Do-it-yourself inverter start-up charger. Starting charger for a car. Video “How to build an adjustable ROM”
Starting the internal combustion engine of even a passenger car in winter, and even after a long period of parking, is often a big problem. This issue is even more relevant for powerful trucks and automotive equipment, of which there are many already in private use - after all, they are operated mainly in conditions of garage-free storage.
And the reason for difficult starting is not always that the battery is “not in its first youth.” Its capacity depends not only on the service life, but also on the viscosity of the electrolyte, which, as is known, thickens with decreasing temperature. And this leads to a slowdown in the chemical reaction with its participation and a decrease in the battery current in starter mode (by about 1% for each degree of temperature decrease). Thus, even a new battery significantly loses its starting capabilities in winter.
Do-it-yourself starting device for a car
To insure against unnecessary hassle associated with starting a car engine in the cold season, I made a starting device with my own hands.The calculation of its parameters was carried out according to the method specified in the list of references.
The operating current of the battery in starter mode is: I = 3 x C (A), where C is the nominal battery capacity in Ah.
As you know, the operating voltage on each battery (“can”) must be at least 1.75 V, that is, for a battery consisting of six “cans,” the minimum operating voltage of the Up battery will be 10.5 V.
Power supplied to the starter: P st = Uр x I р (W)
For example, if a passenger car has a 6 ST-60 battery (C = 60A (4), Rst will be 1890 W.
According to this calculation, according to the scheme given in, a launcher of the appropriate power was manufactured.
However, its operation showed that it was possible to call the device a starting device only with a certain degree of convention. The device was capable of operating only in the “cigarette lighter” mode, that is, in conjunction with the car’s battery.
At low outside temperatures, starting the engine with its help had to be done in two stages:
- recharging the battery for 10 - 20 seconds;
- joint (batteries and devices) engine promotion.
An acceptable starter speed was maintained for 3 - 5 seconds, and then decreased sharply, and if the engine did not start during this time, it was necessary to repeat it all over again, sometimes several times. This process is not only tedious, but also undesirable for two reasons:
- firstly, it leads to overheating of the starter and increased wear;
- secondly, it reduces the battery life.
It became clear that these negative phenomena can be avoided only when the power of the launcher is sufficient to start a cold car engine without the help of a battery.
Therefore, it was decided to manufacture another device that satisfies this requirement. But now the calculation was made taking into account losses in the rectifier unit, supply wires and even on the contact surfaces of the connections during their possible oxidation. One more circumstance was also taken into account. The operating current in the primary winding of the transformer when starting the engine can reach values of 18 - 20 A, causing a voltage drop in the supply wires of the lighting network by 15 - 20 V. Thus, not 220, but only 200 V will be applied to the primary winding of the transformer.
Diagrams and drawings for starting the engine
According to the new calculation according to the method specified in, taking into account all power losses (about 1.5 kW), the new starting device required a step-down transformer with a power of 4 kW, that is, almost four times more than the power of the starter. (Corresponding calculations were made for the manufacture of similar devices intended for starting the engines of various cars, both carburetor and diesel, and even with a 24 V on-board network. Their results are summarized in the table.)
At these powers, a crankshaft rotation speed is ensured (40 - 50 rpm for carburetor engines and 80 - 120 rpm for diesel engines), which guarantees reliable engine starting.
The step-down transformer was made on a toroidal core taken from the stator of a burnt-out 5 kW asynchronous electric motor. Cross-sectional area of the magnetic circuit S, T = a x b = 20 x 135 = 2700 (mm2) (see Fig. 2)!
A few words about preparing the toroidal core. The stator of the electric motor is freed from winding residues and its teeth are cut out using a sharp chisel and hammer. This is not difficult to do, since the iron is soft, but you need to use safety glasses and gloves.
The material and design of the handle and base of the trigger are not critical, as long as they perform their functions. My handle is made of a steel strip with a cross section of 20x3 mm, with a wooden handle. The strip is wrapped in fiberglass impregnated with epoxy resin. A terminal is mounted on the handle, to which the input of the primary winding and the positive wire of the starting device are then connected.
The frame base is made of a steel rod with a diameter of 7 mm in the form of a truncated pyramid, the ribs of which they are. The device is then attracted to the base by two U-shaped brackets, which are also wrapped in fiberglass impregnated with epoxy resin.
A power switch is attached to one side of the base, and a copper plate of the rectifier unit (two diodes) is attached to the other. A minus terminal is mounted on the plate. At the same time, the plate also serves as a radiator.
The switch is type AE-1031, with built-in thermal protection, rated for a current of 25 A. Diodes are type D161 - D250.
The estimated current density in the windings is 3 - 5 A/mm2. The number of turns per 1 V of operating voltage was calculated using the formula: T = 30/Sct. The number of turns of the primary winding of the transformer was: W1 = 220 x T = 220 x 30/27 = 244; secondary winding: W2 = W3 = 16 x T = 16x30/27 = 18.
The primary winding is made of PETV wire with a diameter of 2.12 mm, the secondary winding is made of an aluminum busbar with a cross-sectional area of 36 mm2.
First, the primary winding was wound with a uniform distribution of turns around the entire perimeter. After that, it is turned on through the power cord and the no-load current is measured, which should not exceed 3.5A. It must be remembered that even a slight decrease in the number of turns will lead to a significant increase in the no-load current and, accordingly, to a drop in the power of the transformer and starting device. Increasing the number of turns is also undesirable - it reduces the efficiency of the transformer.
The turns of the secondary winding are also evenly distributed around the entire perimeter of the core. When laying, use a wooden hammer. The leads are then connected to the diodes, and the diodes are connected to the negative terminal on the panel. The middle common terminal of the secondary winding is connected to the “positive” terminal located on the handle.
Now about the wires connecting the starter to the starter. Any carelessness in their manufacture can nullify all efforts. Let's show this with a specific example. Let the resistance Rnp of the entire connecting path from the rectifier to the starter be equal to 0.01 Ohm. Then, at a current I = 250 A, the voltage drop on the wires will be: U pr = I r x Rpr = 250 A x 0.01 Ohm = 2.5 V; in this case, the power loss on the wires will be very significant: P pr = Upr x Iр = 625 W.
As a result, a voltage of not 14, but 11.5 V will be supplied to the starter in operating mode, which, of course, is undesirable. Therefore, the length of the connecting wires should be as short as possible (1_p 100 mm2). The wires must be stranded copper, in rubber insulation. For convenience, the connection to the starter is made quick-release, using pliers or powerful clamps, for example, those used as electrode holders for household welding machines. In order not to confuse the polarity, the handle of the clamps of the positive wire is wrapped with red electrical tape, and the handle of the negative wire is wrapped with black tape.
The short-term operating mode of the starting device (5 - 10 seconds) allows its use in single-phase networks. For more powerful starters (over 2.5 kW), the PU transformer must be three-phase.
A simplified calculation of a three-phase transformer for its manufacture can be made according to the recommendations set out in, or you can use ready-made industrial step-down transformers such as TSPK - 20 A, TMOB - 63, etc., connected to a three-phase network with a voltage of 380 V and producing a secondary voltage of 36 V.
The use of toroidal transformers for single-phase starting devices is not necessary and is dictated only by their best weight and dimensions (weight about 13 kg). At the same time, the technology for manufacturing a starting device based on them is the most labor-intensive.The calculation of the starting device transformer has some features. For example, the calculation of the number of turns per 1 V of operating voltage, made according to the formula: T = 30/Sct (where Sct is the cross-sectional area of the magnetic circuit), is explained by the desire to “squeeze” the maximum possible out of the magnetic circuit to the detriment of efficiency. This is justified by its short-term (5 - 10 seconds) operating mode. If dimensions do not play a decisive role, you can use a more gentle mode by calculating using the formula: T = 35/Sct. The magnetic core is then taken with a cross-section that is 25 - 30% larger.
The power that can be “removed” from the manufactured PU is approximately equal to the power of the three-phase asynchronous electric motor from which the transformer core is made.
When using a powerful starting device in a stationary version, according to safety requirements, it must be grounded. The handles of the connecting pliers must be rubber insulated. To avoid confusion, it is advisable to mark the “plus” part, for example, with red electrical tape.
When starting, the battery does not need to be disconnected from the starter. In this case, the clamps are connected to the corresponding terminals of the battery. To avoid overcharging the battery, the starting device is immediately turned off after starting the engine.
Hello all readers. Today we will consider the option of building a powerful switching power supply that provides an output current of up to 60 Amps at a voltage of 12 Volts, but this is far from the limit; if desired, you can pump out currents of up to 100 Amps, this will give you an excellent starting and charger.
The circuit is a typical push-pull half-bridge network, step-down switching power supply, this is the full name of our block. our favorite microcircuit IR2153 is used as a master oscillator. The output is supplemented with a driver, essentially a regular repeater based on complementary pairs BD139/140. Such a driver can control several pairs of output switches, which will make it possible to remove more power, but in our case there is only one pair of output transistors. 
In my case, powerful n-channel field-effect transistors of type 20N60 with a current of 20 Amperes are used, the maximum operating voltage for these switches is 600 volts, they can be replaced with 18N60, IRF740 or similar, although I don’t really like the 740s because of the upper voltage limit of everything at 400 volts, but they will work. The more popular IRFP460 are also suitable, but the board is designed for keys in the TO-220 package. 
A unipolar rectifier with a middle point is assembled in the output part, in general, to save the transformer window, I advise you to install a regular diode bridge, but I didn’t have any powerful diodes, instead I found Schottky assemblies in a TO-247 package of type MBR 6045, with a current of 60 Amps, and installed them , to increase the current through the rectifier, I connected three diodes in parallel, so our rectifier can easily pass currents up to 90 Amperes, a completely normal question arises - there are 3 diodes, each 60 Amperes, why 90? The fact is that these are Schottky assemblies, in one case there are 2 diodes of 30 amperes each connected with a common cathode. If anyone doesn’t know, these diodes are from the same family as the output diodes in computer power supplies, only their currents are much higher. 
Let's take a superficial look at the principle of operation, although I think for many everyone is clear. 
When the unit is connected to a 220 Volt network through the R1/R2/R3 chain and the diode bridge, the main input electrolytes C4/C5 are smoothly charged, their capacity depends on the power of the power supply, ideally a capacitance of 1 μF per 1 watt of power is selected, but some variation is possible in one direction or another, capacitors must be designed for a voltage of at least 400 Volts. 
Through resistor p5, power is supplied to the pulse generator. Over time, the voltage on the capacitors increases, the supply voltage for the ir2153 microcircuit also increases, and as soon as it reaches a value of 10-15 Volts, the microcircuit starts up and begins to generate control pulses, which are amplified by the driver and supplied to the gates of the field-effect transistors, the latter will operate at a given frequency, which depends on the resistance of resistor r6 and the capacitance of capacitor c8.
Of course, voltage appears on the secondary windings of the transformer, and as soon as it is of sufficient magnitude, the composite transistor KT973 opens, through the open transition of which power is supplied to the relay winding, as a result of which the relay will operate and close contact S1 and the mains voltage will already be supplied to the circuit not through resistors R1, R2, R3 and on the relay contacts.. 
This is called a soft start system, more precisely a delay when turning on, by the way, the relay response time can be adjusted by selecting a capacitor C20, the larger the capacitance, the longer the delay. 
By the way, at the moment the first relay operates, the second one also operates; before it operates, one end of the transformer’s network winding was connected to the main power supply through resistor R13. 
Now the device is already operating in normal mode, and the unit can be overclocked to full power.
In addition to powering the soft start circuit, the 12 Volt low-current output can power a cooler to cool the circuit.
The system is equipped with a short circuit protection function at the output. Let's consider the principle of its operation.
R11/R12 acts as a current sensor; in the event of a short circuit or overload, a voltage drop of sufficient magnitude is formed across them to open the low-power thyristor T1; when it opens, it short-circuits the plus supply for the generator microcircuit to ground, so the microcircuit is not supplied with supply voltage and it stops working. Power is supplied to the thyristor not directly, but through an LED; the latter will light when the thyristor is open, indicating the presence of a short circuit. 
In the archive, the printed circuit board is slightly different, designed to receive bipolar voltage, but I think converting the output part to unipolar voltage will not be difficult.
Archive for the article; download…
That's all, I was with you as always - Aka Kasyan
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You need such a device. Especially if your car constantly has problems at the start and with the battery, who knows where it will happen next time? And if you purchase a charger for personal use, you will not only protect yourself from the possibility of getting stuck in some unpleasant place, but you will also be able to help a person who finds himself in a similar situation, especially in cold weather, when many engines fail start up. In addition, almost any charger can charge a phone or tablet - they have long included such a feature as additional ports, especially for such purposes.
There are several types of starter chargers, and before you start choosing them, you should familiarize yourself with the benefits of each of them.
Pulse. The operation of a pulse device is based on pulse voltage conversion. Under the influence of the frequency of the electric current, the voltage first increases, and then decreases and transforms. These devices, as a rule, have little power and are only suitable for recharging a dead battery. And if the charge is very low and it’s frosty outside, charging with it will take a very long time. Among the advantages of such a charger are an affordable price, light weight and small dimensions. As for the disadvantages, these are, first of all, low power and difficulty in repair. In addition, they are very sensitive to unstable voltage.
Transformer. The operation of such a device is based on a transformer, which converts current and voltage. They are able to increase the charge of any battery, no matter how discharged it is. In addition, such units are absolutely independent of the stability of the network and fluctuations in it do not affect their operation in any way. They work in any condition and in the vast majority of cases will start the engine, even if the battery charge is almost zero. Among the main advantages: power and reliability, absolute unpretentiousness. However, there are also disadvantages. These are the high price of the products, large weight and dimensions.
Boosters, or battery-type jump starters, are portable batteries. They work on the principle of a portable charging unit - first the battery is charged, and the car with a low battery charge is started from the battery. As a rule, they come in two types - household and professional. The difference is in the volume of built-in batteries and dimensions. Household starting devices of this type usually have a small capacity, which is quite enough to power one car. A professional battery device is a full-fledged autonomous charger for a car, and not just one, but several. And thanks to the extremely large capacity, they can be used to start engines with different on-board networks, both 12V and 24V. Their advantage is that they are autonomous and mobile, but due to their weight and dimensions, they can only be conveniently moved on a flat surface on the wheels of the housing.
Capacitor starter. Starting the engine and discharging the battery is carried out according to a rather complex circuit, the main part of which is powerful capacitors. First they charge, and then release their charge to start the engine. Due to the fact that they charge themselves very quickly and also quickly start the engine. They are not very popular due to their high cost. In addition, their use leads to rapid wear of the car battery.
I present to your attention a powerfulstarter charger for charging car batteries voltage of 12 and 24 volts, as well as starting engines of cars and trucks with the corresponding voltages.
Its electrical circuit diagram:
The power source for the starter-charger is 220 volts of industrial frequency. The power consumed from the source can range from tens of watts in charging mode (when the batteries are almost charged and have a voltage of 13.8 - 14.4 volts or 27.6 - 28.8 volts for a pair connected in series) to several kilowatts in the starting mode of the car engine starter.
At the input of the device there is a two-pole circuit breaker with a current Inom = 25 A. The use of a two-pole circuit breaker is due to the reliability of disconnecting both the phase and the zero, since when connected through a standard Euro plug (with a grounding contact), there is no certainty that a single-pole circuit breaker will turn off the phase and thereby the entire device will be de-energized. This circuit breaker (in my version) is installed in a standard wall-mounted box. Frequently turning on the power with this switch does not make sense, and therefore did not install it on the front (front) panel.
Both in the “Start” mode and in the “Charge” mode, the power transformer is turned on by the same magnetic starter KM1, whose coil voltage is 220 volts and the current switched by the contacts is about 20-25 amperes.
The most important part of the starter-charger is the power transformer. I won’t give the circuit data of the power transformer, since I don’t think everyone will rush to copy one to one, I’ll just say what, in my opinion, you should pay attention to. As we have already noticed from the diagram, the transformer has a secondary winding with a branch from the middle. Here, during calculations, and then in practice, it is necessary to set the voltage at the output of the device (clamps on batteries - easier than crocodiles), taking into account the voltage drop across the diodes (in my version D161-250) within 13.8-14.4 volts for 12 volt mode and 27.6-28.8 for 24 volt mode, with a load current of up to 30 amperes. I used crocodiles from the weight of the welding machine, and accordingly painted the plus one red.
The 12/24 volt mode is installed by contactors KM2, KM3, the power contacts of which, rated for 80 amperes, are connected in parallel, giving a total of 240 amperes.
A shunt is installed in the circuit on the 12/24 volt side, and the contacts of the magnetic starter of the "" mode are installed in the ammeter circuit break.Charge" This ammeter must measure the charging current. The scale limit in my version is 0...30 A. The circuit closes in charging mode.
Separately, I would like to talk about the “Charge" As you have already noticed, there is no charge current control circuit here, but it can be said to be maximum. Error? I think no. Let's look at the electrical equipment of the average car. So, there the relay regulator regulates not the charge current, but... drives the generator into the parameters of the on-board network of the car, the same 13.8-14.4 volts, respectively, if you wind the transformer correctly, taking into account the voltage drop on the power diodes, then compare this circuit the car's generator, and as the battery charges, the current will only drop.
And, do not forget, in a diode bridge it is necessary to take into account that two diodes operate in series, that is, the voltage drop must be multiplied by two.
Among the shortcomings of this circuit, I can only highlight the dependence of the network voltage on the charging current. Since my version will be used at service stations, where the network voltage changes little and its main task is to start trucks with a voltage of 24 volts, I don’t see the need to complicate the design. But the solution to the problem can be to install an autotransformer through the free contacts of the magnetic starter KM4, parallel to KM1. Best regards, AZhila.
Every motorist has probably found himself in a situation where his car did not start at the moment when he needed to go somewhere urgently. This happens especially often in winter, when the temperature outside is sub-zero. Anyone can buy a modern model of a car starter charger in a store, but the problem is that a high-quality and reliable device is very expensive, and inexpensive devices quickly break down.
Making your own starter charger is not that difficult. The main thing is to buy all the necessary parts at any radio parts store. At the same time, the assembled device for the car is much cheaper and meets all the needs of the motorist.
Selecting a device diagram
You can select the appropriate circuit for the charger on specialized Internet sites and forums, where you will also find a detailed description of all functions. If you have never assembled such devices yourself before and you do not have experience, stop at simpler circuits. When choosing a circuit, attention should be paid to the presence of a switch or other device that turns off the ammeter during start-up mode.
Various websites suggest making or assembling a step-down transformer with your own hands, but this is a rather complicated process that requires some skills. Thus. It’s better to buy a suitable transformer from the factory - this way you will save your time and nerves. A step-down transformer is the basis of a car starter charger, so it’s better not to skimp on it.
Materials and tools
To assemble the starter charger yourself at home or in the garage, you will need the following tools, materials and equipment:
- soldering iron of sufficient power;
- textolite plate;
- tin solder;
- a step-down transformer;
- radio components;
- cooler or case fan;
- high voltage wires with a cross section of 2-2.5 square;
- screwdriver or drill with drill bits;
- wires for connecting to the battery with a cross-section of at least 10 square copper with clamps;
- fastening elements.
About assembling the device
You need to assemble the charger for the car on a sheet of textolite of the appropriate size. You need to start with a step-down transformer, since this is the most bulky part in the device you are assembling. To fasten parts and pass wires, holes of a suitable diameter are drilled in the textolite plate. For rectifier diodes, it is necessary to provide a reliable cooling system. This requires special metal cooling jackets. Sometimes this may not be enough, so you should consider additional forced cooling using a case fan from the computer.To remove heat, provide heat-dissipating blinds in the housing, which you can make yourself.
Some motorists believe that the assembled charger does not need to be enclosed in a housing, but it provides protection for the equipment from external influences and also protects the owner from electric shocks. A case from an old personal computer works well as a fencing for the charger. With some modifications, you can give your device a complete look. Indicators, switches and all controls can be built into the front panel of the case.
