Sometimes it’s easier to buy than to make a device from scratch with your own hands. But not always. For example, consider 12 volt car chargers. On the one hand, it serves a rather expensive item - a car battery, which, if used incorrectly, can fail, and with noise and crackling noise. But on the other hand, looking at the scheme of cheap industrial memory devices, you just wonder what they charge money for? This question is especially true for the Polish-Chinese 6-12V charger with no identification marks on the box other than a modest inscription Prostownik. I don't know what this word means, but it sounds simple :)

The charger was brought in for repairs, and no one knew what happened to it. It just lay around in the garage for a long time and stopped working. We will conduct an external inspection.

Indeed, on the case there is only the most necessary thing - a 1 ampere mains fuse and a 220 V cord in the rear, and in front there is a 6-12 V switch button, a 10 ampere fuse-link and a 0-8 A dial ammeter. There are not even cable connection terminals.

We disassemble the body and remove the cover. Inside - the same holy simplicity :)

Apart from the transformer and diode bridge, not a single one is observed. At least they installed a minimal electrolytic capacitor for filtering...

For some reason the wires turned out to be disconnected from the scarf with the diode bridge. Alternatively, the output wires may have shorted, the diodes have overheated and the wires have become unsoldered.

With a sinking feeling, I checked the transformer for functionality, because this is the most valuable part of any charger, and if it fails, then buying a similar one will be very expensive. 20 volt 5-10 amp transformers cost at least $10.

Thank God the primary showed a resistance of 22 Ohms, and not infinity :) Now checking the diodes - everything is OK here too. All that remains is to solder the wires according to the standard charging rectifier circuit.

The scheme worked. Measurements showed an alternating voltage from the output of the transformer - 13.8 V, and after the rectifier - 13 V constant. Why so few? - you ask - this is not enough to charge the car battery. Because it is pulsating in nature, and the voltmeter shows the effective average value.

Most batteries manufactured today are maintenance-free. That is, if such a device fails, it is simply replaced with a similar one. However, rechargeable batteries are quite expensive, so they try to extend their service life to the maximum using special devices called rectifiers for charging the battery.

Battery charging rectifier converts alternating current from the main power lines into direct current, suitable for charging the battery. However, the functions of the device do not end there. Good rectifiers allow for desulfation, that is, cleaning the battery plates from lead sulfate crystals. Plaque forms even in unused batteries. Proper battery care can reduce the speed of this process. Improper use of the battery can significantly speed it up.

The deposited sediment significantly reduces the contact area between the electrolyte and the metal, which leads to a decrease in battery capacity. In normal battery operation, it is almost impossible to get rid of lead crystals on the plates. Let's take an example of using an ordinary car battery. When the engine is running, the car's generator acts as a power source. However, the voltage it generates is not enough for desulfation.

You can get rid of crystals only with the help of special increased voltages of electric current. For each type of battery, they have their own optimal values, allowing you to achieve the best results. It is to convert the mains voltage to optimal values, as well as alternating current to direct current, that rectifiers for charging batteries are designed.

When used regularly, battery charging rectifiers can significantly extend battery life. It is also worth noting that the parameters of the current generated by the rectifiers are of high quality, which also has a beneficial effect on the service life of the battery.

Today there is a fairly wide selection of different rectifiers for charging batteries on the market. However, it should be noted that most of the entire range offered are chargers for cars. As a rule, such devices do not allow the user to independently set and control the value of current or voltage, which significantly narrows the scope of their application. Only a few companies produce rectifiers for batteries of specialized vehicles and military equipment, much less produce universal devices.

Company "4AKB-YUG" offers its customers a huge line of rectifiers for charging batteries of its own production. Unlike similar devices from other manufacturers, our VZA allows the operator to independently set the required voltage value and control the entire charging process. They are distinguished by high quality input parameters and high efficiency. Usage pulse converters combined into groups allows you to increase the reliability of the product and extend its service life: when one or more converters output, the device remains operational, only the maximum voltage that it is capable of generating decreases.

The rectifier (Fig. 1) is assembled using a bridge circuit using four diodes D1 - D4 of type D305. The charging current is regulated. using a powerful transistor T1 connected according to a compound triode circuit. When the bias removed to the base of the triode from potentiometer R1 changes, the resistance of the collector-emitter circuit of the transistor changes. In this case, the charging current can be changed from 25 mA to 6 A with a voltage at the rectifier output from 1.5 to 14 V.

Resistor R2 at the rectifier output allows you to set the rectifier output voltage when the load is off. The transformer is assembled on a core with a cross section of 6 cm kvd. The primary winding is designed to be connected to a network with a voltage of 127 V (pins 1-2) or 220 V (1-3) and contains 350+325 turns of PEV 0.35 wire, the secondary winding - 45 turns of PEV 1.5 wire. Transistor T1 is installed on a metal radiator; the surface area of ​​the radiator must be at least 350 cm2. The surface is taken into account on both sides of the plate with a thickness of at least 3 mm.

B. VASILIEV

The diagram shown in Fig. 2 differs from the previous one in that in order to increase the maximum current to 10 o, transistors T1 and T2 are connected in parallel. The bias to the bases of the transistors, by changing which the charging current is regulated, is removed from the rectifier, made on diodes D5 - D6. When charging 6-volt batteries, the switch is set to position 1, 12-volt batteries - to position 2.

Fig.2

The transformer windings contain the following number of turns: la - 328 turns PEV 0.85; 1b - 233 turns PEV 0.63; II - 41+41 turns PEV 1.87; III - 7+7 turns PEV 0.63. Core - УШ35Х 55.

A. VARDASHKIN

(Radio 7 1966)

List of radioelements

Very often there is a problem with charging a car battery, and there is no charger at hand, what to do in this case. Today I decided to publish this article, where I intend to explain all the known methods of charging a car battery, it’s interesting, really. Go!

METHOD ONE - LAMP AND DIODE

Photo 13 This is one of the simplest charging methods, since the “charger” in theory consists of two components - an ordinary incandescent lamp and a rectifying diode. The main disadvantage of this charging is that the diode cuts off only the lower half-cycle, therefore, we do not have a completely constant current at the output of the device, but you can charge a car battery with this current!

The light bulb is the most ordinary one, you can take a 40/60/100 watt lamp, the more powerful the lamp, the greater the output current, in theory the lamp is here only for current extinguishing.

The diode, as I already said, to rectify alternating voltage, it must be powerful, and it must be designed for a reverse voltage of at least 400 Volts! The diode current must be more than 10A! This is a mandatory condition, I highly recommend installing the diode on the heat sink; you may have to cool it additionally.

And in the figure there is an option with one diode, although in this case the current will be 2 times less, therefore the charging time will increase (with a 150 Watt bulb, it is enough to charge a dead battery for 5-10 hours to start the car even in cold weather)

To increase the charge current, you can replace the incandescent lamp with another, more powerful load - a heater, boiler, etc.

METHOD TWO - BOILER

This method works on the same principle as the first, except that the output of this charger is completely constant.

The main load is the boiler; if desired, it can be replaced with a lamp, as in the first option.

You can take a ready-made diode bridge, which can be found in computer power supplies. It is MANDATORY to use a diode bridge with a reverse voltage of at least 400 Volts with a current of AT LEAST 5 Amps, install the finished bridge on a heat sink, since it will overheat quite strongly.

The bridge can also be assembled from 4 powerful rectifier diodes, and the voltage and current of the diodes should be the same as when using the bridge. In general, try to use a powerful rectifier, as powerful as possible; extra power never hurts.

DO NOT USE powerful Schottky diode assemblies from computer power supplies, they are very powerful, but the reverse voltage of these diodes is about 50-60 Volts, so they will burn out.

METHOD THREE - CONDENSER

I like this method the most; the use of a quenching capacitor makes the charging process safer, and the charge current is determined from the capacitor’s capacitance. The charge current can be easily determined by the formula

I = 2 * pi * f * C * U,

where U is the network voltage (Volts), C is the capacitance of the quenching capacitor (uF), f is the alternating current frequency (Hz)

To charge a car battery, you need to have a fairly large current (a tenth of the battery capacity, for example - for a 60 A battery, the charging current should be 6A), but to obtain such a current we need a whole battery of capacitors, so we will limit ourselves to a current of 1.3-1, 4A, for this, the capacitance of the capacitor should be around 20 µF.
A film capacitor is required, with a minimum operating voltage of at least 250 Volts; domestically produced MBGO type capacitors are an excellent option.

DIY 12V battery charger

I made this charger to charge car batteries, the output voltage is 14.5 volts, the maximum charge current is 6 A. But it can also charge other batteries, for example lithium-ion ones, since the output voltage and output current can be adjusted within a wide range. The main components of the charger were purchased on the AliExpress website.

These are the components:

Often car owners have to deal with the phenomenon of the inability to start the engine due to a low 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 don’t have to be an electrician, and the whole process will take no more than a few hours.

Features of battery operation

Not all drivers know that lead-acid batteries are used in cars. Such batteries are distinguished by their endurance, so they can last up to 5 years.

To charge lead-acid batteries, a current equal to 10% of the total battery capacity is used. This means that to charge a battery with a capacity of 55 A/h, a charging current of 5.5 A is required. If a very high current is applied, this can lead to boiling of the electrolyte, which, in turn, will lead to a decrease in service life devices. A small charging current does not extend the life of the battery, but it does not have a negative impact on the integrity of the device.

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

When charging the battery, the charging current flows back to the working one. The voltage for each can should not be higher than 2.7 V. A 12 V battery has 6 cans that are not connected to each other. Depending on the battery voltage, the number of cells differs, as well as the required voltage for each cell. If the voltage is higher, this will lead to a process of decomposition of the electrolyte and plates, which contributes to the failure of the battery. To prevent the electrolyte from boiling, 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.

Example of voltage at the terminals of a charged battery

The charging process is the restoration of spent capacity. Charging batteries can be done in two ways:

1. D.C. In this case, the charging current is regulated, the value of which is 10% of the device capacity. Charging time is 10 hours. The charging voltage varies from 13.8 V to 12.8 V for the entire charging duration. 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 on the batteries 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 supplied to the battery terminals, and the current changes from higher to lower values ​​automatically. Moreover, this change in current depends on such a parameter as time. The longer the battery is charged, the lower the current becomes. The battery will not be able to be recharged 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, which is why this method is popular. However, few car owners know that this charging method is “emergency”. When using it, the service life of the battery is significantly reduced. 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 (in terms of current). With accelerated charge recovery, the service life of the device is reduced, so there is a high probability that you will need to buy a new battery in the near future. Based on the above, the material will consider options for manufacturing chargers based on current and voltage. For production, you can use any available devices, which we will discuss later.

Battery charging requirements

Before carrying out the procedure for making 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, since 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, the protection should be triggered. For implementation, a fuse is included in the circuit.

Polarity reversal is a dangerous process, as a result of which the battery may explode or boil. If the battery is in good condition and only slightly discharged, then if the charger is connected incorrectly, the charging current will increase above the rated one. 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 you start developing a battery charger, it is important to understand that such a device is homemade and can negatively affect the battery life. However, sometimes such devices are simply necessary, as they can significantly save money on the purchase of factory devices. Let's look at what you can make your own battery chargers from and how to do it.

Charging from a light bulb and a semiconductor diode

This charging method is relevant in situations where you need to start a car on a dead battery at home. In order to do this, you will need the components to assemble the device and a 220 V alternating voltage source (socket). The circuit 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 power of the lamp affects the charging speed of the battery, so the higher this indicator, the faster you can start the engine. The best option is a lamp with a power of 100-150 W.
2. Semiconductor diode. An electronic element whose main purpose is to conduct current in only one direction. The need for this element in the charging design is to convert alternating voltage to direct voltage. Moreover, for such purposes you will need a powerful diode that can withstand a heavy load. You can use a diode, either domestic or imported. In order not to buy such a diode, it can be found in old receivers or power supplies.
3. Plug for connecting to a socket.
4. Wires with terminals (crocodiles) for connecting 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 cautious.

Connection diagram of a charger from a light bulb and a diode to a battery

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

Battery charger from rectifier

This option also falls into the category of the simplest homemade chargers. The basis of such a charger 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 apply pulsating AC voltage to the battery terminals. Asymmetric rectifiers have a positive component, and half-wave rectifiers are used as the main design elements. This scheme has better results compared to DC and AC rectifiers. It is its design that will be discussed further.

In order to assemble a high-quality battery charging device, 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.

Electrical circuit of an 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 MLT- brand 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, the transistors are installed on radiators to improve cooling.

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

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

Simplified circuit of a rectifier with a transformer

It is proposed to use a simplified circuit using a transformer and rectifier. In addition, you will need a 12 V and 40 W (car) light bulb. Assembling the circuit is not difficult even for a beginner, 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 this scheme is that it produces a pulsating current. To smooth out pulsations and also reduce strong beats, it is recommended to use the circuit presented below.

A circuit with a diode bridge and a smoothing capacitor reduces ripple and reduces runout

Charger from a computer power supply: step-by-step instructions

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

Initially you will need a working power supply. Even a unit with a power of 200 W is suitable for such purposes. 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 instructions for making a charger for a battery from a computer power supply are as follows:

1. Initially, all excess wires that come out of the power supply are soldered off. You only need to leave the green wire. Its end needs to be soldered to the negative contacts, where the black wires come from. This manipulation is done so that when the unit is connected to the network, the device starts up 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 minus and plus output contacts 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 turn the board over.

   

   The TL494 microcontroller is responsible for the PWM operating mode.

4. Three resistors are connected to the bottom pin of the microcontroller. We are interested in the resistor that 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 indicated by the purple dot must be desoldered

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, you must first solder a regulator (variable resistor) to the contacts of the remote resistor.

   

   A regulator is soldered in place of the removed resistor

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

   

   Output voltage is regulated by variable resistor

7. As soon as the voltage value is reached, the variable resistor should be unsoldered, and then the resulting resistance should be measured. For the example described above, its value is 120.8 kOhm.

   

   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 select it from two elements.

   

   Soldering resistors in series adds up their resistance

9. After this, the functionality of the device is checked. If desired, you can install a voltmeter (or an ammeter) to the power supply, which will allow you to monitor 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, but 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 mix them up.

When connecting the charger 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 55-60 A/h. The video below shows how to make a charger for a battery from a computer power supply with voltage and current regulators.

What other charger options are there for batteries?

Let's consider a few more options for independent battery chargers.

Using a laptop charger for the battery

One of the simplest and fastest ways to revive a dead battery. To implement the scheme for reviving the battery using charging from a laptop, you will need:

1. Charger for any laptop. The charger parameters are 19 V and the current is about 5 A.
2. Halogen lamp with a power of 90 W.
3. Connecting wires with clamps.

Let's move on to the implementation of the scheme. The light bulb is used to limit the current to an optimal value. You can use a resistor instead of a light bulb.

A laptop charger can also be used to “revive” a car battery.

Assembling such a circuit is not difficult. If you do not plan to use the laptop charger for its intended purpose, you can cut off the plug and then connect the clamps to the wires. First, use a multimeter to determine the polarity. The light 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 can voltage be supplied to the power supply.

DIY charger from a microwave oven or similar devices

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

Step-by-step instructions for making a homemade charger from a transformer block from a microwave are presented below.

Connection diagram of a transformer block, diode bridge and capacitor to a car battery

The device can be assembled on any base. 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 circuit of the charger without using a voltage transformer

The role of transformers is performed by capacitors, which are designed for a voltage of 250V. The circuit should include at least 4 capacitors, placing them in parallel. A resistor and an LED are connected in parallel to the capacitors. The role of the resistor is to dampen the residual voltage after disconnecting the device from the network.

The circuit also includes a diode bridge designed to operate with currents up to 6A. The bridge is included in 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. Maintain polarity. It is better to once again check the polarity of a homemade device with a multimeter rather than “biting your elbows”, because the cause of battery failure was an error with the wires.
2. Do not test the battery by shorting 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 a 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 battery charging process must be monitored. The slightest malfunction can cause serious consequences.

Based on the above recommendations, it should be concluded that homemade devices, although acceptable, are still not capable of replacing factory ones. Making your own charger is not safe, especially if you are not confident that you can do it correctly. The material presents the simplest schemes for implementing chargers for car batteries, which will always be useful in the household.