You will need
- Power transformer TS-180-2, wires with a cross-section of 2.5 mm2, four D242A diodes, power plug, soldering iron, solder, fuses 0.5A and 10A;
- household light bulb with a power of up to 200 W;
- a semiconductor diode that conducts electricity in only one direction. You can use a laptop charger as such a diode.
Instructions
A simple charger can be made from an old computer power supply. Since it requires a current of 10% of the battery's total capacity, any power supply with more than 150 volts of power can be an effective charging source. Almost all power supplies have a PWM controller based on a TL494 chip (or a similar KA7500). First of all, you need to unsolder the excess wires (from sources -5V, -12B, +5B, +12B). Then remove R1 and replace it with a trimming resistor with the highest value of 27 kOhm. The sixteenth terminal is also disconnected from the main wire, the fourteenth and fifteenth are cut at the connection point.
On the back plate of the block you need to install a potentiometer-current regulator R10. There are also 2 cords: one for the mains, the other for the battery terminals.
Now you need to deal with pins 1, 14,15 and 16. First, they need to be irradiated. To do this, the wire is cleared of insulation and burned with a soldering iron. This will remove the oxide film, after which the wire is applied to a piece of rosin, and then pressed again with a soldering iron. The wire should turn yellow-brown. Now you need to attach it to a piece of solder and press it with a soldering iron for the third and final time. The wire should turn silver. After completing this procedure, all that remains is to solder the stranded thin wires.
The idle speed must be set using a variable resistor with the potentiometer R10 in the middle position. The open circuit voltage will set the full charge to between 13.8 and 14.2 volts. Clips are installed at the ends of the terminals. It is better to make the insulating tubes multi-colored so as not to get tangled in the wires. This may damage the device. Red usually refers to "plus" and black to "minus".
If the device will only be used to charge the battery, you can do without a voltmeter and ammeter. It will be enough to use the graduated scale of the R10 potentiometer with a value of 5.5-6.5 amperes. The charging process from such a device should be easy, automatic and not require your additional efforts. This charger virtually eliminates the possibility of overheating or overcharging the battery.
Another method of manufacturing a car battery is based on the use of an adapted twelve-volt adapter. It does not require a car battery charger. It is important to remember that the battery voltage and power supply voltage must be equal, otherwise the charger will be useless.
First you need to cut and expose up to 5 cm the end of the adapter wire. Then the opposite wires are separated by 40 cm. Now you need to put an alligator clip on each of the wires. Don't forget to use different colored clips so you don't mix up the polarities. You need to connect each terminal to the battery in series, following the principle “from plus to plus” and “from minus to minus”. Now all that remains is to turn on the adapter. This method is quite simple, the only difficulty is choosing the right power source. This battery can overheat during charging, so it is important to monitor it and interrupt it for a while if it overheats.
A charger for a car battery can be made from an ordinary light bulb and a diode. Such a device will be very simple and requires very few initial elements: a light bulb, a semiconductor diode, wires with terminals and a plug. The light bulb must have a power of up to 200 volts. The higher its power, the faster the charging process will be. A semiconductor diode must conduct electricity in only one direction. You can take, for example, a laptop charger.
The light bulb should burn at half intensity, but if it doesn’t light up at all, you need to modify the circuit. It is possible that the light will turn off when the car battery is fully charged, but this is unlikely. Charging with such a device will take about 10 hours. Then you must disconnect it from the network, otherwise overheating is inevitable, which will damage the battery.
If the situation is urgent, and there is no time to build more complex chargers, you can charge the battery using a powerful diode and a heater using current from the mains. You need to connect to the network in the following sequence: diode, then heater, then battery. This method is ineffective because it consumes a lot of electricity, and the efficiency is only 1%. Therefore, this charger is the most unreliable, but also the easiest to manufacture.
Making the simplest charger will require considerable effort and technical knowledge. It is better to always have a reliable factory charger on hand, but if necessary and sufficient technical skills, you can make it yourself.
Surely each of you has at least once seen or dealt with nickel-cadmium batteries (rechargeable batteries). If you can’t remember what it is, just remember what kind of batteries the first digital cameras ran on. Modern models also operate on batteries, but of a different composition. Nickel-cadmium batteries are used in a wide range of devices, the most common of which is the wireless mouse.
Instructions
Among the well-known charging methods of this type, purchasing a charger stands out. And if your hands are in place and there are a dozen old radio components in the closet, there is no point in spending on something that can be done, especially absolutely. The main advantage of this scheme (shown in the figure) for charging nickel-cadmium batteries is automatic power supply when fully charged and short circuit protection.
According to this diagram, you need to stock up on all the radio components present in the diagram, which you probably have in your closet. You may need to go to the nearest radio parts store. You will also need a printed circuit board, box for batteries and a plastic case. If you have been developing circuits before, it will not be difficult for you to assemble this circuit.
To begin, take a piece of PCB and apply control points on it. Use a drill with a very thin bit. A screwdriver would be an excellent replacement - it allows you to drill in different directions and at different speeds.
After drilling the holes, it is necessary to apply nitroglycerin to all the tracks, and then etch the charger circuit. After complete drying, arm yourself with a soldering iron and suitable parts. All that remains is to solder all the connections and secure the battery box. The charger is ready.
Car battery - an electric battery for vehicles. The battery powers a number of automotive systems, such as the engine control unit, injector, starter, and lighting equipment. Various chargers are used to charge batteries. If you know how to work with a soldering iron and understand the symbols of electrical circuits, you can assemble a simple charger in one evening.
You will need
- -transformer from a tube TV - 1;
- - diodes KD 2010 - 4;
- - 600 ohm resistor, 5 watts - 1;
- -toggle switch for 15 A, 250 V - 1;
- - LED for 12-15 V - 1;
- - mains fuse 1 A - 1;
- - mains plug - 1.
Instructions
Purchase a powerful transformer from a domestic black-and-white tube power supply on the radio market. If you have such a TV lying around at home, remove the transformer from it. Disassemble the transformer, freeing the windings from the core. Determine where the transformer's mains winding is. To do this, check the resistance of all windings. The mains winding will have the highest ohmic resistance. Remove all windings from the transformer and leave only the mains winding. Among the wires you will remove will be a long copper wire with a diameter of 2 millimeters. Use it to wind the secondary winding of the transformer in the amount of 55 turns with a tap from the 10th turn.
Purchase powerful semiconductor diodes, for example, KD 2010, from a radio store. They will be needed to make a diode bridge - a network rectifier. The photo on the left shows the recommended type of installation of a diode bridge. If the diodes become excessively hot during operation, install each of them on a separate small radiator. There, buy a mains power supply, a 1-amp mains fuse, a resistor with a resistance of 600 ohms and a power of 5 watts, as well as any LED designed for a voltage of at least 12 volts.
Start assembling the charger according to the circuit diagram shown in the photo on the left. Connect the mains fuse FU1 to the power plug. Solder the resulting short circuit protection to the primary winding of network transformer Tr1. Next, in accordance with the photo above, assemble a network rectifier - a diode bridge - on a separate board. Connect it to the secondary winding of the transformer according to the circuit diagram. Using a toggle switch, connect the connection of the diode bridge to the 10 volt and 15 volt transformer outputs. Solder a chain consisting of resistor R1 and LED La1 to the output of the rectifier. The resistor limits the current passing through the LED. The LED is used to indicate the operation of the device. If the LED does not light up, swap its leads.
Every motorist sooner or later has problems with the battery. I did not escape this fate either. After 10 minutes of unsuccessful attempts to start my car, I decided that I needed to purchase or make my own charger. In the evening, after checking out the garage and finding a suitable transformer there, I decided to do the charging myself.
There, among the unnecessary junk, I also found a voltage stabilizer from an old TV, which, in my opinion, would work wonderfully as a housing.
Having scoured the vast expanses of the Internet and really assessed my strengths, I probably chose the simplest scheme.
After printing out the diagram, I went to a neighbor who is interested in radio electronics. Within 15 minutes, he collected the necessary parts for me, cut off a piece of foil PCB and gave me a marker for drawing circuit boards. Having spent about an hour, I drew an acceptable board (the dimensions of the case allow for spacious installation). I won’t tell you how to etch the board, there is a lot of information about this. I took my creation to my neighbor, and he etched it for me. In principle, you could buy a circuit board and do everything on it, but as they say to a gift horse...
Having drilled all the necessary holes and displayed the pinout of the transistors on the monitor screen, I took up the soldering iron and after about an hour I had a finished board.
A diode bridge can be purchased on the market, the main thing is that it is designed for a current of at least 10 amperes. I found D 242 diodes, their characteristics are quite suitable, and I soldered a diode bridge on a piece of PCB.
The thyristor must be installed on a radiator, since it gets noticeably hot during operation.
Separately, I must say about the ammeter. I had to buy it in a store, where the sales consultant also picked up the shunt. I decided to modify the circuit a little and add a switch so that I could measure the voltage on the battery. Here, too, a shunt was needed, but when measuring voltage, it is connected not in parallel, but in series. The calculation formula can be found on the Internet; I would add that the dissipation power of the shunt resistors is of great importance. According to my calculations, it should have been 2.25 watts, but my 4-watt shunt was heating up. The reason is unknown to me, I don’t have enough experience in such matters, but having decided that I mainly needed the readings of an ammeter, and not a voltmeter, I decided on it. Moreover, in voltmeter mode the shunt noticeably warmed up within 30-40 seconds. So, having collected everything I needed and checked everything on the stool, I took up the body. Having completely disassembled the stabilizer, I took out all its contents.
Having marked the front wall, I drilled holes for the variable resistor and switch, then using a small diameter drill around the circumference I drilled holes for the ammeter. Sharp edges were finished with a file.
After racking my brains a bit over the location of the transformer and radiator with thyristor, I settled on this option.
I bought a couple more crocodile clips and everything is ready to charge. The peculiarity of this circuit is that it only works under load, so after assembling the device and not finding voltage at the terminals with a voltmeter, do not rush to scold me. Just hang at least a car light bulb on the terminals, and you will be happy.
Take a transformer with a voltage on the secondary winding of 20-24 volts. Zener diode D 814. All other elements are indicated in the diagram.
Every car owner needs a battery charger, but it costs a lot, and regular preventive trips to a car service center are not an option. Battery service at a service station takes time and money. In addition, with a discharged battery, you still need to drive to the service station. Anyone who knows how to use a soldering iron can assemble a working charger for a car battery with their own hands.
A little theory about batteries
Any battery is a storage device for electrical energy. When voltage is applied to it, energy is stored due to chemical changes inside the battery. When a consumer is connected, the opposite process occurs: a reverse chemical change creates voltage at the terminals of the device, and current flows through the load. Thus, in order to get voltage from the battery, you first need to “put it down,” that is, charge the battery.
Almost any car has its own generator, which, when the engine is running, provides power to the on-board equipment and charges the battery, replenishing the energy spent on starting the engine. But in some cases (frequent or difficult engine starts, short trips, etc.) the battery energy does not have time to be restored, and the battery is gradually discharged. There is only one way out of this situation - charging with an external charger.
How to find out the battery status
To decide whether charging is necessary, you need to determine the state of the battery. The simplest option - “turns/does not turn” - is at the same time unsuccessful. If the battery “doesn’t turn”, for example, in the garage in the morning, then you won’t go anywhere at all. The “does not turn” condition is critical, and the consequences for the battery can be dire.
The optimal and 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 voltage on the terminals of the battery disconnected from the load (!) 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, the “car battery” (especially a maintenance-free one) will fail.
Correct 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 realistic and not particularly difficult. To do this, you need to have basic knowledge of electrical engineering and be able to hold a soldering iron in your hands.
Simple 6 and 12 V device
This scheme is the most basic and budget-friendly. Using this charger, you can efficiently charge any lead-acid battery with an operating voltage of 12 or 6 V and an electrical capacity of 10 to 120 A/h.
The device consists of a step-down transformer T1 and a powerful rectifier assembled using 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 circuit of the primary winding of the transformer. Thanks to the multiple “weight” of each switch, various combinations allow you to stepwise adjust the charging current in the range of 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 required, 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. To monitor the voltage on the battery, use a voltmeter PU1, the charging current is monitored using an ammeter PA1.
The design can use any power transformer with a power of about 300 W, including homemade ones. It should produce a voltage of 22–24 V on the secondary winding at a current of up to 10–15 A. 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 are suitable. D214 or D242 are suitable. They should be installed through insulating gaskets on a radiator with a dissipation area of at least 300 cm2.
Capacitors C2-C5 must be non-polar paper with an operating voltage of at least 300 V. Suitable, for example, are MBChG, KBG-MN, MBGO, MBGP, MBM, MBGCh. Similar cube-shaped capacitors were widely used as phase-shifting capacitors for electric motors in household appliances. A DC voltmeter of type M5−2 with a measurement limit of 30 V was used as PU1. 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 adjustment. 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 the charging currents using an ammeter.
With continuously adjustable current
Using this scheme, it is more difficult to assemble a charger for a car battery with your own hands, but it can be repeated and also does not contain scarce parts. With its help, it is possible to charge 12-volt batteries with a capacity of up to 120 A/h, the charge current is smoothly regulated.
The battery is charged using a pulsed current; a thyristor is used as a regulating element. In addition to the knob for smoothly adjusting the current, this design also has a mode switch, when turned on, the charging current doubles.
The charging mode is controlled visually using the RA1 dial gauge. 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 is an indicator lamp. 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 on the secondary winding of 18–24 V at a current of up to 15 A. If you don’t have a suitable device at hand, you can make it yourself from any network transformer with a power of 250–300 W. To do this, wind all windings from the transformer except the mains winding, and wind one secondary winding 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 dispersion area of at least 200 sq. cm. The power installation of the device is done with wires of minimal 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 withstanding 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, monitoring 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 the characteristics of the device will be decent. With its help, batteries are charged with a current of up to 10 A, adjusting the current and charge voltage. The only condition is that the power supply is desirable on the TL494 controller.
For creating DIY car charging from a computer power supply you will have to assemble the circuit shown in the figure.
Step by step steps required to finalize the operation will look like this:
- Bite off all the power bus wires, with the exception of the yellow and black ones.
- Connect the yellow and separately black wires together - these will be the “+” and “-” chargers, respectively (see diagram).
- Cut all traces leading to pins 1, 14, 15 and 16 of the TL494 controller.
- Install variable resistors with a nominal value of 10 and 4.4 kOhm on the power supply casing - these are the controls for regulating the voltage and charging current, respectively.
- Using a suspended installation, assemble the circuit shown in the figure above.
If the installation is done correctly, then the modification is complete. All that remains is to equip the new charger with a voltmeter, an ammeter and wires with alligator clips for connecting to the battery.
In the design it is possible to use any variable and fixed resistors, except for the current resistor (the lower one in the circuit with a nominal value of 0.1 Ohm). Its power dissipation is at least 10 W. 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 10 A shunt from a Chinese digital tester or a C5-16MV resistor. Another option is two 5WR2J resistors connected in parallel. Such resistors are found 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 Extend battery life and maintain your health:
The question of creating a simple battery charger with your own hands has been clarified. Everything is quite simple, all you have to do is stock up on the necessary tools and you can safely get to work.
In order for a car to start, it needs energy. This energy is taken from the battery. As a rule, it is recharged from the generator while the engine is running. When the car is not used for a long time or the battery is faulty, it discharges to such a state that that the car can no longer start. In this case, external charging is required. You can buy such a device or assemble it yourself, but for this you will need a charger circuit.
How a car battery works
A car battery supplies power to various devices in the car when the engine is turned off and is designed to start it. By type of execution, a lead-acid battery is used. Structurally, it is assembled from six batteries with a nominal voltage of 2.2 volts, connected in series. Each element is a set of lattice plates made of lead. The plates are coated with active material and immersed in an electrolyte.
The electrolyte solution contains distilled water and sulfuric acid. The frost resistance of the battery depends on the density of the electrolyte. Recently, technologies have emerged that allow the electrolyte to be adsorbed in glass fiber or thickened using silica gel to a gel-like state.
Each plate has a negative and positive pole, and they are isolated from each other using a plastic separator. The body of the product is made of propylene, which is not destroyed by acid and serves as a dielectric. The positive pole of the electrode is coated with lead dioxide, and the negative with sponge lead. Recently, rechargeable batteries with electrodes made of lead-calcium alloy have begun to be produced. These batteries are completely sealed and require no maintenance.
When a load is connected to the battery, the active material on the plates reacts chemically with the electrolyte solution and produces an electric current. The electrolyte depletes over time due to the deposition of lead sulfate on the plates. The battery begins to lose charge. During the charging process, a chemical reaction occurs in the reverse order, lead sulfate and water are converted, the density of the electrolyte increases and the charge is restored.
Batteries are characterized by their self-discharge value. It occurs in the battery when it is inactive. The main reason is contamination of the battery surface and poor quality of the distiller. The rate of self-discharge accelerates when the lead plates are destroyed.
Types of chargers
A large number of car charger circuits have been developed using different element bases and fundamental approaches. According to the principle of operation, charging devices are divided into two groups:
- Starting chargers, designed to start the engine when the battery is not working. By briefly supplying a large current to the battery terminals, the starter is turned on and the engine starts, and then the battery is charged from the car's generator. They are produced only for a certain current value or with the ability to set its value.
- Pre-start chargers, leads from the device are connected to the battery terminals and current is supplied for a long time. Its value does not exceed ten amperes, during which time the battery energy is restored. In turn, they are divided into: gradual (charging time from 14 to 24 hours), accelerated (up to three hours) and conditioning (about an hour).
Based on their circuit design, pulse and transformer devices are distinguished. The first type uses a high-frequency signal converter and is characterized by small size and weight. The second type uses a transformer with a rectifier unit as a basis; it is easy to manufacture, but have a lot of weight and low efficiency (efficiency).
Whether you made a charger for car batteries yourself or purchased it at a retail outlet, the requirements for it are the same, namely:
- output voltage stability;
- high efficiency value;
- short circuit protection;
- charge control indicator.
One of the main characteristics of the charger is the amount of current that charges the battery. Correctly charging the battery and extending its performance characteristics can only be achieved by selecting the desired value. The charging speed is also important. The higher the current, the higher the speed, but a high speed value leads to rapid degradation of the battery. It is believed that the correct current value will be a value equal to ten percent of the battery capacity. Capacity is defined as the amount of current supplied by the battery per unit of time; it is measured in ampere-hours.
Homemade charger
Every car enthusiast should have a charging device, so if there is no opportunity or desire to purchase a ready-made device, there is nothing left to do but charge the battery yourself. It is easy to make with your own hands both the simplest and multifunctional devices. For this you will need a diagram and a set of radioelements. It is also possible to convert an uninterruptible power supply (UPS) or computer unit (AT) into a device for recharging the battery.
Transformer charger
This device is the easiest to assemble and does not contain scarce parts. The circuit consists of three nodes:
- transformer;
- rectifier block;
- regulator
Voltage from the industrial network is supplied to the primary winding of the transformer. The transformer itself can be used of any type. It consists of two parts: the core and the windings. The core is assembled from steel or ferrite, the windings are made from conductor material.
The operating principle of the transformer is based on the appearance of an alternating 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 smaller compared to the primary. The voltage level on the secondary winding of the transformer is selected to be 19 volts, and its power should provide a threefold reserve of charging current.
From the transformer, the reduced voltage passes through the rectifier bridge and goes to a rheostat connected in series to the battery. The rheostat is designed to regulate the voltage and current by changing the resistance. The rheostat resistance does not exceed 10 Ohms. The amount of current is controlled by an ammeter connected in series in front of the battery. With this circuit it will not be possible to charge a battery with a capacity of more than 50 Ah, since the rheostat begins to overheat.
You can simplify the circuit by removing the rheostat, and install a set of capacitors at the input in front of the transformer, which are used as reactance to reduce the network voltage. The lower the nominal value of the capacitance, the less voltage is supplied to the primary winding in the network.
The peculiarity of such a circuit is that it is necessary to ensure a signal level on the secondary winding of the transformer that is one and a half times greater than the operating voltage of the load. This circuit can be used without a transformer, but it is very dangerous. Without galvanic isolation, you can get an electric shock.
Pulse charger
The advantage of pulsed devices is their high efficiency and compact size. The device is based on a pulse-width modulation (PWM) chip. 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 with a capacity in the range of 47–470 μF and a voltage of at least 350 volts is placed in parallel with the battery. The capacitor removes mains voltage surges and line noise. The diode bridge is used with a rated current of more than four amperes and with a reverse voltage of at least 400 volts. The driver controls powerful N-channel field-effect transistors IRFI840GLC installed on radiators. The current of such charging will be up to 50 amperes, and the output power will be 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 microcircuit as a PWM controller. The modification itself consists of increasing the output signal to 14 volts. To do this, you will need to correctly install the trimmer resistor.
The resistor that connects the first leg of the TL494 to the stabilized + 5 V bus is removed, and instead of the second one, connected to the 12 volt bus, a variable resistor with a nominal value of 68 kOhm is soldered in. This resistor sets the required output voltage level. The power supply is turned on via a mechanical switch, according to the diagram indicated on the power supply housing.
Device on LM317 chip
A fairly simple but stable charging circuit is easily implemented on the LM317 integrated circuit. The microcircuit provides a signal level of 13.6 volts with a maximum current of 3 amperes. The LM317 stabilizer is equipped with built-in short circuit protection.
Voltage is supplied to the device circuit through the terminals from an independent DC power supply of 13-20 volts. The current, passing through the indicator LED HL1 and transistor VT1, is supplied to the stabilizer LM317. From its output directly to the battery via X3, X4. The divider assembled on R3 and R4 sets the required voltage value for opening VT1. Variable resistor R4 sets the charging current limit, and R5 sets the output signal level. The output voltage is adjustable from 13.6 to 14 volts.
The circuit can be simplified as much as possible, but its reliability will decrease.
In it, resistor R2 selects the current. A powerful nichrome wire element is used as a resistor. When the battery is discharged, the charging current is maximum, the VD2 LED lights up brightly; as the battery charges, the current begins to decrease and the LED dims.
Charger from an uninterruptible power supply
You can construct a charger from a conventional uninterruptible power supply even if the electronics unit is faulty. To do this, all electronics are removed from the unit, except for the transformer. A rectifier circuit, current stabilization and voltage limiting are added to the high-voltage winding of the 220 V transformer.
The rectifier is assembled using any powerful diodes, for example, domestic D-242 and a network capacitor of 2200 uF for 35-50 volts. The output will be a signal with a voltage of 18-19 volts. An LT1083 or LM317 microcircuit is used as a voltage stabilizer and must be installed on a radiator.
By connecting the battery, the voltage is set to 14.2 volts. It is convenient to control the signal level using a voltmeter and ammeter. The voltmeter is connected in parallel to the battery terminals, and the ammeter in series. As the battery charges, its resistance will increase and the current will decrease. It’s even easier to make the regulator using a triac connected to the primary winding of the transformer like a dimmer.
When making a device yourself, you should remember about electrical safety when working with a 220 V AC network. As a rule, a correctly made charging device made from serviceable parts starts working immediately, you just need to set the charging current.
Many car enthusiasts know very well that in order to extend the life of the battery, it is required periodically from the charger, and not from the car’s generator.
And the longer the battery life, the more often it needs to be charged to restore charge.
You can't do without chargers
To perform this operation, as already noted, chargers operating from a 220 V network are used. There are a lot of such devices on the automotive market, they may have various useful additional functions.
However, they all do the same job - convert alternating voltage 220 V into direct voltage - 13.8-14.4 V.
In some models, the charging current is manually adjusted, but there are also models with fully automatic operation.
Of all the disadvantages of purchased chargers, one can note their high cost, and the more sophisticated the device, the higher the price.
But many people have a large number of electrical appliances at hand, the components of which may well be suitable for creating a homemade charger.
Yes, a homemade device will not look as presentable as a purchased one, but its task is to charge the battery, and not to “show off” on the shelf.
One of the most important conditions when creating a charger is at least basic knowledge of electrical engineering and radio electronics, as well as the ability to hold a soldering iron in your hands and be able to use it correctly.
Memory from a tube TV
The first scheme will be, perhaps the simplest, and almost any car enthusiast can cope with it.
To make a simple charger, you only need two components - a transformer and a rectifier.
The main condition that the charger must meet is that the current output from the device must be 10% of the battery capacity.
That is, a 60 Ah battery is often used in passenger cars; based on this, the current output from the device should be 6 A. The voltage should be 13.8-14.2 V.
If someone has an old, unnecessary tube Soviet TV, then it is better to have a transformer than not to find one.
The schematic diagram of the TV charger looks like this.
Often, a TS-180 transformer was installed on such televisions. Its peculiarity was the presence of two secondary windings, 6.4 V each and a current strength of 4.7 A. The primary winding also consists of two parts.
First you will need to connect the windings in series. The convenience of working with such a transformer is that each of the winding terminals has its own designation.
To connect the secondary winding in series, you need to connect pins 9 and 9\’ together.
And to pins 10 and 10\’ - solder two pieces of copper wire. All wires that are soldered to the terminals must have a cross-section of at least 2.5 mm. sq.
As for the primary winding, for a series connection you need to connect pins 1 and 1\'. Wires with a plug for connecting to the network must be soldered to pins 2 and 2\’. At this point, work with the transformer is completed.
The diagram shows how the diodes should be connected - the wires coming from pins 10 and 10\', as well as the wires that will go to the battery, are soldered to the diode bridge.
Don't forget about fuses. It is recommended to install one of them on the “positive” terminal of the diode bridge. This fuse must be rated for a current of no more than 10 A. The second fuse (0.5 A) must be installed at terminal 2 of the transformer.
Before starting charging, it is better to check the functionality of the device and check its output parameters using an ammeter and voltmeter.
Sometimes it happens that the current is slightly higher than required, so some install a 12-volt incandescent lamp with a power of 21 to 60 watts in the circuit. This lamp will “take away” the excess current.
Microwave oven charger
Some car enthusiasts use a transformer from a broken microwave oven. But this transformer will need to be redone, since it is a step-up transformer, not a step-down transformer.
It is not necessary that the transformer be in good working order, since the secondary winding in it often burns out, which will still have to be removed during the creation of the device.
Remaking the transformer comes down to completely removing the secondary winding and winding a new one.
An insulated wire with a cross-section of at least 2.0 mm is used as a new winding. sq.
When winding, you need to decide on the number of turns. You can do this experimentally - wind 10 turns of a new wire around the core, then connect a voltmeter to its ends and power the transformer.
According to the voltmeter readings, it is determined what output voltage these 10 turns provide.
For example, measurements showed that there is 2.0 V at the output. This means that 12V at the output will provide 60 turns, and 13V will provide 65 turns. As you understand, 5 turns adds 1 volt.
It is worth pointing out that it is better to assemble such a charger with high quality, then place all the components in a case that can be made from scrap materials. Or mount it on a base.
Be sure to mark where the “positive” wire is and where the “negative” wire is, so as not to “over-plus” and damage the device.
Memory from the ATX power supply (for prepared ones)
A charger made from a computer power supply has a more complex circuit.
For the manufacture of the device, units with a power of at least 200 Watts of the AT or ATX models, which are controlled by a TL494 or KA7500 controller, are suitable. It is important that the power supply is fully operational. The ST-230WHF model from old PCs performed well.
A fragment of the circuit diagram of such a charger is presented below, and we will work on it.
In addition to the power supply, you will also need a potentiometer-regulator, a 27 kOhm trim resistor, two 5 W resistors (5WR2J) and a resistance of 0.2 Ohm or one C5-16MV.
The initial stage of work comes down to disconnecting everything unnecessary, which are the “-5 V”, “+5 V”, “-12 V” and “+12 V” wires.
The resistor indicated in the diagram as R1 (it supplies a voltage of +5 V to pin 1 of the TL494 controller) must be unsoldered, and a prepared 27 kOhm trimmer resistor must be soldered in its place. The +12 V bus must be connected to the upper terminal of this resistor.
Pin 16 of the controller should be disconnected from the common wire, and you also need to cut the connections of pins 14 and 15.
You need to install a potentiometer-regulator in the rear wall of the power supply housing (R10 in the diagram). It must be installed on an insulating plate so that it does not touch the block body.
The wiring for connecting to the network, as well as the wires for connecting the battery, should also be routed through this wall.
To ensure ease of adjustment of the device, from the existing two 5 W resistors on a separate board, you need to make a block of resistors connected in parallel, which will provide an output of 10 W with a resistance of 0.1 Ohm.
Then you should check the correct connection of all terminals and the functionality of the device.
The final work before completing the assembly is to calibrate the device.
To do this, the potentiometer knob should be set to the middle position. After this, the open circuit voltage should be set on the trimmer resistor at 13.8-14.2 V.
If everything is done correctly, then when the battery starts charging, a voltage of 12.4 V with a current of 5.5 A will be supplied to it.
As the battery charges, the voltage will increase to the value set on the trim resistor. As soon as the voltage reaches this value, the current will begin to decrease.
If all operating parameters converge and the device operates normally, all that remains is to close the housing to prevent damage to the internal elements.
This device from the ATX unit is very convenient, because when the battery is fully charged, it will automatically switch to voltage stabilization mode. That is, recharging the battery is completely excluded.
For convenience of work, the device can be additionally equipped with a voltmeter and ammeter.
Bottom line
These are just a few types of chargers that can be made at home from improvised materials, although there are many more options.
This is especially true for chargers that are made from computer power supplies.
If you have experience in making such devices, share it in the comments, many would be very grateful for it.
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