3. Connection to the charger must be made at a temperature from 0 to +60 degrees. If the temperature drops to negative, the unit will automatically stop charging.
4. It is highly sensitive to voltage surges; if U is greater than 4.2 V, the device may fail. Modern engineers insert an electronic board into the energy storage device, which protects the li ion from overheating. You can also use special battery chargers that stop the current supply when fully charged.
5. Choose the right pitch maximum current, which is responsible for the full charge time. The greater the current passed through, the faster the device charges.
6. If the power supply does not require constant use, then charge it at 60-70 percent. Otherwise, you can quickly reduce the power of the device, which will lead to rapid discharge.
7. After charging is complete, the percentage of capacity must be determined and the battery must be disconnected from the power supply.

Controller and its functions

A controller is a device that regulates the level of current and voltage from the source, protecting the power supply from premature damage.

The controller consists of printed circuit board BMS protection and a small battery cell. The design is based on a microcircuit. Field-effect transistors are used to control the protection during charging or discharging.

The controller circuit for charging li ion power supplies is shown in the figure

Data-lazy-type="image" data-src="http://chistyjdom.ru/wp-content/uploads/2018/03/li1.jpg" alt="123" width="700" height="307" ">

The main functions of the controller are:

• The function of the controller is to protect the battery cell when charging no higher than 4.2 V. Otherwise, overcharging will occur and an excess may damage the cell.
• The charge and discharge controller copes with short circuit protection. A thermistor (T) is installed to protect against overvoltage. The controller is responsible for the battery discharge function. When the voltage drops, the unit is disconnected from the current.
• Stop energy consumption in a timely manner to prevent the discharge from reaching a critical level. The controller will save the energy block from destruction and warn against buying a new one. good new model for permanent use it will cost 15-20 thousand rubles. Therefore, it is worth thinking about installing a controller in the circuit.
• Pressure and temperature indicators are recorded when the charge is stopped.

But not all types of controllers have absolutely all of the above functions.

Having a special education, you can do without a controller in the circuit, but you need to be able to use an ammeter and voltmeter. The voltage at the terminals must be at least the maximum charge, then the unit is 70% charged.

Protected and unprotected li ion batteries

A protected battery is a power storage device in a shell with a small circuit board. It differs in that there is protection against overheating and overvoltage, as well as short circuit.

A protective electrical board is welded to the body of the unprotected li ion. After this it is packed into a shell. All parameters must be specified on the shell.

When buying a protected battery model, keep in mind that due to the presence of an outer shell, the dimensions are slightly increased in comparison with those previously mentioned. The height is 3-5 mm larger, and the diameter is up to 1 mm.

Advantages of li ion blocks:

• If used correctly, the energy decreases slowly.
• High energy density, small size hides high energy intensity.
• High voltage should be at least 3.6 V.
• Remains operational with an increased number of charge and discharge cycles.
• Slight loss of capacity after many discharge cycles.

An unprotected battery is an energy storage device hiding under the shell of an unprotected battery. If you remove the outer shell, there will be no unprotected battery underneath. The outer packaging must indicate the parameters of the battery hidden under the shell.

Charging device diagram

Any circuit must use a balancer and a controller board to charge li-ion batteries. They warn him against damaging the charger.

The operation of this circuit is based on the operation of T1 of average power and adjustable stabilizer voltage. Consider:

Data-lazy-type="image" data-src="http://chistyjdom.ru/wp-content/uploads/2018/03/li2.jpg" alt="123" width="578" height="246" ">

When choosing a transistor, the required charging current is taken into account. To charge a small capacity battery, foreign or domestic NPN can be used. Install it on a heatsink if you have high input voltage.

The regulating element is T1. The charging current is limited by resistor (R2). Use R2 power equal to 1 W. Others may have less power.

LED1 is an LED responsible for signaling the charge of li ion. When the battery is turned on, the indicator diode lights up brightly, indicating a discharged state. And after full charging, the discharge indicator stops lighting. Despite the light bulb stopping, the battery continues to charge with a current of less than 50 mA. To prevent overcharging, after charging is complete, disconnect the battery from the charger.

LED2 is the second LED used in the circuit for more precise control.

The choice of design depends on the purpose for which the blocks are used. To assemble the structure yourself, you should have the following parts on hand:

1. Current limiter.
2. Protection against connecting different poles.
3. Automation. The device starts working when it is actually needed.

The circuit is designed to recharge one energy storage device; to use it for another type of charging, the output and charging current must be changed.

It should be remembered that all li ion power supplies differ in their sizes. The most popular are 18650. The balancer is an indispensable assistant in the circuit. It copes with this task in order to prevent the voltage from rising above the permissible limit.

Is it possible to make a charger yourself and how safe is it?

Assemble charger for li ion devices you can do it yourself. In order to assemble a simple li ion charger you need to have certain experience and skills. Theoretically, homemade products can be made at home. In practice, this is an almost impossible task. The device does not always charge correctly from the charger, and then the device will be useless. But before you do it, read a few rules:

1. Lithium batteries cannot be overcharged. The maximum charged voltage should be no more than 4.2 V. Each type has its own set threshold, which should not be exceeded.
2. Check all the parts you will use. And the main thing is to check the accuracy of power measurement, for example, with a voltmeter, in order to avoid mistakes. Check: origin of cans, maximum permissible power, charge. Therefore, the threshold should be lowered to operate the device safely.

If you do not follow certain rules, overheating, swelling of parts, release of gas with an unpleasant odor, explosion of the device or fire may occur.

Branded batteries are equipped with special circuits that provide overvoltage protection, which does not allow the previously stated limit to be exceeded.

The charger circuit is shown in the figure:

Data-lazy-type="image" data-src="http://chistyjdom.ru/wp-content/uploads/2018/03/li3.jpg" alt="123" width="700" height="257" ">

For proper use, the output voltage of the charger is set to U=4.2 V without connecting the battery for charging.

The operation indicator will be a diode; it lights up if the connected battery is discharged, and goes out when the battery is charged.

Charging collection:

• select a case of the appropriate size;
• secure the power supply and elements as in the above diagram. cut out the brass strips and attach them to the sockets;
• set the distance between the contacts and the battery;
• attach a switch that can later change the polarity on the sockets;
• but if there is no need for it, then this point can be excluded;
• Check the lithium ion battery if there is no voltage, the voltmeter will not show a value. This means the circuit was assembled incorrectly, so if you do not have special education, it is better not to experiment with assembling the battery yourself.