http://radiokot.ru/forum/viewtopic.php?f=11&t=116399
Greetings, dear radio cats! Due to modernity, they are widely gaining momentum lithium ion batteries. 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 with a similar problem: the button in the screwdriver, namely the microcircuit hidden in the compound, has failed. 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 more permissible norm and further charging does 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 is a microcontroller, then 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, you may 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 is structured 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 labeled DW01-P in a small package 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. 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 transistors are used to separately control the discharge and charge of the 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.

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.

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 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), then you can find out that after the protection against deep discharge, the charge detection circuit is in effect - 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.

Protected and unprotected lithium-ion batteries - what is the difference? What is the difference between a protected lithium ion battery? Can unprotected batteries be used? You will find answers to these and other questions in our article.

It has long been known that for reliable and long-term operation, batteries need protection. This can be achieved in two ways - either inside the battery itself, or using devices that work with batteries (in our case, these are LED lights and chargers). And for obvious reasons - since making battery protection is much easier than “teaching” a flashlight to work with an unprotected battery - many manufacturers have taken the path of least resistance and shifted the burden of the additional cost of battery protection onto the buyer’s wallet. But not all companies have chosen this path - and at the moment new high-tech flashlights with built-in battery protection have already appeared on the market. This means that we now have the opportunity to safely use unprotected batteries. What benefits does this give us? Let's try to answer this question.

Why do batteries need protection at all?

Everyone knows that lithium-ion batteries must be protected from complete discharge and overcharging. This is done in order to prevent a chemical reaction from occurring inside the battery, which can lead to very unpleasant consequences. Simply put, if batteries are often drained or overcharged, this will kill them: the capacity will greatly decrease, and in some cases chemical reactions may also lead to fire. Therefore, “protected” batteries have long appeared on the battery market, in which a special board is installed that disconnects them from the device in the following situations:

• if the battery is excessively discharged (less than 2.8-3V) or, conversely, charged (more than 4.2-4.3V)
• if too high a current is supplied to it (more than 1-8A)
• if the lithium-ion batteries are not installed correctly
• in case of short circuit.

Lithium-ion battery device

A reservation should be made here - often the protection strip that protects against short circuits is not made very well and wears off over time, which means that the protection is lost. Therefore, there is no complete guarantee that such batteries will not be at risk of a short circuit. The following photo clearly shows that the protection strip has darkened over time, and a black spot has appeared on the battery - this confirms the fact that if the strip is rubbed, a short circuit can occur.

And yet, the advantages of protected batteries have made the task of flashlight manufacturers much easier and freed them from the need to upgrade their products. Protected batteries have eclipsed their unprotected “brothers” and pushed them into the background. They became and still remain the best option power supply for flashlights that do not have protection circuits.

But modern high-quality flashlights produced by the most advanced and responsible brands are able to provide protection to ordinary unprotected batteries. And this gives us the opportunity to choose, which in itself cannot but rejoice.

Why do we need the option of using unprotected batteries?

In a flashlight with a built-in battery protection system, we can use both protected and unprotected batteries. To get a complete understanding of the two types of lithium-ion batteries, let's compare them based on the following basic parameters:

• safety
• convenience

1. Security

The protection board protects lithium-ion batteries from overcharging and discharging. Which, accordingly, ensures their safe operation and extends their service life. That is why, since the appearance of this type of lithium-ion batteries on sale, manufacturers began to highlight them and describe their advantages. After all, it is much easier to give recommendations - with which batteries their flashlights will work better - than to increase production costs and guarantee the same efficiency with all available types of power.

But now the situation has changed a little. On the one hand, modern chargers for lithium ion batteries equipped with their own protection against overcharge and short circuits. On the other hand, new high-tech LED lights have built-in overdischarge protection. When the charge drops to 2.5-2.8V, the system signals this (usually by blinking), the brightness drops, and after a while the flashlight turns off. Such protection gives us the opportunity to use unprotected batteries to power them with complete confidence. This means that all the advantages that protected batteries originally had no longer have the same. of great importance. After all, protection is now provided “from the outside,” by device microcircuits for which the type of power supply no longer matters.

2. Price

Also an important factor when comparing any rechargeable batteries. Everything is simple here - the price for protected lithium batteries higher (the electronic board also costs money). In addition, the use of a protective board slightly reduces the declared capacity. In fact, for the same amount we can buy either an unprotected high-capacity battery, or a protected one, but with a significantly lower capacity. Here everyone chooses for themselves what is more important to them. Of course, if you have an old-style flashlight and charger, and you are afraid to “miss” a dangerous moment, it is still better to play it safe and choose protected batteries. But if you have long acquired new “toys” that will protect your batteries themselves, there is no difference in safety for you. Therefore, to paraphrase the well-known slogan, we can say - “And if there is no difference, why pay more and lose capacity?”

3. Convenience

Here, first of all, I would like to mention the purely technological side. Namely, about size. The dimensions can be judged by the nomenclature, for example 18650 - this means that its diameter is 18 mm, length is 65 mm. The last digit (0) indicates that the battery is cylindrical. From these figures you can understand that protected batteries are 2-3 mm longer than usual - due to the size of the board, and sometimes even a little wider - depending on the thickness of the protection strip.

Lithium battery - protection board

This is mentioned in all sources, usually with the note “but such a difference usually does not interfere.” But, if you read forums and product discussions, you can see that it still interferes, and strongly. After the popularization of protected batteries, the first users immediately began to complain that they did not fit their flashlight - some were too long, others were wider than usual. Taught by the bitter experience of their predecessors, other buyers first tried to find out whether the batteries would fit their flashlight, and then decided whether to take it or not. Not very convenient, would you agree? I was also “pleased” by the proposed solution to the problem - “in extreme cases, the protection can be broken off” (they advise, for example,). That is, if it doesn’t fit at all, break it and get a regular one. Only at the price of a protected one... Which is also very pleasing.

And now about the most important thing - about operation. Are there any advantages to using a flashlight with unprotected batteries? Let's imagine the simplest situation - the batteries are dead. What happens if the flashlight has protected batteries? The protection will work and the flashlight will immediately turn off, and, as often happens, this can happen at the most inconvenient moment. And if at this moment you are in any extreme or dangerous situation? Such an abrupt shutdown can be critical. In addition, you will no longer be able to use your batteries until you put them in the charger at least for a short time - the board has worked and will no longer “allow” you to use the batteries, since this is dangerous for them. But if you use a flashlight with built-in protection and regular batteries, You will be warned in advance that food is running low. The flashlight will not turn off immediately, but will switch to low mode. This will give you time to “get ready” or replace the batteries. In extreme cases, when there is no way to replace the power supply, you can give unprotected batteries a “rest” - part of the charge will be restored, and you will be able to use them for some time. In addition, your flashlight will work longer without recharging - since there is no protection on which additional capacity is lost. Of course, the operating time will not increase much, but extreme situations even a few minutes can make a difference.

So what's the end result?

As a result, we have the following situation. If we purchase a flashlight equipped with a battery protection system, we have the opportunity to use unprotected lithium batteries for power. And this gives us certain advantages:

Saving money on batteries

Longer run time

Possibility to know in advance about the imminent switching off of the flashlight

Using Batteries standard size, which will fit any flashlight and charger

And with all these advantages, our batteries are completely protected and safe to use. That is, the difference between “internal” and “external” battery protection is still not so small. And, apparently, it’s not in vain that manufacturers LED lights gave us the opportunity to choose the method of protection ourselves.

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 decreasing charging current up 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.