At least once in his life, every motorist is faced with the problem of a dead battery. To prevent such a malfunction, it is necessary to properly maintain the battery and charge it on time using a charger. What is a pulse charger for a car battery, what is its operating principle and how to build the device with your own hands - read on.
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Device characteristics
Devices designed for batteries are divided into several types - transformer and pulse. Transformer chargers for car batteries are large in weight and size, while their efficiency is significantly lower than that of other devices. As a result, the demand for such chargers has gradually decreased. Today, the pulse charger is the most popular type.
Design and principle of operation
Any pulse charger for a car battery is a device designed to restore charge.
Structurally, the pulse memory consists of the following elements:
- transformer (pulse);
- rectifier devices;
- stabilizer device;
- indication elements;
- main unit designed to control the charging procedure.
It should be noted that all the elements that make up the pulse charger are small in size when compared with transformer chargers. In principle, building such a device for charging a car battery with your own hands is not so difficult - all you need is a board that will control the transistor. Due to the fact that the design of this type of device is quite simple, and the components for manufacturing are easily accessible, pulse chargers are popular among our car enthusiasts.
As for the principle of operation, the charging procedure itself can be carried out using one of several methods:
- by voltage at constant current;
- voltage of constant parameters;
- combined method.
In principle, the method of stressing constant values is the most correct from a theoretical point of view. This is because pulse chargers for car batteries can automatically control current parameters only if the voltage is constant. If you want to ensure that the charging level is as high as possible, you must also take into account the discharge parameter.
As for the DC voltage method, this option is not the most optimal. This is because when the battery is quickly charged as a result of exposure to direct current, the plates of the device can simply crumble. And it will be impossible to restore them.
The combined battery charging option is one of the most gentle. When using this method, a direct current first passes, and at the very end of the procedure it begins to change to alternating current. Further, this parameter gradually decreases to zero, thus stabilizing the voltage level. According to experts, this operating scheme allows you to prevent or minimize the likelihood of a car battery boiling. In addition, this approach also reduces the likelihood of gas release.
Aspects of equipment selection
If you want to ensure that your car battery works properly, you need to think in advance about purchasing the necessary charger for charging.
There are certain nuances of this issue that it is advisable to take into account:
- First of all, many consumers are interested in the question of whether the charger, working according to its own scheme, will be able to restore a completely discharged car battery. Here you need to take into account that not all chargers sold in car stores can cope with this task. Therefore, when purchasing, you need to clarify this point with the sellers.
- The second, important aspect is the level of the maximum current parameter that the charger produces during operation. In addition, you need to take into account the voltage to which the car battery will be charged. For example, if you choose a pulse charger, then keep in mind that it should have a disable option or a support function that turns on automatically when fully charged (video author - ChipiDip).
When operating a charger with your own hands, you need to consider several points. First of all, this is a sequence of actions. To begin with, it is recommended to dismantle the cover of the device and unscrew the plugs. If it is necessary to add electrolyte to the system, use distilled water to do this; this must be done before the charging procedure is carried out.
Consider several parameters:
- Voltage level. The maximum value in this case should be no more than 14.4 volts.
- Current strength. This parameter is adjustable; to do this, take into account the level of battery discharge. For example, if the car battery is 25% discharged, then when the charger is activated, the current parameter may increase.
- Car battery charging time. If there are no indicators on the charger, then you can understand when the car’s battery is charged by looking at the current value. In particular, if this parameter does not change for three hours, this will indicate that the battery is charged.
Never charge the device for more than 24 hours, this will cause the electrolyte to simply boil and a short circuit to occur inside the circuit.
Instructions for making a pulse charger with your own hands
To build a charger for a car battery with your own hands, use the IR2153 circuit. This circuit differs from the production circuit of a conventional charger in that instead of two capacitors connected to the midpoint, only one electrolyte is used. It should be noted that this do-it-yourself manufacturing scheme allows you to make a charger for a car battery, designed for low power. But this problem can also be solved by using more powerful elements.
In the diagram above, 8N50 type keys are used, equipped with an insulated housing. As for diode bridges, it is better to use those that are installed in computer power supplies. If you don’t have such circuit elements, then you can try to assemble a diode bridge from four rectifier diodes (the author of the video about creating a charger for a car battery is Blaze Electronics).
Now let's move on to the power circuit of the circuit device. To build this component with your own hands, use a resistor to dampen the current; use an 18 kOhm device. After the resistor in the circuit there is a regular rectifier component installed on one diode, while the power itself will in any case be supplied to the board. Directly on the power supply there is an electrolyte, which is connected in parallel to a capacitor (this element can be either film or ceramic). The use of a capacitor is necessary in order to ensure the most optimal smoothing of pulses and noise.
As for the transformer, it can also be removed from the PC power supply. It should be noted that such a transformer is excellent for creating a battery charger, since it allows for a good output current. In addition, a transformer of this type can simultaneously provide several output voltage parameters. The diodes themselves should only be pulsed, since standard elements will not be able to function as a result of too high a frequency.
The filter does not need to be added to the circuit, but instead it is advisable to install several containers and the inductor itself. To reduce the surge level at the input to the filter element, it is advisable to add a 5 Ohm thermistor to the circuit. You can also remove this element with your own hands from the PC power supply. An important point will be the installation of an electrolytic capacitor. It must be selected based on a special ratio of 1 Watt - 1 µF, the voltage level should be 400 volts.
In general, this scheme is quite simple in design. In practice, if you approach this issue correctly, it will not be so difficult to build, even if you have no experience. And considering that you will have the material with all the necessary diagrams and symbols at hand, coping with such a task will be as easy as shelling pears. Of course, if you cannot distinguish a transformer from a resistor, then it is better to just go to the store and buy the necessary charger.
Video “Making a pulse charger with your own hands”
All the nuances that need to be taken into account, as well as detailed step-by-step instructions for making a pulse charger for a car battery, are given below (the author of the video is Soldering Iron TV).
A good and interesting circuit for a high-quality charger based on the IR2153 microcircuit, a self-clocked half-bridge driver, which is often used in electronic ballasts for energy-saving lamps.
The circuit operates from an alternating voltage network of 220 Volts, its output power is about 250 watts, which is about 20 Amperes at 14 Volts of output voltage, which is quite enough to charge car batteries.
There is a surge filter at the input and protection against voltage surges and overload of the power supply. The thermistor protects the keys during the initial moment of turning on the circuit to a 220 Volt network. Then the mains voltage is rectified by a diode bridge.
The voltage passes through a limiting resistance of 47 kOhm to the generator microcircuit. Pulses of a certain frequency follow to the gates of high-voltage switches, which, when triggered, pass voltage into the network winding of the transformer. On the secondary winding we have the voltage required to charge the batteries.
The output voltage of the charger depends on the number of turns in the secondary winding and the operating frequency of the generator. But the frequency should not be raised above 80 kHz, optimally 50-60 kHz.
High voltage switches IRF740 or IRF840. By changing the capacitance of the capacitors in the input circuit, you can increase or decrease the output power of the charger; if necessary, you can reach 600 watt power. But you need 680 uF capacitors and a powerful diode bridge.
The transformer can be taken ready-made from a computer power supply. Or you can do it yourself. The primary winding contains 40 turns of wire with a diameter of 0.8 mm, then we apply a layer of insulation and wind the secondary winding - about 3.5-4 turns of fairly thick wire or use stranded wire.
After the rectifier, a filter capacitor with a capacity of no more than 2000 μF is installed in the circuit.
At the output it is necessary to install pulsed diodes with a current of at least 10-30A, ordinary ones will immediately burn out.
Attention, the charger circuit does not have short circuit protection and will immediately fail if this happens.
Another version of the charger circuit on the IR2153 chip |
The diode bridge consists of any rectifier diodes with a current of at least 2A, or more, and with a reverse voltage of 400 Volts; you can use a ready-made diode bridge from an old computer power supply; it has a reverse voltage of 600 Volts at a current of 6 A.
To ensure the required power parameters of the microcircuit, you need to take a resistance of 45-55 kOhm with a power of 2 watts; if you cannot find such, connect several low-power resistors in series.
Very powerful car charger up to 50 Amps. We have already talked about various battery chargers more than once. This time will be no exception; we will consider a very powerful charger, which can ultimately produce power up to 600 W with the ability to overclock to 1500 W.
It is clear that with such high powers we cannot do without a switching power supply, otherwise the dimensions of such a device will be unaffordable in weight and size. The circuit is quite simple, shown in the figure below.
Principle of operation in general, it is no different from other switching power supplies that we reviewed earlier. The structure of the work is constructed as follows: the initial mains voltage is filtered, unwanted ripples are removed, then it is rectified and supplied to the switches, which form high-frequency pulses corresponding to their control circuit. Next, the pulse transformer lowers the voltage to the required value and is rectified by a conventional bridge rectifier. In general, everything is simple.
In this case, the role of the key control circuit is played by a master oscillator based on the IR2153 chip. The microcircuit body kit is shown in the diagram.
IRF740 transistors were used as keys; you can also use others; we immediately note that it is the transistors that set the final power of the charger. When using the IRF740, approximately 850 watts of power is guaranteed.
In addition to the filter, a thermistor is also installed at the input to limit the inrush current. The thermistor should be no more than 5 Ohms and designed for a current of up to 5 A. There is also a slight subtlety in the circuit, because at the mains voltage input 50 Hz there are no requirements for diodes, except for the standard ones: there are no reverse voltage (600 V) and current (6-10 A), you can take almost any with the given parameters.
The second bridge installed at the output has one feature related to the fact that high-frequency voltage is supplied from the transformer, therefore, in addition to a reverse voltage of at least 25 V and a reverse current of up to 30 A, it is imperative to take ultra-fast diodes. By the way, it is not necessary to use 4 diodes as the first bridge; you can take a ready-made diode assembly from a computer power supply.
It will be much more convenient to install. Electrolytic capacitors installed after the first bridge must be designed for a voltage of at least 250 V and with a capacity of 470 μF, by the way, they can also be taken from a computer power supply. Everything is also simple with the transformer; you can take it from the same computer power supply, which you don’t even need to rewind.
Naturally, power switches must be installed on the heat sink, because The transistors have no common points; we install them either on different radiators, or isolate them with mica spacers.
To facilitate repair work, it is advisable to install the microcircuit in a special case for its easy removal and replacement; this will greatly facilitate repair and configuration. To check the device after installation, turn it on in idle mode, i.e. without load. In this case, the power switches should not heat up at all. The power of 25 Ohm resistors on the field gates is enough to take 0.5 W.
The resistor installed to power the IR2153 microcircuit can be taken in the range from 47 kOhm to 60 kOhm with a wattage of at least 5 W; it is current-limiting for current protection of the microcircuit. The output capacitors must be selected with a voltage of at least 25 V and a capacity of 1000 μF.
I would like to immediately draw your attention to the fact that the circuit does not have protection against short circuits, polarity reversal, there is no indication of operation, etc. All these shortcomings can be easily corrected, especially since they have been described on our resource more than once.
And I also want to note one point: if you need to repair your car or refill your air conditioner, then there is no problem. There is an excellent company that does this on a professional level and at the same time does everything as if it were for itself.
Good day everyone! I’m looking at diagrams on the Internet of switching power supplies and... And I don’t understand! Perhaps the authors don’t read the “Datasheet” for components, or are they specifically discouraged from assembling a UPS??? . Let's look at the description of IR2153: "an improved version of IR2153 -2155, the list of improvements comes down to protection from interference... We read: the recommended load capacitance is 1000 pF, power 0.650 W (short-term)! So this is the data on IR2151!!! And so we have: IR2153 can control keys with a capacitive load of 1n=1000 pf! Look at the "datasheet" of the keys. IR740 - 1450 pf. One and a half times higher than the recommended one. Now the voltage. The recommended maximum voltage of the keys is 600 v (v)! And the keys have 400 v. Well, yes, this more than 310 V! However, everyone who has come across industrial UPS circuits is well aware that switches are placed at a voltage of at least 600 V. Only in Chinese circuits sometimes burnt-out ones at 500 V appear. I hope I explained it clearly?! As for the switch current and resistance key in the open state. This has little effect on the power of the UPS. Let me explain. For a switching power supply, the current is limited by passing through the load and, as a rule, in a pulse does not exceed 2-3 A. In a pulse! We look at the “datasheet” of the keys and see: at a crystal temperature of 100 gr. current with a large margin for the IR740. However, in this case this is a minus for the key! The higher the switch current, the longer the switching time (see the graph there) and, of course, the lower the pulse slope, which means the efficiency is less than the maximum (75%). Accordingly, this key will work, but poorly!!! As a result of the above: this combination leads to burnout of both the keys and the driver! Anyone who wants to repeat this scheme is doomed to a handful of burnt parts! I am wrong? Read the comments on similar diagrams. The question follows: you are so smart, so what do you recommend? I advise everyone who wants to have a simple UPS assembly to take the diagram from the description and recommendation of the IR Company - IR2153 driver with switches for a current of 4-5 A and max. voltage 600-900 V with a control electrode capacitance of no more than 1000 pF. Example STP5NK600C and similar MOSFET triodes. Now about the resistance in the open state for the key: indeed, the greater it is, the stronger the heating of the key. Some will say less efficiency. In this case, the efficiency is not 100% and the effect of resistance is very small. So what affects efficiency? The efficiency is affected by the UPS circuit itself; for an efficiency of up to 94%, we assemble a resonant UPS. Efficiency up to 75% - with the right keys on the IR2153!. Is this efficiency not enough for you? Hm. What about a pulse transformer? How will it limit efficiency? Has anyone already counted? Losses at frequencies above 50 kHz increase significantly, although losses up to 50 kHz are not zero. Let's look at industrial circuits: winding pulse transformers is a very capricious task; two equally wound transformers have different inductances! What is this? And this is what it is! Each IT has its own optimal operating frequency. How do you like this? That's it - read on and look at the UPS diagrams for TVs, powerful amplifiers, and other factory electrical appliances. Good luck to you!
Share to:For a long time I was interested in the topic of how you can use the power supply from a computer to power a power amplifier. But remaking a power supply is still fun, especially a pulsed one with such a dense installation. Even though I’m used to all sorts of fireworks, I really didn’t want to scare my family, and it’s dangerous for myself.
In general, studying the issue led to a fairly simple solution that did not require any special details and practically no setup. Assembled, turned on, works. Yes, and I wanted to practice etching printed circuit boards using photoresist, since recently modern laser printers have become greedy for toner, and the usual laser-iron technology has not worked out well. I was very pleased with the result of working with photoresist; for the experiment, I etched the inscription on the board with a line 0.2 mm thick. And she turned out great! So, enough preludes, I will describe the circuit and process of assembling and setting up the power supply.
The power supply is actually very simple, almost all of it is assembled from parts left over after disassembling a not very good pulse generator from a computer - one of those parts that are not “reported” on. One of these parts is a pulse transformer, which can be used without rewinding in a 12V power supply, or converted, which is also very simple, to any voltage, for which I used Moskatov’s program.
Switching power supply unit diagram:
The following components were used:
driver ir2153 is a microcircuit used in pulse converters to power fluorescent lamps, its more modern analogue is ir2153D and ir2155. In the case of using the ir2153D, the VD2 diode can be omitted, since it is already built into the chip. All 2153 series microcircuits already have a built-in 15.6V zener diode in the power circuit, so you shouldn’t bother too much with installing a separate voltage stabilizer to power the driver itself;
VD1 - any rectifier with a reverse voltage of at least 400V;
VD2-VD4 - “fast-acting”, with a short recovery time (no more than 100ns) for example - SF28; In fact, VD3 and VD4 can be excluded, I did not install them;
as VD4, VD5 - a dual diode from the computer power supply “S16C40” is used - this is a Schottky diode, you can use any other, less powerful one. This winding is needed to power the ir2153 driver after the pulse converter starts. You can exclude both diodes and winding if you do not plan to remove power of more than 150 W;
Diodes VD7-VD10 - powerful Schottky diodes, for a voltage of at least 100V and a current of at least 10 A, for example - MBR10100, or others;
transistors VT1, VT2 - any powerful field-effect ones, the output depends on their power, but you shouldn’t get too carried away here, just as you shouldn’t remove more than 300 W from the unit;
L3 - wound on a ferrite rod and contains 4-5 turns of 0.7 mm wire; This chain (L3, C15, R8) can be eliminated altogether; it is needed to slightly facilitate the operation of the transistors;
Choke L4 is wound on a ring from the old group stabilization choke of the same power supply from the computer, and contains 20 turns each, wound with a double wire.
Capacitors at the input can also be installed with a smaller capacity; their capacity can be approximately selected based on the removed power of the power supply, approximately 1-2 µF per 1 W of power. You should not get carried away with capacitors and place a capacitance of more than 10,000 uF at the output of the power supply, as this can lead to “fireworks” when turned on, since they require a significant current for charging when turned on.
Now a few words about the transformer. The parameters of the pulse transformer are determined in the Moskatov program and correspond to an W-shaped core with the following data: S0 = 1.68 sq. cm; Sc = 1.44 cm2; Lsr.l. = 86cm; Conversion frequency - 100 kHz;
The resulting calculation data:
Winding 1- 27 turns 0.90mm; voltage - 155V; Wound in 2 layers with wire consisting of 2 cores of 0.45 mm each; The first layer - the inner one contains 14 turns, the second layer - the outer one contains 13 turns;
winding 2- 2 halves of 3 turns of 0.5mm wire; this is a “self-supply winding” with a voltage of about 16V, wound with a wire so that the winding directions are in different directions, the middle point is brought out and connected on the board;
winding 3- 2 halves of 7 turns, also wound with stranded wire, first - one half in one direction, then through the insulation layer - the second half, in the opposite direction. The ends of the windings are brought out into a “braid” and connected to a common point on the board. The winding is designed for a voltage of about 40V.
In the same way, you can calculate a transformer for any desired voltage. I have assembled 2 such power supplies, one for the TDA7293 amplifier, the second for 12V to power all sorts of crafts, used as a laboratory one.
Power supply for amplifier for voltage 2x40V:
12V switching power supply:
Power supply assembly in housing:
Photo of tests of a switching power supply - the one for an amplifier using a load equivalent of several MLT-2 10 Ohm resistors, connected in different sequences. The goal was to obtain data on power, voltage drop and voltage difference in the +/- 40V arms. As a result, I got the following parameters:
Power - about 200W (I didn’t try to shoot anymore);
voltage, depending on load - 37.9-40.1V over the entire range from 0 to 200W
Temperature at maximum power 200W after a test run for half an hour:
transformer - about 70 degrees Celsius, diode radiator without active blowing - about 90 degrees Celsius. With active airflow, it quickly approaches room temperature and practically does not heat up. As a result, the radiator was replaced, and in the following photos the power supply is already with a different radiator.
When developing the power supply, materials from the vegalab and radiokot websites were used; this power supply is described in great detail on the Vega forum; there are also options for the unit with short-circuit protection, which is not bad. For example, during an accidental short circuit, a track on the board in the secondary circuit instantly burned out
Attention!
The first power supply should be turned on through an incandescent lamp with a power of no more than 40W. When you turn it on for the first time, it should flash briefly and go out. It should practically not glow! In this case, you can check the output voltages and try to lightly load the unit (no more than 20W!). If everything is in order, you can remove the light bulb and begin testing.
PS: During the assembly and adjustment of the power supply, not a single animal was harmed, although once a “fireworks display” with sparks and special effects was caught when the power switches exploded. After replacing them, the unit started working as if nothing had happened;
ZZY: Attention! This power supply has circuits connected to the high voltage network! If you do not understand what it is and what it can lead to, it is better to abandon the idea of assembling this block. In addition, in the high voltage circuit there is an effective voltage of about 320V!
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