The electrical circuit of the charger. Simple automatic charger. Microwave charger

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

The principle of operation of a car battery

The car battery supplies power to various devices in the car when the engine is off and is designed to start it. By type of execution, a lead-acid battery is used. Structurally, it is assembled from six batteries with a nominal voltage value of 2.2 volts, connected in series. Each element is a set of lattice plates made of lead. The plates are coated with an 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. IN Lately technologies have appeared that allow adsorbing the electrolyte in a glass fiber or thickening it using silica gel to a gel-like state.

Each plate has a negative and a 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 spongy lead. Recently, batteries with lead-calcium alloy electrodes have been 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 an electric current is generated. The electrolyte depletes over time due to the deposition of lead sulfate on the plates. The battery (battery) begins to lose charge. During charging chemical reaction occurs in the reverse order, lead sulfate and water are converted, the density of the electrolyte increases and the charge value is restored.

Batteries are characterized by a self-discharge value. It occurs in the battery when it is inactive. The main reason is contamination of the battery surface and Bad quality distiller. The rate of self-discharge is accelerated by the destruction of lead plates.

Types of chargers

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

1. Starting and charging, designed to start the engine when the battery is not working. Briefly supplying current to the battery terminals large size, 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 possibility of setting its value.
2. Pre-start chargers, terminals 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 this 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).

According to their circuitry, pulse and transformer devices are distinguished. The first type is used in the work of a high-frequency signal converter, characterized by small size and weight. The second type is used as a basis for a transformer with a rectifier unit, easy to manufacture, but have a lot of weight and low coefficient of performance (COP).

Made charger for car batteries with your own hands or purchased at a retail outlet, the requirements for it are the same, namely:

• output voltage stability;
• high value of efficiency;
• defence from short circuit;
• charge control indicator.

One of the main characteristics of the charge device is the amount of current that charges the battery. It will be possible to properly charge the battery and extend its performance only when selecting its desired value. In this case, 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 given off by the battery per unit of time, it is measured in ampere-hours.

Homemade charger

Every motorist should have a charging device, so if there is no opportunity or desire to purchase a ready-made device, there is nothing left but to charge the battery yourself. It is easy to make with your own hands both the simplest and the multifunctional device. This will require a diagram. and a set of radio elements. It is also possible to convert an uninterruptible power supply (UPS) or a computer unit (AT) into a device for recharging the battery.

Transformer charger

Such a device is the easiest to assemble and does not contain scarce parts. The scheme 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 kind. It consists of two parts: core and windings. The core is assembled from steel or ferrite, the windings are made from conductive material.

The principle of operation of the transformer is based on the appearance of a variable magnetic field when current passes through the primary winding and transfers it to the secondary. To obtain the required voltage level at the output, the number of turns in the secondary winding is made less than in the primary. The voltage level on the secondary winding of the transformer is chosen to be 19 volts, and its power should provide a threefold reserve for the charge current.

From the transformer, the reduced voltage passes through the rectifier bridge and enters the rheostat connected in series to the battery. The rheostat is designed to regulate the magnitude of voltage and current by changing the resistance. The resistance of the rheostat does not exceed 10 ohms. The current value is controlled by an ammeter connected in series in front of the battery. Such a scheme will not be able to charge batteries with a capacity of more than 50 Ah, since the rheostat starts 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 reactances to reduce the mains voltage. The smaller the nominal value of the capacitance, the less voltage is supplied to the primary winding in the network.

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

Pulse charger

The advantage of impulse devices in high efficiency and compact size. The device is based on a chip 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 polar capacitor C1 is placed in parallel with the battery with a capacitance in the range of 47–470 microfarads and a voltage of at least 350 volts. The capacitor removes mains voltage spikes 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 IRFI840GLC field-effect transistors mounted on heatsinks. The current of such charging will be equal to 50 amperes, and output power up to 600 watts.

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 chip as a PWM controller. The alteration itself consists in increasing the output signal to 14 volts. To do this, you need to correctly install the tuning resistor.

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

Device on the LM317 chip

A fairly simple, but stable charging circuit is easily performed on integrated circuit LM317. The microcircuit provides a signal level setting of 13.6 volts at a maximum current strength 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 power supply unit with a constant voltage of 13–20 volts. The current, passing through the indicator LED HL1 and the transistor VT1, is supplied to the LM317 stabilizer. From its output directly to the battery through X3, X4. The divider, assembled on R3 and R4, sets the required voltage value for opening VT1. The variable resistor R4 sets the charging current limit, and R5 the output signal level. The output voltage is set from 13.6 to 14 volts.

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

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

Charger from an uninterruptible power supply

It is possible to construct a charger from a conventional uninterruptible power supply even with a malfunction of the electronics assembly. 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 on any powerful diodes, for example, domestic D-242 and a network capacitor 2200 uF at 35-50 volts. The output will be a signal with a voltage of 18-19 volts. As a voltage stabilizer, an LT1083 or LM317 chip is used with a mandatory installation on a radiator.

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

At self-manufacturing devices should be aware of electrical safety when working with a 220 V AC mains. As a rule, a correctly made charging device from serviceable parts starts working immediately, you just need to set the charge current.

Now it makes no sense to assemble a charger for car batteries on your own: there is a huge selection of ready-made devices in stores, their prices are reasonable. However, let's not forget that it's nice to do something useful with your own hands, especially since a simple charger for a car battery can be assembled from improvised parts, and its price will be a penny.

The only thing to immediately warn about is that circuits without precise adjustment of the current and output voltage, which do not have a current cutoff at the end of the charge, are suitable for charging only lead- acid batteries. For AGM and the use of such chargers damages the battery!

How to make a simple transformer device

The circuit of this charger from a transformer is primitive, but workable and is assembled from available parts - factory chargers of the simplest type are designed in the same way.

At its core, this is a full-wave rectifier, hence the requirements for the transformer: since the voltage at the output of such rectifiers is equal to the nominal AC voltage multiplied by the root of two, then at 10V on the transformer winding we will get 14.1 V at the charger output. Any diode bridge is taken with a direct current of more than 5 amperes or it can be assembled from four separate diodes, and a measuring ammeter is selected with the same current requirements. The main thing is to place it on a radiator, which in the simplest case is an aluminum plate with an area of ​​at least 25 cm2.

The primitiveness of such a device is not only a minus: due to the fact that it has neither adjustment nor automatic shutdown, it can be used to “resuscitate” sulfated batteries. But we must not forget about the lack of protection against polarity reversal in this circuit.

The main problem is where to find a transformer of suitable power (at least 60 W) and with a given voltage. Can be used if a Soviet incandescent transformer turns up. However, its output windings have a voltage of 6.3V, so you will have to connect two in series, unwinding one of them so that you get a total of 10V at the output. An inexpensive transformer TP207-3 is suitable, in which the secondary windings are connected as follows:

At the same time, we unwind the winding between terminals 7-8.

Simple electronic charger

However, you can do without rewinding by supplementing the circuit with an electronic output voltage regulator. In addition, such a scheme will be more convenient in garage applications, as it will allow you to adjust the charge current during supply voltage drops, it is also used for small-capacity car batteries if necessary.

The role of the regulator here is played by composite transistor KT837-KT814, a variable resistor regulates the current at the output of the device. When assembling the charge, the 1N754A zener diode can be replaced with the Soviet D814A.

The circuit of the regulated charger is simple to repeat, and is easily assembled by surface mounting without the need for PCB etching. However, please note that FETs placed on a radiator, the heating of which will be noticeable. It is more convenient to use an old computer cooler by connecting its fan to the charger outlets. Resistor R1 must have a power of at least 5 W, it is easier to wind it from nichrome or fechral on your own or connect 10 one-watt resistors of 10 ohms in parallel. You can not put it, but we must not forget that it protects the transistors in the event of a short circuit.

When choosing a transformer, be guided by output voltage 12.6-16V, take either an incandescent transformer by connecting two windings in series, or select a ready-made model with the desired voltage.

Video: The simplest battery charger

Alteration of the charger from the laptop

However, you can do without looking for a transformer if you have an unnecessary laptop charger at hand - with a simple alteration, we will get a compact and lightweight impulse block power supply capable of charging car batteries. Since we need to get a voltage at the output of 14.1-14.3 V, no ready-made power supply will work, but the conversion is simple.
Let's look at a section of a typical scheme, according to which devices of this kind are assembled:

In them, maintaining a stabilized voltage is carried out by a circuit from a TL431 microcircuit that controls an optocoupler (not shown in the diagram): as soon as the output voltage exceeds the value set by resistors R13 and R12, the microcircuit lights up the optocoupler LED, informs the PWM controller of the converter a signal to reduce the duty cycle of the supplied to the pulse transformer. Difficult? In fact, everything is easy to make with your own hands.

Having opened the charger, we find not far from the TL431 output connector and two resistors connected to the Ref leg. It is more convenient to adjust the upper arm of the divider (in the diagram - resistor R13): by reducing the resistance, we reduce the voltage at the output of the charger, increasing it - we raise it. If we have a 12 V charger, we need a resistor with a large resistance, if the charger is 19 V, then with a smaller one.

Video: Charging for car batteries. Protection against short circuit and polarity reversal. DIY

We solder the resistor and instead install a trimmer, pre-configured by the multimeter for the same resistance. Then, having connected a load (a light bulb from a headlight) to the output of the charger, we turn it on and smoothly rotate the trimmer engine, while simultaneously controlling the voltage. As soon as we get a voltage in the range of 14.1-14.3 V, we turn off the memory from the network, fix the trimming resistor engine with varnish (at least for nails) and assemble the case back. It will take no more time than you spent reading this article.

There are also more complex stabilization schemes, and they can already be found in Chinese blocks. For example, here the optocoupler is controlled by the TEA1761 chip:

However, the setting principle is the same: the resistance of the resistor soldered between the positive output of the power supply and the 6th leg of the microcircuit changes. In the above diagram, two parallel resistors are used for this (thus, a resistance that is out of the standard series is obtained). We also need to solder a trimmer instead of them and adjust the output to the desired voltage. Here is an example of one of these boards:

By dialing, you can understand that we are interested in a single resistor R32 on this board (circled in red) - we need to solder it.

Similar recommendations are often found on the Internet on how to make a homemade charger from a computer power supply. But keep in mind that all of them are essentially reprints of old articles from the beginning of the 2000s, and such recommendations are not applicable to more or less modern power supplies. It is no longer possible to simply raise the 12 V voltage to the desired value in them, since other output voltages are also controlled, and they will inevitably “float away” with this setting, and the power supply protection will work. You can use laptop chargers that produce a single output voltage, they are much more convenient for rework.

Batteries in electrical engineering are usually called chemical current sources that can replenish, restore the expended energy due to the application of an external electric field.

Devices that supply electricity to the battery plates are called chargers: they bring the current source into working condition, charge it. In order to properly operate the battery, it is necessary to understand the principles of their operation and the charger.

How the battery works

A chemical recirculating power source in operation can:

1. power the connected load, such as a light bulb, motor, mobile phone and other appliances, consuming your supply electrical energy;

2. consume external electricity connected to it, spending it on restoring the reserve of its capacity.

In the first case, the battery is discharged, and in the second case, it receives a charge. There are many designs of batteries, but they have common principles of operation. Let us analyze this issue using the example of nickel-cadmium plates placed in an electrolyte solution.

Battery discharge

Two electrical circuits work simultaneously:

1. external, applied to the output terminals;

2. internal.

When discharged to a light bulb, in the external attached circuit, a current flows from the wires and filament, formed by the movement of electrons in metals, and in the internal part, anions and cations move through the electrolyte.

Graphite-laced nickel oxides form the basis of the positively charged plate, while cadmium sponge is used on the negative electrode.

When the battery is discharged, part of the active oxygen of nickel oxides moves into the electrolyte and moves to the plate with cadmium, where it oxidizes it, reducing the overall capacity.

Battery charge

The load from the output terminals for charging is most often removed, although in practice the method is used when the load is connected, as on the battery of a moving car or put on charge mobile phone on which the conversation is taking place.

Voltage is supplied to the battery terminals from an external source of higher power. It has the form of a constant or smoothed, pulsating form, exceeds the potential difference between the electrodes, is unipolar with them.

This energy causes the current to flow in the internal battery circuit in the opposite direction to the discharge, when active oxygen particles are “squeezed out” from sponge cadmium and through the electrolyte enter their original place. Due to this, the consumed capacity is restored.

During charging and discharging changes chemical composition plates, and the electrolyte serves as a transfer medium for the passage of anions and cations. Intensity passing through the internal circuit electric current affects the rate of restoration of the properties of the plates during charging and the speed of discharge.

Accelerated processes lead to rapid release of gases, excessive heating, which can deform the design of the plates, disrupt their mechanical state.

Too low charging currents significantly lengthen the recovery time of the spent capacity. With frequent use of a delayed charge, the sulfation of the plates increases, and the capacity decreases. Therefore, the load applied to the battery and the power of the charger are always taken into account to create the optimal mode.

How the charger works

The modern range of batteries is quite extensive. For each model, optimal technologies are selected that may not be suitable or be harmful to others. Manufacturers of electronic and electrical equipment experimentally investigate the operating conditions of chemical current sources and create their own products for them, which differ appearance, design, output electrical characteristics.

Charging structures for mobile electronic devices

Dimensions of chargers for mobile products different power differ significantly from each other. They create special working conditions for each model.

Even for the same type of AA or AAA batteries of different capacities, it is recommended to use your own charging time, depending on the capacity and characteristics of the current source. Its values ​​are indicated in the accompanying technical documentation.

A certain part of chargers and batteries for mobile phones are equipped with automatic protection that turns off the power at the end of the process. But, control over their work should still be carried out visually.

Charging structures for automotive batteries

It is especially important to follow the charging technology when using car batteries designed to work in difficult conditions. For example, in winter, in frost, with their help, it is necessary to spin the cold rotor of an internal combustion engine with a thickened lubricant through an intermediate electric motor - a starter.

Discharged or improperly prepared batteries usually do not cope with this task.

Empirical methods revealed the relationship of the charging current for lead acid and alkaline batteries. It is generally accepted that the optimal value of the charge (ampere) is 0.1 capacity (ampere hours) for the first type and 0.25 for the second.

For example, a battery has a capacity of 25 amp hours. If it is acidic, then it must be charged with a current of 0.1 ∙ 25 = 2.5 A, and for alkaline - 0.25 ∙ 25 = 6.25 A. To create such conditions, you will need to use different devices or use one universal one with a large number functions.

A modern lead acid battery charger must support a number of tasks:

control and stabilize the charge current;

take into account the temperature of the electrolyte and prevent it from heating more than 45 degrees by interrupting the power supply.

The ability to conduct a control-training cycle for an acid car battery using a charger is a necessary function that includes three stages:

1. full charge of the battery until the maximum capacity is reached;

2. ten-hour discharge with a current of 9÷10% of the nominal capacity (empirical dependence);

3. recharging a discharged battery.

During the CTC, the change in the density of the electrolyte and the completion time of the second stage are controlled. Its value is used to judge the degree of wear of the plates, the duration of the remaining resource.

Charging device for alkaline batteries, less than complex structures, because such current sources are not so sensitive to undercharging and overcharging modes.

The graph of the optimal charge of acid-base batteries for cars shows the dependence of capacity gain on the form of current change in the internal circuit.

At first technological process charging, it is recommended to maintain the current at the maximum allowable value, and then reduce its value to the minimum for the final completion of the physicochemical reactions that restore the capacity.

Even in this case, it is required to control the temperature of the electrolyte, to introduce corrections for the environment.

The complete completion of the charge cycle of lead acid batteries is controlled by:

restoration of voltage on each bank 2.5 ÷ 2.6 volts;

achievement of the maximum density of the electrolyte, which ceases to change;

the formation of rapid gas evolution, when the electrolyte begins to "boil";

achievement of battery capacity exceeding by 15÷20% the value given during discharge.

Battery charger current waveforms

The condition for charging a battery is that a voltage must be applied to its plates, creating a current in the internal circuit in a certain direction. He can:

1. have a constant value;

2. or change in time according to a certain law.

In the first case, the physical and chemical processes of the internal circuit proceed unchanged, and in the second case, according to the proposed algorithms with a cyclic increase and decay, creating oscillatory effects on anions and cations. The latest version of the technology is used to combat plate sulfation.

Some of the time dependences of the charge current are illustrated by graphs.

The lower right picture shows a clear difference in the output current shape of the charger, which uses thyristor control to limit the opening moment of the half-cycle of the sinusoid. Due to this, the load on the electrical circuit is regulated.

Naturally, numerous modern chargers can create other forms of currents not shown in this diagram.

Principles for creating circuits for chargers

A single-phase 220 volt network is usually used to power the charger equipment. This voltage is converted to a safe low voltage that is applied to the battery input terminals through various electronic and semiconductor components.

There are three schemes for converting industrial sinusoidal voltage in chargers due to:

1. use of electromechanical voltage transformers operating on the principle of electromagnetic induction;

2. application of electronic transformers;

3. without the use of transformer devices based on voltage dividers.

Technically, inverter voltage conversion is possible, which has become widely used for frequency converters that control electric motors. But, for charging batteries, this is quite expensive equipment.

Charging circuits with transformer separation

The electromagnetic principle of transferring electrical energy from the primary winding of 220 volts to the secondary completely ensures the separation of the potentials of the supply circuit from the consumed circuit, prevents it from entering the battery and causing damage in the event of insulation failures. This method is the most secure.

Schemes of power parts of devices with a transformer have many different developments. The picture below shows three principles for creating different power section currents from chargers through the use of:

1. diode bridge with a ripple-smoothing capacitor;

2. diode bridge without ripple smoothing;

3. a single diode that cuts off the negative half-wave.

Each of these circuits can be used independently, but usually one of them is the basis, the basis for creating another, more convenient for operation and control in terms of the output current.

The use of sets of power transistors with control circuits in the upper part of the picture in the diagram allows you to reduce the output voltage at the output contacts of the charger circuit, which provides adjustment of the values ​​of direct currents passed through the connected batteries.

One of the options for a similar design of a current regulated charger is shown in the figure below.

The same connections in the second circuit allow you to adjust the amplitude of the ripples, limit it at different stages of charging.

The same average circuit works effectively when two opposite diodes in the diode bridge are replaced by thyristors, which equally regulate the current strength in each alternating half-cycle. And the elimination of negative half-harmonics is assigned to the remaining power diodes.

Replacing a single diode in the bottom picture with a semiconductor thyristor with a separate electronic circuit for the control electrode, allows you to reduce the current pulses due to their later opening, which is also used for various ways battery charging.

One of the options for such a circuit implementation is shown in the figure below.

Assembling it with your own hands is not difficult. It can be made independently from available parts, allows you to charge batteries with currents up to 10 amperes.

The industrial version of the Electron-6 transformer charger circuit is based on two KU-202N thyristors. To control the opening cycles of half-harmonics, each control electrode has its own circuit of several transistors.

Among motorists, devices are popular that allow not only charging batteries, but also using the energy of a 220-volt supply network to connect it in parallel to start a car engine. They are called launchers or launchers. They have an even more complex electronic and power circuit.

Circuits with an electronic transformer

Such devices are produced by manufacturers to power halogen lamps with a voltage of 24 or 12 volts. They are relatively cheap. Some enthusiasts try to connect them to charge low-power batteries. However, this technology has not been widely developed and has significant drawbacks.

Charging circuits without transformer separation

When several loads are connected in series to a current source, the total input voltage is divided into component sections. Due to this method, dividers work, creating a voltage drop to a certain value on the working element.

On this principle, numerous chargers with resistive-capacitive resistances for low-power batteries are created. Due to the small dimensions of the components, they are built directly into the flashlight.

Internal circuit diagram completely placed in a factory insulated case, which excludes human contact with the potential of the network when charging.

Numerous experimenters are trying to implement the same principle for charging car batteries, offering a connection scheme from a household network through a capacitor assembly or an incandescent bulb with a power of 150 watts and passing current pulses of one polarity.

Similar designs can be found on the sites of do-it-yourself masters, who praise the simplicity of the circuit, the cheapness of parts, and the ability to restore the capacity of a discharged battery.

But, they are silent about the fact that:

open wiring 220 represents ;

the filament of a lamp under voltage heats up, changes its resistance according to a law unfavorable for the passage of optimal currents through the battery.

When switched on under load, very large currents pass through the cold filament and the entire series-connected circuit. In addition, charging should be completed with small currents, which is also not performed. Therefore, a battery that has undergone several series of such cycles quickly loses its capacity and performance.

Our advice: don't use this method!

Chargers are designed to work with certain types batteries, take into account their characteristics and conditions for the restoration of capacity. When using universal, multifunctional devices, you should choose the charge mode that best suits a particular battery.

Often car owners have to deal with such a phenomenon as the impossibility of starting the engine due to the discharge of the battery. To solve the problem, you will need to use a battery charger, which costs a lot of money. In order not to spend money on buying a new charger for a car battery, you can make it yourself. It is only important to find a transformer with the necessary characteristics. To make a homemade device, you do not have to be an electrician, and the whole process as a whole will take no more than a few hours.

Features of the functioning of batteries

Not all drivers are aware that lead-acid batteries are used in cars. Such batteries are distinguished by their endurance, therefore they are able to serve up to 5 years.

To charge lead batteries, a current is used that is equal to 10% of the total battery capacity. This means that to charge a battery with a capacity of 55 Ah, it takes charging current at 5.5 A. If a very large current is applied, this can lead to boiling of the electrolyte, which, in turn, will lead to a decrease in the service life of the device. A small charging current does not extend the life of the battery, but it is not capable of negatively affecting the integrity of the device.

This is interesting! When a current of 25 A is applied, the battery is quickly recharged, so after 5-10 minutes after connecting a charger with this rating, you can start the engine. Such a large current is given out by modern inverter chargers, only it negatively affects the battery life.

When the battery is charging, the charging current flows back to the working one. The voltage for each bank should not be higher than 2.7 V. There are 6 cans installed in the 12 V battery, which are not connected to each other. Depending on the voltage of the battery, the number of cans differs, as well as the required voltage for each can. If the voltage is higher, then this will lead to the process of decomposition of the electrolyte and plates, which contributes to the failure of the battery. To exclude the occurrence of the electrolyte boiling process, the voltage is limited to 0.1 V.

The battery is considered discharged if, when connecting a voltmeter or multimeter, the devices show a voltage of 11.9-12.1 V. Such a battery should be recharged immediately. A charged battery has a voltage at the terminals of 12.5-12.7 V.

An example of the voltage at the terminals of a charged battery

The charging process is the restoration of the spent capacity. Batteries can be charged in two ways:

1. D.C. In this case, the charging current is regulated, the value of which is 10% of the device's capacity. Charging time is 10 hours. The charge voltage in this case changes from 13.8 V to 12.8 V for the entire duration of the charge. The disadvantage of this method is that it is necessary to control the charging process and turn off the charger in time before the electrolyte boils. This method is gentle for the battery and has a neutral effect on their service life. To implement this method, transformer chargers are used.
2. Constant pressure. In this case, a voltage of 14.4 V is applied to the battery terminals, and the current changes from large values ​​to smaller ones automatically. Moreover, this change in current depends on such a parameter as time. The longer the battery is charged, the lower the current becomes. Recharging the battery will not be able to get, unless you forget to turn off the device and leave it for several days. The advantage of this method is that after 5-7 hours the battery will be charged by 90-95%. The battery can also be left unattended, so this method is popular. However, few car owners are aware that this charging method is an “emergency”. Using it significantly reduces battery life. In addition, the more often you charge in this way, the faster the device will discharge.

Now even inexperienced driver can understand that if there is no need to rush to charge the battery, then it is better to give preference to the first option (by current). With the accelerated charge recovery, the service life of the device is reduced, so it is highly likely that you will need to buy a new battery in the near future. Based on the foregoing, the material will consider options for the manufacture of chargers for current and voltage. For manufacturing, you can use any improvised devices, which we will talk about later.

Battery charging requirements

Before carrying out the procedure for manufacturing a homemade battery charger, you must pay attention to the following requirements:

1. Providing a stable voltage of 14.4 V.
2. Device autonomy. This means that a homemade device should not require supervision, as the battery is often charged at night.
3. Ensuring that the charger turns off when the charging current or voltage increases.
4. Reverse polarity protection. If the device is connected to the battery incorrectly, then protection should work. For implementation, a fuse is included in the circuit.

Polarity reversal is a dangerous process, as a result of which the battery can explode or boil. If the battery is in good condition and only slightly discharged, then if the charger is connected incorrectly, the charge current will increase above the nominal value. If the battery is discharged, then when the polarity is reversed, an increase in voltage above the set value is observed and, as a result, the electrolyte boils.

Options for homemade battery chargers

Before proceeding with the development of a battery charger, it is important to understand that such a device is homemade and can negatively affect battery life. However, sometimes such devices are simply necessary, as they can significantly save money on the purchase of factory devices. Consider what you can make do-it-yourself chargers for batteries from and how to do it.

Charging from a light bulb and a semiconductor diode

This charging method is relevant for such options when you need to start a car on a dead battery at home. In order to do this, you will need the constituent elements for assembling the device and a source of alternating voltage 220 V (socket). The scheme of a homemade charger for a car battery contains the following elements:

1. Incandescent lamp. An ordinary light bulb, which is also popularly referred to as "Ilyich's lamp". The lamp power affects the battery charge rate, so the higher this indicator, the faster the engine can be started. The best option is a lamp with a power of 100-150 watts.
2. semiconductor diode. An electronic element whose main purpose is to conduct current in one direction only. The need for this element in the charging design is to convert AC voltage into permanent. Moreover, for such purposes, you will need a powerful diode that can withstand a large load. Diode can be used domestic production, as well as imported. In order not to buy such a diode, it can be found in old receivers or power supplies.
3. Plug for connection to a socket.
4. Wires with terminals (crocodiles) for connection to the battery.

It is important! Before assembling such a circuit, you need to understand that there is always a risk to life, so you should be extremely careful and careful.

Scheme for connecting a charger from a light bulb and a diode to a battery

Connect the plug to the outlet only after the entire circuit has been assembled and the contacts have been insulated. To avoid the occurrence of a short circuit current, a 10 A circuit breaker is included in the circuit. When assembling the circuit, it is important to consider the polarity. A light bulb and a semiconductor diode must be connected to the positive battery terminal circuit. When using a 100 W light bulb, a charging current of 0.17 A will flow to the battery. To charge a 2A battery, you need to charge it for 10 hours. The greater the power of the incandescent lamp, the higher the value of the charging current.

It makes no sense to charge a completely dead battery with such a device, but recharging it in the absence of a factory charger is quite realistic.

Rectifier battery charger

This option also belongs to the category of the simplest homemade chargers. The basis of such a memory includes two main elements - a voltage converter and a rectifier. There are three types of rectifiers that charge the device in the following ways:

• D.C;
• alternating current;
• asymmetrical current.

Rectifiers of the first option charge the battery exclusively direct current, which is cleared of ripples of alternating voltage. AC rectifiers supply a pulsating AC voltage to the battery terminals. Asymmetric rectifiers have a positive component, and half-wave rectifiers are used as the main structural elements. This circuit has a better result compared to DC and AC rectifiers. It is its design that will be discussed further.

In order to assemble a high-quality battery charger, you will need a rectifier and a current amplifier. The rectifier consists of the following elements:

• fuse;
• powerful diode;
• Zener diode 1N754A or D814A;
• switch;
• variable resistor.

Circuit diagram of asymmetric rectifier

In order to assemble the circuit, you will need to use a fuse rated for a maximum current of 1 A. The transformer can be taken from an old TV, the power of which should not exceed 150 W, and the output voltage should be 21 V. As a resistor, you need to take a powerful element of the brand MLT- 2. The rectifier diode must be rated for a current of at least 5 A, therefore best option- these are models of the type D305 or D243. The amplifier is based on a regulator based on two transistors of the KT825 and 818 series. During installation, transistors are installed on radiators to improve cooling.

The assembly of such a circuit is carried out by a hinged method, that is, on a track cleared old board all elements are located and connected to each other using wires. Its advantage is the ability to adjust the output current for battery charging. The disadvantage of the scheme is the need to find the necessary elements, as well as correctly position them.

The simplest analogue of the scheme presented above is a more simplified version, shown in the photo below.

Simplified diagram of a rectifier with a transformer

It is proposed to use a simplified circuit using a transformer and a rectifier. In addition, you will need a 12 V and 40 W light bulb (car). It will not be difficult even for a beginner to assemble the circuit, but it is important to pay attention to the fact that the rectifier diode and the light bulb must be located in the circuit that is fed to the negative terminal of the battery. The disadvantage of such a scheme is to obtain a pulsating current. To smooth out ripples, as well as reduce strong beats, it is recommended to use the diagram below.

Diode bridge circuit with smoothing capacitor reduces ripple and reduces runout

Charger from a computer power supply: step by step instructions

Recently, this option has become popular car charging, which you can make yourself using a computer power supply.

Initially, you will need a working power supply. For such purposes, even a unit with a power of 200 watts is suitable. It produces a voltage of 12 V. It will not be enough to charge the battery, so it is important to increase this value to 14.4 V. Step-by-step instruction manufacturing a memory for a battery from a power supply from a computer is as follows:

1. Initially, all extra wires that come out of the power supply are soldered. Leave only the green wire. Its end must be soldered to the negative contacts, from where the black wires came out. This manipulation is done so that when the unit is connected to the network, the device starts immediately.

   

   The end of the green wire must be soldered to the negative contacts where the black wires were located.

2. The wires that will be connected to the battery terminals must be soldered to the output contacts of the minus and plus of the power supply. The plus is soldered to the exit point of the yellow wires, and the minus to the exit point of the black ones.
3. At the next stage, it is necessary to reconstruct the operating mode of pulse-width modulation (PWM). The TL494 or TA7500 microcontroller is responsible for this. For reconstruction, you will need the lower leftmost leg of the microcontroller. To get to it, you need to flip the board.

   

   The TL494 microcontroller is responsible for the PWM operation mode

4. Three resistors are connected to the bottom pin of the microcontroller. We are interested in the resistor, which is connected to the output of the 12 V block. It is marked in the photo below with a dot. This element should be unsoldered, and then measure the resistance value.

   

   The resistor marked with a purple dot must be soldered

5. The resistor has a resistance of about 40 kOhm. It must be replaced with a resistor with a different resistance value. To clarify the value of the required resistance, it is required to initially solder the regulator (variable resistor) to the contacts of the remote resistor.

   

   Solder the regulator in place of the removed resistor.

6. Now the device should be connected to the network, having previously connected a multimeter to the output terminals. The output voltage is changed with a regulator. You need to get a voltage value of 14.4 V.

   

   The output voltage is regulated by a variable resistor

7. As soon as the voltage value is reached, you should unsolder the variable resistor, and then measure the resulting resistance. For the example described above, its value is 120.8 kΩ.

   

   The resulting resistance should be 120.8 kOhm

8. Based on the obtained resistance value, you should select a similar resistor, and then solder it in place of the old one. If you cannot find a resistor of this resistance value, then you can choose it from two elements.

   

   Soldering resistors in series adds up their resistance

9. After that, the operability of the device is checked. Optionally, a voltmeter can be installed to the power supply (you can also use an ammeter), which will allow you to control the voltage and charging current.

General view of the charger from the computer power supply

This is interesting! The assembled charger has the function of protection against short circuit current, as well as against overload, however, it does not protect against polarity reversal, so you should solder the output wires of the appropriate color (red and black) so as not to be confused.

When the charger is connected to the battery terminals, a current of about 5-6 A will be supplied, which is the optimal value for devices with a capacity of 55-60A / h. The video below shows how to make a battery charger from a computer power supply with voltage and current regulators.

What other storage options are available for the battery

Consider a few more options for independent battery chargers.

Using laptop charger for battery

One of the simplest and quick ways reviving a dead battery. To implement a battery revitalization scheme using a laptop charger, you will need:

1. Charger from any laptop. The parameters of the chargers are 19 V and the current is about 5 A.
2. Lamp halogen power 90 W.
3. Connecting wires with clips.

We turn to the implementation of the scheme. The light bulb is used to limit the current to the optimum value. Instead of a light bulb, you can use a resistor.

A laptop charger can also be used to "revitalize" a car battery.

It is not difficult to assemble such a scheme. If charging from a laptop is not planned to be used for its intended purpose, then the plug can be cut off, and then connected to the wires with clamps. First, use a multimeter to determine the polarity. The bulb is connected to a circuit that goes to the positive terminal of the battery. The negative terminal from the battery is connected directly. Only after connecting the device to the battery, you can supply voltage to the power supply.

Do-it-yourself memory from a microwave oven or similar devices

Using the transformer block that is inside the microwave, you can make a charger for the battery.

A step-by-step instruction for making a home-made charger from a microwave transformer block is presented below.

Scheme for connecting a transformer unit, a diode bridge and a capacitor to a car battery

The assembly of the device can be carried out on any basis. At the same time, it is important that all structural elements are reliably protected. If necessary, the circuit can be supplemented with a switch, as well as a voltmeter.

Transformerless charger

If the search for a transformer has led to a dead end, then you can use the simplest circuit without step-down devices. Below is a diagram that allows you to implement a charger for a battery without using voltage transformers.

Electrical diagram of the charger without the use of a voltage transformer

The role of transformers is performed by capacitors, which are designed for a voltage of 250V. At least 4 capacitors should be included in the circuit, placing them in parallel. In parallel with the capacitors, a resistor and an LED are connected to the circuit. The role of the resistor is to dampen the residual voltage after the device is disconnected from the network.

The circuit also includes a diode bridge, designed to work with currents up to 6A. The bridge is connected to the circuit after the capacitors, and the wires going to the battery for charging are connected to its terminals.

How to charge a battery from a homemade device

Separately, you should understand the question of how to properly charge the battery with a homemade charger. To do this, it is recommended to adhere to the following recommendations:

1. Polarity respect. It is better to once again check the polarity of a home-made device with a multimeter than to “bite your elbows”, because the reason for the failure of the battery was an error with the wires.
2. Do not test the battery by closing the contacts. This method only "kills" the device, and does not revive it, as indicated in many sources.
3. The device should be connected to the 220 V network only after the output terminals are connected to the battery. The device is turned off in the same way.
4. Compliance with safety precautions, since work is carried out not only with electricity, but also with battery acid.
5. The charging process of the battery must be controlled. The slightest malfunction can lead to serious consequences.

Based on the above recommendations, it can be concluded that homemade devices although they are acceptable, they are still not able to replace the factory ones. Making homemade chargers is not safe, especially if you are not sure that you can do it right. The material presents the most simple circuits implementation of chargers for car batteries, which will always be useful in the household.

Under normal operating conditions, the vehicle's electrical system is self-sufficient. It's about about power supply - a bunch of a generator, a voltage regulator, and a battery, works synchronously and provides uninterruptible power supply all systems.

It's in theory. In practice, car owners amend this orderly system. Or the equipment refuses to work in accordance with the set parameters.

For example:

1. Operating a battery that has reached its end of life. The battery does not hold a charge
2. Irregular travel. Long idle time of the car (especially during the period of " hibernation"") leads to self-discharge of the battery
3. The car is used in the mode of short trips, with frequent muffling and starting the engine. The battery just can't get recharged.
4. Connection additional equipment increases the load on the battery. Often leads to increased self-discharge current when the engine is off
5. extreme low temperature accelerates self-discharge
6. A faulty fuel system leads to increased load: the car does not start immediately, you have to turn the starter for a long time
7. A faulty alternator or voltage regulator prevents the battery from charging normally. This problem includes frayed power wires and poor contact in the charge circuit.
8. And finally, you forgot to turn off the headlights, dimensions or music in the car. To completely discharge the battery overnight in the garage, sometimes it is enough to loosely close the door. Interior lighting consumes a lot of energy.

Any of listed reasons leads to an unpleasant situation: you have to go, and the battery is unable to crank the starter. The problem is solved by external recharge: that is, a charger.

In the tab, there are four proven and reliable charger schemes for a car, from the simplest to the most complex. Choose any and it will work.

A simple 12V charger circuit.

Charger with adjustable charging current.

Adjustment from 0 to 10A is carried out by changing the delay in opening the trinistor.

Diagram of a battery charger with self-shutoff after charging.

For charging batteries with a capacity of 45 amperes.

The scheme of a smart charger that will warn of incorrect connection.

It is quite easy to assemble with your own hands. An example of a charger made from an uninterruptible power supply.