Every car enthusiast at least once in his life has encountered a problem when his vehicle does not start for some reason. The inability to start the engine may be due to the inoperability of certain components, and sometimes the problem is simply a dead battery. Below you can find out how to choose the right starting charger for a car battery and how you can make it yourself.
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Step-by-step guide to choosing a ROM
Today in Russian auto stores you can find many different pre-start devices from different manufacturers. Each of them is characterized by the presence of certain functions, power, and other features. To choose the right starting charger for your car battery, you need to follow a few simple recommendations.
Briefly about them:
- Functions.
- First of all, you need to decide whether you really need to buy a jump starter charger with a motor starting function. If you understand that you need such a function, then the choice must be built directly from the ROM. If you just need a charger that will allow you to charge your car battery, then the best option would be to choose a regular charger. Such a device will be enough for these purposes, especially since its cost will be significantly lower compared to ROM. Next, having decided on the device, you need to pay attention to the inrush current characteristics. This indicator is selected depending on the starting current of the battery installed on the car. It should be noted that the starting currents of cars with diesel engines differ significantly from the current indicators in gasoline cars. Often you can find ROMs on sale that do not allow you to regulate the current value, but have the function of accelerated or normal charging mode. It must be taken into account that the accelerated mode is carried out with a higher current, accordingly, the car battery can be charged more quickly. However, experts do not recommend using this mode often, as this will affect the service life of the battery.
As for the normal mode, it is carried out with a lower current, but such charging takes longer. Thanks to the operation of the normal mode, sulfate is completely dissolved on the plates, and accordingly, this will have a good effect on the battery capacity. It must be taken into account that the starting current depends on the battery capacity, which determines the ability of the battery to produce maximum current for thirty seconds. In any case, the characteristics of the purchased device must fully correspond to the characteristics of the battery in the car. - Device type.
- The next step is to decide on the type of ROM for your vehicle. You can find both standalone and networked models on sale. As you understand, autonomous options can function without connecting to the network; they do not need electricity, since they are equipped with a built-in powerful battery. As for the network options, they can only function from the network. This means that their operation is only possible near the house or in the garage, and only if there is electricity in it. is an important point. So that the driver can always know how the charging process is carried out, experts recommend buying devices equipped with built-in voltmeters or ammeters. Today, most of the model options allow for the process of desulfation of the car battery. When the battery is in operation, insoluble lead crystals form on its internal elements, which can result in a short circuit inside the battery cans. In order to remove this plaque and increase the service life of the device, such crystals can be destroyed as a result of exposure to current.
It is also necessary to consider that modern vehicles typically use lead-acid or gel devices. Lead-acid is much more common, so most jump starters you find on sale are designed to work only with lead-acid. As for gel batteries, not all ROMs are suitable for charging such batteries. - Temperature selection is an important point. Any launcher has a certain operating mode; you need to familiarize yourself with this characteristic before choosing a device. The temperature regime determines at what temperatures the device can start the engine. If the problem with starting the engine in your case is relevant in the winter season, then this characteristic cannot be ignored.
Before choosing a device, you need to consider that the device is being purchased for a long time. Even if today you own a small car with a 60 Ah battery, perhaps in a few years you will have a more powerful car with a more powerful battery. Therefore, in order to purchase the ROM correctly, it is advisable to take the device with a reserve. If you buy a device designed for a current of 15 amperes, this will make it possible to charge even the most powerful batteries.
Whatever ROM you choose, you must take into account that, unlike traditional ROMs, these devices operate with high currents. Therefore, during operation it is always necessary to observe safety precautions - the wires are always connected strictly - plus to plus, minus to minus.
DIY instructions
If necessary, you can easily assemble a starting charger for a car at home with your own hands. This will save money, but to assemble it yourself you need to have certain skills. If you have them, then we offer detailed instructions (the author of the video is Anton Buryy).
Materials and equipment
So, if you want to make a starting battery charger with your own hands, then first of all you need to make sure that you have everything at hand.
We are talking about the following materials and tools:
- a working soldering iron with all consumables;
- textolite tiles;
- transformer, you will need a step-down device;
- a small fan, can be used from the computer power supply or from the PC case;
- high voltage cable, cross-section should be 2-2.5 millimeters;
- You will also need wires with which the ROM will be connected to the battery; these wires must be equipped with special clamps.
Of course, in addition to this, you must have all the necessary radio components, as well as elements for fastening.
Device assembly process
Now let's move directly to the issue of assembling a starting charging device with our own hands in accordance with the diagram. There can be many schemes; you can find dozens of different schemes on the Internet. We bring to your attention one of the simplest schemes that will allow you to assemble it yourself.
- Assembling the device with your own hands is carried out on a PCB tile that you have prepared in advance; its size must be appropriate. One of the most basic and largest elements of a starting battery charger is the transformer, so we will start with it. In the PCB tile, using a drill, you need to drill holes of the required sizes into which fasteners and wiring will be installed.
- Rectifier diodes can get very hot during operation, so you need to think about proper cooling for them in advance. For example, special iron cooling elements (so-called jackets) can be used for these purposes. Sometimes installing metal jackets may not be enough to provide cooling for the rectifier diodes. In this case, you will need the same fan that you removed from the old computer case or power supply. If there is no such fan, then you can use heat removal devices from the computer processor, a radiator. In order for a home-made starting charger to remove heat, the case must be equipped with appropriate heat-dissipating blinds in advance.
- According to many car enthusiasts, a home-made starting battery charger does not necessarily need to be installed in the case. But if you have already assembled the device, is it really difficult to equip it with a housing? Moreover, it is the case that allows you to protect the battery charger from various external influences, which is especially important if you plan to carry the device with you in the car. Moreover, when working with ROM, the driver will be protected from the effects of current, and this is important.
- To equip the case, you can use a box of appropriate sizes. For example, this could be a case from an old desktop computer. You will have to modify it a little, but in the end you will get a full-fledged starting charger, made by yourself. In addition, all indicators and switches, as well as other control components, can be mounted on the front of the computer case. Learn more about how to make an adjustable ROM with your own hands from the video. The author of the video, valeriyvalki, states that even a person who does not have knowledge in the field of radio electronics can cope with such a task.
Of course, if you decide to start such an important process, then you will want the device that is made for you to last a long time and to be able to rely on it at any time. Achieving this can sometimes be difficult, especially if you have no experience in making such devices and are encountering this for the first time.
So, in order to do everything correctly with your own hands, you need to take into account some recommendations, we will talk about them further:
- Firstly, you need to take a responsible approach to choosing a transformer. You need to choose a device that has a good power reserve. If the device is more powerful, then during operation, when charging the vehicle battery, it will heat up less. Accordingly, the service life of such a device will be longer. If in the future you suddenly decide to upgrade your ROM, making it more functional and, accordingly, more energy-consuming, then more power will also be to your advantage. Thanks to the high power, you don't have to buy a new transformer or reassemble it. Remember that the transformer is one of the main components of any ROM. You also need to take into account that the transformer itself must be of high quality; if you see that its condition is deplorable, then it is better not to use such an element for making ROM. Otherwise, you may even damage your car battery.
- An equally important component of any ROM circuit is the high voltage wires. When purchasing such wires, you need to make a choice in favor of elements characterized by excellent insulation. First of all, insulation is an excellent protection for wiring from possible external influences. In addition, high voltage cables will not be as tangled as regular wires, and this will greatly simplify the ROM assembly procedure.
- If you have a problem choosing cables for charging and connecting to the battery, then this problem can be solved. You can build such wires yourself by cutting off a certain part of the insulating layer on the cable, in particular, at the point of connection to the ROM and battery. You can use a soft copper wire as a cable; of course, it must have excellent insulation, which will avoid possible problems. When you have to force the engine to start, a cable with a poor cross-section will begin to heat up quickly, and accordingly, the insulation may also begin to lose its characteristics. As a result, this may cause a short circuit. Therefore, immediately make sure that the cables for starting the motor are removable; in this case, using the device will be more convenient.
- Please ensure that the fan that will perform the cooling function is operational. Cooling during operation of the starter is very important. If the ROM is not cooled properly, it will overheat during operation, which can lead to certain problems.
- If this is your first time encountering the issue of arranging such a system, then it is advisable to make the diagram as simple as possible. Connecting too complex circuits can confuse you, and if some actions are performed incorrectly, this can lead to a short circuit, which will negatively affect the battery's condition as a whole. If you doubt that you will be able to perform all the steps correctly and end up with a device that you can use, then the best option would be to buy a new ROM.
Video “Production of a starter-charger at home”
You can learn more about developing a circuit and creating a ROM with your own hands using improvised means from the video below (the author of the video is Evseenko Technology).
Sorry, there are no surveys available at this time.The starting charger allows you to start your car engine in winter. Since starting an internal combustion engine with a dead battery requires a lot of effort and time. The density of the electrolyte noticeably decreases in winter, and the sulfation process occurring inside the battery increases its internal resistance and reduces the starting current of the battery. In addition, in winter, the viscosity of the engine oil increases, so the battery requires more starting power. To make it easier to start the engine in winter, you can warm up the oil in the car’s crankcase, start the car from another battery, push start it, or use a car starting charger.
The starting charger for a car consists of a transformer and powerful rectifier diodes. For normal operation of the starting device, an output current of at least 90 amperes and a voltage of 14 volts are required, so the transformer must be powerful enough, at least 800 W.
To make a transformer, it is easiest to use a core from any LATR. The primary winding should be from 265 to 295 turns of wire with a diameter of at least 1.5 mm, preferably 2.0 mm. Winding must be done in three layers. There is good insulation between layers.
After winding the primary winding, we test it by connecting it to the network and measure the no-load current. It should be between 210 - 390 mA. If it is less, then rewind a few turns, and if it is more, then vice versa.
The secondary winding of the transformer consists of two windings and contains 15:18 turns of stranded wire with a cross-section of 6 mm. The windings are wound simultaneously. The voltage at the output of the windings should be about 13 volts.
Wires connecting the device to the battery must be multi-core, with a cross-section of at least 10 mm. The switch must withstand a current of at least 6 Amps.
The starting circuit of a car charger contains a triac voltage regulator, a power transformer, a rectifier with powerful diodes and a starter battery. The charging current is set by the current regulator on the triac and is regulated by variable resistance R2 and depends on the capacity of the battery. The input and output charging circuits contain filter capacitors, which reduce the degree of radio interference during operation of the triac regulator. The triac operates correctly at mains voltages from 180 to 230 V.
The rectifier bridge synchronizes the switching on of the triac in both half-cycles of the mains voltage. In the “Regeneration” mode, only the positive half-cycle of the mains voltage is used, which cleans the battery plates from existing crystallization.
The power transformer was borrowed from the Rubin TV. You can also take the TCA-270 transformer. We leave the primary windings unchanged, but we will redo the secondary windings. To do this, we separate the frames from the core, unwind the secondary windings to the foil of the screens, and in their place wind them with copper wire with a cross-section of 2.0 mm in one layer until the secondary windings are filled. As a result of rewinding, approximately 15 ... 17 V should come out
When adjusting, an internal battery is connected to the starting charger, and the charging current adjustment is tested with resistance R2. Then we check the charging current in charge, start and regeneration modes. If it is no more than 10...12 amperes, then the device is in working condition. When connecting the device to a car battery, the charging current initially increases by about 2-3 times, and after 10 - 30 minutes it decreases. After this, switch SA3 is switched to the “Start” mode, and the car engine starts. If the attempt is unsuccessful, we additionally recharge for 10 - 30 minutes and try again.
The diagram contains: stabilized power supply(diodes VD1-VD4, VD9, VD10, capacitors C1, SZ, resistor R7 and transistor VT2)
synchronization node(transistor VT1, resistors R1/R3/R6, capacitor C4 and elements D1.3 and D1.4, made on the K561TL1 microcircuit);
pulse generator(elements D1.1, D1.2, resistors R2, R4, R5 and capacitor C2);
pulse counter(chip D2K561IE16);
amplifier(transistor VT3, resistors R8 and R9);
power unit(optocoupler thyristor modules VS1 MTO-80, VS2, power diodes V-50 VD5-VD8, shunt R10, instruments - ammeter and voltmeter);
short circuit detection unit(transistor VT4, resistors R11-R14).
The scheme works as follows. When voltage is applied at the output of the bridge (diodes VD1-VD4), a half-wave voltage appears (graph 1 in Fig. 2), which, after passing through the circuit VT1-D1.3.-D1.4, is converted into pulses of positive polarity (graph 2 in Fig. 2). These pulses for counter D2 are a reset signal to the zero state. After the reset pulse disappears, the generator pulses (D1.1, D1.2) are summed up in counter D2 and when the number 64 is reached, a pulse appears at the counter output (pin 6) with a duration of at least 10 generator pulse periods (graph 3, Fig. 2). This pulse opens the thyristor VS1 and voltage appears at the output of the ROM (graph 4 in Fig. 2). To illustrate the limits of voltage regulation, graph 5 of Fig. 2 shows the case of setting almost the full output voltage.
With the parameters of the frequency-setting circuit (resistors R2, R4, R5 and capacitor C2 in Fig. 1), the opening angle of thyristor VS1 lies within 17 (f = 70 kHz) - 160 (f = 7 kHz) electrical degrees, which gives the lower limit of the output voltage about 0.1 times the input value. The frequency of the generator output signals is determined by the expression
f=450/(R 4 +R 5)С 2
,where the dimension f is kHz; R - kOhm; C - nF. If necessary, the ROM can be used to regulate only the AC voltage. To do this, the bridge on diodes VD5-VD8 should be excluded from the circuit (Fig. 1), and the thyristors should be connected back-to-back (in Fig. 1 this is shown by the dashed line).
In this case, using the circuit (Fig. 1), you can regulate the output voltage from 20 to 200 V, but it should be remembered that the output voltage is far from sinusoidal, i.e. Only electric heating devices or incandescent lamps can serve as a consumer. In the latter case, you can sharply increase the service life of the lamps, since they can be turned on smoothly by changing the voltage from 20 to 200 V with resistor R5. Setting up the ROM comes down to adjusting the level of protection against short circuit currents. To do this, remove the jumpers between points A and B (Fig. 1) and temporarily apply +Up voltage to point B. By changing the position of the slider of resistor R14, we determine the voltage level (point C in Fig. 1) at which transistor VT4 opens. The protection response level in amperes can be determined by the formula I>k /R10, where k=Up/Ut.c., Up - supply voltage; Ut.s. - voltage at point C at which VT4 is triggered; R10 - shunt resistance.
In conclusion, we can recommend the procedure for putting the ROM into operation and inform about possible replacements of components, tolerances and manufacturing features: the D1 microcircuit can be replaced with the K561LA7 microcircuit; microcircuit D2 - microcircuit K561IE10, connecting both counters in series; all resistors in the MLT type circuit are 0.125 W, with the exception of resistor R8, which must be at least 1 W; tolerances on all resistors, with the exception of resistor R8, and on all capacitors +30%; the shunt (R10) can be made of nichrome with a total cross-section of at least 6 mm (total diameter about 3 mm, length 1.3-1.5 mm). Put the ROM into operation only in the following sequence: turn off the load, set resistor R5 to the required voltage, turn off the ROM, connect the load and, if necessary, increase the voltage with resistor R5 to the required value.
To solve the problem of starting the engine in winter, we will use an electric starter that will allow motorists to start a cold engine even with a partially charged battery and thereby extend its life.
Calculation. Carrying out an accurate calculation of the magnetic core of the transformer is impractical, since it is under load for a short time, especially since neither the grade nor the technology for rolling the electrical steel of the magnetic core is known. Find the required power of the transformer. The main criterion is the operating current of the electric starter Istart, which is in the range of 70 - 100 A. Electric starter power (W) Rap = 15 Istart. Determine the cross-section of the magnetic circuit (cm 2) S = 0.017 x Rap = 18...25.5 cm2. The electric starter circuit is very simple; you just need to correctly install the transformer windings. To do this, you can use toroidal iron from any LATRA or from an electric motor. For the electric starter, I used the transformer iron of an asynchronous electric motor, which I chose taking into account the cross section. The parameters S = aw must be no less than the calculated ones.
The stator of the electric motor has protruding grooves that were used for laying the windings. When calculating the cross section, do not take them into account. You need to remove them with a simple or special chisel, but you don’t have to remove them (I didn’t remove them). This only affects the consumption of the electrical wires of the primary and secondary windings and the mass of the electric starter. The outer diameter of the magnetic core is in the range of 18 - 28 cm. If the cross-section of the electric motor stator is larger than the calculated one, it will have to be divided into several parts. Using a metal hacksaw, we saw through the outer ties in the grooves and separate the torus of the required cross-section. Use a file to remove sharp corners and protrusions. We carry out insulating work on the finished magnetic circuit using varnished cloth or fabric-based insulating tape.
Now we proceed to the primary winding, the number of turns of which is determined by the formula: n1 = 45 U1/S, where U1 is the voltage of the primary winding, usually U1 = 220 V; S is the cross-sectional area of the magnetic circuit.
For it we take copper wire PEV-2 with a diameter of 1.2 mm. We first calculate the total length of the primary winding L1. L1 = (2a + 2b) Ku, where Ku is the stacking coefficient, which is equal to 1.15 - 1.25; a and c are the geometric dimensions of the magnetic circuit (Fig. 2).
Then we wind the wire onto the shuttle and install the winding in bulk. Having connected the leads to the primary winding, we treat it with electrical varnish, dry it and carry out insulation work. Number of turns of the secondary winding n2 = n1 U2/U1, where n2 and n1 are the number of turns of the primary and secondary windings, respectively; U1 and U2 - voltage of the primary and secondary windings (U2 = 15 V).
The winding is made with insulated stranded wire with a cross-section of at least 5.5 mm2. The use of busbar trunking is preferable. Inside the wire we place turn to turn, and on the outside with a small gap - for uniform placement. Its length is determined taking into account the dimensions of the primary winding. We place the finished transformer between two square getinaks plates 1 cm thick and 2 cm wider than the diameter of the wound transformer, having previously drilled holes in the corners for fastening with coupling bolts. On the top plate we place the leads of the primary (insulated) and secondary windings, a diode bridge and a handle for transportation. We connect the outputs of the secondary winding to the diode bridge, and equip the outputs of the latter with M8 wing nuts and mark them “+”, “-”. The starting current of a passenger car is 120 - 140 A. But since the battery and electric starter operate in parallel mode, we take into account the maximum electric starter current of 100 A. Diodes VD1 - VD4 type B50 for a permissible current of 50 A. Although the engine starting time is short, it is advisable to place diodes on radiators. We install any switch S1 with a permissible current of 10 A. The connecting wires between the electric starter and the motor are multi-core, with a diameter of at least 5.5 mm in different colors, and we equip the ends of the output tips with alligator clips.
Start-charger PZU-14-100 |
The diagram of the starting-charger clearly shows that the thyristors are controlled by current pulses of the circuit capacitance C4 - transistors VT5, VT6, VT7 - diodes VD4, VD5. The unlocking phase of the thyristors and the flow of current in the power circuit depend on the rate of increase in voltage across the capacitor C4, that is, on the current through the resistances of the current regulator R23-R25 and through the start bipolar transistor VT3. VT3 turns on in the “start” mode if the voltage on the battery drops below 11 V. The key transistor VT4 turns on the control circuit when properly connected to the battery and protects it when the current is exceeded and the windings overheat. For reliable operation of this circuit, the halves of the secondary winding are required to be as identical as possible; they are usually made by winding them into two wires or by dividing the ends of the “pigtail” in two. The current flowing in the winding is measured by the voltage difference on the loaded and free halves, since they are loaded in turn.
Reliable engine starting a passenger car in winter can sometimes become a problem. This issue is especially relevant for powerful automotive and tractor equipment of agricultural enterprises, road and municipal services, which operate it in non-garage storage conditions. This will not happen if there is an electronic assistant at hand, which can be made by an averagely qualified radio amateur.
Fig. 1 Diagram of a single-phase starting device.
Sct = 27 cm2, Sct = a? in (Sct – cross-sectional area of the magnetic circuit, cm2)
Fig. 3 General view of a single-phase starting device.
The described method for calculating the starting device is universal and applicable to engines of any power. Let us demonstrate this using the example of the ST-222 A starter, used on tractors T-16, T-25, T-30 from the Vladimir Tractor Plant.
Basic information about the ST-222 A starter:
- rated voltage – 12 V;
- rated power – 2.2 kW;
- battery type – 2?3ST-150.
Means:
Iр=3 · С20= 3 · 150 А = 450 А,
The power supplied to the starter will be:
Рst = 10.5 V · 450 A = 4725 W.
Taking into account power losses:
Рп = 1–1.3 kW.
Starter transformer power:
Rtr = Rst + Rp = 6 kW.
Magnetic circuit cross-section Sct = 46–50 cm2. The current density in the windings is taken equal to:
j = 3 – 5 A/mm2.
The short-term operating mode of the starting device (5–10 seconds) allows its use in single-phase networks. For more powerful starters, the starting transformer must be three-phase. Let's talk about the features of its design using the example of a starting device for a powerful diesel tractor “Kirovets” (K-700, K-701). Its starter ST-103A-01 has a rated power of 8.2 kW at a rated voltage of 24 V. The power of the starting device transformer (including losses) will be:
Rtr = 16 – 20 kW.
A simplified calculation of a three-phase transformer is carried out taking into account the recommendations set out in. If possible, you can use industrial step-down transformers such as TSPK-20A, TMOB-63, etc., connected to a three-phase network with a voltage of 380/220 V and a secondary voltage of 36 V. Such transformers are used for electrical heating of floors, premises in livestock farming, pig farming, etc. .d. The circuit diagram of the starting device on a three-phase transformer looks like this (see Fig. 4).
Fig.4 Starting device on a three-phase transformer.
MP – magnetic starter type PML-4000, PMA-4000 or similar for switching devices with a power of 20 kW. Start button SB1 type KU-121-1, KU-122-1M, etc.
A three-phase half-wave rectifier is used here, which allows an open-circuit voltage of 36 V to be obtained. Its increased value is explained by the use of longer cables connecting the starting device to the starter (for large-sized equipment, the cable length reaches 4 m). The use of a three-phase transformer provides greater opportunities for obtaining the required starting voltage. Its value can be changed, including star and delta windings, and half-wave or full-wave (Larionov circuit) rectification can be used.
In conclusion, some general tips and recommendations:
– The use of toroidal transformers for single-phase starting devices is not necessary and is dictated by their better mass and dimensions. At the same time, the technology for their production is the most labor-intensive.
– Transformer calculation The starting device has some features. For example, calculating the number of turns per 1 V of operating voltage using the formula: T = 30/Sst 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/Sst. The cross-section of the magnetic circuit is 25–30% larger.
– The power that can be “removed” from the existing toroidal core is approximately equal to the power of the three-phase asynchronous electric motor from which this core is made. If the engine power is not known, then it can be approximately calculated using the formula:
Рдв = Sst? OK,
where Рдв – engine power, W; Sst – cross-sectional area of the magnetic core, cm2 Sst = а?в Sok – area of the magnetic core window, cm2 (see Fig. 2)
Sok = 0.785 D2
– The transformer core is attached to the base frame with two U-shaped brackets. Using insulating washers, it is necessary to avoid the appearance of a short-circuited turn formed by the bracket with the frame.
– Considering that the no-load voltage in the three-phase starting device is higher than 28 V, the engine is started in the following sequence:
- 1. Connect the starter clamps to the starter terminals.
- 2. The driver turns on the starter.
- 3. The assistant presses the start button SB1 and immediately releases it after stable engine operation.
– 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” tick, 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 turned off after starting the engine.
– To reduce magnetic scattering, it is better to wind the secondary windings of the transformer first on the core, and then wind the primary winding.
Winter, frost, the car won’t start, while we tried to start it, the battery is completely discharged, we are scratching our heads, thinking about how to solve the problem... Is this a familiar situation? I think those who live in the northern regions of our vast country have more than once encountered problems with their car in the cold season. And when such a case arises, we begin to think that it would be nice to have on hand a starting device designed specifically for such purposes. Naturally, buying such an industrially produced device is not a cheap pleasure, so the purpose of this article is to provide you with information on how you can make a starting device with your own hands at minimal cost.
The starting device circuit that we want to offer you is simple but reliable, see Figure 1.
This device is designed to start the engine of a vehicle with a 12 volt on-board network. The main element of the circuit is a powerful step-down transformer. The bold lines in the diagram indicate the power circuits going from the starter to the battery terminals. At the output of the secondary winding of the transformer there are two thyristors, which are controlled by a voltage control unit. The control unit is assembled on three transistors; the response threshold is determined by the value of the zener diode and two resistors forming a voltage divider.
The device works as follows. After connecting the power wires to the battery terminals and turning on the mains, no voltage is supplied to the battery. We begin to start the engine, and if U of the battery drops below the operating threshold of the voltage control unit (this is below 10 volts), it will give a signal to open the thyristors, the battery will receive recharge from the starting device. When the voltage at the terminals reaches above 10 volts, the starting device will disable the thyristors and recharge the battery will stop. As the author of this design says, this method avoids harming the car battery.
Transformer for starting device.
In order to estimate how much power a transformer is needed for a starting device, you need to take into account that at the moment the starter starts, it consumes a current of about 200 amperes, and when it spins up, it consumes 80-100 amperes (voltage 12 - 14 volts). Since the starting device is connected directly to the battery terminals, when the car starts, some of the electricity will be supplied by the battery itself, and some will come from the starting device. We multiply the current by the voltage (100 x 14), we get a power of 1400 watts. Although the author of the above diagram claims that a 500-watt transformer is enough to start a car with a 12-volt on-board network.
Just in case, let us recall the formula for the ratio of wire diameter to cross-sectional area, this is the diameter squared multiplied by 0.7854. That is, two wires with a diameter of 3 mm will give (3 * 3 * 0.7854 * 2) 14.1372 square meters. mm.
It doesn’t make much sense to provide specific data on the transformer in this article, because first you need to at least have more or less suitable transformer hardware, and then, based on the actual dimensions, calculate the winding data specifically for it.
We have a separate article on the calculation of transformers on our website, where everything is described in detail and in an accessible manner. To go to this page you can click on this link:
The remaining elements of the scheme.
Thyristors: with a full-wave circuit - for a current of 80A and above. For example: TS80, T15-80, T151-80, T242-80, T15-100, TS125, T161-125, etc. When implementing the second option using a bridge rectifier (see diagram above), the thyristors must be 2 times more powerful. For example: T15-160, T161-160, TS161-160, T160, T123-200, T200, T15-250, T16-250 and the like.
Diodes:
for the bridge, choose ones that hold a current of about 100 amperes. For example: D141-100, 2D141-100, 2D151-125, V200 and the like. As a rule, the anode of such diodes is made in the form of a thick rope with a tip.
KD105 diodes can be replaced with KD209, D226, KD202, any with a current of at least 0.3 ampere will do.
The stabilization zener diode U should have about 8 volts, you can use 2S182, 2S482A, KS182, D808.
Transistors: KT3107 can be replaced with KT361 with a gain (h21e) greater than 100, KT816 can be replaced with KT814.
Resistors: In the circuit of the thyristor control electrode we place resistors with a power of 1 watt, the rest are not critical.
If you decide to make the power wires removable, ensure that the connection connector can withstand inrush currents. Alternatively, you can use connectors from a welding transformer or inverter.
The cross-section of the connecting wires coming from the transformer and thyristors to the terminals must be no less than the cross-section of the wire with which the secondary winding of the transformer is wound. It is advisable to install the wire connecting the starting device to a 220 volt network with a core cross-section of 2.5 square meters. mm.
In order for this starting device to work with cars whose on-board network has a voltage of 24 volts, the secondary winding of the step-down transformer must be designed for a voltage of 28...32 volts. The zener diode in the voltage control unit must also be replaced, i.e. D814A must be replaced with two D814V or D810 connected in series. Other zener diodes are also suitable, for example, KS510, 2S510A or 2S210A.
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.
Starter chargers come in several types, 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.
