The lithium battery controller turns off the power. Li-Ion charge controller on MCP73833

Progress is moving forward, and lithium batteries are increasingly replacing the traditionally used NiCd (nickel-cadmium) and NiMh (nickel-metal hydride) batteries.
With a comparable weight of one element, lithium has a higher capacity, in addition, the element voltage is three times higher - 3.6 V per element, instead of 1.2 V.
The cost of lithium batteries has begun to approach that of conventional alkaline batteries, their weight and size are much smaller, and besides, they can and should be charged. The manufacturer says they can withstand 300-600 cycles.
There are different sizes and choosing the right one is not difficult.
The self-discharge is so low that they sit for years and remain charged, i.e. The device remains operational when needed.

"C" stands for Capacity

A designation like “xC” is often found. This is simply a convenient designation of the charge or discharge current of the battery with shares of its capacity. Derived from the English word “Capacity” (capacity, capacity).
When they talk about charging with a current of 2C, or 0.1C, they usually mean that the current should be (2 × battery capacity)/h or (0.1 × battery capacity)/h, respectively.
For example, a battery with a capacity of 720 mAh, for which the charge current is 0.5 C, must be charged with a current of 0.5 × 720 mAh / h = 360 mA, this also applies to discharge.

You can make a simple or not very simple charger yourself, depending on your experience and capabilities.

Circuit diagram of a simple LM317 charger

Rice. 5.

The application circuit provides fairly accurate voltage stabilization, which is set by potentiometer R2.
Current stabilization is not as critical as voltage stabilization, so it is enough to stabilize the current using a shunt resistor Rx and an NPN transistor (VT1).

The required charging current for a particular lithium-ion (Li-Ion) and lithium-polymer (Li-Pol) battery is selected by changing the Rx resistance.
The resistance Rx approximately corresponds to the following ratio: 0.95/Imax.
The value of resistor Rx indicated in the diagram corresponds to a current of 200 mA, this is an approximate value, it also depends on the transistor.

It is necessary to provide a radiator depending on the charging current and input voltage.
The input voltage must be at least 3 Volts higher than the battery voltage for normal operation of the stabilizer, which for one can is 7-9 V.

Circuit diagram of a simple charger on LTC4054

Rice. 6.

You can remove the LTC4054 charge controller from an old cell phone, for example, Samsung (C100, C110, X100, E700, E800, E820, P100, P510).

Rice. 7. This small 5-legged chip is labeled "LTH7" or "LTADY"

I won’t go into the smallest details of working with the microcircuit; everything is in the datasheet. I will describe only the most necessary features.
Charge current up to 800 mA.
The optimal supply voltage is from 4.3 to 6 Volts.
Charge indication.
Output short circuit protection.
Overheating protection (reduction of charge current at temperatures above 120°).
Does not charge the battery when its voltage is below 2.9 V.

The charge current is set by a resistor between the fifth terminal of the microcircuit and ground according to the formula

I=1000/R,
where I is the charge current in Amperes, R is the resistor resistance in Ohms.

Lithium battery low indicator

Here is a simple circuit that lights up an LED when the battery is low and its residual voltage is close to critical.

Rice. 8.

Any low-power transistors. The LED ignition voltage is selected by a divider from resistors R2 and R3. It is better to connect the circuit after the protection unit so that the LED does not drain the battery completely.

The nuance of durability

The manufacturer usually claims 300 cycles, but if you charge lithium just 0.1 Volt less, to 4.10 V, then the number of cycles increases to 600 or even more.

Operation and Precautions

It is safe to say that lithium-polymer batteries are the most “delicate” batteries in existence, that is, they require mandatory compliance with several simple but mandatory rules, failure to comply with which can cause trouble.
1. Charge to a voltage exceeding 4.20 Volts per jar is not allowed.
2. Do not short circuit the battery.
3. Discharge with currents that exceed the load capacity or heat the battery above 60°C is not allowed. 4. A discharge below a voltage of 3.00 Volts per jar is harmful.
5. Heating the battery above 60°C is harmful. 6. Depressurization of the battery is harmful.
7. Storage in a discharged state is harmful.

Failure to comply with the first three points leads to a fire, the rest - to complete or partial loss of capacity.

From the experience of many years of use, I can say that the capacity of batteries changes little, but the internal resistance increases and the battery begins to work less time at high current consumption - it seems that the capacity has dropped.
For this reason, I usually install a larger container, as the dimensions of the device allow, and even old cans that are ten years old work quite well.

For not very high currents, old cell phone batteries are suitable.

You can get a lot of perfectly working 18650 batteries out of an old laptop battery.

Where do I use lithium batteries?

I converted my screwdriver and electric screwdriver to lithium a long time ago. I don't use these tools regularly. Now, even after a year of non-use, they work without recharging!

I put small batteries in children's toys, watches, etc., where 2-3 “button” cells were installed from the factory. Where exactly 3V is needed, I add one diode in series and it works just right.

I put them in LED flashlights.

Instead of the expensive and low-capacity Krona 9V, I installed 2 cans in the tester and forgot all the problems and extra costs.

In general, I put it wherever I can, instead of batteries.

Where do I buy lithium and related utilities

For sale. At the same link you will find charging modules and other useful items for DIYers.

The Chinese usually lie about the capacity and it is less than what is written.

Honest Sanyo 18650

Protection of lithium-ion batteries (Li-ion). I think that many of you know that, for example, inside a mobile phone battery there is also a protection circuit (protection controller), which ensures that the battery (cell, bank, etc....) is not overcharged above a voltage of 4.2 V , or discharged less than 2...3 V. Also, the protection circuit saves from short circuits by disconnecting the can itself from the consumer at the moment of a short circuit. When the battery reaches the end of its service life, you can remove the protection controller board from it and throw away the battery itself. The protection board can be useful for repairing another battery, for protecting a can (which does not have protection circuits), or you can simply connect the board to the power supply and experiment with it.

I had many protection boards for batteries that had become unusable. But a search on the Internet for the markings of the microcircuits yielded nothing, as if the microcircuits were classified. On the Internet there was documentation only for assemblies of field-effect transistors, which are included in the protection boards. Let's look at the design of a typical lithium-ion battery protection circuit. Below is a protection controller board assembled on a controller chip designated VC87 and a transistor assembly 8814 ():

In the photo we see: 1 - protection controller (the heart of the entire circuit), 2 - assembly of two field-effect transistors (I will write about them below), 3 - resistor setting the protection operation current (for example during a short circuit), 4 - power supply capacitor, 5 - resistor (for powering the controller chip), 6 - thermistor (found on some boards to control the battery temperature).

Here is another version of the controller (there is no thermistor on this board), it is assembled on a chip with the designation G2JH, and on a transistor assembly 8205A ():

Two field-effect transistors are needed so that you can separately control the charging protection (Charge) and the discharge protection (Discharge) of the battery. There were almost always datasheets for transistors, but none for controller chips!! And the other day I suddenly came across an interesting datasheet for some kind of lithium-ion battery protection controller ().

And then, out of nowhere, a miracle appeared - after comparing the circuit from the datasheet with my protection boards, I realized: The circuits match, they are one and the same thing, clone chips! After reading the datasheet, you can use similar controllers in your homemade products, and by changing the value of the resistor, you can increase the permissible current that the controller can deliver before the protection is triggered.

Integrated power management circuits from ON Semiconductor (ONS) are already well known to domestic developers. These are AC/DC converters and PWM controllers, power factor correctors, DC/DC converters and, of course, linear regulators. However, almost no portable device can do without a battery and, accordingly, without microcircuits to charge and protect it. The ONS company has in its product line a number of solutions for managing battery charge, which, traditionally for ONS, combine sufficient functionality with low cost and ease of use.

Main types of batteries used

In modern electronics, the most common are NiCd/NiMH and Li-Ion/Li-Pol batteries. Each of them has its own advantages and disadvantages. Nickel-cadmium (NiCd) batteries are cheap and also have the highest number of discharge/charge cycles and high load current. The main disadvantages are: high self-discharge, as well as the “memory effect”, which leads to a partial loss of capacity when frequently charging an incompletely discharged battery.

Nickel metal hydride (NiMH) batteries is an attempt to eliminate the shortcomings of NiCd, in particular the “memory effect”. These batteries are less critical to charging after incomplete discharge and are almost twice as high as NiCd in terms of specific capacity. There are also losses; NiMH batteries have a lower number of discharge/charge cycles and a higher self-discharge compared to NiCd.

Lithium-ion (Li-Ion) batteries have the highest energy density, which allows them to surpass other types of batteries in terms of capacity with the same overall dimensions. Low self-discharge and the absence of a “memory effect” make this type of battery unpretentious to use. However, to ensure safe use, lithium-ion batteries require the use of technologies and design solutions (polyolefin films to insulate the positive and negative electrodes, the presence of a thermistor and a safety valve to relieve excess pressure), which lead to an increase in the cost of lithium-based batteries compared to other power elements.

Lithium polymer (Li-Pol) batteries is an attempt to solve the safety problem of lithium-based batteries by using a solid dry electrolyte instead of the gel electrolyte in Li-Ion. This solution allows you to obtain characteristics similar to Li-Ion batteries at a lower cost. In addition to increased safety, the use of solid electrolyte allows the thickness of the battery to be reduced (up to 1.5 mm). The only drawback compared to Li-Ion batteries is the smaller operating temperature range; in particular, Li-Pol batteries are not recommended to be charged at sub-zero temperatures.

MC33340/42 - charge control of NiCd and NiMH batteries

Today's portable applications require the fastest battery charging possible, avoiding overcharging, maximizing battery life, and preventing capacity loss. MC33340 And MC33342- charge controllers from ON Semiconductor, which combine everything you need to quickly charge and protect NiCd and NiMH batteries.

MC33340/42 controllers implement:

fast charge and trickle charging;
end of charging based on changes in voltage and temperature;
detection of disposable batteries and refusal to charge them;
programmable fast charging time from one to four hours;
detection of battery overcharge and undercharge, overheating and input overvoltage;
pause before turning off charging when detecting a voltage change (177 s for MC33340 and 708 s for MC33342).

These controllers, combined with an external linear or pulse converter, form a complete battery charging system. An example of such a charging circuit using a classic stabilizer LM317 shown in Fig. 1.

Rice. 1.

LM317 in this circuit works as a stabilized current source with the charging current set by resistor R7:

I chg(fast) = (V ref + I adjR8)/R7. The trickle charging current is set by resistor R5:

I chg(trickle) = (V in - V f(D3) - V batt)/R5. The R2/R1 divider must be designed in such a way that when the battery is fully charged, the Vsen input is less than 2 V:

R2 = R1(V batt /V sen - 1).

Using pins t1, t2, t3, three-bit logic (keys in the diagram) sets either the charging time to 71...283 minutes, or the upper and lower limits of temperature detection.

Based on the presented circuit, ON Semiconductor offers development boards MC33340EVB And MC33342EVB.

NCP1835B - microcircuit for charging Li-Ion and Li-Pol batteries

Lithium batteries require high stability of the charging voltage, for example, for the LIR14500 battery from EEMB, the charging voltage must be within 4.2±0.05 V. For charging lithium-based batteries, ONS offers a fully integrated solution - NCP1835B. This is a charge chip with a linear regulator, a CCCV (constant current, constant voltage) charge profile and a charging current of 30...300 mA. Nutrition NCP1835B can be carried out either from a standard AC/DC adapter or from a USB port. A variant of the connection circuit is shown in Fig. 2.

Rice. 2.

Main characteristics:

integrated current and voltage stabilizer;
ability to charge a completely discharged battery (current 30mA);
determination of the end of charging;
programmable charging current;
status and charging error outputs;
2.8V output for determining the presence of an adapter at the input or powering the microcontroller with a current of up to 2mA;
input voltage from 2.8 to 6.5V;
protection against prolonged charge (programmable maximum charge time 6.6...784 min).

NCP349 and NCP360 - protection
overvoltage protection with integrated
MOSFET transistor

Another important point in battery charging systems is protection against exceeding the permissible input voltage. ONS solutions disconnect the output from the target circuit when an unacceptable voltage is present at the input.

NCP349- a new product from ONS that protects against input overvoltage up to 28 V. The microcircuit turns off the output when the input voltage exceeds the upper threshold or if the lower threshold is not reached. A FLAG# output is also provided to indicate input overvoltage. A typical application diagram is shown in Fig. 3.

Rice. 3.

This microcircuit is available with various lower (2.95 and 3.25 V) and upper (5.68; 6.02; 6.4; 6.85 V) response thresholds, which are encoded in the name. NCP360 has the same functionality as NCP349, except for the maximum input voltage: 20 V.

Conclusion

ON Semiconductor, compared to its competitors, does not have a very wide range of microcircuits for charging batteries. However, the presented solutions in their segment are characterized by competitive characteristics and price, as well as ease of use.

Miniature charge controller boards for a lithium-ion battery have arrived. 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. Данную особенность необходимо учитывать если вдруг захочется собрать маломощный низковольтный источник бесперебойного питания. При этом, в случае глубокого разряда аккумулятора, плата автоматически отключит потребителя, а вот его последующее включение необходимо обеспечить только при достижении U >3.6 V. But you still need to calculate the current consumption in order to create normal charging conditions. Perhaps there are some other "pitfalls" that 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

And again a device for do-it-yourselfers.
The module allows you to charge Li-Ion batteries (both protected and unprotected) from a USB port using a 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 the 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