A charger (charger) for a battery is necessary for every car enthusiast, but it costs a lot, and regular preventive trips to a car service are not an option. Servicing a battery in a workshop takes time and money. In addition, on a discharged battery, you still need to get to the service. Anyone who knows how to use a soldering iron can assemble a workable charger for a car battery with their own hands.
Some battery theory
Any accumulator (battery) is a store of electrical energy. When voltage is applied to it, energy accumulates due to chemical changes inside the battery. When a consumer is connected, the opposite process occurs: the reverse chemical change creates voltage at the terminals of the device, current flows through the load. Thus, in order to receive voltage from the battery, it must first be “put”, that is, the battery must be charged.
Almost any car has its own generator, which, when the engine is running, provides power to on-board equipment and charges the battery, replenishing the energy spent on starting the engine. But in some cases (frequent or heavy starting of the engine, short trips, etc.), the battery energy does not have time to recover, the battery gradually discharges. There is only one way out of this situation - charging with an external charger.
How to check battery status
To decide on the need for charging, you need to determine the state of the battery. The simplest option - "twists / does not twist" - at the same time is unsuccessful. If the battery "does not turn", for example, in the morning in the garage, then you will not go anywhere at all. The “not spinning” condition is critical, and the consequences for the battery can be sad.
The best and most 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 the voltage on the terminals of a disconnected from the load (!) battery 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, then the "car battery" (especially maintenance-free) will fail.
Proper 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 real and not very difficult. To do this, you need to have basic knowledge of electrical engineering and be able to hold a soldering iron in your hands.
A simple device for 6 and 12 V
Such a scheme is the most elementary and budgetary. With this charger, you can charge any lead-acid battery with an operating voltage of 12 or 6 V and an electric capacity of 10 to 120 A/h.
The device consists of a step-down transformer T1 and a powerful rectifier assembled on 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 supply circuit of the primary winding of the transformer. Due to the multiple "weight" of each switch, various combinations allow you to stepwise adjust the charging current within 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 needed, 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. A voltmeter PU1 is used to control the voltage on the battery, the charging current is monitored using an ammeter PA1.
In the design, you can use any power transformer with a power of about 300 W, including a home-made one. It should produce a voltage of 22–24 V at a current of up to 10–15 A on the secondary winding. 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 will do. D214 or D242 will do. They should be installed through insulating gaskets on a radiator with a scattering area of at least 300 cm2.
Capacitors C2-C5 must be non-polar paper with an operating voltage of at least 300 V. For example, MBCHG, KBG-MN, MBGO, MBGP, MBM, MBGCH are suitable. Similar cube-shaped capacitors were widely used as phase-shifters for electric motors in household appliances. As PU1, a DC voltmeter of the M5-2 type with a measurement limit of 30 V was used. 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 to be adjusted. 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 in the charging currents by the ammeter.
Continuously adjustable current
According to this scheme, it is more difficult to assemble a car battery charger with your own hands, but it can be repeated and also does not contain scarce parts. With its help, it is permissible to charge 12-volt batteries with a capacity of up to 120 A / h, the charge current is smoothly adjustable.
The battery is charged by a pulsed current, a thyristor is used as a regulating element. In addition to the smooth current adjustment knob, this design also has a mode switch, when turned on, the charging current is doubled.
The charging mode is controlled visually by the pointer device RA1. 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 - indicator. 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 through the secondary winding of 18–24 V at a current of up to 15 A. If there was no suitable device at hand, then you can make it yourself from any network transformer with a power of 250–300 W. To do this, all windings are wound from the transformer, except for the mains winding, and one secondary winding is wound 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 dissipation area of at least 200 cm2. The power installation of the device is made with wires of minimum 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 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, controlling 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 on the other hand, the characteristics of the device will turn out to be decent. With its help, batteries are charged with a current of up to 10 A, adjusting the current and voltage of the charge. The only condition is that the PSU is desirable on the TL494 controller.
For creating do-it-yourself car charging from a computer power supply you will have to assemble the circuit shown in the figure.
Step-by-step operations necessary for finalization will look like this:
- Bite off all the wires of the power buses, except for the yellow and black ones.
- Connect the yellow and black wires separately - these will be the “+” and “-” memory, 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 casing of the power supply unit - these are the voltage and current adjustment bodies, respectively.
- Hinged mounting to assemble the circuit shown in the figure above.
If the installation is done correctly, then the revision is completed. It remains to equip the new charger with a voltmeter, ammeter and wires with "crocodiles" for connecting to the battery.
It is possible to use any variable and fixed resistors in the design, except for the current one (the lower one according to the circuit with a nominal value of 0.1 Ohm). Its power dissipation is at least 10 watts. 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 shunt from a Chinese digital tester for 10 A or a C5-16MV resistor. Another option is two 5WR2J resistors connected in parallel. Such resistors are 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 prolong battery life and keep your health:
The question of creating a simple do-it-yourself battery charger has been clarified. Everything is quite simple, it remains to stock up on the necessary tools and you can safely get to work.
V. VOEVODA, p. Konstantinovka, Amur Region
Currently, the market offers the motorist a wide variety of chargers ~ automatic and semi-automatic, including simple ones, but their cost is very high. However, if the owner of the car is familiar with the basics of electronics, it is quite possible for him to undertake the independent manufacture of a simple charger.
I bring to the attention of readers a simple device with electronic control of the charging current, made on the basis of a trinistor phase-pulse power controller. It allows you to charge car batteries with a current of 0 to 10 A, and can also serve as a regulated power source for a powerful low-voltage soldering iron, vulcanizer, and portable lamp.
The device is operable at ambient temperature from -35 to +35 °C. It does not contain scarce parts; with obviously good elements, it does not require adjustment. For it, a ready-made network step-down transformer of the required power with a secondary winding voltage of 18 to 22 V can be used. A transformer with windings without leads is also suitable. Charging current is close to pulsed in shape, which some radio amateurs believe helps prolong battery life.
In the future, the charger can be supplemented with various automatic units (shutdown at the end of charging, maintaining normal battery voltage during long-term storage, signaling the correct polarity of the battery connection, protection against output short circuits, etc.).
The disadvantage of the device is the fluctuations in the charging current with an unstable voltage of the electric lighting network. Like all similar trinistor pulse-phase regulators, the device interferes with radio reception. To combat them, you should provide a network LC filter, similar to that used in switching network power supplies.
The scheme of the device is shown in fig. 1. It is a traditional trinistor power regulator with pulse-phase control, powered from the winding II of the step-down transformer T1 through the diode bridge VD1-VD4. The trinistor control unit is made on the analogue of the unijunction transistor VT1VT2. The time during which the capacitor C2 is charged before switching the unijunction transistor can be adjusted by the variable resistor R1. With the extreme right position of its engine according to the diagram, the charging current will be maximum, and vice versa.
Diode VD5 protects the control circuit of the trinistor from reverse voltage that occurs when the trinistor VS1 is turned on.
All parts of the device, except for the transformer T1, rectifier diodes VD1 -VD4, variable resistor R1, fuse FU1 and trinistor VS1, are mounted on a printed circuit board made of foil fiberglass 1.5 mm thick. The drawing of the board is shown in fig. 2.
Capacitor C2-K73-11, with a capacity of 0.47 to 1 μF, or K73-16, K73-17, K42U-2, MBGP. Diodes VD1-VD4 can be any for a forward current of 10 A and a reverse voltage of at least 50 V (series D242, D243, D245, KD203, KD210, KD213). Instead of the trinistor KU202V, KU202G-KU202E will do; It has been verified in practice that the device works normally with more powerful trinistors T-160, T-250.
We will replace the KT361A transistor with KT361B-KT361E, KT3107A, KT502V, KT502G, KT501Zh-KT501K, and KT315A - with KT315B-KT315D, KT312B, KT3102A, KT503V-KT503G, P307. Instead of KD105B, diodes KD105V, KD105G or D226 with any letter index are suitable.
Variable resistor R1 - SP-1, SPZ-Z0a or SPO-1. Ammeter RA1 - any direct current with a scale of 10A. It can be made independently from any milliammeter by selecting a shunt according to a standard ammeter.
The FU1 fuse is a fusible one, but it is also convenient to use a 10A network automat or a bimetallic car fuse for the same current.
The charger is mounted in a durable metal or plastic casing of suitable dimensions. The rectifier diodes and the trinistor are mounted on heat sinks, each with a usable area of about 100 cm2. To improve the thermal contact of devices with heat sinks, it is desirable to use heat-conducting pastes.
It should be noted that it is permissible to use the metal wall of the casing directly as a heat sink for the trinistor. Then, however, there will be a negative output of the device on the case, which is generally undesirable because of the danger of accidental short circuits of the output positive wire to the case. If you mount the trinistor through a mica gasket, there will be no danger of a short circuit, but the heat transfer from it will worsen.
If the transformer has a voltage on the secondary winding of more than 18 V, the resistor R5 should be replaced with another one with a higher resistance (at 24 ... 26 V up to 200 Ohms). In the case when the secondary winding of the transformer has a tap from the middle, or there are two identical windings and the voltage of each is within the specified limits, then it is better to make the rectifier according to the standard two-half-wave circuit on two diodes.
With a secondary winding voltage of 28 ... 36 V, you can completely abandon the rectifier - its role will be simultaneously played by the trinistor VS1 (rectification is half-wave). For such a variant of the power supply, it is necessary to turn on the separating diode KD105B or D226 with any letter index (cathode to the board) between output 2 of the board and the positive wire. In addition, the choice of a trinistor is limited here - only those that allow operation under reverse voltage (for example, KU202E) are suitable.
From the editor. For the described device, a unified transformer TN-61 is suitable. Its three secondary windings must be connected in series according to; they are capable of delivering current up to 8 A.
Radio 2001 No. 11
A little bit of gag:
1. Transformer TS-250-2P from a tube TV, remove all secondary windings. Wind 40 turns in two PEV-1.2mm wires (approximately 25-27V).
2. Diode bridge from KD213. Transistors can be used KT814 and KT815. Thyristor KU202N. R5-180 ohm. Instead of C1, use a surge protector from a computer power supply or UPS-a, C2 - 0.5 uFx250V
3. Can be supplemented with short circuit protection. R1 must be removed. You can hang an LED on the disconnect contacts, it will light up in case of a short circuit. If you use this scheme, then the battery must be charged, at least 70%, otherwise the relay will not work and charging will not start. For discharged batteries, this protection will not work, or it is necessary to short-circuit the contacts K1.1.
4. ...and reverse polarity protection
For car battery chargers, it is necessary to select a relay for a rated voltage of 12 B with a permissible current through the contacts of at least 20 A. These conditions are met by the REN-34 HP4.500.030-01 relay, the contacts of which should be connected in parallel.
6. The fuse can be made based on:
7. Indicator - voltmeter is the simplest
Z.Y. The memory is simple, it is done in 3-4 days slowly after work, the parts used are not in short supply, in general, I am satisfied. Written.
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The device with electronic control of the charging current is made on the basis of a thyristor phase-pulse power controller. It does not contain scarce parts; with obviously good elements, it does not require adjustment.
This thyristor-based charger allows you to charge car batteries with a current of 0 to 10 A, and can also serve as an adjustable power source for a powerful low-voltage soldering iron, vulcanizer, and portable lamp.
Charging current is close to pulsed in shape, which is believed to prolong battery life. The device is operable at ambient temperature from - 35 °С to + 35 °С. The scheme of the device is shown in fig. one.
Click on the picture to view.
The charger is a thyristor power regulator with phase-pulse control, fed from the winding II of the step-down transformer T1 through the diode bridge VD1 + VD4.
The thyristor control unit is made on the analog of the unijunction transistor VT1, VT2 The time during which the capacitor C2 is charged before switching the unijunction transistor can be adjusted by the variable resistor R1. With the extreme right position of its engine according to the diagram, the charging current will be maximum, and vice versa.
Diode VD5 protects the control circuit of the thyristor VS1 from the reverse voltage that occurs when the thyristor is turned on.
In the future, the thyristor charger can be supplemented with various automatic units (shutdown at the end of charging, maintaining normal battery voltage during long-term storage, signaling the correct polarity of the battery connection, protection against output short circuits, etc.).
The disadvantages of the device include fluctuations in the charging current with an unstable voltage of the electric lighting network.
Like all similar thyristor phase-pulse controllers, the device interferes with radio reception. To combat them, you should provide a network LC filter, similar to that used in switching network power supplies.
Capacitor C2 - K73-11, with a capacity of 0.47 to 1 uF, or. K73-16, K73-17, K42U-2, MBGP.
We will replace the KT361A transistor with KT361B - KT361Yo, KT3107L, KT502V, KT502G, KT501Zh - KT50IK, and KT315L - with KT315B + KT315D KT312B, KT3102L, KT503V + KT503G, P307 Diode or KD105B instead of KD105B D226 with any letter index.
Variable resistor R1 - SP-1, SPZ-30a or SPO-1.
Ammeter RA1 - any direct current with a scale of 10 A. It can be made independently from any milliammeter by selecting a shunt according to a standard ammeter.
The F1 fuse is fusible, but it is also convenient to use a 10 A circuit breaker or a car bimetallic one for the same current.
Diodes VD1 + VP4 can be any for a forward current of 10 A and a reverse voltage of at least 50 V (series D242, D243, D245, KD203, KD210, KD213).
The rectifier diodes and the thyristor are mounted on heat sinks, each with a usable area of about 100 cm 2. To improve the thermal contact of devices with heat sinks, it is desirable to use heat-conducting pastes.
instead of a thyristor. KU202V fit KU202G - KU202E; It has been verified in practice that the device works normally with more powerful thyristors T-160, T-250.
It should be noted that it is permissible to use the metal wall of the casing directly as a thyristor heat sink. Then, however, there will be a negative output of the device on the case, which is generally undesirable because of the danger of accidental short circuits of the output positive wire to the case. If you mount the thyristor through a mica gasket, there will be no danger of a short circuit, but the heat transfer from it will worsen.
A ready-made network step-down transformer of the required power with a secondary winding voltage of 18 to 22 V can be used in the device.
If the transformer has a voltage on the secondary winding of more than 18 V, the resistor R5 should be replaced with another one with a higher resistance (for example, at 24 ... 26 V, the resistance of the resistor should be increased to 200 Ohms).
In the case when the secondary winding of the transformer has a tap from the middle, or there are two identical windings and the voltage of each is within the specified limits, then it is better to make the rectifier according to the standard two-diode full-wave circuit.
With a secondary winding voltage of 28 ... 36 V, you can completely abandon the rectifier - its role will be simultaneously played by the thyristor VS1 (rectification is half-wave). For this version of the power supply, it is necessary to connect a separating diode KD105B or D226 with any letter index (cathode to resistor R5) between the resistor R5 and the positive wire. The choice of thyristor in such a circuit will be limited - only those that allow operation under reverse voltage (for example, KU202E) will do.
For the described device, a unified transformer TN-61 is suitable. Its three secondary windings must be connected in series in accordance, while they are capable of delivering current up to 8 A.
All parts of the device, except for the transformer T1, rectifier diodes VD1 - VD4, variable resistor R1, fuse FU1 and thyristor VS1, are mounted on a printed circuit board made of foil fiberglass 1.5 mm thick.
Now the presence of a battery charger is an integral part for any motorist.
Of course, you can buy yourself a good charger, but I did not look for easy ways for myself, and decided to assemble something of my own. Remember the article. This is a continuation of work on
charger
This part of the charger is the main control of the entire charging, since it is she who is responsible for supplying the charging current, which can be set from 1 to 10A. Which is enough for home use.
Elements:
C1 = 1mF (160V)
F1 = 10A
R1 = 300
R2 = 6.8k
R3 = 3k
R4 = 110
R5=51
R6 = 150
R7 = 15k
T1 \u003d KU202V (G, D and so on. Lizh would be suitable for voltage. I set it in general And)
VD1 = KD105B
VT1 = KT361A
VT2 = KT315A
As you can see, the device is not complicated, and does not contain scarce parts. Everything I needed I found in my workshop.
The charging process is similar to pulsed, which has a positive effect on battery performance, according to many radio amateurs.
The device is a simple trinistor power regulator with pulse-phase control. The trinistor is controlled by a node assembled on two transistors. The time for which the capacitor will be charged before switching the transistor is set through a variable resistor, which, in fact, sets the charge current
The diode serves to protect the control circuit of the trinistor from reverse voltage
A trinistor needs a nice heatsink. I put a radiator not bigger, but I will put a fan for cooling
Don't forget to use wires of the correct diameter.
The scheme is just great, but there are drawbacks:
1. Voltage fluctuations on the supply lead to fluctuations in the charging current, which is bad for the charger. But this is Reshimo, you just need to assemble a 10A stabilizer. What will I do
2. No short circuit protection except fuse
3. The device gives interference to the network, which can also be solved using an LC filter
Here is my assembled device
Signet for an adjustable charger on a trinistor KU202
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CAR CHARGER
The topic of car battery chargers is very popular, so we bring to your attention another proven and well-proven charging scheme. The transformer in this device was used factory-made, 36 volts, in control circuits. On its secondary there are two windings of 18 volts connected to the midpoint. Diodes for a current of 30 A, obtained from the car's generator (those that were at hand), are installed on a common radiator with a thyristor.
The thyristor itself is insulated from the radiator housing with a mica gasket, and the radiator, in turn, is isolated from the housing. It turned out to be simple and compact, and even at maximum load, the temperature of the radiator did not rise above 40-45 degrees.
Different thyristors were tried, the entire KU202 series, but in the end T25-xxx was installed, the inscription is poorly visible, but I know for sure that this is a thyristor for a current of 25 A.
Management is assembled on a separate board,The ammeter was used for alternating current, with a total deviation of 5 A, therefore it is included before the diodes.
Naturally, you can put a pointer indicator in this car charger for direct current, and not necessarily an ammeter, but even a voltmeter - with a shunt from a low-resistance resistor.
The limits for adjusting the charging current are 0.7-5 A, if the current is too low, generation can be disrupted (all the subtleties of setting up the generator circuits and selecting a thyristor) - this is who wants to have a charging current from scratch.
On the front panel of the case there is a power switch, a charging current regulator and an ammeter to control the battery charging process.At the back, wire terminals for connecting the battery are installed on a textolite strip. The whole box is painted black.
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