Charger for car batteries.
It’s not new to anyone if I say that any motorist should have a battery charger in their garage. Of course, you can buy it in a store, but when faced with this question, I came to the conclusion that I don’t want to buy an obviously not very good device at an affordable price. There are those in which the charging current is regulated by a powerful switch, which adds or reduces the number of turns in the secondary winding of the transformer, thereby increasing or decreasing the charging current, while in principle there is no current control device. This is probably the cheapest option for a factory-made charger, but a smart device is not that cheap, the price is really steep, so I decided to find a circuit on the Internet and assemble it myself. The selection criteria were:
A simple scheme, without unnecessary bells and whistles;
- availability of radio components;
- smooth adjustment of charging current from 1 to 10 amperes;
- it is desirable that this is a diagram of a charging and training device;
- easy setup;
- stability of operation (according to reviews of those who have already done this scheme).
Searching the Internet, I came across an industrial diagram charger with regulating thyristors.
Everything is typical: a transformer, a bridge (VD8, VD9, VD13, VD14), a pulse generator with adjustable duty cycle (VT1, VT2), thyristors as switches (VD11, VD12), a charge control unit. Simplifying this construction somewhat, we get more simple diagram:
There is no charge control unit in this diagram, and the rest is almost the same: trans, bridge, generator, one thyristor, measuring heads and fuse. Please note that the circuit contains a KU202 thyristor; it is a little weak, so in order to prevent breakdown by high current pulses, it must be installed on a radiator. The transformer is 150 watt, or you can use a TS-180 from an old tube TV.
Adjustable charger with a charge current of 10A on the KU202 thyristor.
And one more device that does not contain scarce parts, with a charging current of up to 10 amperes. It represents a simple thyristor regulator power with phase-pulse control.
The thyristor control unit is assembled on two transistors. The time during which capacitor C1 will charge before switching the transistor is set by variable resistor R7, which, in fact, sets the value of the battery charging current. Diode VD1 serves to protect the thyristor control circuit from reverse voltage. The thyristor, as in the previous schemes, is placed on a good radiator, or on a small one with a cooling fan. The printed circuit board of the control unit looks like this:
The scheme is not bad, but it has some disadvantages:
- fluctuations in supply voltage lead to fluctuations in the charging current;
- no short circuit protection other than a fuse;
- the device interferes with the network (can be treated with an LC filter).
Charging and restoring device for rechargeable batteries.
This pulse device can charge and restore almost any type of battery. The charging time depends on the condition of the battery and ranges from 4 to 6 hours. Due to the pulsed charging current, the battery plates are desulfated. See the diagram below.
In this scheme, the generator is assembled on a microcircuit, which ensures more stable operation. Instead of NE555 you can use the Russian analogue - timer 1006VI1. If anyone doesn’t like the KREN142 for powering the timer, it can be replaced with a conventional parametric stabilizer, i.e. resistor and zener diode with the required voltage stabilization, and reduce resistor R5 to 200 Ohm. Transistor VT1- on the radiator without fail, it gets very hot. The circuit uses a transformer with a 24 volt secondary winding. A diode bridge can be assembled from diodes like D242. For better cooling of the transistor heatsink VT1 You can use a fan from a computer power supply or system unit cooling.
Restoring and charging the battery.
As a result of improper use of car batteries, their plates can become sulfated and the battery fails.
There is a known method for restoring such batteries when charging them with an “asymmetrical” current. In this case, the ratio of charging and discharging current is selected to be 10:1 (optimal mode). This mode allows you not only to restore sulfated batteries, but also to carry out preventive treatment of serviceable ones.
Rice. 1. Electrical diagram charger
In Fig. 1 shows a simple charger designed to use the method described above. The circuit provides a pulse charging current of up to 10 A (used for accelerated charging). To restore and train batteries, it is better to set the pulse charging current to 5 A. In this case, the discharge current will be 0.5 A. The discharge current is determined by the value of the resistor R4.
The circuit is designed in such a way that the battery is charged by current pulses during one half of the period of the mains voltage, when the voltage at the output of the circuit exceeds the voltage at the battery. During the second half-cycle, diodes VD1, VD2 are closed and the battery is discharged through load resistance R4.
The charging current value is set by regulator R2 using an ammeter. Considering that when charging the battery, part of the current also flows through resistor R4 (10%), the readings of ammeter PA1 should correspond to 1.8 A (for a pulse charging current of 5 A), since the ammeter shows the average value of the current over a period of time, and the charge produced during half the period.
The circuit provides protection for the battery from uncontrolled discharge in the event of an accidental loss of mains voltage. In this case, relay K1 with its contacts will open the battery connection circuit. Relay K1 is used of the RPU-0 type with an operating winding voltage of 24 V or a lower voltage, but in this case a limiting resistor is connected in series with the winding.
For the device, you can use a transformer with a power of at least 150 W with a voltage in the secondary winding of 22...25 V.
The PA1 measuring device is suitable with a scale of 0...5 A (0...3 A), for example M42100. Transistor VT1 is installed on a radiator with an area of at least 200 square meters. cm, for which it is convenient to use the metal case of the charger design.
The circuit uses a transistor with a high gain (1000...18000), which can be replaced with a KT825 when changing the polarity of the diodes and zener diode, since it has a different conductivity (see Fig. 2). The last letter in the transistor designation can be anything.
Rice. 2. Electrical circuit of the charger
To protect the circuit from accidental short circuit, fuse FU2 is installed at the output.
The resistors used are R1 type C2-23, R2 - PPBE-15, R3 - C5-16MB, R4 - PEV-15, the value of R2 can be from 3.3 to 15 kOhm. Any VD3 zener diode is suitable, with a stabilization voltage from 7.5 to 12 V.
reverse voltage.
Which wire is better to use from the charger to the battery.
Of course, it is better to take flexible copper stranded, but the cross-section needs to be selected based on the maximum current that will flow through these wires, for this we look at the plate:
If you are interested in the circuitry of pulsed charge-recovery devices using the 1006VI1 timer in the master oscillator, read this article:
Hello uv. reader of the blog “My Radio Amateur Laboratory”.
In today's article we will talk about a long-used, but very useful diagram thyristor phase-pulse power regulator, which we will use as a charger for lead-acid batteries.
Let's start with the fact that the charger on the KU202 has a number of advantages:
— Ability to withstand charging current up to 10 amperes
— The charge current is pulsed, which, according to many radio amateurs, helps extend the life of the battery
— The circuit is assembled from non-scarce, inexpensive parts, which makes it very affordable in the price range
- And the last plus is the ease of repetition, which will make it possible to repeat it, both for a beginner in radio engineering, and simply for a car owner who has no knowledge of radio engineering at all, who needs high-quality and simple charging.
Over time, I tried a modified scheme with automatic battery shutdown, I recommend reading it
At one time, I assembled this circuit on my knee in 40 minutes, along with wiring the board and preparing the circuit components. Well, enough stories, let's look at the diagram.
Scheme of a thyristor charger on KU202
List of components used in the circuit
C1 = 0.47-1 µF 63V
R1 = 6.8k - 0.25W
R2 = 300 - 0.25 W
R3 = 3.3k - 0.25W
R4 = 110 - 0.25 W
R5 = 15k - 0.25W
R6 = 50 - 0.25W
R7 = 150 - 2W
FU1 = 10A
VD1 = current 10A, it is advisable to take a bridge with a reserve. Well, at 15-25A and the reverse voltage is not lower than 50V
VD2 = any pulse diode, reverse voltage not lower than 50V
VS1 = KU202, T-160, T-250
VT1 = KT361A, KT3107, KT502
VT2 = KT315A, KT3102, KT503
As was said earlier, the circuit is a thyristor phase-pulse power regulator with electronic regulator charging current.
The thyristor electrode is controlled by a circuit using transistors VT1 and VT2. The control current passes through VD2, which is necessary to protect the circuit from reverse surges in the thyristor current.
Resistor R5 determines the battery charging current, which should be 1/10 of the battery capacity. For example, a battery with a capacity of 55A must be charged with a current of 5.5A. Therefore, it is advisable to place an ammeter at the output in front of the charger terminals to monitor the charging current.
Regarding the power supply, for this circuit we select a transformer with an alternating voltage of 18-22V, preferably in terms of power without reserve, because we use a thyristor in the control. If the voltage is higher, raise R7 to 200 Ohm.
We also do not forget that the diode bridge and the control thyristor must be installed on the radiators through heat-conducting paste. Also, if you use simple diodes such as D242-D245, KD203, remember that they must be isolated from the radiator body.
We put a fuse at the output for the currents you need; if you do not plan to charge the battery with a current higher than 6A, then a 6.3A fuse will be enough for you.
Also, to protect your battery and charger, I recommend installing mine or, which, in addition to protection against polarity reversal, will protect the charger from connecting dead batteries with a voltage of less than 10.5V.
Well, in principle, we looked at the charger circuit for the KU202.
Printed circuit board of the thyristor charger on KU202
Assembled from Sergei
Good luck with your repetition and I look forward to your questions in the comments.
For safe, high-quality and reliable charging of any types of batteries, I recommend
So as not to miss Latest updates in the workshop, subscribe to updates in In contact with or Odnoklassniki, you can also subscribe to updates by e-mail in the column on the right
Don’t want to delve into the routine of radio electronics? I recommend paying attention to the proposals of our Chinese friends. For a very reasonable price you can purchase quite high-quality chargers
A simple charger with LED indicator charging, green battery is charging, red battery is charged.
There is short circuit protection and reverse polarity protection. Perfect for charging Moto batteries with a capacity of up to 20A/h; a 9A/h battery will charge in 7 hours, 20A/h in 16 hours. The price for this charger is only 403 rubles, free delivery
This type of charger is capable of automatically charging almost any type of 12V car and motorcycle batteries up to 80A/H. It has a unique charging method in three stages: 1. Constant current charging, 2. Constant voltage charging, 3. Drop charging up to 100%.
There are two indicators on the front panel, the first indicates the voltage and charging percentage, the second indicates the charging current.
Quite a high-quality device for home needs, the price is just RUR 781.96, free delivery. At the time of writing these lines number of orders 1392, grade 4.8 out of 5. Eurofork
Charger for a wide variety of 12-24V battery types with current up to 10A and peak current 12A. Able to charge Helium batteries and SA\SA. The charging technology is the same as the previous one in three stages. The charger is capable of charging both automatically and manually. The panel has an LCD indicator indicating voltage, charging current and charging percentage.
A good device if you need to charge all possible types of batteries of any capacity, up to 150Ah
The price for this miracle 1,625 rubles, delivery is free. At the time of writing these lines, the number 23 orders, grade 4.7 out of 5. When ordering, do not forget to indicate Eurofork
In order for a car to start, it needs energy. This energy is taken from the battery. As a rule, it is recharged from the generator while the engine is running. When the car is not used for a long time or the battery is faulty, it discharges to such a state that that the car can no longer start. In this case, external charging is required. You can buy such a device or assemble it yourself, but for this you will need a charger circuit.
How a car battery works
A car battery supplies power to various devices in the car when the engine is turned off and is designed to start it. By type of execution, a lead-acid battery is used. Structurally, it is assembled from six batteries with a nominal voltage of 2.2 volts, connected in series. Each element is a set of lattice plates made of lead. The plates are coated with active material and immersed in an electrolyte.
The electrolyte solution contains distilled water and sulfuric acid. The frost resistance of the battery depends on the density of the electrolyte. IN Lately Technologies have emerged that make it possible to adsorb the electrolyte in glass fiber or thicken it using silica gel to a gel-like state.
Each plate has a negative and positive pole, and they are isolated from each other using a plastic separator. The body of the product is made of propylene, which is not destroyed by acid and serves as a dielectric. The positive pole of the electrode is coated with lead dioxide, and the negative with sponge lead. Recently, rechargeable batteries with electrodes made of lead-calcium alloy have begun to be produced. These batteries are completely sealed and require no maintenance.
When a load is connected to the battery, the active material on the plates enters into a chemical reaction with the electrolyte solution, and electricity. The electrolyte depletes over time due to the deposition of lead sulfate on the plates. The battery begins to lose charge. While charging chemical reaction occurs in the reverse order, lead sulfate and water are converted, the density of the electrolyte increases and the charge is restored.
Batteries are characterized by their self-discharge value. It occurs in the battery when it is inactive. The main reason is contamination of the battery surface and poor quality of the distiller. The rate of self-discharge accelerates when the lead plates are destroyed.
Types of chargers
A large number of car charger circuits have been developed using different element bases and fundamental approaches. According to the principle of operation, charging devices are divided into two groups:
- Starting chargers, designed to start the engine when the battery is not working. By briefly supplying a large current to the battery terminals, the starter is turned on and the engine starts, and then the battery is charged from the car's generator. They are produced only for a certain current value or with the ability to set its value.
- Pre-start chargers, leads from the device are connected to the battery terminals and current is supplied for a long time. Its value does not exceed ten amperes, during which time the battery energy is restored. In turn, they are divided into: gradual (charging time from 14 to 24 hours), accelerated (up to three hours) and conditioning (about an hour).
Based on their circuit design, pulse and transformer devices are distinguished. The first type uses a high-frequency signal converter and is characterized by small size and weight. The second type uses a transformer with a rectifier unit as a basis; it is easy to manufacture, but have a lot of weight and low efficiency (efficiency).
Whether you made a charger for car batteries yourself or purchased it at a retail outlet, the requirements for it are the same, namely:
- output voltage stability;
- high efficiency value;
- short circuit protection;
- charge control indicator.
One of the main characteristics of the charger is the amount of current that charges the battery. Correctly charging the battery and extending its performance characteristics can only be achieved by selecting the desired value. The charging speed is also important. The higher the current, the higher the speed, but a high speed value leads to rapid degradation of the battery. It is believed that the correct current value will be a value equal to ten percent of the battery capacity. Capacity is defined as the amount of current supplied by the battery per unit of time; it is measured in ampere-hours.
Homemade charger
Every car enthusiast should have a charging device, so if there is no opportunity or desire to purchase a ready-made device, there is nothing left to do but charge the battery yourself. It is easy to make with your own hands both the simplest and multifunctional devices. For this you will need a diagram and a set of radioelements. It is also possible to remake the uninterruptible power supply (UPS) or computer unit(AT) into the device for recharging the battery.
Transformer charger
This device is the easiest to assemble and does not contain scarce parts. The circuit consists of three nodes:
- transformer;
- rectifier block;
- regulator
Voltage from industrial network enters the primary winding of the transformer. The transformer itself can be used of any type. It consists of two parts: the core and the windings. The core is assembled from steel or ferrite, the windings are made from conductor material.
The operating principle of the transformer is based on the appearance of an alternating magnetic field when current passes through the primary winding and transfers it to the secondary. To obtain the required voltage level at the output, the number of turns in the secondary winding is made smaller compared to the primary. The voltage level on the secondary winding of the transformer is selected to be 19 volts, and its power should provide a threefold reserve of charging current.
From the transformer, the reduced voltage passes through the rectifier bridge and goes to a rheostat connected in series to the battery. The rheostat is designed to regulate the voltage and current by changing the resistance. The rheostat resistance does not exceed 10 Ohms. The amount of current is controlled by an ammeter connected in series in front of the battery. With this circuit it will not be possible to charge a battery with a capacity of more than 50 Ah, since the rheostat begins to overheat.
You can simplify the circuit by removing the rheostat, and install a set of capacitors at the input in front of the transformer, which are used as reactance to reduce the network voltage. The lower the nominal value of the capacitance, the less voltage is supplied to the primary winding in the network.
The peculiarity of such a circuit is that it is necessary to ensure a signal level on the secondary winding of the transformer that is one and a half times greater than the operating voltage of the load. This circuit can be used without a transformer, but it is very dangerous. Without galvanic isolation, you can get an electric shock.
Pulse charger
The advantage of pulsed devices is their high efficiency and compact size. The device is based on a pulse-width modulation (PWM) chip. You can assemble a powerful pulse charger with your own hands according to the following scheme.
The IR2153 driver is used as a PWM controller. After the rectifier diodes, a polar capacitor C1 with a capacity in the range of 47–470 μF and a voltage of at least 350 volts is placed in parallel with the battery. The capacitor removes mains voltage surges and line noise. The diode bridge is used with a rated current of more than four amperes and with a reverse voltage of at least 400 volts. The driver controls powerful N-channel field-effect transistors IRFI840GLC installed on radiators. The current of such charging will be up to 50 amperes, and the output power will be up to 600 watts.
You can make a pulse charger for a car with your own hands using a converted AT format computer power supply. They use the common TL494 microcircuit as a PWM controller. The modification itself consists of increasing the output signal to 14 volts. To do this, you will need to correctly install the trimmer resistor.
The resistor that connects the first leg of the TL494 to the stabilized + 5 V bus is removed, and instead of the second one, connected to the 12 volt bus, a variable resistor with a nominal value of 68 kOhm is soldered in. This resistor sets the required output voltage level. The power supply is turned on via a mechanical switch, according to the diagram indicated on the power supply housing.
Device on LM317 chip
A fairly simple but stable charging circuit is easily implemented on the LM317 integrated circuit. The microcircuit provides a signal level of 13.6 volts with a maximum current of 3 amperes. The LM317 stabilizer is equipped with built-in short circuit protection.
Voltage is supplied to the device circuit through the terminals from an independent DC power supply of 13-20 volts. The current, passing through the indicator LED HL1 and transistor VT1, is supplied to the stabilizer LM317. From its output directly to the battery via X3, X4. The divider assembled on R3 and R4 sets the required voltage value for opening VT1. Variable resistor R4 sets the charging current limit, and R5 sets the output signal level. The output voltage is adjustable from 13.6 to 14 volts.
The circuit can be simplified as much as possible, but its reliability will decrease.
In it, resistor R2 selects the current. A powerful nichrome wire element is used as a resistor. When the battery is discharged, the charging current is maximum, the VD2 LED lights up brightly; as the battery charges, the current begins to decrease and the LED dims.
Charger from an uninterruptible power supply
The rectifier is assembled using any powerful diodes, for example, domestic D-242 and a network capacitor of 2200 uF for 35-50 volts. The output will be a signal with a voltage of 18-19 volts. An LT1083 or LM317 microcircuit is used as a voltage stabilizer and must be installed on a radiator.
By connecting battery, the voltage is set to 14.2 volts. It is convenient to control the signal level using a voltmeter and ammeter. The voltmeter is connected in parallel to the battery terminals, and the ammeter in series. As the battery charges, its resistance will increase and the current will decrease. It’s even easier to make the regulator using a triac connected to the primary winding of the transformer like a dimmer.
When making a device yourself, you should remember about electrical safety when working with the network. alternating current 220 V. As a rule, a correctly made charging device made from serviceable parts starts working immediately, you just need to set the charging current.
