Review of car battery charger circuits. Electrical circuit of the charger. Charger from an uninterruptible power supply

Very often, especially in the cold season, car enthusiasts are faced with the need to charge a car battery. It is possible, and advisable, to purchase a factory charger, preferably a charging and starting one for use in the garage.

But, if you have electrical engineering skills and certain knowledge in the field of radio engineering, then you can make a simple charger for a car battery with your own hands. In addition, it is better to prepare in advance for possible case when the battery suddenly discharges away from home or a parking and maintenance site.

General information about the battery charging process

Charging a car battery is necessary when the voltage drop across the terminals is less than 11.2 Volts. Despite the fact that the battery can start the car engine even with such a charge, during long-term parking at reduced voltages plate sulfation processes begin, which lead to loss of battery capacity.

Therefore, when wintering a car in a parking lot or garage, it is necessary to constantly recharge the battery and monitor the voltage at its terminals. More best option– remove the battery, put it in a warm place, but still do not forget about maintaining its charge.

The battery is charged using constant or pulsed current. In the case of charging from a constant voltage source, a charge current equal to one tenth of the battery capacity is usually selected.

For example, if the capacity battery is 60 ampere-hours, the charging current should be selected at 6 amperes. However, research shows that the lower the charge current, the less intense the sulfation processes.

Moreover, there are methods for desulfating battery plates. They are as follows. First, the battery is discharged to a voltage of 3–5 Volts with high currents of short duration. For example, such as when turning on the starter. Then there is a slow full charge with a current of about 1 Ampere. Such procedures are repeated 7-10 times. There is a desulfation effect from these actions.

Desulfating pulse chargers are practically based on this principle. The battery in such devices is charged with pulsed current. During the charging period (several milliseconds), a short discharge pulse of reverse polarity and a longer charging pulse of direct polarity are applied to the battery terminals.

It is very important during the charging process to prevent the effect of overcharging the battery, that is, the moment when it is charged to the maximum voltage (12.8 - 13.2 Volts, depending on the type of battery).

This can cause an increase in the density and concentration of the electrolyte, irreversible destruction of the plates. That is why factory chargers are equipped with an electronic control and shutdown system.

Schemes of homemade simple chargers for a car battery

Protozoa

Let's consider the case of how to charge a battery using improvised means. For example, a situation when you left your car near your house in the evening, forgetting to turn off some electrical equipment. By morning the battery was discharged and would not start the car.

In this case, if your car starts well (with half a turn), it is enough to “tighten” the battery a little. How to do this? First, you need a constant voltage source ranging from 12 to 25 volts. Secondly, restrictive resistance.

What can you recommend?

Nowadays, almost every home has a laptop. The power supply of a laptop or netbook, as a rule, has an output voltage of 19 Volts and a current of at least 2 amperes. The external pin of the power connector is minus, the internal pin is positive.

As a limiting resistance, and it is mandatory!!!, you can use the car's interior light bulb. You can, of course, have more power from turn signals or even worse stops or dimensions, but there is a possibility of overloading the power supply. The simplest circuit is assembled: minus the power supply - light bulb - minus the battery - plus the battery - plus the power supply. In a couple of hours the battery will be charged enough to start the engine.

If you don’t have a laptop, you can pre-purchase a powerful rectifier diode on the radio market with a reverse voltage of more than 1000 Volts and a current of 3 Amperes. It is small in size and can be put in the glove compartment for an emergency.

What to do in an emergency?

Conventional lamps can be used as a limiting load incandescent at 220 Volt. For example, a 100 Watt lamp (power = voltage X current). Thus, when using a 100-watt lamp, the charge current will be about 0.5 Ampere. Not much, but overnight it will give 5 Amp-hours of capacity to the battery. Usually it is enough to crank the car starter a couple of times in the morning.

If you connect three 100-watt lamps in parallel, the charging current will triple. You can charge your car battery almost halfway overnight. Sometimes they turn on an electric stove instead of lamps. But here the diode may already fail, and at the same time the battery.

In general, this kind of experiments with direct charging of the battery from an alternating voltage network of 220 Volts extremely dangerous. They should only be used in extreme cases when there is no other option.

From computer power supplies

Before you start making your own charger for a car battery, you should evaluate your knowledge and experience in the field of electrical and radio engineering. In accordance with this, select the complexity level of the device.

First of all, you should decide on the element base. Very often, computer users are left with old system units. There are power supplies there. Along with the +5V supply voltage, they contain a +12 Volt bus. As a rule, it is designed for current up to 2 Amperes. This is quite enough for a weak charger.

Video - step by step instructions on the manufacture and diagram of a simple charger for a car battery from computer unit power supply:

But 12 volts is not enough. It is necessary to “overclock” it to 15. How? Usually using the "poke" method. Take a resistance of about 1 kiloOhm and connect it in parallel with other resistances near the microcircuit with 8 legs in the secondary circuit of the power supply.

Thus, the transmission coefficient of the feedback circuit changes, respectively, and the output voltage.

It’s difficult to explain in words, but usually users succeed. By selecting the resistance value, you can achieve an output voltage of about 13.5 Volts. This is enough to charge a car battery.

If you don’t have a power supply at hand, you can look for a transformer with a secondary winding of 12 - 18 Volts. They were used in old tube televisions and other household appliances.

Now such transformers can be found in used uninterruptible power supplies; you can buy them for pennies at secondary market. Next, we begin manufacturing the transformer charger.

Transformer chargers

Transformer chargers are the most common and safe devices widely used in automotive practice.

Video - a simple charger for a car battery using a transformer:

The simplest circuit of a transformer charger for a car battery contains:

• network transformer;
• rectifier bridge;
• restrictive load.

A large current flows through the limiting load and it gets very hot, so to limit the charging current, capacitors are often used in the primary circuit of the transformer.

In principle, in such a circuit you can do without a transformer if you choose the capacitor wisely. But without galvanic isolation from the network AC such a circuit will be dangerous from the point of view of electric shock.

More practical are charger circuits for car batteries with regulation and limitation of the charge current. One of these schemes is shown in the figure:

You can use the rectifier bridge of a faulty car generator as powerful rectifier diodes by slightly reconnecting the circuit.

More complex pulse chargers with desulfation function are usually made using microcircuits, even microprocessors. They are difficult to manufacture and require special installation and configuration skills. In this case, it is easier to purchase a factory device.

Security requirements

Conditions that must be met when using a homemade car battery charger:

• The charger and battery must be located on a fireproof surface during charging;
• when using simple chargers, it is necessary to use personal protective equipment (insulating gloves, rubber mat);
• when using newly manufactured devices, constant monitoring of the charging process is necessary;
• basic controlled parameters charging process - current, voltage at the battery terminals, temperature of the charger body and battery, control of the boiling point;
• When charging at night, it is necessary to have residual current devices (RCDs) in the network connection.

Video - diagram of a charger for a car battery from a UPS:

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Comments on the article:

Lyokha

The information presented here is certainly interesting and informative. As a former radio engineer of the Soviet school, I read it with great interest. But in reality, now even “desperate” radio amateurs are unlikely to bother searching for circuit diagrams for a homemade charger and later assembling it with a soldering iron and radio components. Only radio fanatics will do this. It’s much easier to buy a factory-made device, especially since the prices, I think, are affordable. As a last resort, you can turn to other car enthusiasts with a request to “light up”, fortunately, now there are plenty of cars everywhere. What is written here is useful not so much for its practical value (although that too), but for instilling interest in radio engineering in general. After all, most modern children not only cannot distinguish a resistor from a transistor, but they won’t be able to pronounce it the first time. And this is very sad...

Michael

When the battery was old and half-dead, I often used a laptop power supply to recharge. I used an unnecessary old one as a current limiter. rear light with four 21 Watt bulbs connected in parallel. I control the voltage at the terminals, at the beginning of charging it is usually about 13 V, the battery greedily eats up the charge, then the charging voltage increases, and when it reaches 15 V, I stop charging. It takes half an hour to an hour to reliably start the engine.

Ignat

I have a Soviet charger in my garage, it’s called “Volna”, made in 1979. Inside is a hefty and heavy transformer and several diodes, resistors and transistors. Almost 40 years in service, and this despite the fact that my father and brother use it constantly, not only for charging, but also as a 12 V power supply. And now, indeed, it’s easier to buy a cheap Chinese device for five hundred square meters than to bother with soldering iron. And on Aliexpress you can even buy it for one and a half hundred, although it will take a long time to send it. Although I liked the option from the computer power supply, I have a dozen old ones lying around in the garage, but they work quite well.

San Sanych

Hmmm. Of course, the Pepsicol generation is growing... :-\ The correct charger should produce 14.2 volts. No more and no less. With a greater potential difference, the electrolyte will boil, and the battery will swell so that it will then be problematic to remove it or, conversely, not to install it back in the car. With a smaller potential difference, the battery will not charge. The most normal circuit presented in the material is with a step-down transformer (first). In this case, the transformer must produce exactly 10 volts at a current of at least 2 amperes. There are plenty of these on sale. It is better to install domestic diodes - D246A (must be installed on a radiator with mica insulators). At worst - KD213A (these can be glued to an aluminum radiator with superglue). Any electrolytic capacitor with a capacity of at least 1000 uF for an operating voltage of at least 25 volts. A very large capacitor is also not needed, since due to the ripples of the under-rectified voltage we obtain the optimal charge for the battery. In total we get 10 * root of 2 = 14.2 volts. I myself have had such a charger since the days of the 412th Muscovite. Not killable at all. 🙂

Kirill

In principle, if you have the necessary transformer, it is not so difficult to assemble a transformer charger circuit yourself. Even for me, not a very big specialist in the field of radio electronics. Many people say, why bother if it’s easier to buy. I agree, but this is not about the final result, but about the process itself, because it is much more pleasant to use something made with your own hands than something purchased. And most importantly, if this homemade product breaks down, then the one who assembled it knows his battery charger thoroughly and is able to fix it quickly. And if a purchased product burns out, then you still need to dig around and it’s not at all a fact that a breakdown will be found. I vote for self-built devices!

Oleg

In general, I think that the ideal option is an industrial charger, so I have one and carry it in the trunk all the time. But in life situations are different. Once I was visiting my daughter in Montenegro, and there they generally don’t carry anything with them and rarely do anyone even have one. So she forgot to close the door at night. The battery is drained. No diode at hand, no computer. I found a Boschevsky screwdriver with 18 volts and 1 ampere current. So I used his charger. True, I charged it all night and periodically checked for overheating. But she couldn’t stand it, in the morning they started her with half a kick. So there are many options, you have to look. Well, regarding homemade chargers, as a radio engineer I can only recommend transformer ones, i.e. isolated via the network, they are safe compared to capacitors, diodes with a light bulb.

Sergey

Charging the battery with non-standard devices can lead to either complete irreversible wear or a decrease in guaranteed operation. The whole problem is connecting homemade products, so that the rated voltage does not exceed the permissible one. It is necessary to take into account temperature differences and this is a very important point, especially in winter time. When we decrease by a degree, we increase it and vice versa. There is an approximate table depending on the type of battery - it is not difficult to remember. Another important point is that all measurements of voltage and, of course, density are made only when the engine is cold, with the engine not running.

Vitalik

In general, I use the charger extremely rarely, maybe once every two or three years, and only when I go away for a long time, for example in the summer for a couple of months to the south to visit relatives. And so basically the car is in operation almost every day, the battery is charged and there is no need for such devices. Therefore, I think that buying for money something that you practically never use is not very smart. The best option- assemble such a simple craft, say, from a computer power supply, and let it lie around, waiting in the wings. After all, the main thing here is not to fully charge the battery, but to cheer it up a little to start the engine, and then the generator will do its job.

Nikolay

Just yesterday we recharged the battery using a screwdriver charger. The car was parked outside, the frost was -28, the battery was spun a couple of times and stopped. We took out a screwdriver, a couple of wires, connected it, and after half an hour the car started up safely.

Dmitry

A ready-made store charger is of course an ideal option, but who wants to use their own hands, and considering that you don’t have to use it often, you don’t have to spend money on the purchase and do the charging yourself.
A homemade charger should be autonomous, not require supervision or current control, since we charge most often at night. In addition, it must provide a voltage of 14.4 V and ensure that the battery is turned off when the current and voltage exceed the norm. It should also provide protection against polarity reversal.
The main mistakes that “Kulibins” make are connecting directly to a household electrical network, this is not even a mistake, but a violation of safety regulations, the next limiting the charging current is by capacitors, and it’s also more expensive: one bank of capacitors 32 uF at 350-400 V (less than that is not possible) will cost like a cool branded charger.
The easiest way is to use a computer switching power supply (UPS), it is now more affordable than a hardware transformer, and you don’t need to do separate protection, everything is ready.
If you don't have a computer power supply, you need to look for a transformer. A power supply with filament windings from old tube TVs - TS-130, TS-180, TS-220, TS-270 - is suitable. They have plenty of power behind their eyes. You can find an old TN filament transformer at the car market.
But all this is only for those who are friends with electricians. If not, don’t bother - you won’t do the exercises that meet all the requirements, so buy ready-made ones and don’t waste time.

Laura

I got a charger from my grandfather. Since Soviet times. Homemade. I don’t understand this at all, but when my friends see it, they click their tongues in admiration and respect, saying, this is a thing “for centuries.” They say it was assembled using some lamps and still works. True, I practically don’t use it, but that’s not the point. Everyone criticizes Soviet technology, but it turns out to be many times more reliable than modern technology, even homemade ones.

Vladislav

In general, a useful thing in the household, especially if there is a function for adjusting the output voltage

Alexey

I’ve never had the opportunity to use or assemble homemade chargers, but I can quite imagine the principle of assembly and operation. I think that homemade products are no worse than factory ones, it’s just that no one wants to tinker, especially since store-bought ones are quite affordable.

Victor

In general, the schemes are simple, there are few parts and they are accessible. It is also possible to do adjustments if you have some experience. So it's quite possible to collect. Of course, it is very pleasant to use a device assembled with your own hands)).

Ivan

The charger is, of course, a useful thing, but now there are more interesting specimens on the market - their name is start-chargers

Sergey

There are a lot of charger circuits and as a radio engineer I have tried many of them. Until last year, I had a scheme that worked for me since Soviet times and it worked perfectly. But one day (through my fault) the battery completely died in the garage and I needed a cyclic mode to restore it. Then I didn’t bother (due to lack of time) with creating new scheme, but just went and bought it. And now I carry a charger in the trunk just in case.

Assessing the characteristics of a particular charger is difficult without understanding how an exemplary charge of a li-ion battery should actually proceed. Therefore, before moving directly to the diagrams, let's remember a little theory.

What are lithium batteries?

Depending on what material the positive electrode is made of lithium battery, there are several varieties of them:

• 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):

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 voltage idle speed circuits will never be able to 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-warming the battery, which is important when charging at low temperatures environment (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 stages of charging a lithium-ion battery (including the pre-charge 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, overcharging and overdischarging of the lithium battery. As a rule, overheating protection is also built into 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):

Analogs 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 similar to p-n-p 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 of the LM317 chip, 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 precisely.

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 is also cheaper than the 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 scheme, 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 pair 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 heat is removed through the 3rd leg, so you can make this path very wide and thick (fill it excessive quantity 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, 2, 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 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:

1. Monitoring the voltage of the connected battery (this happens all the time).
2. 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.
3. Charging with a maximum constant current (1000 mA at R prog = 1.2 kOhm);
4. 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.
5. 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.
6. 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 the temperature sensor built into the lithium-ion battery(usually this is average output battery cell phone). If the voltage at the output 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 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).

Any pnp transistor is suitable, 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 most difficult thing here is to find 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). Based on it, we get a very budget-friendly charging option (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.

Among the undeniable advantages I would like to note the following:

1. Minimum number of body parts.
2. Possibility of charging a completely discharged battery (precharge current 30 mA);
3. Determining the end of charging.
4. Programmable charging current - up to 1000 mA.
5. Charge and error indication (capable of detecting non-chargeable batteries and signaling this).
6. 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 located 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).

Most main drawback Such charging requires constant monitoring of 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.

Who has not encountered in their practice the need to charge a battery and, disappointed in the lack of a charger with the necessary parameters, was forced to purchase a new charger in a store, or reassemble the necessary circuit?
So I have repeatedly had to solve the problem of charging various batteries when there was no suitable charger at hand. I had to quickly assemble something simple, in relation to a specific battery.

The situation was tolerable until the need for mass preparation and, accordingly, charging the batteries arose. It was necessary to produce several universal chargers - inexpensive, working in wide range input and output voltages and charging currents.

The charger circuits proposed below were designed for charging lithium-ion batteries, but it is possible to charge other types of batteries and composite batteries (using the same type of cells, hereinafter referred to as AB).

All presented schemes have the following main parameters:
input voltage 15-24 V;
charge current (adjustable) up to 4 A;
output voltage (adjustable) 0.7 - 18 V (at Uin=19V).

All circuits were designed to work with power supplies from laptops or to work with other power supplies with DC output voltages from 15 to 24 Volts and were built on widespread components that are present on the boards of old computer power supplies, power supplies of other devices, laptops, etc.

Memory circuit No. 1 (TL494)

The inverse input (pin 2) of the same error amplifier is supplied with a comparison voltage, regulated by a variable resistor PR1, from a reference voltage source built into the chip (ION - pin 14), which changes the potential difference between the inputs of the error amplifier.
As soon as the voltage value on R10 exceeds the voltage value (set by the variable resistor PR1) at pin 2 of the TL494 microcircuit, the charging current pulse will be interrupted and resumed again only at the next cycle of the pulse sequence generated by the microcircuit generator.
By thus adjusting the width of the pulses on the gate of transistor VT2, we control the battery charging current.

Transistor VT1, connected in parallel with the gate of a powerful switch, provides the necessary discharge rate of the gate capacitance of the latter, preventing “smooth” locking of VT2. In this case, the amplitude of the output voltage in the absence of a battery (or other load) is almost equal to the input supply voltage.

With an active load, the output voltage will be determined by the current through the load (its resistance), which allows this circuit to be used as a current driver.

When charging the battery, the voltage at the switch output (and, therefore, at the battery itself) will tend to increase over time to a value determined by the input voltage (theoretically) and this, of course, cannot be allowed, knowing that the voltage value of the lithium battery being charged should be limited to 4.1V (4.2V). Therefore, the memory uses a threshold device circuit, which is a Schmitt trigger (hereinafter referred to as TS) on an op-amp KR140UD608 (IC1) or on any other op-amp.

When the required voltage value on the battery is reached, at which the potentials at the direct and inverse inputs (pins 3, 2 - respectively) of IC1 are equal, a high logical level (almost equal to the input voltage) will appear at the output of the op-amp, causing the LED indicating the end of charging HL2 and the LED to light up optocoupler VH1 which will open its own transistor, blocking the supply of pulses to output U1. The key on VT2 will close and the battery will stop charging.

Once the battery is charged, it will begin to discharge through the reverse diode built into VT2, which will be directly connected in relation to the battery and the discharge current will be approximately 15-25 mA, taking into account the discharge also through the elements of the TS circuit. If this circumstance seems critical to someone, a powerful diode (preferably with a low forward voltage drop) should be placed in the gap between the drain and the negative terminal of the battery.

The TS hysteresis in this version of the charger is chosen such that the charge will begin again when the voltage on the battery drops to 3.9 V.

This charger can also be used to charge series-connected lithium (and other) batteries. It is enough to calibrate the required response threshold using variable resistor PR3.
So, for example, a charger assembled according to scheme 1 operates with a three-section serial battery from a laptop, consisting of dual elements, which was mounted to replace the nickel-cadmium battery of a screwdriver.
The power supply from the laptop (19V/4.7A) is connected to the charger, assembled in the standard case of the screwdriver charger instead of the original circuit. The charging current of the “new” battery is 2 A. At the same time, transistor VT2, working without a radiator, heats up to a maximum temperature of 40-42 C.
The charger is switched off, naturally, when the battery voltage reaches 12.3V.

The TS hysteresis when the response threshold changes remains the same as a PERCENTAGE. That is, if at a shutdown voltage of 4.1 V, the charger was turned on again when the voltage dropped to 3.9 V, then in this case the charger was turned on again when the voltage on the battery decreased to 11.7 V. But if necessary, the hysteresis depth can be changed.

Charger Threshold and Hysteresis Calibration

Setting the current mode is even easier.
1. We turn off the threshold device using any available (but safe) methods: for example, by “connecting” the PR3 engine to the common wire of the device or by “shorting” the LED of the optocoupler.
2. Instead of the battery, we connect a load in the form of a 12-volt light bulb to the output of the charger (for example, I used a pair of 12V 20-watt lamps to set up).
3. We connect the ammeter to the break of any of the power wires at the input of the charger.
4. Set the PR1 engine to minimum (to the maximum left according to the diagram).
5. Turn on the memory. Smoothly rotate the PR1 adjustment knob in the direction of increasing current until the required value is obtained.
You can try to change the load resistance towards lower values ​​of its resistance by connecting in parallel, say, another similar lamp or even “short-circuiting” the output of the charger. The current should not change significantly.

During testing of the device, it turned out that frequencies in the range of 100-700 Hz were optimal for this circuit, provided that IRF3205, IRF3710 were used (minimum heating). Since the TL494 is underutilized in this circuit, the free error amplifier on the IC can be used to drive a temperature sensor, for example.

It should also be borne in mind that if the layout is incorrect, even a correctly assembled pulse device will not work correctly. Therefore, one should not neglect the experience of assembling power pulse devices, described repeatedly in the literature, namely: all “power” connections of the same name should be located at the shortest distance relative to each other (ideally at one point). So, for example, connection points such as the collector VT1, the terminals of resistors R6, R10 (connection points with the common wire of the circuit), pin 7 of U1 - should be combined at almost one point or through a straight short and wide conductor (bus). The same applies to drain VT2, the output of which should be “hung” directly onto the “-” terminal of the battery. The terminals of IC1 must also be in close “electrical” proximity to the battery terminals.

Memory circuit No. 2 (TL494)

As you can see, to quickly change the current mode and work with different numbers of elements connected in series, fixed settings have been introduced with trimming resistors PR1-PR3 (current setting), PR5-PR7 (setting the end of charging threshold for a different number of elements) and switches SA1 (current selection charging) and SA2 (selecting the number of battery cells to be charged).
The switches have two directions, where their second sections switch the mode selection indication LEDs.

Another difference from the previous device is the use of a second error amplifier TL494 as a threshold element (connected according to the TS circuit) that determines the end of battery charging.

Well, and, of course, a p-conductivity transistor was used as a key, which simplified the full use of the TL494 without the use of additional components.

The method for setting the end of charging thresholds and current modes is the same, as for setting previous version Memory Of course, for a different number of elements, the response threshold will change multiples.

When testing this circuit, we noticed stronger heating of the switch on the VT2 transistor (when prototyping I use transistors without a heatsink). For this reason, you should use another transistor (which I simply didn’t have) of appropriate conductivity, but with better current parameters and lower open-channel resistance, or double the number of transistors indicated in the circuit, connecting them in parallel with separate gate resistors.

The use of these transistors (in a “single” version) is not critical in most cases, but in this case, the placement of the device components is planned in a small-sized case using small radiators or no radiators at all.

Memory circuit No. 3 (TL494)

Charger circuit No. 3a (TL494)

Memory circuit No. 4 (TL494)

Such a module is always useful for bench tests of both batteries and other devices. It makes sense to use built-in devices (voltmeter, ammeter). Formulas for calculating storage and interference chokes are described in the literature. I’ll just say that I used ready-made various chokes (with a range of specified inductances) during testing, experimenting with a PWM frequency from 20 to 90 kHz. I didn’t notice any particular difference in the operation of the regulator (in the range of output voltages 2-18 V and currents 0-4 A): minor changes in the heating of the key (without a radiator) suited me quite well. The efficiency, however, is higher when using smaller inductances.
The regulator worked best with two series-connected 22 µH chokes in square armored cores from converters integrated into laptop motherboards.

Memory circuit No. 5 (MC34063)

Memory circuit No. 6 (UC3843)

In schemes 5 and 6, the same sets of components (including chokes) were used in the experiments. According to the test results, all of the listed circuits are not much inferior to each other in the declared range of parameters (frequency/current/voltage). Therefore, a circuit with fewer components is preferable for repetition.

Memory circuit No. 7 (TL494)

A relay is used to switch the battery from the “charge” mode to the “load” mode.

Working with the memory is similar to working with previous devices. Calibration is carried out by switching the toggle switch to the “calibration” mode. In this case, the contact of the toggle switch S1 connects the threshold device and a voltmeter to the output of the integral regulator IC2. Having set the required voltage for the upcoming charging of a specific battery at the output of IC2, using PR3 (smoothly rotating) the HL2 LED lights up and, accordingly, relay K1 operates. By reducing the voltage at the output of IC2, HL2 is suppressed. In both cases, control is carried out by a built-in voltmeter. After setting the PU response parameters, the toggle switch is switched to charge mode.

Scheme No. 8

Charger design

He designed several digital pulse duration meters, different in functionality and elemental base.

More than 30 improvement proposals for the modernization of units of various specialized equipment, incl. - power supply. For a long time now I have been increasingly involved in power automation and electronics.

Why am I here? Yes, because everyone here is the same as me. There is a lot of interest here for me, since I am not strong in audio technology, but I would like to have more experience in this area.

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Many car enthusiasts know very well that in order to extend the life of the battery, it is required periodically from the charger, and not from the car’s generator.

And the longer the battery life, the more often it needs to be charged to restore charge.

You can't do without chargers

To perform this operation, as already noted, chargers operating from a 220 V network are used. There are a lot of such devices on the automotive market, they may have various useful additional functions.

However, they all do the same job - convert alternating voltage 220 V into direct voltage - 13.8-14.4 V.

In some models, the charging current is manually adjusted, but there are also models with fully automatic operation.

Of all the disadvantages of purchased chargers, one can note their high cost, and the more sophisticated the device, the higher the price.

But many people have a large number of electrical appliances at hand, the components of which may well be suitable for creating a homemade charger.

Yes, a homemade device will not look as presentable as a purchased one, but its task is to charge the battery, and not to “show off” on a shelf.

One of the most important conditions when creating a charger is at least basic knowledge of electrical engineering and radio electronics, as well as the ability to hold a soldering iron in your hands and be able to use it correctly.

Memory from a tube TV

The first scheme will be, perhaps the simplest, and almost any car enthusiast can cope with it.

To make a simple charger, you only need two components - a transformer and a rectifier.

The main condition that the charger must meet is that the current output from the device must be 10% of the battery capacity.

That is, a 60 Ah battery is often used in passenger cars; based on this, the current output from the device should be 6 A. The voltage should be 13.8-14.2 V.

If someone has an old, unnecessary tube Soviet TV, then it’s better to have a transformer than not to find one.

The schematic diagram of the TV charger looks like this.

Often, a TS-180 transformer was installed on such televisions. Its peculiarity was the presence of two secondary windings, 6.4 V each and a current strength of 4.7 A. The primary winding also consists of two parts.

First you will need to connect the windings in series. The convenience of working with such a transformer is that each of the winding terminals has its own designation.

To connect the secondary winding in series, you need to connect pins 9 and 9\’ together.

And to pins 10 and 10\’ - solder two pieces of copper wire. All wires that are soldered to the terminals must have a cross-section of at least 2.5 mm. sq.

Regarding primary winding, then for a serial connection you need to connect pins 1 and 1\’. Wires with a plug for connecting to the network must be soldered to pins 2 and 2\’. At this point, work with the transformer is completed.

The diagram shows how the diodes should be connected - the wires coming from terminals 10 and 10\', as well as the wires that will go to the battery, are soldered to the diode bridge.

Don't forget about fuses. It is recommended to install one of them on the “positive” terminal with diode bridge. This fuse must be rated for a current of no more than 10 A. The second fuse (0.5 A) must be installed at terminal 2 of the transformer.

Before starting charging, it is better to check the functionality of the device and check its output parameters using an ammeter and voltmeter.

Sometimes it happens that the current is slightly higher than required, so some install a 12-volt incandescent lamp with a power of 21 to 60 watts in the circuit. This lamp will “take away” the excess current.

Microwave oven charger

Some car enthusiasts use a transformer from a broken microwave oven. But this transformer will need to be redone, since it is a step-up transformer, not a step-down transformer.

It is not necessary that the transformer be in good working order, since the secondary winding in it often burns out, which will still have to be removed during the creation of the device.

Remaking the transformer comes down to completely removing the secondary winding and winding a new one.

An insulated wire with a cross-section of at least 2.0 mm is used as a new winding. sq.

When winding, you need to decide on the number of turns. You can do this experimentally - wind 10 turns of a new wire around the core, then connect a voltmeter to its ends and power the transformer.

According to the voltmeter readings, it is determined what output voltage these 10 turns provide.

For example, measurements showed that there is 2.0 V at the output. This means that 12V at the output will provide 60 turns, and 13V will provide 65 turns. As you understand, 5 turns adds 1 volt.

It is worth pointing out that it is better to assemble such a charger with high quality, then place all the components in a case that can be made from scrap materials. Or mount it on a base.

Be sure to mark where the “positive” wire is and where the “negative” wire is, so as not to “over-plus” and damage the device.

Memory from the ATX power supply (for prepared ones)

A charger made from a computer power supply has a more complex circuit.

For the manufacture of the device, units with a power of at least 200 Watts of the AT or ATX models, which are controlled by a TL494 or KA7500 controller, are suitable. It is important that the power supply is fully operational. The ST-230WHF model from old PCs performed well.

A fragment of the circuit diagram of such a charger is presented below, and we will work on it.

In addition to the power supply, you will also need a potentiometer-regulator, a 27 kOhm trim resistor, two 5 W resistors (5WR2J) and a resistance of 0.2 Ohm or one C5-16MV.

The initial stage of work comes down to disconnecting everything unnecessary, which are the “-5 V”, “+5 V”, “-12 V” and “+12 V” wires.

The resistor indicated in the diagram as R1 (it supplies a voltage of +5 V to pin 1 of the TL494 controller) must be unsoldered, and a prepared 27 kOhm trimmer resistor must be soldered in its place. The +12 V bus must be connected to the upper terminal of this resistor.

Pin 16 of the controller should be disconnected from the common wire, and you also need to cut the connections of pins 14 and 15.

You need to install a potentiometer-regulator in the rear wall of the power supply housing (R10 in the diagram). It must be installed on an insulating plate so that it does not touch the block body.

The wiring for connecting to the network, as well as the wires for connecting the battery, should also be routed through this wall.

To ensure ease of adjustment of the device, from the existing two 5 W resistors on a separate board, you need to make a block of resistors connected in parallel, which will provide an output of 10 W with a resistance of 0.1 Ohm.

Then you should check the correct connection of all terminals and the functionality of the device.

The final work before completing the assembly is to calibrate the device.

To do this, the potentiometer knob should be set to the middle position. After this, the open circuit voltage should be set on the trimmer resistor at 13.8-14.2 V.

If everything is done correctly, then when the battery starts charging, a voltage of 12.4 V with a current of 5.5 A will be supplied to it.

As the battery charges, the voltage will increase to the value set on the trim resistor. As soon as the voltage reaches this value, the current will begin to decrease.

If all operating parameters converge and the device operates normally, all that remains is to close the housing to prevent damage to the internal elements.

This device from the ATX unit is very convenient, because when the battery is fully charged, it will automatically switch to voltage stabilization mode. That is, recharging the battery is completely excluded.

For convenience of work, the device can be additionally equipped with a voltmeter and ammeter.

Bottom line

These are just a few types of chargers that can be made at home from improvised materials, although there are many more options.

This is especially true for chargers that are made from computer power supplies.

If you have experience in making such devices, share it in the comments, many would be very grateful for it.

How does the battery charge? Is the circuit of this device complicated or not, in order to make the device with your own hands? Is it fundamentally different from what is used for mobile phones? We will try to answer all the questions posed further in the article.

General information

The battery plays a very important role in the functioning of devices, units and mechanisms that require electricity to operate. So, in vehicles it helps start the car engine. And in mobile phones, batteries allow us to make calls.

Charging the battery, circuit and principles of operation of this device are considered even in a school physics course. But, alas, by the time they graduate, much of this knowledge is forgotten. Therefore, we hasten to remind you that the battery’s operation is based on the principle of a voltage difference (potential) between two plates, which are specially immersed in an electrolyte solution.

The first batteries were copper-zinc. But since then they have improved and modernized significantly.

How does a battery work?

The only visible element of any device is the case. It provides commonality and integrity to the design. It should be noted that the name “battery” can be fully applied to only one battery cell (they are also called banks), and for the same standard 12 V car battery there are only six of them.

Let's return to the body. Strict demands are placed on him. So, it should be:

• resistant to aggressive chemicals;
• able to withstand significant temperature fluctuations;
• possessing good performance vibration resistance.

All these requirements are met by modern synthetic material - polypropylene. More detailed differences should only be highlighted when working with specific samples.

Operating principle

We'll look at lead-acid batteries as an example.

When there is a load on the terminal, a chemical reaction begins to occur, which is accompanied by the release of electricity. Over time, the battery will drain. How is it restored? Is there a simple diagram?

Charging a battery is not difficult. It is necessary to implement reverse process- electricity is supplied to the terminals, chemical reactions occur again (pure lead is restored), which in the future will allow the use of the battery.

Also, during charging, the density of the electrolyte increases. Thus, the battery restores its original properties. The better the technology and materials used in manufacturing, the more charge/discharge cycles the battery can withstand.

What electrical circuits for charging batteries exist?

The classic device is made of a rectifier and transformer. If we consider the same car batteries with a voltage of 12 V, then the chargers for them have a constant current of approximately 14 V.

Why is this so? This voltage is necessary so that current can flow through a discharged car battery. If he himself has 12 V, then a device of the same power will not be able to help him, which is why they take higher values. But in everything you need to know when to stop: if you increase the voltage too much, it will have a detrimental effect on the service life of the device.

Therefore, if you want to make a device with your own hands, you need to look for suitable charging schemes for car batteries for cars. The same applies to other technology. If a charging circuit is needed, then a 4 V device is needed and no more.

Recovery process

Let's say you have a circuit for charging a battery from a generator, according to which the device was assembled. The battery is connected and the recovery process begins immediately. As it progresses, the devices will grow. The charging current will drop along with it.

When the voltage approaches the maximum possible value, this process practically does not occur at all. This indicates that the device has successfully charged and can be turned off.

It is necessary to ensure that the battery current is only 10% of its capacity. Moreover, it is not recommended to either exceed this figure or reduce it. So, if you follow the first path, the electrolyte will begin to evaporate, which will significantly affect maximum capacity and battery life. On the second path, the necessary processes will not occur at the required intensity, which is why the negative processes will continue, although to a somewhat lesser extent.

Charger

The described device can be purchased or assembled with your own hands. For the second option, we will need electrical circuits for charging batteries. The choice of technology by which it will be made should depend on which batteries are the target. You will need the following components:

1. (designed on ballast capacitors and a transformer). The higher the indicator can be achieved, the greater the current will be. In general, this should be enough for charging to work. But the reliability of this device is very low. So, if the contacts are broken or something is mixed up, then both the transformer and the capacitors will fail.
2. Protection in case of connecting the “wrong” poles. To do this, you can construct a relay. So, the conditional connection is based on a diode. If you confuse plus and minus, it will not pass current. And since there is a relay connected to it, it will be de-energized. Moreover, use this diagram possible with a device based on both thyristors and transistors. It must be connected to the break in the wires with which the charging itself is connected to the battery.
3. Automation that battery charging should have. The circuit in this case must ensure that the device will work only when it is really needed. To do this, resistors change the response threshold of the control diode. 12 V batteries are considered to be fully rated when their voltage is within 12.8 V. Therefore, this indicator is desirable for this circuit.

Conclusion

So we looked at what battery charging is. The circuit of this device can be made on a single board, but it should be noted that this is quite complicated. That's why they are made multi-layered.

Within the framework of the article, various circuit diagrams, which make it clear how batteries are actually charged. But it is necessary to understand that these are only general images, and more detailed ones, with indications of ongoing chemical reactions, are specific to each type of battery.