Let's consider the operation of the circuit (Fig. 1) in the first mode. An alternating voltage of 220 V is supplied to the step-down transformer Tr1. In the secondary winding, two voltages of 24 V are generated relative to the midpoint. We managed to find a transformer with a midpoint in the secondary winding, which makes it possible to reduce the number of diodes in the rectifiers, create a power reserve and ease the thermal regime. The alternating voltage from the secondary winding of the transformer is supplied to a rectifier using diodes D6, D7. The plus from the middle point of the transformer goes to resistor R8, which limits the current of the zener diode D1. Zener diode D1 determines the operating voltage of the circuit. A thyristor control generator is assembled on transistors T1 and T2. Capacitor C1 is infected through the circuit: power supply plus, variable resistor R3, R1, C1, minus. The charging rate of capacitor C1 is controlled by variable resistor R3. Capacitor C1 is discharged along the circuit: emitter - collector T1, base - emitter T2, R4 capacitor mine. Transistors T1 and T2 open and a positive pulse from the emitter T2 through the limiting resistor R7 and decoupling diodes D4 - D5 arrives at the control electrodes of the thyristors. In this case, switch Vk 1 is turned on, Vk 2 is turned off. The thyristors, depending on the minus phase of the alternating voltage, open one by one, and the minus of each half-cycle goes to the minus of the battery. Plus from the midpoint of the transformer through the ammeter to the plus of the battery. Resistors R5 and R6 determine the operating mode of transistors T1-2. R4 is the load of the T2 emitter on which a positive control pulse is released. R2 - for more stable operation of the circuit (in some cases it can be neglected).
Operation of the memory circuit in the second mode (Vk1 – off; Vk2 – on). When Vk1 is turned off, the control circuit of thyristor D3 is interrupted, while it remains permanently closed. One thyristor D2 remains in operation, which rectifies only one half-cycle and produces a charge pulse during one half-cycle. During the idle second half-cycle, the battery is discharged through the switched on Vk2. The load is an incandescent light bulb 24V x 24 W or 26V x 24 W (when the voltage on it is 12V, it consumes a current of 0.5 A). The light bulb is placed outside the housing so as not to heat the structure. The charging current value is set by regulator R3 using an ammeter. Considering that when charging the battery, part of the current flows through load L1 (10%). Then the ammeter reading should correspond to 1.8A (for a pulse charging current of 5A). since the ammeter has an inertia and shows the average value of the current over a period of time, and the charge is made during half the period.
Details and design of the charger. Any transformer with a power of at least 150 W and a voltage in the secondary winding of 22 - 25 V is suitable. If you use a transformer without a midpoint in the secondary winding, then all elements of the second half-cycle must be excluded from the circuit. (Bk1, D5, D3). The circuit will be fully operational in both modes, only in the first it will work on one half-cycle. Thyristors can be used KU202 for a voltage of at least 60V. They can be installed on a radiator without isolation from each other. Any D4-7 diodes for an operating voltage of at least 60V. Transistors can be replaced with germanium low-frequency transistors with appropriate conductivity. works on any pairs of transistors: P40 – P9; MP39 – MP38; KT814 – KT815, etc. Zener diode D1 is any 12–14V. You can connect two in series to set the desired voltage. As an ammeter, I used the head of a 10 mA, 10 division miliammeter. The shunt was selected experimentally, wound with 1.2 mm wire without a frame to a diameter of 8 mm, 36 turns.
Setting up the charger. If assembled correctly, it works immediately. Sometimes it is necessary to set the Min - Max regulation limits. selection of C1, usually in the direction of increase. If there are regulation failures, select R3. Usually I connected a powerful light bulb from an overhead projector 24V x 300W as a load for adjustment. It is advisable to install a 10A fuse in the open circuit of the battery charge.
Discuss the article BATTERY CHARGER
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 as follows:
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).
After searching on the Internet, I came across an industrial circuit for a 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 design somewhat, we get a simpler 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 is a simple thyristor power regulator 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 stabilization voltage, 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 circuit of the 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:
Under normal operating conditions, the vehicle's electrical system is self-sufficient. We are talking about energy supply - a combination of a generator, a voltage regulator, and a battery works synchronously and ensures uninterrupted power supply to all systems.
This is in theory. In practice, car owners make amendments to this harmonious system. Or the equipment refuses to work in accordance with the established parameters.
For example:
- Operating a battery that has exhausted its service life. The battery does not hold a charge
- Irregular trips. Prolonged downtime of the car (especially during hibernation) leads to self-discharge of the battery
- The car is used for short trips, with frequent stopping and starting of the engine. The battery simply does not have time to recharge
- Connecting additional equipment increases the load on the battery. Often leads to increased self-discharge current when the engine is turned off
- Extremely low temperature accelerates self-discharge
- A faulty fuel system leads to increased load: the car does not start immediately, you have to turn the starter for a long time
- A faulty generator or voltage regulator prevents the battery from charging properly. This problem includes worn power wires and poor contact in the charging circuit.
- And finally, you forgot to turn off the headlights, lights or music in the car. To completely discharge the battery overnight in the garage, sometimes it is enough to close the door loosely. Interior lighting consumes quite a lot of energy.
Any of the following reasons leads to an unpleasant situation: you need to drive, but the battery is unable to crank the starter. The problem is solved by external recharge: that is, a charger.
The tab contains four proven and reliable car charger circuits from simple to the most complex. Choose any one and it will work.
A simple 12V charger circuit.
Charger with adjustable charging current.
Adjustment from 0 to 10A is carried out by changing the opening delay of the SCR. 
Circuit diagram of a battery charger with self-shutdown after charging.
For charging batteries with a capacity of 45 amps.
Scheme of a smart charger that will warn about incorrect connection. 
It is absolutely easy to assemble it with your own hands. An example of a charger made from an uninterruptible power supply.
Any car charger circuit consists of the following components:
- Power unit.
- Current stabilizer.
- Charge current regulator. Can be manual or automatic.
- Indicator of current level and (or) charge voltage.
- Optional - charge control with automatic shutdown.
Any charger, from the simplest to an intelligent machine, consists of the listed elements or a combination thereof.
Simple diagram for a car battery
Normal charge formula as simple as 5 kopecks - the basic battery capacity divided by 10. The charging voltage should be a little more than 14 volts (we are talking about a standard 12 volt starter battery).
Compact thyristor charger
Figure 1 shows a diagram of a simple charger for a car battery.
Fig.1
When a certain voltage value is reached (set by the circuit R2, V1, V2), the charger on the SCR disconnects it from the battery. The reference voltage on the battery is compared at each positive half-cycle while the thyristor is closed. When the battery is discharged, the thyristor opens at the moments of each positive half-cycle with some delay, but only as the battery is close to being fully charged, the thyristor will open with a greater delay and when a certain value is reached, when the battery is fully charged, the thyristor will stop opening. The voltage comparison takes place in the thyristor control electrode circuit.
The voltage at the thyristor output depends on its parameters, so it is possible to select a thyristor if the voltage of 13.5V turns out to be slightly underestimated.
Any transformer for a voltage in the secondary winding of 20V based on the value of the charging current.
Bornovolokov E.P., Florov V.V. Amateur radio circuits - 3rd edition, revised. and additional - K.: Technology, 1985
Automatic charger
Figure 2 shows a diagram of an automatic charger that allows you to charge a car battery when discharged and stop charging when the battery is fully charged. It is advisable to use such a device for batteries that are stored for a long time.
Fig.2
Switching to charging mode is done by measuring the voltage at the battery terminals. Charging begins when the voltage at the battery terminals drops below 11.5 V and stops when it reaches 14 V.
The op amp in the circuit serves as a precision voltage comparator that monitors the battery voltage level. Its inverting input receives a reference voltage of 1.8 V, and a battery voltage of about 2 V is supplied to the non-inverting input through a divider (when the battery is fully charged). In this case, the relay is disabled because the op-amp output is at a high voltage level. When the voltage drops at the battery terminals, the voltage at the non-inverting input of the op-amp becomes 1.8 V, the comparator switches, this causes the relay to turn on, and the battery begins to charge.
After assembling the charger, it must be adjusted:
1. Discharge the battery to 11.5 V
2. Connect the charger to the battery
3. Adjust R6 until the relay operates
4. When charging the battery, measure the voltage at its terminals; when it reaches 14 V, adjust potentiometer R5 until the relay turns off
Repeat the setup process if necessary
Charger for LM317
Fig.3
Based on the LM317 stabilizer, you can make a simple and effective charger. The proposed device is designed for charging 12 V batteries. The maximum charging current is 1.5A. The charging current can be adjusted using potentiometer R5. As the battery charges, the charger reduces the charging current. The LM317 stabilizer must be installed on the radiator.
Charge current indication unit
If your car battery charger does not have an ammeter, it is difficult to ensure reliable charging. There may be deterioration (loss) of the contact on the batteries, which is quite difficult to detect. Instead of an ammeter, a simple indicator is proposed in Fig. 4. It is connected to the gap in the “positive” wire from the charger to the battery.
Fig.4
The circuit is a transistor switch VT1, which turns on the LED HL1 when charging current flows through R1. In this case, the voltage drop across resistor R1 (more than 0.6V) is sufficient to open transistor VT1 to ignite HL1. For a specific battery, the R1 rating is selected so that the LED lights up at the required charging current. By the brightness of its glow, you can approximately estimate the charging current. Resistor R1 is a wire-wound resistor, made of 6…12 turns of winding wire with a diameter of 1 mm. You can use wire with high resistivity (nichrome) or an industrial resistor, for example, PEVR-10.
Charger with car voltage regulator
A simple charger, shown in Fig. 5, will serve to charge the battery and keep it in working condition for a long time.
Fig.5
From the secondary winding of transformer T1, the current in which is limited by connection in series with the primary winding of the ballast capacitor (C1 or C1+C2), the current is supplied to the diode-thyristor bridge, the load of which is the battery ( G.B. 1). An automotive 14 V generator voltage regulator (GVR) of any type, intended for generators with a grounded brush, is used as a regulating element. Thus, the battery maintains a voltage of 14 V at a charging current determined by the capacitance of capacitor C2, which is approximately calculated by the formula:
3200 . I z . U 2
C (uF) = --------------- --------,
U 1 2
where I z - charging current (A), U 2 - voltage of the secondary winding during “normal” switching on of the transformer (V), U 1 - mains voltage.
The device requires virtually no setup. You may need to check the capacitance of the capacitor by monitoring the current with an ammeter. In this case, it is necessary to short-circuit terminals 15 and 67 (B, V and Sh).
From railway (RL 5-99)
Reversing attachment for the charger
This attachment, the circuit of which is shown in Fig. 6, is made on a powerful composite transistor and is intended for charging a car battery with a voltage of 12V alternating asymmetric current. This ensures automatic training of the battery, which reduces its tendency to sulfate and extends its service life. The set-top box can work together with almost any full-wave pulse charger that provides the required charging current.
Fig.6
When connecting the output of the set-top box to a battery (the charger is not connected), when capacitor C1 is still discharged, the initial charging current of the capacitor begins to flow through the resistor R 1, transistor emitter junction VT 1 and resistor R 2. Transistor VT 1 opens, and a significant battery discharge current flows through it, quickly charging capacitor C1. With an increase in the voltage on the capacitor, the battery discharge current decreases to almost zero.
After connecting the charger to the input of the set-top box, a battery charging current appears, as well as a small current through the resistor R 1 and diode VD 1. In this case, the transistor VT 1 is closed because the voltage drops across the open diode VD 1 is not enough to turn on the transistor. Diode VD 3 is also closed, since there is a diode to it VD 2, the reverse voltage of the charging capacitor C1 is applied.
At the beginning of the half-cycle, the output voltage of the charger is added to the voltage on the capacitor, and the battery is charged through the diode VD 2, which results in the energy stored in the capacitor being returned to the battery. Next, the capacitor is completely discharged and the diode opens VD 3, through which the battery now continues to charge. A decrease in the output voltage of the charger at the end of the half-cycle to the level of the battery EMF and below leads to a change in the polarity of the voltage on the diode VD 3, closing it and stopping the charging current.
At the same time, the transistor opens again VT 1 and a new impulse occurs in discharging the battery and charging the capacitor. With the beginning of a new half-cycle of the charger's output voltage, the next battery charging cycle begins.
The amplitude and duration of the battery discharge pulse depend on the resistor values R 2 and capacitor C1. They are selected according to the recommendations.
The transistor and diodes are placed on separate heat sinks with an area of at least 120 cm 2 each.
In addition to the KT827A transistor indicated in the diagram, you can use KT827B, KT827V. The set-top box can use transistors KT825G - KT825E and diodes KD206A, but the polarity of the diodes, capacitor, as well as the input and output terminals of the set-top box must be changed to the opposite.
Fomin.V
Nizhny Novgorod
Simple automatic charger
A typical charger for charging starter batteries consists of a transformer, the winding of which has taps, a diode half-wave rectifier and an ammeter that measures the charging current. Such a charger cannot control the charging process and cannot restore sulfated batteries.
Fig.7
If at the output of such a charger you turn on a node, the diagram of which is shown in Fig. 7, then the device will become automatic and learn to restore the batteries with a training current.
When the battery is connected, the thyristor opens only on positive half-cycles of the pulsating voltage. On the negative side (when the rectifier diode of the charger is closed), the thyristor is closed and the battery is discharged through a resistor. R 3.
At the beginning of each half-cycle, even before the thyristor opens, the voltage on the battery is measured. If this is the voltage of a fully charged battery (13.5 V), then the zener diode opens and prevents the thyristor from opening.
As the battery charges, the thyristor opens closer to the top of the pulsating voltage. The closing of the thyristor occurs at the decline of the half-wave of the pulsating voltage, when this voltage becomes lower than the voltage on the battery.
Karavkin V.
Literature:
Vasiliev V.
"Charger"
and. Radio No. 3 1976
Car battery recharging device
If the car sits idle for a long time, its battery gradually discharges. This is especially felt when storing a car in unheated garages in the winter - at subzero temperatures. Starting the engine involves searching for a starting device from familiar car enthusiasts or trying to get a charged battery from them for temporary use. A car battery recharger can help avoid this problem. The simplicity of the circuit and the absence of scarce radio components make it accessible for repetition.
It is well known that all chemical current sources are subject to self-discharge. The degree of self-discharge depends on a number of reasons. The reasons due to the design features of the batteries are not discussed in this article - motorists have to use the batteries that are on their vehicles. The technological (for cars) reason for battery discharge is due to the storage conditions of the battery. Both the service life of the battery and the degree of its readiness to work in the electrical equipment of the car will depend on this.
The self-discharge current of car batteries largely depends on the “age” of the battery. Approximately, we can assume that the self-discharge current of a battery when stored in an unheated room or outdoors is up to 180 mA. Approximately this battery charging current will ensure its constant readiness for operation.
In the circuit (Fig. 8) there is a low-power transformer TR 1 reduces the voltage of 220 V to approximately 12 V.
Fig.8
AC voltage is rectified by a bridge rectifier D 1 and through a resistor R 3 is supplied to output " OUT " Possible to use car plug XR 1, which can be inserted into the car's cigarette lighter socket. When power is applied to the circuit, the green light ( GREEN ) LED D 2.
When a car battery recharge current flows through a resistor R 3 a voltage drop is created. Being applied to the base of transistor T1 through a resistor R 4 this voltage causes the transistor to saturate and the LED to light up D 3 (RED).
Yakovlev E.L.
Uzhgorod
(“Radioamator” No. 12, 2009)
Battery charger
In the absence of a full-fledged charger, a fairly simple rectifier can be made according to the simple circuit in Fig. 9.
Fig.9
It cannot replace a full-fledged charger, since the charging current is only 0.4 ... 0.5 A, but it is quite suitable for, for example, bringing the battery to the working state that was lost in 2 ... 3 days during the months of winter inactivity. The rectifier is assembled on four silicon diodes. A 220V lamp with a power of 70...100 W is connected in series with them, limiting the charging current. The circuit can use diodes having a maximum permissible reverse voltage of at least 400 V and an average rectifying current of at least 0.4 A. Diodes D7Zh, D226, D226D, D237B, D231, D231B, D232 or others with similar characteristics are suitable.
When working with the rectifier, care should be taken, since all its parts are connected directly to the electrical network through the lamp and therefore touching them is dangerous. If the rectifier is connected to the network, then you should not even touch the battery case, as it may be covered with a thin film of electrolyte - a conductor of electric current. If it is necessary to measure the voltage or density of the electrolyte in the battery, the rectifier must be disconnected from the network.
Gornushkin Yu.
“Practical advice for a car owner”
Simple charger
The circuit is a simple transformerless power supply that produces a constant voltage of 14.4 V, with a current of up to 0.4 A. (Fig. 10)
Fig.10
The design is simple and is used to recharge a battery that has been stored for a long time.
As practice shows, restoration requires a small current, about 0.1-0.3 A (for 6ST-55). If the stored battery is periodically, approximately once a month, recharged for 2-3 days, then you can be sure that it will be ready for use at any time, even after several years of such storage (practically tested).
The source is built according to the circuit of a parametric stabilizer with capacitive ballast resistance. The voltage from the mains is supplied to the bridge rectifier VD 1...VD 4 via capacitor C 1. A zener diode is switched on at the rectifier output VD 5 to 14.4 V. Capacitor C 1 dampens excess voltage and limits the current to no more than 0.4 A. Capacitor C 2 smoothes out the ripples of the rectified voltage. The battery is connected in parallel VD 5.
The device works as follows. When the battery self-discharges to a voltage below 14.4 V, its “soft” charging begins with a weak current, and the value of this current is inversely dependent on the voltage on the battery. But in any case (even with a short circuit) it does not exceed 0.4 A. When charging the battery to a voltage of 14.4 V, the charging current stops altogether.
The device uses: capacitor C 1 - paper BMT or any non-polar 3...5 µF and voltage not lower than 300 V, C2 - K50-3 or any electrolytic 100...500 µF, voltage not lower than 25 V; rectifier diodes VD 1…VD 4 - D226, KD105, KD208, KD209, etc.; Zener diode D815E or others for a voltage of 14 -14.5 V at a current of not less than 0.7 A. It is advisable to mount the zener diode on a heat sink plate.
When operating devices of this type, you must follow safety rules when working with electrical installations.
