Built-in li ion battery charge controller. Full review of li-ion battery charging board - electronics - reviews - high-quality reviews of products from China. What are the types?
Greetings, dear radio cats! Due to modernity, lithium-ion batteries are widely gaining momentum. As you know, they have excellent characteristics in terms of power output, service life, and all this in a relatively small size. But they have one small drawback: charge and discharge control is required. Otherwise, they will simply fail irreversibly.
I hope that discussing my situation will help others in similar problem: the button in the screwdriver has failed, namely the microcircuit hidden in the compound. We don’t have such a button anywhere, so we had to redo it, eliminating the electronic filling completely, leaving only the contact for closing the electric motor circuit. After some time, it turned out that the batteries were discharged beyond the permissible limit and further charging did not help. I concluded that the microcircuit in the button was responsible not only for the number of revolutions per minute, but also for controlling the discharge. Having disassembled the battery, I found out that out of 5 cans, 3 were still working. There is a second similar “semi-working” battery. That is, you can assemble one from two. But the problem will be finally solved if you assemble the discharge controller yourself (and at the same time figure out how it works) and build it into a screwdriver. The charge controller is already included in the charger.
Unfortunately, little is said about this on the Internet and I didn’t find what I needed there. I smell the spring scent of microcontrollers
http://www.kosmopoisk72.ru/index.php?op ... &Itemid=70 Here the controller operates only on 2 banks. Please help me calculate it so that it works for five cans.
http://www.radioscanner.ru/forum/topic38439.html here it only works for one can.
http://radiokot.ru/konkursCatDay2014/06/ Here it is too complicated, because a programmer and a corresponding microcircuit are needed. In addition, this circuit also includes a charge controller. I am a beginner radio amateur. Maybe there is something more accessible and simpler? If not, then I'm happy to learn microcontrollers.
1. Tell me how to calculate the discharge controller for 5 cans?
2. If the best option will be on a microcontroller, which one should I buy?
3. What homemade (most simple) programmer can be used to program it?
4. How to write a program (code) for a microcontroller yourself?
5. Is it better to control the discharge of 5 cans by taking one as a basis? And build it into the battery itself, and not into the screwdriver? Just if you use a screwdriver, then one circuit will be enough for both the first battery and the second. (I can’t turn on two of them at once)
The load current of a screwdriver is known to be large: 10-12 A. The nominal voltage of one can is standard: 3.7 V, therefore five cans: 18.5 V. It would be great if there was also short-circuit protection (that is, if it went current over 12 A)
There is only one solution... use ready-made protection boards. Or collective farms with powering up the keys for those built into cellular and other low-power scarves, or take ready-made ones like these http://zapas-m.ru/shop/UID_282.html (there are more powerful ones in the link, I threw out the IP keys and installed ordinary field keys .
Li-ion battery controller circuit
Design and principle of operation of the Li-ion/polymer battery protective controller
If you pick any battery from cell phone, then you can find that a small printed circuit board is soldered to the terminals of the battery cell. This is the so-called protection circuit, or Protection IC. Due to its characteristics lithium batteries require constant monitoring. Let's take a closer look at how the protection circuit works and what elements it consists of.
The ordinary circuit of a lithium battery charge controller is a small board on which a electronic circuit from SMD components. The controller circuit of 1 cell ("bank") at 3.7V, as a rule, consists of two microcircuits. One control chip, and the other executive - an assembly of two MOSFET transistors.
The photo shows a charge controller board from a 3.7V battery.
The microcircuit marked DW01-P in a small case is essentially the “brain” of the controller. Here is a typical circuit diagram for connecting this microcircuit. In the diagram G1 is a lithium-ion or polymer battery cell. FET1, FET2 are MOSFET transistors.
Tsokolevka, appearance and pin assignment of the DW01-P chip.
MOSFET transistors are not included in the DW01-P microcircuit and are designed as a separate microcircuit assembly of 2 N-type MOSFET transistors. Typically an assembly labeled 8205 is used, and the package can be either 6-pin (SOT-23-6) or 8-pin (TSSOP-8). The assembly may be labeled as TXY8205A, SSF8205, S8205A, etc. You can also find assemblies marked 8814 and similar ones.
Here is the pinout and composition of the S8205A chip in the TSSOP-8 package.
Two field effect transistor are used to separately control the discharge and charge of a battery cell. For convenience, they are manufactured in one case.
The transistor (FET1) that is connected to the OD pin ( Overdischarge) DW01-P microcircuit, monitors battery discharge - connects/disconnects the load. And the one (FET2) that is connected to the OC pin ( Overcharge) – connects/disconnects the power source ( Charger). Thus, by opening or closing the corresponding transistor, you can, for example, turn off the load (consumer) or stop charging the battery cell.
Let's look at the logic of the control chip and the entire protection circuit as a whole.
Overcharge Protection.
As you know, overcharging a lithium battery above 4.2 - 4.3V is fraught with overheating and even explosion.If the cell voltage reaches 4.2 - 4.3V ( Overcharge Protection Voltage - VOCP), then the control chip closes transistor FET2, thereby preventing further charging of the battery. The battery will be disconnected from the power source until the voltage across the cell drops below 4 - 4.1V ( Overcharge Release Voltage – VOCR) due to self-discharge. This is only the case if there is no load connected to the battery, for example it is removed from a cell phone.
If the battery is connected to a load, then FET2 transistor opens again when the voltage across the cell drops below 4.2V.
Overdischarge Protection.
If the battery voltage drops below 2.3 - 2.5V ( Overdischarge Protection Voltage- VODP), then the controller turns off the MOSFET transistor of the FET1 discharge - it is connected to the DO pin.There is quite interesting condition. Until the voltage on the battery cell exceeds 2.9 - 3.1V ( Overdischarge Release Voltage - VODR), the load will be completely disconnected. There will be 0V at the controller terminals. Those who are little familiar with the logic of the protective circuit may mistake this state of affairs for the “death” of the battery. Here's just a small example.
Miniature Li-polymer battery 3.7V from an MP3 player. Composition: control controller - G2NK (series S-8261), assembly of field-effect transistors - KC3J1.
The battery has discharged below 2.5V. The control circuit disconnected it from the load. The controller output is 0V.
Moreover, if you measure the voltage on the battery cell, then after disconnecting the load it increased slightly and reached a level of 2.7V.
In order for the controller to reconnect the battery to the “outside world”, that is, to the load, the voltage on the battery cell must be 2.9 - 3.1V ( VODR).
A very reasonable question arises here.
The diagram shows that the Drain terminals of transistors FET1, FET2 are connected together and are not connected anywhere. How does current flow through such a circuit when overdischarge protection is triggered? How can we recharge the battery “jar” again so that the controller turns on the discharge transistor - FET1 - again?
If you rummage through the datasheets for Li-ion/polymer protection chips (including DW01-P,G2NK) that after the deep discharge protection is triggered, the charge detection circuit operates - Charger Detection. That is, when the charger is connected, the circuit will determine that the charger is connected and will allow the charging process.
Charging to a level of 3.1V after a deep discharge of a lithium cell can take a very long time - several hours.
To restore a lithium-ion/polymer battery, you can use special devices, for example, universal charger Turnigy Accucell 6. I have already talked about how to do this. Here.
It was with this method that I managed to restore a Li-polymer 3.7V battery from an MP3 player. Charging from 2.7V to 4.2V took 554 minutes and 52 seconds, which is more than 9 hours! This is how long a “recovery” charge can last.
Among other things, the functionality of lithium battery protection microcircuits includes overcurrent protection ( Overcurrent Protection) And short circuit. Overcurrent protection is triggered in the event of a sudden drop in voltage by a certain amount. After this, the microcircuit limits the load current. If there is a short circuit (short circuit) in the load, the controller completely turns it off until the short circuit is eliminated.
Controller charge-discharge (PCM) for Li-Ion batteries 14.8V 4A 4S-EBD01-4http://zapas-m.ru/shop/UID_282.htmlArticle: 0293Rated voltage: 14.8V Rated operating current: 4A Overcharge/overdischarge/overload protection Built-in thermistor 335 rub.
|
|
Specifications Model: 4S-EBD01-4 Number of series-connected Li-Ion batteries: 4 pcs. Operating voltage: 11.2V... 16.8V Cell Overcharge Voltage (VCU): 4.275±0.025V Over-discharge voltage (VDD): 2.3±0.1V Rated operating current: 3A - 4A Threshold current (IEC): 4A - 6A Overcharge protection Overdischarge protection Short circuit protection Dimensions, mm: 15 x 46.1 x 2.62 Weight, g: 2 Controller: S-8254A Datasheeton S-8254A Voltage control on each cell: When the voltage on any of the cells exceeds the threshold values, the entire battery is automatically turned off. Current control: When the load current exceeds the threshold values, the entire battery is automatically turned off. Description of pins:
|
Controllers themselves are useful devices. And in order to better understand this topic, it is necessary to work with a specific example. That's why we'll look at the battery charge controller. What is he? How is it arranged? What are the specific features of the job?
What does a battery charge controller do?
It serves to monitor the recovery of energy losses and waste. First, he monitors the conversion of electrical energy into chemical energy, so that later, if necessary, the required circuits or devices can be supplied. Making a battery charge controller with your own hands is not difficult. But it can also be recovered from power supplies that have failed.
How the controller works
Of course, there is no universal scheme. But many people in their work use two triple resistors that regulate the upper and lower voltage limits. When it goes beyond given framework, then interaction with the relay windings begins, and it turns on. While it is working, the voltage will not drop below a certain, technically predetermined level. Here we should talk about the fact that there is a different range of boundaries. So, the battery can be set to three, five, twelve, or fifteen volts. Theoretically, everything depends on the hardware implementation. Let's look at how the battery charge controller works in different cases.
What are the types?
It should be noted that there is a significant variety that battery charge controllers can boast of. If we talk about their types, let's make a classification depending on the scope of application:
- For renewable energy sources.
- For household appliances.
- For mobile devices.
Of course, there are much more species themselves. But since we are looking at the battery charge controller from a general point of view, they will suffice for us. If we talk about those that are used for wind turbines, then their upper voltage limit is usually 15 volts, while the lower one is 12 V. In this case, the battery can generate 12 V in standard mode. The energy source is connected to it using normally closed contacts relay. What happens when the battery voltage exceeds the set 15 V? In such cases, the controller closes the relay contacts. As a result, the source of electricity from the battery is switched to the load ballast. It should be noted that they are not particularly popular with solar panels due to certain side effects. But for them they are mandatory. Appliances and mobile devices have their own characteristics. Moreover, the battery charge controller for tablets, touchscreen and push-button cell phones are almost identical.
Let's look inside a lithium-ion cell phone battery
If you pick apart any battery, you will notice that a small one is soldered to the terminals of the cell. It is called a protection circuit. The fact is that they require constant monitoring. A typical controller circuit is a miniature board on which a circuit made of SMD components is based. It, in turn, is divided into two microcircuits - one of them is the control one, and the other is the executive one. Let's talk in more detail about the second one.
Executive scheme
It is based on There are usually two. The microcircuit itself can have 6 or 8 pins. To separately control the charge and discharge of a battery cell, two field-effect transistors are used, which are located in the same housing. So, one of them can connect or disconnect the load. The second transistor does the same actions, but with a power source (which is the charger). Thanks to this implementation scheme, you can easily influence the operation of the battery. If desired, you can use it in another place. But it should be borne in mind that the battery charge controller circuit and it itself can only be applied to devices and elements that have a limited operating range. We will now talk about such features in more detail.
Overcharge protection
The fact is that if the voltage exceeds 4.2, overheating and even an explosion may occur. For this purpose, microcircuit elements are selected that will stop charging when this indicator is reached. And usually, until the voltage reaches 4-4.1 V due to use or self-discharge, further charging will be impossible. This is an important function that is assigned to the lithium battery charge controller.
Overdischarge protection
When the voltage reaches critically low values that make the operation of the device itself problematic (usually in the range of 2.3-2.5V), the corresponding MOSFET transistor, which is responsible for supplying current to the mobile phone, is turned off. Next, there is a transition to sleep mode with minimal consumption. And there is a rather interesting aspect of the work. So, until the battery cell voltage exceeds 2.9-3.1 V, the mobile device cannot be turned on to operate in normal mode. You may have probably noticed that when you connect your phone, it shows that it is charging, but it doesn’t want to turn on and function normally.
Conclusion
As you can see, the Li-Ion battery charge controller plays an important role in ensuring the longevity of mobile devices and has a positive effect on their service life. Due to their ease of production, they can be found in almost any phone or tablet. If you want to see with your own eyes and touch with your hands the Li-Ion battery charge controller and its contents, then during disassembly you should remember that you are working with a chemical element, so you should be careful.
Assessing the characteristics of a particular charger is difficult without understanding how an exemplary li-charge should actually flow. ion battery. Therefore, before moving directly to the diagrams, let's remember a little theory.
What are lithium batteries?
Depending on what material the positive electrode of a lithium battery is made of, there are several varieties:
- with lithium cobaltate cathode;
- with a cathode based on lithiated iron phosphate;
- based on nickel-cobalt-aluminium;
- based on nickel-cobalt-manganese.
All of these batteries have their own characteristics, but since these nuances are not of fundamental importance for the general consumer, they will not be considered in this article.
Also, all li-ion batteries are produced in various sizes and form factors. They can be either cased (for example, the popular 18650 today) or laminated or prismatic (gel-polymer batteries). The latter are hermetically sealed bags made of a special film, which contain electrodes and electrode mass.
The most common sizes of li-ion batteries are shown in the table below (all of them have a nominal voltage of 3.7 volts):
| Designation | Standard size | Similar size |
|---|---|---|
| XXYY0, Where XX- indication of diameter in mm, YY- length value in mm, 0 - reflects the design in the form of a cylinder |
10180 | 2/5 AAA |
| 10220 | 1/2 AAA (Ø corresponds to AAA, but half the length) | |
| 10280 | ||
| 10430 | AAA | |
| 10440 | AAA | |
| 14250 | 1/2 AA | |
| 14270 | Ø AA, length CR2 | |
| 14430 | Ø 14 mm (same as AA), but shorter length | |
| 14500 | AA | |
| 14670 | ||
| 15266, 15270 | CR2 | |
| 16340 | CR123 | |
| 17500 | 150S/300S | |
| 17670 | 2xCR123 (or 168S/600S) | |
| 18350 | ||
| 18490 | ||
| 18500 | 2xCR123 (or 150A/300P) | |
| 18650 | 2xCR123 (or 168A/600P) | |
| 18700 | ||
| 22650 | ||
| 25500 | ||
| 26500 | WITH | |
| 26650 | ||
| 32650 | ||
| 33600 | D | |
| 42120 |
Internal electrochemical processes proceed in the same way and do not depend on the form factor and design of the battery, so everything said below applies equally to all lithium batteries.
How to properly charge lithium-ion batteries
The most correct way to charge lithium batteries is to charge in two stages. This is the method Sony uses in all of its chargers. Despite a more complex charge controller, this ensures a more complete charge of li-ion batteries without reducing their service life.
Here we are talking about a two-stage charge profile for lithium batteries, abbreviated as CC/CV (constant current, constant voltage). There are also options with pulse and step currents, but they are not discussed in this article. You can read more about charging with pulsed current.
So, let's look at both stages of charging in more detail.
1. At the first stage A constant charging current must be ensured. The current value is 0.2-0.5C. For accelerated charging, it is allowed to increase the current to 0.5-1.0C (where C is the battery capacity).
For example, for a battery with a capacity of 3000 mAh, the nominal charge current at the first stage is 600-1500 mA, and the accelerated charge current can be in the range of 1.5-3A.
To ensure a constant charging current of a given value, the charger circuit must be able to increase the voltage at the battery terminals. In fact, at the first stage the charger works as a classic current stabilizer.
Important: If you plan to charge batteries with a built-in protection board (PCB), then when designing the charger circuit you need to make sure that the open circuit voltage of the circuit can never exceed 6-7 volts. Otherwise, the protection board may be damaged.
At the moment when the voltage on the battery rises to 4.2 volts, the battery will gain approximately 70-80% of its capacity (the specific capacity value will depend on the charging current: with accelerated charging it will be a little less, with a nominal charge - a little more). This moment marks the end of the first stage of charging and serves as a signal for the transition to the second (and final) stage.
2. Second charge stage- this is the battery charge constant voltage, but with a gradually decreasing (falling) current.
At this stage, the charger maintains a voltage of 4.15-4.25 volts on the battery and controls the current value.
As the capacity increases, the charging current will decrease. As soon as its value decreases to 0.05-0.01C, the charging process is considered complete.
An important nuance of the correct charger operation is its complete disconnection from the battery after charging is complete. This is due to the fact that for lithium batteries it is extremely undesirable for them to remain under high voltage for a long time, which is usually provided by the charger (i.e. 4.18-4.24 volts). This leads to accelerated degradation of the chemical composition of the battery and, as a consequence, a decrease in its capacity. Long-term stay means tens of hours or more.
During the second stage of charging, the battery manages to gain approximately 0.1-0.15 more of its capacity. The total battery charge thus reaches 90-95%, which is an excellent indicator.
We looked at two main stages of charging. However, coverage of the issue of charging lithium batteries would be incomplete if another charging stage were not mentioned - the so-called. precharge.
Preliminary charge stage (precharge)- this stage is used only for deeply discharged batteries (below 2.5 V) to bring them to normal operating mode.
At this stage the charge is ensured DC reduced value until the battery voltage reaches 2.8 V.
The preliminary stage is necessary to prevent swelling and depressurization (or even explosion with fire) of damaged batteries that have, for example, an internal short circuit between the electrodes. If a large charge current is immediately passed through such a battery, this will inevitably lead to its heating, and then it depends.
Another benefit of precharging is pre-heating the battery, which is important when charging at low ambient temperatures (in an unheated room during the cold season).
Intelligent charging should be able to monitor the voltage on the battery during the preliminary charging stage and, if the voltage does not rise for a long time, draw a conclusion that the battery is faulty.
All charge stages lithium ion battery(including the precharge stage) are schematically depicted in this graph: 
Exceeding the rated charging voltage by 0.15V can reduce the battery life by half. Lowering the charge voltage by 0.1 volt reduces the capacity of a charged battery by about 10%, but significantly extends its service life. The voltage of a fully charged battery after removing it from the charger is 4.1-4.15 volts.
Let me summarize the above and outline the main points:
1. What current should I use to charge a li-ion battery (for example, 18650 or any other)?
The current will depend on how quickly you would like to charge it and can range from 0.2C to 1C.
For example, for a battery size 18650 with a capacity of 3400 mAh, the minimum charge current is 680 mA, and the maximum is 3400 mA.
2. How long does it take to charge, for example, the same 18650 batteries?
The charging time directly depends on the charging current and is calculated using the formula:
T = C / I charge.
For example, the charging time of our 3400 mAh battery with a current of 1A will be about 3.5 hours.
3. How to properly charge a lithium polymer battery?
All lithium batteries charge the same way. It doesn't matter whether it is lithium polymer or lithium ion. For us, consumers, there is no difference.
What is a protection board?
The protection board (or PCB - power control board) is designed to protect against short circuit, overcharge and overdischarge of the lithium battery. As a rule, overheating protection is also built into the protection modules.
For safety reasons, it is prohibited to use lithium batteries in household appliances unless they have a built-in protection board. That's why all cell phone batteries always have a PCB board. The battery output terminals are located directly on the board: 
These boards use a six-legged charge controller on a specialized device (JW01, JW11, K091, G2J, G3J, S8210, S8261, NE57600 and other analogues). The task of this controller is to disconnect the battery from the load when the battery is completely discharged and disconnect the battery from charging when it reaches 4.25V.
Here, for example, is a diagram of the BP-6M battery protection board that was supplied with old Nokia phones: 
If we talk about 18650, they can be produced either with or without a protection board. The protection module is located near the negative terminal of the battery. 
The board increases the length of the battery by 2-3 mm. 
Batteries without a PCB module are usually included in batteries that come with their own protection circuits.
Any battery with protection can easily turn into a battery without protection; you just need to gut it. 
Today, the maximum capacity of the 18650 battery is 3400 mAh. Batteries with protection must have a corresponding designation on the case ("Protected"). 
Do not confuse the PCB board with the PCM module (PCM - power charge module). If the former serve only the purpose of protecting the battery, then the latter are designed to control the charging process - they limit the charge current at a given level, control the temperature and, in general, ensure the entire process. The PCM board is what we call a charge controller.
I hope now there are no questions left, how to charge an 18650 battery or any other lithium battery? Then we move on to a small selection of ready-made circuit solutions for chargers (the same charge controllers).
Charging schemes for li-ion batteries
All circuits are suitable for charging any lithium battery; all that remains is to decide on the charging current and the element base.
LM317
Diagram of a simple charger based on the LM317 chip with a charge indicator: 
The circuit is the simplest, the whole setup comes down to setting the output voltage to 4.2 volts using trimming resistor R8 (without a connected battery!) and setting the charging current by selecting resistors R4, R6. The power of resistor R1 is at least 1 Watt.
As soon as the LED goes out, the charging process can be considered completed (the charging current will never decrease to zero). It is not recommended to keep the battery on this charge for a long time after it is fully charged.
The lm317 microcircuit is widely used in various voltage and current stabilizers (depending on the connection circuit). It is sold on every corner and costs pennies (you can take 10 pieces for only 55 rubles).
LM317 comes in different housings: 
Pin assignment (pinout): 
Analogues of the LM317 chip are: GL317, SG31, SG317, UC317T, ECG1900, LM31MDT, SP900, KR142EN12, KR1157EN1 (the last two are domestically produced).
The charging current can be increased to 3A if you take LM350 instead of LM317. It will, however, be more expensive - 11 rubles/piece.
The printed circuit board and circuit assembly are shown below: 
The old Soviet transistor KT361 can be replaced with a similar one pnp transistor(for example, KT3107, KT3108 or bourgeois 2N5086, 2SA733, BC308A). It can be removed altogether if the charge indicator is not needed.
Disadvantage of the circuit: the supply voltage must be in the range of 8-12V. This is due to the fact that for normal operation LM317 microcircuit, the difference between the battery voltage and the supply voltage must be at least 4.25 Volts. Thus, it will not be possible to power it from the USB port.
MAX1555 or MAX1551
MAX1551/MAX1555 are specialized chargers for Li+ batteries, capable of operating from USB or from a separate power adapter (for example, a phone charger).
The only difference between these microcircuits is that MAX1555 produces a signal to indicate the charging process, and MAX1551 produces a signal that the power is on. Those. 1555 is still preferable in most cases, so 1551 is now difficult to find on sale.
A detailed description of these microcircuits from the manufacturer is.
The maximum input voltage from the DC adapter is 7 V, when powered by USB - 6 V. When the supply voltage drops to 3.52 V, the microcircuit turns off and charging stops.
The microcircuit itself detects at which input the supply voltage is present and connects to it. If the power is supplied via the USB bus, then the maximum charging current is limited to 100 mA - this allows you to plug the charger into the USB port of any computer without fear of burning the south bridge.
When powered by a separate power supply, the typical charging current is 280 mA.
The chips have built-in overheating protection. But even in this case, the circuit continues to operate, reducing the charge current by 17 mA for each degree above 110 ° C.
There is a pre-charge function (see above): as long as the battery voltage is below 3V, the microcircuit limits the charge current to 40 mA.
The microcircuit has 5 pins. Here is a typical connection diagram: 
If there is a guarantee that the voltage at the output of your adapter cannot under any circumstances exceed 7 volts, then you can do without the 7805 stabilizer.
The USB charging option can be assembled, for example, on this one. 
The microcircuit does not require either external diodes or external transistors. In general, of course, gorgeous little things! Only they are too small and inconvenient to solder. And they are also expensive ().
LP2951
The LP2951 stabilizer is manufactured by National Semiconductors (). It provides the implementation of a built-in current limiting function and allows you to generate a stable charge voltage level for a lithium-ion battery at the output of the circuit.
The charge voltage is 4.08 - 4.26 volts and is set by resistor R3 when the battery is disconnected. The voltage is kept very accurately.
The charge current is 150 - 300mA, this value is limited by the internal circuits of the LP2951 chip (depending on the manufacturer).
Use the diode with a small reverse current. For example, it can be any of the 1N400X series that you can purchase. The diode is used as a blocking diode to prevent reverse current from the battery into the LP2951 chip when the input voltage is turned off. 
This charger produces a fairly low charging current, so any 18650 battery can charge overnight.
The microcircuit can be purchased both in a DIP package and in a SOIC package (costs about 10 rubles per piece).
MCP73831
The chip allows you to create the right chargers, and it’s also cheaper than the much-hyped MAX1555. 
A typical connection diagram is taken from: 
An important advantage of the circuit is the absence of low-resistance powerful resistors that limit the charge current. Here the current is set by a resistor connected to the 5th pin of the microcircuit. Its resistance should be in the range of 2-10 kOhm.
The assembled charger looks like this: 
The microcircuit heats up quite well during operation, but this does not seem to bother it. It fulfills its function.
Here's another option printed circuit board with SMD LED and micro USB connector: 
LTC4054 (STC4054)
Very simple circuit, great option! Allows charging with current up to 800 mA (see). True, it tends to get very hot, but in this case the built-in overheating protection reduces the current. 
The circuit can be significantly simplified by throwing out one or even both LEDs with a transistor. Then it will look like this (you must admit, it couldn’t be simpler: a couple of resistors and one condenser): 
One of the printed circuit board options is available at . The board is designed for elements of standard size 0805.
I=1000/R. You shouldn’t set a high current right away; first see how hot the microcircuit gets. For my purposes, I took a 2.7 kOhm resistor, and the charge current turned out to be about 360 mA.
It is unlikely that it will be possible to adapt a radiator to this microcircuit, and it is not a fact that it will be effective due to the high thermal resistance of the crystal-case junction. The manufacturer recommends making the heat sink “through the leads” - making the traces as thick as possible and leaving the foil under the chip body. In general, the more “earth” foil left, the better.
By the way, most of the heat is dissipated through the 3rd leg, so you can make this trace very wide and thick (fill it with excess solder). 
The LTC4054 chip package may be labeled LTH7 or LTADY.
LTH7 differs from LTADY in that the first can lift a very low battery (on which the voltage is less than 2.9 volts), while the second cannot (you need to swing it separately).
The chip turned out to be very successful, so it has a bunch of analogues: STC4054, MCP73831, TB4054, QX4054, TP4054, SGM4054, ACE4054, LP4054, U4054, BL4054, WPM4054, IT4504, Y1880, PT6102, PT6181, VS61 02, HX6001, LC6000, LN5060, CX9058, EC49016, CYT5026, Q7051. Before using any of the analogues, check the datasheets.
TP4056
The microcircuit is made in a SOP-8 housing (see), it has a metal heat sink on its belly that is not connected to the contacts, which allows for more efficient heat removal. Allows you to charge the battery with a current of up to 1A (the current depends on the current-setting resistor). 
The connection diagram requires the bare minimum of hanging elements: 
The circuit implements the classical charging process - first charging with a constant current, then with a constant voltage and a falling current. Everything is scientific. If you look at charging step by step, you can distinguish several stages:
- Monitoring the voltage of the connected battery (this happens all the time).
- Precharge phase (if the battery is discharged below 2.9 V). Charge with a current of 1/10 from the one programmed by the resistor R prog (100 mA at R prog = 1.2 kOhm) to a level of 2.9 V.
- Charging with a maximum constant current (1000 mA at R prog = 1.2 kOhm);
- When the battery reaches 4.2 V, the voltage on the battery is fixed at this level. A gradual decrease in the charging current begins.
- When the current reaches 1/10 of the one programmed by the resistor R prog (100 mA at R prog = 1.2 kOhm), the charger turns off.
- After charging is complete, the controller continues monitoring the battery voltage (see point 1). The current consumed by the monitoring circuit is 2-3 µA. After the voltage drops to 4.0V, charging starts again. And so on in a circle.
The charge current (in amperes) is calculated by the formula I=1200/R prog. The permissible maximum is 1000 mA.
A real charging test with a 3400 mAh 18650 battery is shown in the graph: 
The advantage of the microcircuit is that the charge current is set by just one resistor. Powerful low-resistance resistors are not required. Plus there is an indicator of the charging process, as well as an indication of the end of charging. When the battery is not connected, the indicator blinks every few seconds.
The supply voltage of the circuit should be within 4.5...8 volts. The closer to 4.5V, the better (so the chip heats up less).
The first leg is used to connect a temperature sensor built into the lithium-ion battery (usually the middle terminal of a cell phone battery). If the output voltage is below 45% or above 80% of the supply voltage, charging is suspended. If you don't need temperature control, just plant that foot on the ground.
Attention! This circuit has one significant drawback: the absence of a battery reverse polarity protection circuit. In this case, the controller is guaranteed to burn out due to exceeding the maximum current. In this case, the supply voltage of the circuit directly goes to the battery, which is very dangerous.
The signet is simple and can be done in an hour on your knee. If time is of the essence, you can order ready-made modules. Some manufacturers of ready-made modules add protection against overcurrent and overdischarge (for example, you can choose which board you need - with or without protection, and with which connector). 
You can also find ready-made boards with a contact for a temperature sensor. Or even a charging module with several parallel TP4056 microcircuits to increase the charging current and with reverse polarity protection (example).
LTC1734
Also a very simple scheme. The charging current is set by resistor R prog (for example, if you install a 3 kOhm resistor, the current will be 500 mA).
Microcircuits are usually marked on the case: LTRG (they can often be found in old Samsung phones). 
A transistor will do just fine any p-n-p, the main thing is that it is designed for a given charging current.
There is no charge indicator on the indicated diagram, but on the LTC1734 it is said that pin “4” (Prog) has two functions - setting the current and monitoring the end of the battery charge. For example, a circuit with control of the end of charge using the LT1716 comparator is shown. 
The LT1716 comparator in this case can be replaced with a cheap LM358.
TL431 + transistor
It is probably difficult to come up with a circuit using more affordable components. The hardest part here is finding the TL431 reference voltage source. But they are so common that they are found almost everywhere (rarely does a power source do without this microcircuit). 
Well, the TIP41 transistor can be replaced with any other one with a suitable collector current. Even the old Soviet KT819, KT805 (or less powerful KT815, KT817) will do.
Setting up the circuit comes down to setting the output voltage (without a battery!!!) using a trim resistor at 4.2 volts. Resistor R1 sets the maximum value of the charging current.
This circuit fully implements the two-stage process of charging lithium batteries - first charging with direct current, then moving to the voltage stabilization phase and smoothly reducing the current to almost zero. The only drawback is the poor repeatability of the circuit (it is capricious in setup and demanding on the components used).
MCP73812
There is another undeservedly neglected microcircuit from Microchip - MCP73812 (see). On its basis it turns out very a budget option charging (and inexpensive!). The whole body kit is just one resistor!
By the way, the microcircuit is made in a solder-friendly package - SOT23-5. 
The only negative is that it gets very hot and there is no charge indication. It also somehow doesn’t work very reliably if you have a low-power power source (which causes a voltage drop). 
In general, if the charge indication is not important for you, and a current of 500 mA suits you, then the MCP73812 is a very good option.
NCP1835
A fully integrated solution is offered - NCP1835B, providing high stability of the charging voltage (4.2 ±0.05 V).
Perhaps the only drawback of this microcircuit is its too miniature size (DFN-10 case, size 3x3 mm). Not everyone can provide high-quality soldering of such miniature elements. 
From undeniable advantages I would like to note the following:
- Minimum number of body parts.
- Possibility of charging a completely discharged battery (precharge current 30 mA);
- Determining the end of charging.
- Programmable charging current - up to 1000 mA.
- Charge and error indication (capable of detecting non-chargeable batteries and signaling this).
- Protection against long-term charging (by changing the capacitance of the capacitor C t, you can set the maximum charging time from 6.6 to 784 minutes).
The cost of the microcircuit is not exactly cheap, but also not so high (~$1) that you can refuse to use it. If you are comfortable with a soldering iron, I would recommend choosing this option.
More detailed description is in .
Can I charge a lithium-ion battery without a controller?
Yes, you can. However, this will require close control of the charging current and voltage.
In general, it will not be possible to charge a battery, for example, our 18650, without a charger. You still need to somehow limit the maximum charge current, so at least the most primitive memory will still be required.
The simplest charger for any lithium battery is a resistor connected in series with the battery: 
The resistance and power dissipation of the resistor depend on the voltage of the power source that will be used for charging.
As an example, let's calculate a resistor for a 5 Volt power supply. We will charge an 18650 battery with a capacity of 2400 mAh.
So, at the very beginning of charging, the voltage drop across the resistor will be:
U r = 5 - 2.8 = 2.2 Volts
Let's say our 5V power supply is rated for a maximum current of 1A. The circuit will consume the highest current at the very beginning of the charge, when the voltage on the battery is minimal and amounts to 2.7-2.8 Volts.
Attention: these calculations do not take into account the possibility that the battery may be very deeply discharged and the voltage on it may be much lower, even to zero.
Thus, the resistor resistance required to limit the current at the very beginning of the charge at 1 Ampere should be:
R = U / I = 2.2 / 1 = 2.2 Ohm
Resistor power dissipation:
P r = I 2 R = 1*1*2.2 = 2.2 W
At the very end of the battery charge, when the voltage on it approaches 4.2 V, the charge current will be:
I charge = (U ip - 4.2) / R = (5 - 4.2) / 2.2 = 0.3 A
That is, as we see, all values do not go beyond the permissible limits for a given battery: the initial current does not exceed the maximum permissible charging current for a given battery (2.4 A), and the final current exceeds the current at which the battery no longer gains capacity ( 0.24 A).
The main disadvantage of such charging is the need to constantly monitor the voltage on the battery. And manually turn off the charge as soon as the voltage reaches 4.2 Volts. The fact is that lithium batteries tolerate even short-term overvoltage very poorly - the electrode masses begin to quickly degrade, which inevitably leads to loss of capacity. At the same time, all the prerequisites for overheating and depressurization are created.
If your battery has a built-in protection board, which was discussed just above, then everything becomes simpler. When a certain voltage is reached on the battery, the board itself will disconnect it from the charger. However, this charging method has significant disadvantages, which we discussed in.
The protection built into the battery will not allow it to be overcharged under any circumstances. All you have to do is control the charge current so that it does not exceed the permissible values for a given battery (protection boards cannot limit the charge current, unfortunately).
Charging using a laboratory power supply
If you have a power supply with current protection (limitation), then you are saved! Such a power source is already a full-fledged charger that implements the correct charge profile, which we wrote about above (CC/CV).
All you need to do to charge li-ion is set the power supply to 4.2 volts and set the desired current limit. And you can connect the battery.
At first, when the battery is still discharged, laboratory block power supply will operate in current protection mode (i.e. it will stabilize the output current at a given level). Then, when the voltage on the bank rises to the set 4.2V, the power supply will switch to voltage stabilization mode, and the current will begin to drop.
When the current drops to 0.05-0.1C, the battery can be considered fully charged.
As you can see, the laboratory power supply is an almost ideal charger! The only thing it can’t do automatically is make a decision to fully charge the battery and turn off. But this is a small thing that you shouldn’t even pay attention to.
How to charge lithium batteries?
And if we are talking about a disposable battery that is not intended for recharging, then the correct (and only correct) answer to this question is NO.
The fact is that any lithium battery (for example, the common CR2032 in the form of a flat tablet) is characterized by the presence of an internal passivating layer that covers the lithium anode. This layer prevents a chemical reaction between the anode and the electrolyte. And the supply of external current destroys the above protective layer, leading to damage to the battery.
By the way, if we talk about the non-rechargeable CR2032 battery, then the LIR2032, which is very similar to it, is already a full-fledged battery. It can and should be charged. Only its voltage is not 3, but 3.6V.
How to charge lithium batteries (be it a phone battery, 18650 or any other li-ion battery) was discussed at the beginning of the article.
And again a device for homemade ones.
The module allows you to charge Li-Ion batteries (both protected and unprotected) from USB port via miniUSB cable.
The printed circuit board is double-sided fiberglass with metallization, the installation is neat. 
Charging is assembled on the basis of a specialized charge controller TP4056.
Real scheme. 
On the battery side, the device does not consume anything and can be left constantly connected to the battery. Short circuit protection at the output - yes (with current limitation 110mA). There is no protection against battery reverse polarity.
The miniUSB power supply is duplicated by nickels on the board. 
The device works like this:
When connecting power without a battery, the red LED lights up and the blue LED blinks periodically.
When you connect a discharged battery, the red LED goes out and the blue LED lights up - the charging process begins. As long as the battery voltage is less than 2.9V, the charging current is limited to 90-100mA. With an increase in voltage above 2.9V, the charge current sharply increases to 800mA with a further smooth increase to a nominal 1000mA.
When the voltage reaches 4.1V, the charging current begins to gradually decrease, then the voltage stabilizes at 4.2V and after the charging current decreases to 105mA, the LEDs begin to switch periodically, indicating the end of the charge, while the charge still continues by switching to the blue LED . Switching occurs in accordance with the hysteresis of the battery voltage control.
The nominal charge current is set by a 1.2 kOhm resistor. If necessary, the current can be reduced by increasing the resistor value according to the controller specification.
R (kOhm) - I (mA)
10 - 130
5 - 250
4 - 300
3 - 400
2 - 580
1.66 - 690
1.5 - 780
1.33 - 900
1.2 - 1000
The final charge voltage is hard-set at 4.2V - i.e. Not every battery will be 100% charged.
Controller specification.
Conclusion: The device is simple and useful for a specific task.
Planning to buy +167 Add to favorites I liked the review +96 +202We've arrived miniature boards charge controllers for lithium-ion batteries. Judging by the number of orders and reviews on Aliexpress, the thing is mega-popular. I also couldn’t resist and ordered 3 pieces. for a total of $1. Moreover, relatives have long been asking to repair an LED flashlight with a faulty acid battery. I will fix it later, but for now I tested it and thought a little.
In fact, you can see a detailed description of the board itself. There is also a datasheet for the controller. Therefore, I will not repeat myself. On my own behalf, I’ll just add that at a charge current of 1 A, the controller microcircuit heats up noticeably, in connection with this, I resoldered the setting resistor R3 to 2.4 kOhm, the current dropped to 550 mA. After the modification, the board began to heat up to about 60 degrees, which is quite tolerable.
I checked the protection modes against short circuit in the load and against deep battery discharge. Everything works as stated. When the battery voltage is below 2.5 V, the load is safely turned off.
Charging a severely discharged battery (U< 3 В), происходит малым током и только при достижении напряжения 3 В, включается зарядка номинальным током. На аккумуляторе с заявленной ёмкостью 3 А*ч данный процесс занимает время порядка 1 минуты. В этом режиме нагрузка должна быть отключена, иначе заряд аккумулятора происходить не будет. This feature must be taken into account if you suddenly want to assemble a low-power low-voltage source uninterruptible power supply. At the same time, in the event of a deep discharge of the battery, the board will automatically turn off the consumer, but its subsequent switching on must be ensured only when U > 3.6 V is reached. But you still need to calculate the current consumption in order to create normal charging conditions. Perhaps there are some more" underwater rocks", which are not visible at first glance. For example, how will the battery behave in the mode of constantly applied voltage and/or chronic undercharging?
If the output is short-circuited, the protection is triggered, and even after eliminating the short circuit, it is necessary to disconnect the load, only after this the protection will be reset. The board also does not have a pin for connecting a battery temperature sensor, although the controller provides this possibility. If you really want, you can solder it, but it would be much better if there was a normal contact pad and space was left for soldering a resistive divider.
Lyrical digression. Several years ago, I was faced with a shortage of small-sized low-voltage incandescent lamps. Anticipating that things would only get worse, I accidentally saw them on sale and immediately bought them in bulk. The photo shows a Chinese-made light bulb 3.8 V, 0.3 A. After a short glow, I noticed that the bulb was smoked from the inside! I've never seen this before
