Charger attachment. Automatic attachment for a car battery charger. Description of the operation of the machine for disconnecting the charger

For example, for car batteries, it can be significantly improved by adding this attachment - an automatic device that turns it on when the voltage on the battery drops to a minimum and turns it off after charging. This is especially true when storing the battery for a long time without operation - to prevent self-discharge. The diagram of the console is shown in the figure below.

The maximum voltage for car batteries is within 14.2...14.5 V. The minimum permissible during discharge is 10.8 V. After connecting the battery and turning on the network, press the SB1 “Start” button. Transistors VT1 and VT2 close, opening the key VT3, VT4, which turns on relay K1. With its normally closed contacts K1.2, it turns off relay K2, the normally closed contacts of which (K2.1), when closed, connect the charger to the network. Such a complex switching scheme is used for two reasons: firstly, it ensures decoupling of the high-voltage circuit from the low-voltage one; secondly, so that relay K2 turns on at the maximum battery voltage and turns off at the minimum, because The RES22 relay used has a switching voltage of 12 V.

Contacts K1.1 of relay K1 switch to the lower position according to the diagram. During the battery charging process, the voltage across resistors R1 and R2 increases, and when the unlocking voltage is reached at the base of VT1, transistors VT1 and VT2 open, closing the key VT3, VT4. Relay K1 turns off, including K2. The normally closed contacts K2.1 open and de-energize the charger. Contacts K1.1 move to the top position according to the diagram. Now the voltage at the base of the composite transistor VT1, VT2 is determined by the voltage drop across resistors R1 and R2. As the battery discharges, the voltage at the base of VT1 decreases, and at some point VT1, VT2 close, opening the key VT3, VT4. The charging cycle begins again. Capacitor C1 serves to eliminate interference from the bounce of contacts K1.1 at the time of switching.

The device is adjusted without a battery or charger. An adjustable constant voltage source with regulation limits of 10...20 V is required. It is connected to the circuit terminals instead of GB1. The resistor R1 slider is moved to the upper position, and the R5 slider is moved to the lower position. The source voltage is set equal to the minimum battery voltage (11.5...12 V). By moving the R5 engine, relay K1 and LED VD7 are turned on. Then, raising the source voltage to 14.2...14.5 V, moving the R1 slider turns off K1 and the LED. By changing the source voltage in both directions, make sure that the device turns on at a voltage of 11.5...12 V, and turns off at 14.2...14.5 V. The photo shows a homemade charger for car batteries, with a built-in prefix.

An interesting simple design of a 3x3x3 LED cube using LEDs and microcircuits.

In this article we will look at the circuit of a simple voice recorder. Sometimes there is a need to record signals or speech fragments of short duration. This device is designed to record sound over a short period of time. The microphone used is an electret one, which can be found everywhere, for example in a Chinese tape recorder.

By supplementing your existing car battery charger with the proposed automatic one, you can rest assured about the battery charging mode - as soon as the voltage at its terminals reaches (14.5+-0.2) V, charging will stop. When the voltage drops to 12.8...13 V, charging will resume.
The attachment can be made as a separate unit or built into the charger. In any case, a necessary condition for its operation will be the presence of a pulsating voltage at the output of the charger.
This voltage is obtained, say, when installing a full-wave rectifier in the device without a smoothing capacitor.
The diagram of the machine attachment is shown in Fig. 1. It consists of a thyristor VS1, a control unit for thyristor A1, a circuit breaker SA1 and two indication circuits - on LEDs HL1 and HL2. The first circuit indicates the charging mode, the second controls the reliability of connecting the battery to the terminals of the machine. If the charger has a dial indicator - an ammeter, the first indication circuit is not necessary.

Rice. 1. Schematic diagram of the machine attachment
The control unit contains a trigger on transistors VT2, VT3 and a current amplifier on transistor VT1. The base of the transistor VT3 is connected to the engine of the tuning resistor R9, which sets the switching threshold of the trigger, i.e. the switching voltage of the charging current. The switching “hysteresis” (the difference between the upper and lower switching thresholds) depends mainly on the resistor R7 and with the resistance indicated on the diagram it is about 1.5 V.
The trigger is connected to conductors connected to the terminals of the battery and switches depending on the voltage on them.
Transistor VT1 is connected by a base circuit to the trigger and operates in electronic key mode. The collector circuit of the transistor is connected through resistors R2, R3 and the control electrode section - the cathode of the SCR with the negative terminal of the charger. Thus, the base and collector circuits of transistor VT1 are powered from different sources: the base circuit from the battery, and the collector circuit from the charger.
SCR VS1 acts as a switching element. Using it instead of the contacts of an electromagnetic relay, which is sometimes used in these cases, provides a large number of switches on and off of the charging current necessary to recharge the battery during long-term storage.
As can be seen from the diagram, the SCR is connected by the cathode to the negative wire of the charger, and by the anode to the negative terminal of the battery. With this option, the control of the thyristor is simplified: when the instantaneous value of the pulsating voltage at the output of the charger increases, current immediately begins to flow through the control electrode of the thyristor (if, of course, transistor VT1 is open). And when a positive (relative to the cathode) voltage appears at the anode of the thyristor, the thyristor will be reliably open. In addition, such a connection is advantageous in that the thyristor can be attached directly to the metal body of the set-top box or the body of the charger (if the set-top box is placed inside it) as a heat sink.
You can turn off the set-top box using switch SA1 by placing it in the “Manual” position. Then the contacts of the switch will be closed, and through resistor R2 the control electrode of the thyristor will be connected directly to the terminals of the charger. This mode is needed, for example, to quickly charge the battery before installing it on the car.
Transistor VT1 can be the series indicated on the diagram with letter indices A - G; VT2 and VT3 - KT603A - KT603G; diode VD1 - any of the D219, D220 series or another silicon; Zener diode VD2 - D814A, D814B, D808, D809; SCR - KU202 series with letter indices G, E, I, L, N, as well as D238G, D238E; LEDs - any of the AL102, AL307 series (limiting resistors R1 and R11 set the required forward current of the LEDs used).
Fixed resistors - MLT-2 (R2), MLT-1 (R6), MLT-0.5 (Rl, R3, R8, R11), MLT-0.25 (rest). Trimmer resistor R9 is SP5-16B, but another one with a resistance of 330 Ohm..L.5 kOhm will do. If the resistance of the resistor is greater than that indicated in the diagram, a constant resistor of such resistance is connected parallel to its terminals so that the total resistance is 330 Ohms.

Rice. 2. Printed circuit board of the set-top box
The parts of the control unit are mounted on a board (Fig. 2) made of one-sided foil fiberglass laminate with a thickness of 1.5 mm. The tuning resistor is fixed in a hole with a diameter of 5.2 mm so that its axis protrudes from the printing side.
The board is mounted inside a case of suitable dimensions or, as mentioned above, inside the charger case, but always as far as possible from heating parts (rectifier diodes, transformer, SCR). In any case, a hole is drilled in the housing wall opposite the axis of the trimming resistor. LEDs and switch SA1 are mounted on the front wall of the case.
To install the SCR, you can make a heat sink with a total area of about 200 cm2. For example, a duralumin plate with a thickness of 3 mm and dimensions of 100X100 mm is suitable. The heat sink is attached to one of the walls of the case (say, the back) at a distance of about 10 mm - to ensure air convection. It is also possible to attach the heat sink to the outside of the wall by cutting a hole in the housing for the thyristor.
Before attaching the control unit, you need to check it and determine the position of the trimmer resistor motor. A DC rectifier with an adjustable output voltage of up to 15 V is connected to points 1 and 2 of the board, and the indication circuit (resistor R1 and LED HL1) is connected to points 2 and 5. The trimmer resistor motor is set to the lowest position according to the diagram and voltage is supplied to the control unit about 13 V. The LED should light up.
By moving the trimmer resistor slider up in the circuit, the LED goes out. Smoothly increasing the supply voltage of the control unit to 15 V and decreasing to 12 V, use a trimming resistor to ensure that the LED lights up at a voltage of 12.8...13 V and goes out at 14.2...14.7 V.

Literature

Popular scientific publication TO HELP A RADIO AMATEUR Issue 100\A.Korobkov

A. Korobkov

Korobkov Alexander Vasilievich- leading specialist at one of the Moscow enterprises, born in 1936. He took up amateur radio at school, where he assembled a detector receiver as an eighth-grader. Two years later I mastered superheterodyne. In the 60s he developed and assembled a transistor tape recorder. The first publications in the magazine “Radio” date back to the same period. A little later he began to publish in the VRL collection. The main topics of publications in the last decade- automotive electronics.

Having supplemented the charger at your disposal for a car battery with the proposed automatic device, you can be calm about the battery charging mode - as soon as the voltage at its terminals reaches (14.5 ± 0.2) V, charging will stop. When the voltage drops to 12.8...13 V, charging will resume.

The attachment can be made as a separate unit or built into the charger. In any case, a necessary condition for its operation will be the presence of a pulsating voltage at the output of the charger. This voltage is obtained, say, when installing a full-wave rectifier in the device without a smoothing capacitor.

The diagram of the machine attachment is shown in Fig. 1. It consists of a trinistor VS1, a trinistor control unit A1, a circuit breaker SA1 and two indication circuits - on LEDs HL1 and HL2. The first circuit indicates the charging mode, the second circuit controls the reliability of connecting the battery to the terminals of the machine. If the charger has a dial indicator - an ammeter, the first indication circuit is not necessary.

Rice. 1. Schematic diagram of the machine attachment

The control unit contains a trigger on transistors VT2, VT3 and a current amplifier on transistor VT1. The base of the transistor VT3 is connected to the engine of the tuning resistor R9, which sets the switching threshold of the trigger, i.e. the switching voltage of the charging current. The switching “hysteresis” (the difference between the upper and lower switching thresholds) depends mainly on the resistor R7 and with the resistance indicated on the diagram it is about 1.5 V.

The trigger is connected to conductors connected to the terminals of the battery and switches depending on the voltage on them.

Transistor VT1 is connected by a base circuit to the trigger and operates in electronic key mode. The collector circuit of the transistor is connected through resistors R2, R3 and the control electrode section - the cathode of the SCR with the negative terminal of the charger. Thus, the base and collector circuits of transistor VT1 are powered from different sources: the base circuit from the battery, and the collector circuit from the charger.

SCR VS1 acts as a switching element. Using it instead of the contacts of an electromagnetic relay, which is sometimes used in these cases, provides a large number of switches on and off of the charging current necessary to recharge the battery during long-term storage.

As can be seen from the diagram, the SCR is connected by the cathode to the negative wire of the charger, and by the anode to the negative terminal of the battery. With this option, the control of the SCR is simplified: when the instantaneous value of the pulsating voltage at the output of the charger increases, current immediately begins to flow through the control electrode of the SCR (if, of course, transistor VT1 is open). And when a positive (relative to the cathode) voltage appears at the anode of the thyristor, the thyristor will be reliably open. In addition, such a connection is advantageous in that the thyristor can be attached directly to the metal body of the set-top box or the body of the charger (if the set-top box is placed inside it) as a heat sink.

You can turn off the set-top box using switch SA1 by placing it in the “Manual” position. Then the contacts of the switch will be closed, and through resistor R2 the control electrode of the thyristor will be connected directly to the terminals of the charger. This mode is needed, for example, to quickly charge the battery before installing it on the car.

Transistor VT1 can be the series indicated on the diagram with letter indices A - G; VT2 and VT3 - KT603A - KT603G; diode VD1 - any of the D219, D220 series or another silicon; Zener diode VD2 - D814A, D814B, D808, D809; SCR - KU202 series with letter indices G, E, I, L, N, as well as D238G, D238E; LEDs - any of the AL102, AL307 series (limiting resistors R1 and R11 set the desired forward current of the LEDs used).

Fixed resistors - MLT-2 (R2), MLT-1 (R6), MLT-0.5 (Rl, R3, R8, R11), MLT-0.25 (others). The trimming resistor R9 is SP5-16B, but another one with a resistance of 330 Ohm..L, 5 kOhm will do. If the resistance of the resistor is greater than that indicated in the diagram, a constant resistor of such resistance is connected parallel to its terminals so that the total resistance is 330 Ohms.

Rice. 2. Printed circuit board of the set-top box

The parts of the control unit are mounted on a board (Fig. 2) made of one-sided foil fiberglass laminate with a thickness of 1.5 mm. The tuning resistor is fixed in a hole with a diameter of 5.2 mm so that its axis protrudes from the printing side.

The board is mounted inside a case of suitable dimensions or, as mentioned above, inside the charger case, but always as far as possible from heating parts (rectifier diodes, transformer, SCR). In any case, a hole is drilled in the housing wall opposite the SS trimmer. LEDs and switch SA1 are mounted on the front wall of the case.

To install an SCR, you can make a heat sink with a total area of about 200 cm 2 . For example, a duralumin plate with a thickness of 3 mm and dimensions of 100X100 mm is suitable. The heat sink is attached to one of the walls of the case (say, the back) at a distance of about 10 mm - to ensure air convection. It is also possible to attach the heat sink to the outside of the wall by cutting a hole in the housing for the greenistor.

Before attaching the control unit, you need to check it and determine the position of the trimmer resistor motor. A DC rectifier with an adjustable output voltage of up to 15 V is connected to points 1 and 2 of the board, and the indication circuit (resistor R1 and LED HL1) is connected to points 2 and 5. The trimmer resistor motor is set to the lowest position according to the diagram and voltage is supplied to the control unit about 13 V. The LED should light up. By moving the trimmer resistor slider up in the circuit, the LED goes out. Smoothly increasing the supply voltage of the control unit to 15 V and decreasing to 12 V, use a trimming resistor to ensure that the LED lights up at a voltage of 12.8...13 V and goes out at 14.2...14.7 V.

Automatic charger attachment

The magazine has always paid a lot of attention to issues of proper maintenance of automobile batteries. So, for example, a previous article on this topic was published last year (I. Herzen. “Automatic attachment to a charger” in “Radio”, 1997, No. 7, pp. 45, 46). The work below is another step in this direction.

During long-term (several months) storage of car batteries, they self-discharge, and therefore it is recommended to recharge the battery at least once a month. However, conventional recharging is not able to prevent sulfation of the plates, which gradually leads to a decrease in battery capacity and a decrease in its service life. Therefore, the battery is periodically discharged with a current, in amperes, numerically equal to 1/20 of the nominal capacity, expressed in ampere-hours, to a voltage of 10.5 V, followed by charging to a voltage of 14.2...14.5 V. Such The charge-discharge cycle should be repeated several times if the battery is heavily sulfated or has been in a semi-discharged state for a long time.

The attachment described below is designed to work in conjunction with chargers that provide the required charging current and have a pulsating charging voltage at the output. Suitable, for example, are industrially produced devices UZ-A-6/12 (Vyborg), UZR-P-12-6.3 (Yuryev-Polsky), as well as amateur devices described in. The set-top box allows you to discharge the battery to a voltage of 10.5 V and, upon completion of the discharge, automatically begin charging with a current with a discharge component (with a ratio of charge and discharge components of 10:1). The device stops charging when the voltage at the battery terminals reaches 14.2...14.5 V, which corresponds to its 100% charge. It controls the voltage when there is no charging current. If the mains voltage fails, the device stops discharging the battery. Discharge-charge cycles can be single or multiple.

The schematic diagram of the machine attachment is shown in Fig. 1.

(click to enlarge)

The power supply of the set-top box is combined - from the mains, from the charger and from the rechargeable battery GB1 while the optocoupler dinistor U3 is closed.

Timer comparators DA1 with voltage dividers R7R10 and R8R11 were used as a threshold element that generates a signal at two voltage values on the battery - 14.2...14.5 V when charging and 10.5 V when discharging. At its inputs R and S, the voltage on the battery being charged or discharged is compared with the above threshold values determined by the supply voltage of the timer, the resistance of the resistors of the internal voltage divider of the timer, and the voltage at its input UR (it is removed from the zener diode VD2). The lower and upper response thresholds of the comparator can be changed using trimming resistors R10 and R11. The timer is powered by a VD3R9 parametric stabilizer.

The voltage of a not too strongly discharged twelve-volt battery is usually 12...12.6 V. When the device is connected to the network with the battery connected, the timer will be set to a state corresponding to the high-level voltage at its output, transistor VT1 will be open. The dinistor of the optocoupler U3 will open and the battery will begin charging, which will be indicated by the HL1 LED turning on.

However, as a rule, the state of charge of the connected battery is unknown, so before starting charging it is advisable to discharge it to a voltage of 10.5 V. To turn on the discharge mode, after connecting the battery, briefly press the SB1 “Start” button. Through contacts SB1.1, the input R of the timer will receive voltage from the battery connected to the output and switch it to the opposite state (low level at the output), transistor VT1 will close and turn off the LED HL1.

At the same time, through the closed contacts SB1.2, a low level comes to the upper input of the RS trigger, assembled on elements DD1.1, DD2.2. The trigger is set to a state when a high level voltage appears at the output of element DD1.1.

When the contact position of switch SA1 is shown in the diagram, a low level voltage operates at the output of elements DD1.3, DD1.4, switched on by inverters. Since the phototransistor of the optocoupler U2 is open (and it is open all the time while the mains voltage is supplied to the console), a current sufficient to saturate this transistor flows through the base of the transistor VT4, resistor R23, the phototransistor of the optocoupler and the output of logic elements DD1.3 and DD1.4.

The battery discharge current flows through the EL1 incandescent lamp - about 2.5 A - which corresponds to the 20-hour discharge mode of the 6ST55 battery. When servicing a battery of a different capacity, use a lamp of the appropriate power.

The mains voltage is supplied through the damping resistor R1 to the diode bridge VD1 and, after rectification, powers the series-connected LEDs of the optocouplers U1 and U2. Capacitor C1 and resistor R2 form a smoothing filter for the LED of optocoupler U2. When the mains voltage is lost, the phototransistor of this optocoupler closes, which leads to the closing of the VT4 transistor and stopping the battery from discharging.

As the battery discharges, the voltage at its terminals decreases. When it reaches 10.5 V, the timer will switch and transistors VT1 and VT2 will open. Opening transistor VT1 will cause the device to enter charging mode, switching the RS trigger and closing transistor VT4, as well as opening transistor VT3.

The charging current is set using a charger in accordance with the battery operating instructions, i.e. equal to 1/10 or 1/20 of the battery capacity. If charging is carried out without operator control, it is necessary to ensure that fluctuations in the charging current are limited due to fluctuations in the mains voltage. The easiest way to stabilize the current is to connect a chain of two or three parallel-connected car lamps with a power of 40...50 W into the break of one of the output wires of the charger. The same effect is achieved by plugging a 220 V lamp with a power of 200...300 W into one of the input (mains) wires of the charger.

The charging current contains a dosed discharge component, which has a beneficial effect on the flow of electrochemical processes in the battery. The current of the discharge component is determined by resistor R19 (approximately 0.5 A).

During the charging process, the voltage at the battery pole terminals gradually increases. It is known that the voltage of a fully charged battery is 14.2...14.5 V. This voltage is measured in the absence of charging current, since charging pulses, depending on the degree of discharge of the battery, increase the instantaneous voltage value at its terminals by 1...3 V.

To ensure this measurement mode, the device uses elements U1, R4, VT2. In charging mode, transistor VT2 is open. In Fig. Figure 2 shows voltage and current diagrams explaining the operation of optocouplers U1 and U2. The mains voltage is rectified by a diode bridge (diagram 1) and supplied to the LEDs of optocouplers U1 and U2.

The phototransistor of the optocoupler U1 opens at moments when the current through the LED of the optocoupler U1 (diagram 2) exceeds the opening current of the phototransistor. In this case, resistor R4 bypasses trimming resistor R11 and the upper threshold for timer DA1 increases. When the mains voltage crosses zero, the phototransistor closes and the timer threshold decreases to 14.2...14.5 V. It is at this time that no charging current flows through the battery. The measurement occurs in every half-cycle of the network, i.e. 100 times per second. Measurement duration - 1...3 ms.

Current flows through the LED of optocoupler U2 as long as mains voltage is applied to the set-top box, due to which the phototransistor of optocoupler U2 is open.

As soon as the voltage on the battery reaches 14.2...14.5 V in the absence of charging current, timer DA1 will switch (a low level will appear at the output) and charging will stop. Since the output of the RS flip-flop still remains high, the device can remain in this state for a long time, up to several days. The current consumed from the battery is small (20...30 mA) and cannot cause significant discharge.

If repeated battery training with discharge-charge cycles is necessary, the SA1 switch contacts are moved to the lower position according to the diagram. In this case, the RS trigger is disabled and charging and discharging will alternate as long as there is mains voltage and the battery being charged is connected.

Capacitors C2, C3 increase the noise immunity of the timer. Resistors R19, R22 ensure reliable retention of transistors VT3, VT4 closed in the absence of base current.

Instead of KT608B, the device can use any transistors from the KT603, KT608, KT3117, KT815 series; KT503B - KT315, KT501, KT503, KT3117; KT814B - KT814, KT816, KT818, KT837 and instead of KT825G - any of this series. The optocoupler dinistor TO125-10 can be replaced with T0125-12.5, TO2-10, TO2-40, TSO-10.

We will replace the KTs407A diode bridge with KTs402, KTs405 with letter indices A, B, V. It is advisable to use the VD3 zener diode with a small stabilization TKN; any zener diodes of the D818 series are suitable.

Oxide capacitor C1 - K50-16, K50-35 or K50-29; C2, C3 - KM-66, K10-23, K73-17, etc. Trimmer resistors R10, R11 - any multi-turn, for example SP5-2. Resistor R20 - PEV with a power of 10 or 15 W (in extreme cases 7.5 W); the rest are MLT, OMLT, S2-23. Button SB1 and switch SA1 - any, for example, KM2-1 and MT1, respectively.

Most of the elements of the device are mounted on a printed circuit board made of foil-coated fiberglass laminate 2 mm thick (Fig. 3).

Optocoupler dinistor U3 and transistor VT4 are installed on heat sinks with a cooling surface of 100... 150 cm2. The board is mounted in any case of suitable dimensions (in the author’s version - 260X100X70 mm). Connections through which charging and discharging current flow must be made with a wire with a cross-section of at least 2 mm2. It is advisable to choose flexible wires connecting the device to the battery.

To set up the device, you will need a laboratory DC source with a voltage adjustable from 9 to 15 V with a load current of at least 0.6 A, and a voltmeter. First, the charger and lamp EL1 are temporarily disconnected, and the battery being charged is replaced with a laboratory current source.

Having set the source voltage to 10.5 V using the voltmeter, use trimming resistor R10 to set the lower threshold for the comparator to turn on LED HL1, and then, setting the voltage to 14.2...14.5 V, use trimmer resistor R11 to set the upper threshold to turn on LED HL2.

The appearance of the assembled console is shown in Fig. 4.

To ensure the electrical safety of the entire charging installation as a whole, it is necessary that the load (battery) be galvanically isolated (separated) from the supply network. The role of decoupling elements in the set-top box is played by optocouplers (U1 and U2. Unfortunately, the optocouplers of the AOT110 series chosen by the author are not able to eliminate the danger of electric shock, since their rated insulation voltage does not exceed 100 V. Only those optocouplers are suitable for the set-top box, the insulation voltage of which is not less than 500 V, the phototransistor is composite (this is especially true for optocoupler U2), for example, from the AOT127 series.

Literature

Bolotovsky V.I., Vaisgant Z.I. Operation, maintenance and repair of lead-acid batteries. - L.: Energoatomizdat. Leningr. department, 1988, 208 p.
Kudinov G., Savchuk G. Automatic charger. - Radio, 1982, No. 1, p. 44-48.
Talanov N., Fomin V. Charger for starter batteries. - Radio, 1994, No. 7, p. 29.
Zeldin E. Application of the integrated timer KR1006VI1. - Radio, 1986, No. 9, p. 36, 37.
Korobkov A. Device for automatic training of batteries: Collection: "To help the radio amateur", vol. 96, p. 61-70. -M.: DOSAAF, 1987.
Gazizov M. Automatic device for charging and restoring batteries.: Sat.: "To help the radio amateur", vol. 94, p. 3-7. - M.: DOSAAF, 1986.