Thyristor charging current regulator. Scheme and principle of operation of the thyristor charger. Features of the functioning of batteries

CAR CHARGER

The topic of car battery chargers is very popular, so we bring to your attention another proven and well-proven charging scheme. The transformer in this device was used factory-made, 36 volts, in control circuits. On its secondary there are two windings of 18 volts connected to the midpoint. Diodes for a current of 30 A, obtained from the car's generator (those that were at hand), are installed on a common radiator with a thyristor.

The thyristor itself is insulated from the radiator housing with a mica gasket, and the radiator, in turn, is isolated from the housing. It turned out to be simple and compact, and even at maximum load, the temperature of the radiator did not rise above 40-45 degrees.

Different thyristors were tried, the entire KU202 series, but in the end T25-xxx was installed, the inscription is poorly visible, but I know for sure that this is a thyristor for a current of 25 A.
Management is assembled on a separate board,The ammeter was used for alternating current, with a total deviation of 5 A, therefore it is included before the diodes.

Naturally, you can put a pointer indicator in this car charger for direct current, and not necessarily an ammeter, but even a voltmeter - with a shunt from a low-resistance resistor.

The limits for adjusting the charging current are 0.7-5 A, if the current is too low, generation can be disrupted (all the subtleties of setting up the generator circuits and selecting a thyristor) - this is who wants to have a charging current from scratch.

On the front panel of the case there is a power switch, a charging current regulator and an ammeter to control the battery charging process.At the back, wire terminals for connecting the battery are installed on a textolite strip. The whole box is painted black.

There are cases, especially in winter, when car owners need to recharge the car battery from an external power source. Of course, people who do not have good skills in working with electrical engineering, it is advisable to buy a factory battery charger, it is even better to purchase a starter-charger to start the engine with a discharged battery without wasting time for external recharging.

But if you have a little knowledge in the field of electronics, you can assemble a simple charger do it yourself.

general characteristics

To properly maintain the battery and extend its service life, recharging is required when the voltage at the terminals drops below 11.2 V. At this voltage, the engine is likely to start, but if it is parked for a long time in winter, this will lead to sulfation of the plates and, as a result, to a decrease in capacity batteries. When parking for a long time in winter, it is necessary to regularly monitor the voltage at the battery terminals. It should be 12 V. It is best to remove the battery and bring it to a warm place, remembering to monitor charge level.

The battery is charged with direct or pulsed current. When using a constant voltage power supply, the current for proper charging should be one tenth of the battery capacity. If the battery capacity is 50 Ah, then a current of 5 amperes is required for charging.

To extend the life of the battery, methods of desulfation of battery plates are used. The battery is discharged to less than five volts by repeatedly drawing a large current of short duration. An example of such consumption is starting a starter. After that, a slow full charge is made with a small current within one ampere. Repeat the process 8-9 times. The desulfation method is long in time, but according to all studies it gives a good result.

It must be remembered that when charging it is important not to overcharge the battery. The charge is made up to a voltage of 12.7-13.3 volts and depends on the battery model. Maximum charge indicated in the documentation for the battery, which can always be found on the Internet.

Overcharging causes boiling, increases the density of the electrolyte and, as a consequence, the destruction of the plates. Factory charging devices have charge control and subsequent shutdown systems. Build your own systems, without having sufficient knowledge in electronics, it is quite difficult.

Do-it-yourself assembly schemes

It is worth talking about simple charging devices that can be assembled with minimal knowledge in electronics, and the charge capacity can be tracked by connecting a voltmeter or an ordinary tester.

Charging scheme for emergency cases

There are times when a car that has stood overnight near the house cannot be started in the morning due to a dead battery. There can be many reasons for this unfortunate circumstance.

If the battery was in good condition and slightly discharged, the following will help solve the problem:

Great as a power source laptop charger. It has an output voltage of 19 volts and a current of two amperes, which is quite enough to complete the task. On the output connector, as a rule, the internal input is positive, the external circuit of the plug is negative.

As a limiting resistance, which is mandatory, you can use a salon light bulb. Can be used more powerful lamps, for example, on the dimensions, but this will create an extra load on the power supply, which is very undesirable.

An elementary circuit is being assembled: the minus of the power supply is connected to the light bulb, the light bulb to the minus of the battery. Plus goes directly from the battery to the power supply. Within two hours, the battery will receive a charge to start the engine..

From the power supply from a desktop computer

Such a device is more difficult to manufacture, but it can be assembled with minimal knowledge of electronics. The basis will be an unnecessary block from the system unit of the computer. The output voltages of such blocks are +5 and +12 volts with an output current of about two amperes. These parameters allow you to assemble a weak charger, which, when properly assembled, will serve the owner for a long time and reliably. Fully charging the battery will take a long time and will depend on the capacity of the battery, but there will be no plate desulfation effect. So, step by step assembly of the device:

1. Disassemble the power supply and unsolder all wires except green. Remember or mark the input points of black (GND) and yellow +12 V.
2. Solder the green wire to the place where the black one was (this is necessary to start the unit without a PC motherboard). In place of the black wire, solder a tap, which will be negative for charging the battery. In place of the yellow wire, solder the positive battery charging lead.
3. You need to find a TL 494 chip or its equivalent. The list of analogues is easy to find on the Internet, one of them will definitely be found in the circuit. With all the variety of blocks, they are not produced without these microcircuits.
4. From the first leg of this microcircuit - it is the lower left one, find the resistor that goes to the +12 volt output (yellow wire). This can be done visually along the tracks in the diagram, you can use a tester by connecting the power and measuring the voltage at the input of the resistors going to the first leg. Do not forget that a voltage of 220 volts goes to the primary winding of the transformer, so safety measures must be observed when starting the unit without a case.
5. Solder the found resistor, measure its resistance with a tester. Choose a variable resistor that is close in value. Set it to the value of the required resistance and solder it in place of the removed circuit element with flexible wires.
6. Starting the power supply by adjusting the variable resistor, get a voltage of 14 V, ideally 14.3 V. The main thing is not to overdo it, remembering that 15 V is usually the limit for working out protection and, as a result, shutdown.
7. Solder a variable resistor without knocking down its setting, and measure the resulting resistance. Select the required or as close as possible resistance value or dial from several resistors and solder it into the circuit.
8. Check the unit, the output should be the desired voltage. If desired, a voltmeter can be connected to the outputs on the plus and minus circuit by placing it on the case for clarity. Subsequent assembly occurs in the reverse order. The device is ready for use.

The unit will perfectly replace the inexpensive factory charger and is quite reliable. But it is MANDATORY to remember that the device has overload protection, but this will not save you from a polarity error. Simply put, if you confuse plus and minus when connecting to a battery, the charger will fail instantly..

Charger circuit from an old transformer

If there is no old computer power supply at hand, and radio engineering experience allows you to independently mount simple circuits, then you can use the following rather interesting battery charging circuit with control and regulation of the supplied voltage.

To assemble the device, you can use transformers from old uninterruptible power supplies or Soviet-made TVs. Any powerful step-down transformer with a total set of voltages on the secondary windings of about 25 volts is suitable.

The diode rectifier is assembled on two KD 213A diodes (VD 1, VD 2), which must be installed on the radiator and can be replaced by any imported analogues. There are many analogues, and they are easily selected from reference books on the Internet. Surely the necessary diodes can be found at home in old unnecessary equipment.

The same method can be applied to replace the control transistor KT 827A (VT 1) and the zener diode D 814 A (VD 3). The transistor is mounted on a radiator.

Adjustment of the supplied voltage is carried out by a variable resistor R2. The scheme is simple and obviously working. It can be collected by a person with minimal knowledge of electronics.

Pulse charging for batteries

The circuit is difficult to assemble, but this is the only drawback. Finding a simple circuit for a pulsed charging unit is unlikely to succeed. This is offset by the pluses: such blocks almost do not heat up, while they have serious power and high efficiency, they are distinguished by their compact size. The proposed circuit, mounted on a board, fits into a container with a size of 160 * 50 * 40 mm. To assemble the device, it is necessary to understand the principle of operation of the PWM (Pulse Width Modulation) generator. In the proposed version, it is implemented using a common and inexpensive controller IR 2153.

With the applied capacitors, the power of the device is 190 watts. This is enough to charge any light car battery with a capacity of up to 100 Ah. By installing capacitors of 470 microfarads, the power will double. It will be possible to charge a battery with a capacity of up to two hundred ampere / hours.

When using devices without automatic battery charge control, you can use the simplest network, daily Chinese-made relay. This eliminates the need to monitor the time the unit is disconnected from the network.

The cost of such a device is about 200 rubles. Knowing the approximate charging time of your battery, you can set the desired shutdown time. This ensures that the power supply is interrupted in a timely manner. You can get distracted by business and forget about the battery, which can lead to boiling, destruction of the plates and battery failure. A new battery will cost much more.

Precautionary measures

When using self-assembled devices, the following safety precautions should be observed:

1. All appliances, including batteries, must be placed on a fireproof surface.
2. During the initial use of the manufactured device, it is necessary to ensure full control of all charging parameters. It is imperative to control the heating temperature of all charging elements and batteries, do not allow the electrolyte to boil. The voltage and current parameters are controlled by the tester. Primary control will help determine the time to fully charge the battery, which will come in handy in the future.

Assembling a battery charger is easy even for a beginner. The main thing is to do everything carefully and observe safety measures, because you will have to deal with an open voltage of 220 volts.

Now the presence of a battery charger is an integral part for any motorist.

Of course, you can buy yourself a good charger, but I did not look for easy ways for myself, and decided to assemble something of my own. Remember the article. This is a continuation of work on
charger

This part of the charger is the main control of the entire charging, since it is she who is responsible for supplying the charging current, which can be set from 1 to 10A. Which is enough for home use.

Elements:

C1 = 1mF (160V)
F1 = 10A
R1 = 300
R2 = 6.8k
R3 = 3k
R4 = 110
R5=51
R6 = 150
R7 = 15k
T1 \u003d KU202V (G, D and so on. Lizh would be suitable for voltage. I set it in general AND)
VD1 = KD105B
VT1 = KT361A
VT2 = KT315A

As you can see, the device is not complicated, and does not contain scarce parts. Everything I needed I found in my workshop.

The charging process is similar to pulsed, which has a positive effect on battery performance, according to many radio amateurs.

The device is a simple trinistor power regulator with pulse-phase control. The trinistor is controlled by a node assembled on two transistors. The time for which the capacitor will be charged before switching the transistor is set through a variable resistor, which, in fact, sets the charge current

The diode serves to protect the control circuit of the trinistor from reverse voltage
A trinistor needs a nice heatsink. I put a radiator not bigger, but I will put a fan for cooling

Don't forget to use wires of the correct diameter.

The scheme is just great, but there are drawbacks:
1. Voltage fluctuations on the supply lead to fluctuations in the charging current, which is bad for the charger. But this is Reshimo, you just need to assemble a 10A stabilizer. What will I do
2. No short circuit protection except fuse
3. The device gives interference to the network, which can also be solved using an LC filter

Here is my assembled device

Signet for an adjustable charger on a trinistor KU202

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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, a charging current of 5.5 A is required. devices. 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 an 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 to DC. Moreover, for such purposes, you will need a powerful diode that can withstand a large load. You can use a diode, both domestically produced and 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 with direct current, which is cleared of alternating voltage ripples. 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 designed for a current of at least 5 A, so the best option is models like 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 in a hinged way, that is, all elements are located on the old board cleared of tracks and are 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, such a variant of car charging has become popular, 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. A step-by-step instruction for making a charger for a battery from a computer power supply 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 easiest and fastest ways to revive 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 should be concluded that home-made devices, although acceptable, are still not able to replace factory ones. Making homemade chargers is not safe, especially if you are not sure that you can do it right. The material presents the simplest schemes for the implementation of chargers for car batteries, which will always be useful on the farm.

A charger (charger) for a battery is necessary for every car enthusiast, but it costs a lot, and regular preventive trips to a car service are not an option. Servicing a battery in a workshop takes time and money. In addition, on a discharged battery, you still need to get to the service. Anyone who knows how to use a soldering iron can assemble a workable charger for a car battery with their own hands.

Some battery theory

Any accumulator (battery) is a store of electrical energy. When voltage is applied to it, energy accumulates due to chemical changes inside the battery. When a consumer is connected, the opposite process occurs: the reverse chemical change creates voltage at the terminals of the device, current flows through the load. Thus, in order to receive voltage from the battery, it must first be “put”, that is, the battery must be charged.

Almost any car has its own generator, which, when the engine is running, provides power to on-board equipment and charges the battery, replenishing the energy spent on starting the engine. But in some cases (frequent or heavy starting of the engine, short trips, etc.), the battery energy does not have time to recover, the battery gradually discharges. There is only one way out of this situation - charging with an external charger.

How to check battery status

To decide on the need for charging, you need to determine the state of the battery. The simplest option - "twists / does not twist" - at the same time is unsuccessful. If the battery "does not turn", for example, in the morning in the garage, then you will not go anywhere at all. The “not spinning” condition is critical, and the consequences for the battery can be sad.

The best and most reliable method for checking the condition of a battery is to measure the voltage on it with a conventional tester. At an air temperature of about 20 degrees dependence of the degree of charge on the voltage on the terminals of a disconnected from the load (!) battery is as follows:

• 12.6…12.7 V - fully charged;
• 12.3…12.4 V - 75%;
• 12.0…12.1 V - 50%;
• 11.8…11.9 V - 25%;
• 11.6 ... 11.7 V - discharged;
• below 11.6 V - deep discharge.

It should be noted that the voltage of 10.6 volts is critical. If it drops below, then the "car battery" (especially maintenance-free) will fail.

Proper charging

There are two methods of charging a car battery - constant voltage and constant current. Everyone has their own features and disadvantages:

Homemade battery chargers

Assembling a charger for a car battery with your own hands is real and not very difficult. To do this, you need to have basic knowledge of electrical engineering and be able to hold a soldering iron in your hands.

A simple device for 6 and 12 V

Such a scheme is the most elementary and budgetary. With this charger, you can charge any lead-acid battery with an operating voltage of 12 or 6 V and an electric capacity of 10 to 120 A/h.

The device consists of a step-down transformer T1 and a powerful rectifier assembled on diodes VD2-VD5. The charging current is set by switches S2-S5, with the help of which quenching capacitors C1-C4 are connected to the power supply circuit of the primary winding of the transformer. Due to the multiple "weight" of each switch, various combinations allow you to stepwise adjust the charging current within 1-15 A in 1 A increments. This is enough to select the optimal charging current.

For example, if a current of 5 A is needed, then you will need to turn on the toggle switches S4 and S2. Closed S5, S3 and S2 will give a total of 11 A. A voltmeter PU1 is used to control the voltage on the battery, the charging current is monitored using an ammeter PA1.

In the design, you can use any power transformer with a power of about 300 W, including a home-made one. It should produce a voltage of 22–24 V at a current of up to 10–15 A on the secondary winding. In place of VD2-VD5, any rectifier diodes that can withstand a forward current of at least 10 A and a reverse voltage of at least 40 V will do. D214 or D242 will do. They should be installed through insulating gaskets on a radiator with a scattering area of ​​​​at least 300 cm2.

Capacitors C2-C5 must be non-polar paper with an operating voltage of at least 300 V. For example, MBCHG, KBG-MN, MBGO, MBGP, MBM, MBGCH are suitable. Similar cube-shaped capacitors were widely used as phase-shifters for electric motors in household appliances. As PU1, a DC voltmeter of the M5-2 type with a measurement limit of 30 V was used. PA1 is an ammeter of the same type with a measurement limit of 30 A.

The circuit is simple, if you assemble it from serviceable parts, then it does not need to be adjusted. This device is also suitable for charging six-volt batteries, but the "weight" of each of the switches S2-S5 will be different. Therefore, you will have to navigate in the charging currents by the ammeter.

Continuously adjustable current

According to this scheme, it is more difficult to assemble a car battery charger with your own hands, but it can be repeated and also does not contain scarce parts. With its help, it is permissible to charge 12-volt batteries with a capacity of up to 120 A / h, the charge current is smoothly adjustable.

The battery is charged by a pulsed current, a thyristor is used as a regulating element. In addition to the smooth current adjustment knob, this design also has a mode switch, when turned on, the charging current is doubled.

The charging mode is controlled visually by the pointer device RA1. Resistor R1 is homemade, made of nichrome or copper wire with a diameter of at least 0.8 mm. It serves as a current limiter. Lamp EL1 - indicator. In its place, any small-sized indicator lamp with a voltage of 24-36 V will do.

A step-down transformer can be used ready-made with an output voltage through the secondary winding of 18–24 V at a current of up to 15 A. If there was no suitable device at hand, then you can make it yourself from any network transformer with a power of 250–300 W. To do this, all windings are wound from the transformer, except for the mains winding, and one secondary winding is wound with any insulated wire with a cross section of 6 mm. sq. The number of turns in the winding is 42.

Thyristor VD2 can be any of the KU202 series with the letters V-N. It is installed on a radiator with a dissipation area of ​​at least 200 cm2. The power installation of the device is made with wires of minimum length and with a cross section of at least 4 mm. sq. In place of VD1, any rectifier diode with a reverse voltage of at least 20 V and a current of at least 200 mA will work.

Setting up the device comes down to calibrating the RA1 ammeter. This can be done by connecting several 12-volt lamps with a total power of up to 250 W instead of a battery, controlling the current using a known-good reference ammeter.

From a computer power supply

To assemble this simple charger with your own hands, you will need a regular power supply from an old ATX computer and knowledge of radio engineering. But on the other hand, the characteristics of the device will turn out to be decent. With its help, batteries are charged with a current of up to 10 A, adjusting the current and voltage of the charge. The only condition is that the PSU is desirable on the TL494 controller.

For creating do-it-yourself car charging from a computer power supply you will have to assemble the circuit shown in the figure.

Step-by-step operations necessary for finalization will look like this:

1. Bite off all the wires of the power buses, except for the yellow and black ones.
2. Connect the yellow and separately black wires to each other - these will be respectively "+" and "-" memory (see diagram).
3. Cut all traces leading to pins 1, 14, 15 and 16 of the TL494 controller.
4. Install variable resistors with a nominal value of 10 and 4.4 kOhm on the casing of the power supply unit - these are the voltage and current adjustment bodies, respectively.
5. Hinged mounting to assemble the circuit shown in the figure above.

If the installation is done correctly, then the revision is completed. It remains to equip the new charger with a voltmeter, ammeter and wires with "crocodiles" for connecting to the battery.

It is possible to use any variable and fixed resistors in the design, except for the current one (the lower one according to the circuit with a nominal value of 0.1 Ohm). Its power dissipation is at least 10 watts. You can make such a resistor yourself from a nichrome or copper wire of the appropriate length, but you can actually find a ready-made one, for example, a shunt from a Chinese digital tester for 10 A or a C5-16MV resistor. Another option is two 5WR2J resistors connected in parallel. Such resistors are in switching power supplies for PCs or TVs.

What you need to know when charging a battery

When charging a car battery, it is important to follow a number of rules. This will help you prolong battery life and keep your health:

The question of creating a simple do-it-yourself battery charger has been clarified. Everything is quite simple, it remains to stock up on the necessary tools and you can safely get to work.