How to make your own battery charger. Automotive diagrams, diagrams for cars, do it yourself

For car batteries, since industrial designs are quite expensive. And you can make such a device yourself quite quickly, and from scrap materials that almost everyone has. From the article you will learn how to make chargers yourself at minimal cost. Two designs will be considered - with and without automatic control of the charge current.

The base of the charger is a transformer

In any charger you will find the main component - a transformer. It is worth noting that there are diagrams of devices built using a transformerless circuit. But they are dangerous because there is no protection against mains voltage. Therefore, you may receive an electric shock during manufacturing. They are much more effective and simpler transformer circuits, they have galvanic isolation from the mains voltage. To make a charger you will need a powerful transformer. It can be found by disassembling an unusable microwave oven. However, spare parts from this electrical appliance can be used to make a battery charger with your own hands.

Old tube TVs used transformers TS-270, TS-160. These models are perfect for constructing a charger. It turns out to be even more effective to use them, since they already have two windings of 6.3 volts each. Moreover, they can collect current up to 7.5 amperes. And when charging a car battery, a current equal to 1/10 of the capacity is required. Therefore, with a battery capacity of 60 Ah, you need to charge it with a current of 6 amperes. But if there are no windings that satisfy the condition, you will need to make one. And now about how to make a homemade charger for a car as quickly as possible.

Transformer rewinding

So, if you decide to use a converter from a microwave oven, then you need to remove the secondary winding. The reason lies in the fact that these step-up transformers convert the voltage to a value of about 2000 volts. The magnetron requires a power supply of 4000 volts, so a doubling circuit is used. You won’t need such values, so mercilessly get rid of the secondary winding. Instead, wind a wire with a cross-section of 2 square meters. mm. But you don’t know how many turns are needed? This needs to be found out; you can use several methods. And this must be done when making a battery charger with your own hands.

The simplest and most reliable is experimental. Wind ten turns of the wire you will use. Clean its edges and plug in the transformer. Measure the voltage on the secondary winding. Let's say these ten turns produce 2 V. Therefore, 0.2 V (a tenth part) is collected from one turn. You need at least 12 V, and it is better if the output has a value close to 13. Five turns will give one volt, now you need 5*12=60. The desired value is 60 turns of wire. The second method is more complicated; you will have to calculate the cross-section of the transformer's magnetic core, you need to know the number of turns of the primary winding.

Rectifier block

We can say that the simplest homemade chargers for car batteries consist of two units - a voltage converter and a rectifier. If you do not want to spend a lot of time on assembly, then you can use a half-wave circuit. But if you decide to assemble the charger, as they say, conscientiously, then it is better to use the pavement. It is advisable to choose diodes reverse current which are 10 amperes and above. They usually have a metal body and a fastening with a nut. It is also worth noting that each semiconductor diode should be installed on a separate heatsink to improve cooling of its case.

Minor modernization

However, you can stop there, a simple homemade charger is ready for use. But it can be supplemented with measuring instruments. Having assembled all the components in a single case and securely fastened them in their places, you can start designing the front panel. You can place two instruments on it - an ammeter and a voltmeter. With their help, you can control the charging voltage and current. If desired, install an LED or incandescent lamp, which is connected to the output of the rectifier. With the help of such a lamp you will see whether the charger is plugged in. If necessary, add a small switch.

Automatic adjustment of charging current

Good results are shown by homemade chargers for car batteries that have an automatic current adjustment function. Despite their apparent complexity, these devices are very simple. True, some components will be required. The circuit uses current stabilizers, for example LM317, as well as its analogues. It is worth noting that this stabilizer has earned the trust of radio amateurs. It is trouble-free and durable, its characteristics are superior to domestic analogues.

In addition to this, you will also need adjustable zener diode, for example TL431. All microcircuits and stabilizers used in the design must be mounted on separate radiators. The operating principle of the LM317 is that “extra” voltage is converted into heat. Therefore, if you have 15 V rather than 12 V coming from the rectifier output, then the “extra” 3 V will go into the radiator. Many homemade car battery chargers are made without strict outer casing requirements, but it is better if they are enclosed in an aluminum case.

Conclusion

At the end of the article, I would like to note that a device such as a car charger needs high-quality cooling. Therefore, it is necessary to provide for the installation of coolers. It is best to use those that are mounted in computer power supplies. Just pay attention to the fact that they need a power supply of 5 volts, not 12. Therefore, you will have to supplement the circuit by introducing a 5-volt voltage stabilizer into it. Much more can be said about chargers. The autocharger circuit is easy to repeat, and the device will be useful in any garage.

We have talked with you many times about all sorts of chargers ah for car batteries on a pulse basis, today is also no exception. And we will consider the design of an SMPS, which can have an output power of 350-600 watts, but this is not the limit, since the power, if desired, can be raised to 1300-1500 watts, therefore, on such a basis it is possible to build starter-charger, because at a voltage of 12-14 Volts, up to 120 Amperes of current can be removed from a 1500-watt unit! well of course

The design attracted my attention a month ago, when an article caught my eye on one of the sites. The power regulator circuit seemed quite simple, so I decided to use this circuit for my design, which is very simple and does not require any adjustment. The circuit is designed for charging powerful acid batteries with a capacity of 40-100A/h, implemented on a pulse basis. The main power part of our charger is the mains pulse block power supply

Just recently I decided to make several chargers for car batteries, which I was going to sell on the local market. There were quite beautiful industrial buildings available; all you had to do was make a good filling and that was it. But then I encountered a number of problems, starting from the power supply and ending with the output voltage control unit. I went and bought a good old electronic transformer like Tashibra (Chinese brand) for 105 watts and started reworking it.

A fairly simple automatic charger can be implemented on the LM317 chip, which is linear stabilizer voltage with adjustable output voltage. The microcircuit can also work as a current stabilizer.

A high-quality charger for a car battery can be purchased on the market for $50, and today I’ll tell you the easiest way to make such a charger with minimal costs Money, it is simple and even a novice radio amateur can make it.

The design of a simple charger for car batteries can be implemented in half an hour at minimal cost; the process of assembling such a charger will be described below.

The article discusses a charger (charger) with a simple circuit design for batteries of various classes intended to power the electrical networks of cars, motorcycles, flashlights, etc. The charger is easy to use, does not require adjustments while charging the battery, and is not afraid of short circuits, easy and cheap to manufacture.

Recently, I came across a diagram of a powerful charger for car batteries with a current of up to 20A on the Internet. It's actually powerful adjustable block power supply assembled on only two transistors. The main advantage of the circuit is the minimum number of components used, but the components themselves are quite expensive, we are talking about transistors.

Naturally, everyone in the car has cigarette lighter chargers for all kinds of devices: navigator, phone, etc. The cigarette lighter is naturally not without dimensions, and especially since there is only one (or rather, a cigarette lighter socket), and if there is also a person who smokes, then the cigarette lighter itself must be taken out somewhere and put somewhere, and if you really need to connect something to the charger, then using the cigarette lighter for its intended purpose is simply impossible , you can solve the connection of all kinds of tees with a socket like a cigarette lighter, but it’s like that

Recently I came up with the idea of ​​assembling a car charger based on cheap Chinese power supplies with a price of $5-10. In electronics stores you can now find units that are designed to power LED strips. Since such tapes are powered by 12 Volts, therefore the output voltage of the power supply is also within 12 Volts

I present the design of a simple DC-DC converter, which will allow you to charge mobile phone, tablet computer or any other portable device from the car on-board network 12 Volt. The heart of the circuit is specialized chip 34063api is designed specifically for such purposes.

After the article charger from an electronic transformer, many letters were sent to my email address asking me to explain and tell how to power up the circuit of an electronic transformer, and in order not to write to each user separately, I decided to print this article, where I will talk about the main components that need will be modified to increase the output power of the electronic transformer.

Analysis of more than 11 circuits for making a charger with your own hands at home, new circuits for 2017 and 2018, how to assemble a circuit diagram in an hour.

TEST:

1. What are the main reasons why a car battery discharges on the road?

A) The motorist got out of the vehicle and forgot to turn off the headlights.

B) The battery has become too hot due to exposure to sunlight.

1. Can the battery fail if the car is not used? for a long time(standing in the garage without starting)?

A) If left idle for a long time, the battery will fail.

B) No, the battery will not deteriorate, it will only need to be charged and it will function again.

1. What current source is used to recharge the battery?

A) There is only one option - a network with a voltage of 220 volts.

B) 180 Volt network.

1. Be sure to shoot battery when connecting homemade device?

A) It is advisable to remove the battery from its installed location, otherwise there is a risk of damaging the electronics due to high voltage.

B) It is not necessary to remove the battery from its installed location.

1. If you confuse “minus” and “plus” when connecting a charger, will the battery fail?

A) Yes, at incorrect connection, the equipment will burn out.

B) The charger simply will not turn on; you will need to move the necessary contacts to the correct places.

Answers:

1. A) Headlights not turned off when stopping and sub-zero temperatures are the most common causes of battery discharge on the road.
2. A) The battery fails if it is not recharged for a long time when the car is idle.
3. A) For recharging, a mains voltage of 220 V is used.
4. A) It is not advisable to charge the battery with a homemade device if it is not removed from the car.
5. A) The terminals should not be mixed up, otherwise the homemade device will burn out.

Battery on vehicles require periodic charging. The reasons for the discharge can be different - from the headlights that the owner forgot to turn off, to negative temperatures V winter period on the street. For recharge battery You will need a good charger. This device is available in large varieties in auto parts stores. But if there is no opportunity or desire to purchase, then memory You can do it yourself at home. There are also a large number of schemes - it is advisable to study them all in order to choose the most suitable option.

Definition: A car charger is designed to transmit electric current with a given voltage directly to Battery

Answers to 5 Frequently Asked Questions

1. Will I need to take any additional measures before charging the battery in my car?– Yes, you will need to clean the terminals, since acid deposits appear on them during operation. Contacts It needs to be cleaned very well so that current flows to the battery without difficulty. Sometimes motorists use grease to treat terminals; this should also be removed.
2. How to wipe charger terminals?— You can buy a specialized product in a store or prepare it yourself. Water and soda are used as a self-made solution. The components are mixed and stirred. This great option for treating all surfaces. When the acid comes into contact with soda, a reaction will occur and the motorist will definitely notice it. This area will need to be thoroughly wiped to get rid of all acids. If the terminals were previously treated with grease, it can be removed with any clean rag.
3. If there are covers on the battery, do they need to be opened before charging?— If there are covers on the body, they must be removed.
4. Why is it necessary to unscrew the battery caps?— This is necessary so that the gases formed during the charging process can freely exit the case.
5. Is there a need to pay attention to the electrolyte level in the battery?- This is done in mandatory. If the level is lower than required, then you need to add distilled water inside the battery. Determining the level is not difficult - the plates must be completely covered with liquid.

It’s also important to know: 3 nuances about operation

The homemade product differs somewhat in its method of operation from the factory version. This is explained by the fact that the purchased unit has built-in functions, helping in work. They are difficult to install on a device assembled at home, and therefore you will have to adhere to several rules when operation.

1. A charger assembled by yourself will not turn off when fully charged battery That is why it is necessary to periodically monitor the equipment and connect it to multimeter– for charge control.
2. You need to be very careful not to confuse “plus” and “minus”, otherwise Charger will burn.
3. The equipment must be turned off when connecting to charger.

By following these simple rules, you will be able to recharge correctly battery and avoid unpleasant consequences.

Top 3 charger manufacturers

If you don’t have the desire or ability to assemble it yourself memory, then pay attention to the following manufacturers:

1. Stack.
2. Sonar.
3. Hyundai.

How to avoid 2 mistakes when charging a battery

It is necessary to follow the basic rules in order to properly nourish battery by car.

1. Direct to mains battery connection is prohibited. Chargers are intended for this purpose.
2. Even device made with high quality and good materials, you will still need to periodically monitor the process charging, so that troubles don't happen.

Following simple rules will ensure reliable operation of self-made equipment. It is much easier to monitor the unit than to spend money on components for repairs.

The simplest battery charger

Scheme of a 100% working 12 volt charger

Look at the picture for the diagram memory at 12 V. The equipment is intended for charging car batteries with a voltage of 14.5 Volts. Maximum current, obtained during charging is 6 A. But the device is also suitable for other batteries - lithium-ion, since the voltage and output current can be adjusted. All the main components for assembling the device can be found on the Aliexpress website.

Required components:

1. dc-dc buck converter.
2. Ammeter.
3. Diode bridge KVRS 5010.
4. Hubs 2200 uF at 50 volts.
5. transformer TS 180-2.
6. Circuit breakers.
7. Plug for connecting to the network.
8. "Crocodiles" for connecting terminals.
9. Radiator for diode bridge.

Transformer any one can be used at your own discretion. The main thing is that its power is not lower than 150 W (with a charging current of 6 A). It is necessary to install thick and short wires on the equipment. The diode bridge is fixed on a large radiator.

Look at the picture of the charger circuit Dawn 2. It is compiled according to the original Memory If you master this scheme, you will be able to independently create a high-quality copy that is no different from the original sample. Structurally, the device is a separate unit, closed with a housing to protect the electronics from moisture and exposure to bad weather conditions. It is necessary to connect a transformer and thyristors on the radiators to the base of the case. You will need a board that will stabilize the current charge and control the thyristors and terminals.

1 smart memory circuit

Look at the picture for a circuit diagram of a smart charger. The device is necessary for connection to lead-acid batteries with a capacity of 45 amperes per hour or more. This type of device is connected not only to batteries that are used daily, but also to those on duty or in reserve. This is a fairly budget version of the equipment. It does not provide indicator, and you can buy the cheapest microcontroller.

If you have the necessary experience, then you can assemble the transformer yourself. There is no need to install either sound signals alerts - if battery connects incorrectly, the discharge lamp will light up to indicate an error. The equipment must be equipped with a switching power supply of 12 volts - 10 amperes.

1 industrial memory circuit

Look at the industrial diagram charger from Bars 8A equipment. Transformers are used with one 16-volt power winding, several vd-7 and vd-8 diodes are added. This is necessary in order to provide a bridge rectifier circuit from one winding.

1 inverter device diagram

Look at the picture for a diagram of an inverter charger. This device discharges the battery to 10.5 Volts before charging. The current is used with a value of C/20: “C” indicates the capacity of the installed battery. After that process the voltage rises to 14.5 Volts using a discharge-charge cycle. The ratio of charge and discharge is ten to one.

1 electrical circuit charger electronics

1 powerful memory circuit

Look at the picture at the diagram of a powerful charger for a car battery. The device is used for acidic battery, having high capacity. The device easily charges a car battery with a capacity of 120 A. Output voltage The device is self-adjusting. It ranges from 0 to 24 volts. Scheme It is notable for the fact that it has few components installed, but it does not require additional settings during operation.

Many could already see the Soviet Charger. It looks like a small metal box and may seem quite unreliable. But this is not true at all. The main difference between the Soviet model and modern models is reliability. The equipment has structural capacity. In the event that to the old device connect the electronic controller, then charger it will be possible to revive. But if you no longer have one at hand, but there is a desire to assemble it, you need to study the diagram.

To the features their equipment includes a powerful transformer and rectifier, with the help of which it is possible to quickly charge even a very discharged battery. Many modern devices will not be able to reproduce this effect.

Electron 3M

In an hour: 2 do-it-yourself charging concepts

Simple circuits

1 the simplest scheme for an automatic charger for a car battery

The vehicle's on-board network is powered by the battery until the power plant starts. But it itself does not generate electrical energy. The battery is simply a container for electricity, which is stored in it and, if necessary, given to consumers. Afterwards, the expended energy is restored due to the operation of the generator, which produces it.

But even constant recharging The battery from the generator is not capable of fully recovering the energy consumed. This requires periodic charging from an external source rather than a generator.

Design and principle of operation of the charger

Chargers are used to produce. These devices operate from a 220 V network. In fact, the charger is a conventional electrical energy converter.

It takes the 220 V alternating current, lowers it and converts it into D.C. voltage up to 14 V, that is, up to the voltage that the battery itself produces.

Nowadays a large number of all kinds of chargers are produced - from primitive and simple ones to devices with a large number of various additional functions.

Chargers are also sold, which, in addition to possibly recharging the battery installed on the car, can also start the power plant. Such devices are called charging and starting devices.

There are also autonomous charging and starting devices that can recharge the battery or start the engine without connecting the device itself to a 220 V network. Inside such a device, in addition to equipment that converts electrical energy, there is also one, which makes such a device autonomous, although the battery of the device is also After each release of electricity, charging is required.

Video: How to make a simple charger

As for conventional chargers, the simplest of them consists of only a few elements. The main element of such a device is a step-down transformer. It lowers the voltage from 220 V to 13.8 V, which is the most optimal for charging the battery. However, the transformer only lowers the voltage, but transforming it with alternating current DC is performed by another element of the device - a diode bridge, which rectifies the current and divides it into positive and negative poles.

Behind the diode bridge, an ammeter is usually included in the circuit, which shows the current strength. The simplest device uses a dial ammeter. In more expensive devices, it can be digital; in addition to the ammeter, a voltmeter can also be built-in. Some chargers have the ability to select voltage; for example, they can charge both 12-volt and 6-volt batteries.

Wires with “positive” and “negative” terminals come out of the diode bridge, which connect the device to the battery.

All this is enclosed in a housing, from which comes a wire with a plug for connecting to the network, and wires with terminals. To protect the entire circuit from possible damage, it contains a fuse.

In general, this is the entire circuit of a simple charger. Charging the battery is relatively simple. The terminals of the device are connected to the discharged battery, but it is important not to mix up the poles. The device is then connected to the network.

At the very beginning of charging, the device will supply voltage with a current of 6-8 amperes, but as charging progresses, the current will decrease. All this will be displayed on the ammeter. If the battery is fully charged, the ammeter needle will drop to zero. This is the entire process of charging the battery.

The simplicity of the charger circuit makes it possible to manufacture it yourself.

Making your own car charger

Now let's look at the simplest chargers that you can make yourself. The first will be a device that schematic diagram very similar to what was described.

The diagram shows:
S1 - power switch (toggle switch);
FU1 - 1A fuse;
T1 - transformer TN44;
D1-D4 - diodes D242;
C1 - capacitor 4000 uF, 25 V;
A - 10A ammeter.

So, to make a homemade charger you will need a step-down transformer TS-180-2. Such transformers were used on old tube TVs. Its feature is the presence of two primary and secondary windings. Moreover, each of the secondary output windings has 6.4 V and 4.7 A. Therefore, in order to achieve the 12.8 V required for charging the battery, which this transformer is capable of, you need to connect these windings in series. For this, a short wire with a cross-section of at least 2.5 mm is used. sq. The jumper connects not only the secondary windings, but also the primary ones.

Video: The simplest battery charger

Next, you will need a diode bridge. To create it, 4 diodes are taken, designed for a current of at least 10 A. These diodes can be fixed on a textolite plate, and then they can be connected correctly. Wires are connected to the output diodes, which the device will connect to the battery. At this point, the assembly of the device can be considered complete.

Now about the correctness of the charging process. When connecting a device to a battery, do not reverse the polarity, otherwise you can damage both the battery and the device.

When connecting to a battery, the device must be completely de-energized. You can turn it on only after connecting it to the battery. It should also be disconnected from the battery after disconnecting from the network.

A heavily discharged battery cannot be connected to the device without a means that reduces the voltage and current, otherwise the device will supply a high current to the battery, which can damage the battery. An ordinary 12-volt lamp, which is connected to the output terminals in front of the battery, can act as a reducing agent. The lamp will light up when the device is operating, thereby partially absorbing the voltage and current. Over time, after the battery is partially charged, the lamp can be removed from the circuit.

When charging, you need to periodically check the state of charge of the battery, for which you can use a multimeter, voltmeter or load plug.

A fully charged battery, when checking its voltage, should show at least 12.8 V; if the value is lower, further charging is required to bring this indicator to the desired level.

Video: DIY car battery charger

Since this circuit does not have a protective housing, you should not leave the device unattended during operation.

And even if this device does not provide the optimal 13.8 V output, it is quite suitable for recharging the battery, although after about two years of using the battery, you will still need to charge it with a factory device that provides all the optimal parameters for charging the battery.

Transformerless charger

An interesting design is the circuit of a homemade device that does not have a transformer. Its role in this device is played by a set of capacitors designed for a voltage of 250 V. There must be at least 4 such capacitors. The capacitors themselves are connected in parallel.

A resistor is connected in parallel to the set of capacitors, designed to suppress the residual voltage after disconnecting the device from the network.

Next, you will need a diode bridge to operate with a permissible current of at least 6 A. It is connected to the circuit after a set of capacitors. And then the wires that will connect the device to the battery are connected to it.

In order for a car to start, it needs energy. This energy is taken from the battery. As a rule, it is recharged from the generator while the engine is running. When the car is not used for a long time or the battery is faulty, it discharges to such a state that that the car can no longer start. In this case it is required external charging. You can buy such a device or assemble it yourself, but for this you will need a charger circuit.

The principle of operation of a car battery

A car battery supplies power to various devices in the car when the engine is turned off and is designed to start it. By type of type of execution it is used lead acid battery. Structurally, it is assembled from six batteries with a nominal voltage of 2.2 volts, connected in series. Each element is a set of lattice plates made of lead. The plates are coated with active material and immersed in an electrolyte.

The electrolyte solution contains distilled water and sulfuric acid. The frost resistance of the battery depends on the density of the electrolyte. Recently, technologies have emerged that allow the electrolyte to be adsorbed in glass fiber or thickened using silica gel to a gel-like state.

Each plate has a negative and positive pole, and they are isolated from each other using a plastic separator. The body of the product is made of propylene, which is not destroyed by acid and serves as a dielectric. The positive pole of the electrode is coated with lead dioxide, and the negative with sponge lead. Recently, rechargeable batteries with electrodes made of lead-calcium alloy have begun to be produced. These batteries are completely sealed and require no maintenance.

When a load is connected to the battery, the active material on the plates reacts chemically with the electrolyte solution and produces an electric current. The electrolyte depletes over time due to the deposition of lead sulfate on the plates. The battery begins to lose charge. While charging chemical reaction occurs in the reverse order, lead sulfate and water are converted, the density of the electrolyte increases and the charge is restored.

Batteries are characterized by their self-discharge value. It occurs in the battery when it is inactive. The main reason is contamination of the battery surface and poor quality of the distiller. The rate of self-discharge accelerates when the lead plates are destroyed.

Types of chargers

A large number of car charger circuits have been developed using different element bases and fundamental approaches. According to the principle of operation, charging devices are divided into two groups:

1. Starting chargers, designed to start the engine when the battery is not working. By briefly supplying a large current to the battery terminals, the starter is turned on and the engine starts, and then the battery is charged from the car's generator. They are produced only for a certain current value or with the ability to set its value.
2. Pre-start chargers, leads from the device are connected to the battery terminals and current is supplied for a long time. Its value does not exceed ten amperes, during which time the battery energy is restored. In turn, they are divided into: gradual (charging time from 14 to 24 hours), accelerated (up to three hours) and conditioning (about an hour).

Based on their circuit design, pulse and transformer devices are distinguished. The first type uses a high-frequency signal converter and is characterized by small size and weight. The second type uses a transformer with a rectifier unit as a basis; it is easy to manufacture, but have heavy weight and low efficiency (efficiency).

Do-it-yourself charger for car batteries or purchased from point of sale, the requirements for it are the same, namely:

• output voltage stability;
• high efficiency value;
• short circuit protection;
• charge control indicator.

One of the main characteristics of the charger is the amount of current that charges the battery. Correctly charging the battery and extending its performance characteristics can only be achieved by selecting the desired value. The charging speed is also important. The higher the current, the higher the speed, but a high speed value leads to rapid degradation of the battery. It is believed that the correct current value will be a value equal to ten percent of the battery capacity. Capacity is defined as the amount of current supplied by the battery per unit of time; it is measured in ampere-hours.

Homemade charger

Every car enthusiast should have a charging device, so if there is no opportunity or desire to purchase a ready-made device, there is nothing left to do but charge the battery yourself. It is easy to make with your own hands both the simplest and multifunctional devices. For this you will need a diagram and a set of radioelements. It is also possible to remake the uninterruptible power supply (UPS) or computer unit(AT) into the device for recharging the battery.

Transformer charger

This device is the easiest to assemble and does not contain scarce parts. The circuit consists of three nodes:

• transformer;
• rectifier block;
• regulator

Voltage from the industrial network is supplied to the primary winding of the transformer. The transformer itself can be used of any type. It consists of two parts: the core and the windings. The core is assembled from steel or ferrite, the windings are made from conductor material.

The operating principle of a transformer is based on the appearance of an alternating magnetic field when current passes through primary winding and transferring it to the secondary. To obtain the required voltage level at the output, the number of turns in the secondary winding is made smaller compared to the primary. The voltage level on the secondary winding of the transformer is selected to be 19 volts, and its power should provide a threefold reserve of charging current.

From the transformer, the reduced voltage passes through the rectifier bridge and goes to a rheostat connected in series to the battery. The rheostat is designed to regulate the voltage and current by changing the resistance. The rheostat resistance does not exceed 10 Ohms. The amount of current is controlled by an ammeter connected in series in front of the battery. With such a circuit it will not be possible to charge a battery with a capacity of more than 50 Ah, since the rheostat begins to overheat.

You can simplify the circuit by removing the rheostat, and install a set of capacitors at the input in front of the transformer, which are used as reactance to reduce the network voltage. The lower the nominal value of the capacitance, the less voltage is supplied to the primary winding in the network.

The peculiarity of such a circuit is that it is necessary to ensure a signal level on the secondary winding of the transformer that is one and a half times greater than the operating voltage of the load. This circuit can be used without a transformer, but it is very dangerous. Without galvanic isolation, you can get an electric shock.

Pulse charger

Dignity pulse devices V high efficiency and compact sizes. The device is based on a microcircuit with pulse width modulation(PWM). You can assemble a powerful pulse charger with your own hands according to the following scheme.

The IR2153 driver is used as a PWM controller. After the rectifier diodes, a parallel battery is placed polar capacitor C1 with a capacity in the range of 47-470 μF and a voltage of at least 350 volts. The capacitor removes mains voltage surges and line noise. The diode bridge is used with a rated current of more than four amperes and with a reverse voltage of at least 400 volts. The driver controls powerful N-channel field effect transistors IRFI840GLC mounted on radiators. The current of such charging will be equal to 50 amperes, and output power up to 600 Watt.

You can make a pulse charger for a car with your own hands using a converted AT format computer power supply. They use the common TL494 microcircuit as a PWM controller. The modification itself consists of increasing the output signal to 14 volts. To do this, you will need to correctly install the trimmer resistor.

The resistor that connects the first leg of the TL494 to the stabilized + 5 V bus is removed, and instead of the second one, connected to the 12 volt bus, a variable resistor with a nominal value of 68 kOhm is soldered in. This resistor sets the required output voltage level. The power supply is turned on via a mechanical switch, according to the diagram indicated on the power supply housing.

Device on LM317 chip

A fairly simple but stable charging circuit is easily implemented on the LM317 integrated circuit. The microcircuit provides a signal level of 13.6 volts with a maximum current of 3 amperes. The LM317 stabilizer is equipped with built-in short circuit protection.

Voltage is supplied to the device circuit through the terminals from an independent DC power supply of 13-20 volts. The current, passing through the indicator LED HL1 and transistor VT1, is supplied to the stabilizer LM317. From its output directly to the battery via X3, X4. The divider assembled on R3 and R4 sets the required voltage value for opening VT1. Variable resistor R4 sets the charging current limit, and R5 sets the output signal level. The output voltage is adjustable from 13.6 to 14 volts.

The circuit can be simplified as much as possible, but its reliability will decrease.

In it, resistor R2 selects the current. A powerful nichrome wire element is used as a resistor. When the battery is discharged, the charging current is maximum, the VD2 LED lights up brightly; as the battery charges, the current begins to decrease and the LED dims.

Charger from an uninterruptible power supply

You can construct a charger from a conventional uninterruptible power supply even if the electronics unit is faulty. To do this, all electronics are removed from the unit, except for the transformer. A rectifier circuit, current stabilization and voltage limiting are added to the high-voltage winding of the 220 V transformer.

The rectifier is assembled using any powerful diodes, for example, domestic D-242 and a network capacitor of 2200 uF for 35-50 volts. The output will be a signal with a voltage of 18-19 volts. An LT1083 or LM317 chip with mandatory installation to the radiator.

By connecting the battery, the voltage is set to 14.2 volts. It is convenient to control the signal level using a voltmeter and ammeter. The voltmeter is connected in parallel to the battery terminals, and the ammeter in series. As the battery charges, its resistance will increase and the current will decrease. It’s even easier to make the regulator using a triac connected to the primary winding of the transformer like a dimmer.

At self-production devices, you should remember about electrical safety when working with an alternating current network of 220 V. As a rule, a correctly made charging device made from serviceable parts begins to work immediately, you just need to set the charging current.