Wires and cables

Schemes of simple universal chargers. Universal charger for small batteries

The device provides a stable charging current and automatically turns off when the specified battery voltage is reached. The scheme works like this:

Within a few seconds, a charging current is supplied to the battery, then it automatically turns off for about 1 second and the EMF on the battery is measured.

As a rule, the emf of a fully charged nickel-cadmium battery is 1.35 V - if this value is reached on the battery, the comparator switches and operates R.S. trigger that turns off the charging current and turns on the LED " Battery is charged".

The charger allows you to charge batteries with a maximum voltage of up to 18 V . The charging current is regulated by a variable resistor within the range of 10 - 200 mA, and the required value of the battery EMF at which charging stops is also set by a variable resistor.

While the charging current is flowing, the "Charge" LED flashes periodically.

The output transistor must be installed on a small radiator, the area of which depends on the required charging current and battery voltage.

It is advisable to attach handles with pointers to the axis of variable resistors, and use a multimeter to perform calibration with marks on the front panel of the device.

Simple automatic charger.

Device for charging cell phone batteries.

The figure shows a diagram of a device for charging cell phones on nickel-metal hydride (Ni-MH) and lithium (Li-ion) batteries with a nominal voltage of 3.6-3.8V with status indication and automatic adjustment of the output current.

To change the values of output current and voltage, it is necessary to change the ratings of elements VD4, R5, R6.

The initial current of the charger is 100 mA, this value is determined by the output voltage of the secondary winding of transformer Tr1 and the resistance value of resistor R2. Both of these parameters can be adjusted by selecting a step-down transformer or the resistance of the limiting resistor.
The 220V network voltage is reduced by transformer Tr1 to 10V on the secondary winding, then rectified by the diode bridge VD1 and smoothed by capacitor C1. The rectified voltage through the current-limiting resistor R2 and the current amplifier on transistors VT2, VT3 is supplied through connector XI to the cell phone battery and charges it with a minimum current. In this case, the glow of the HL1 LED indicates the presence of charging current in the circuit. If this LED does not light, it means that the battery is fully charged, or there is no contact in the charging circuit with the load (battery).
The glow of the second indicator LED HL2 at the very beginning of the charging process is not noticeable, since the voltage at the output of the charger is not enough to open the transistor switch VT1. At the same time, the composite transistor VT2, VT3 is in saturation mode, and the charging current is present in the circuit (flows through the battery).
When the voltage at the battery contacts reaches 3.8V, which indicates a fully charged battery, the zener diode VD2 opens, transistor VT1 also opens and LED HL2 lights up, and transistors VT2, VT3 close accordingly and the charging current in the battery power circuit (XI) decreases almost to zero.

Setting up.
The setup comes down to setting the maximum charging current and voltage at the output of the device, at which the HL2 LED lights up.
To do this, you will need two cell phone batteries of the same type with a nominal voltage of 3.6-3.8V. One battery is completely discharged, and the other is fully charged with a standard charger.
The maximum current is established experimentally:
A obviously discharged cell phone is connected to the output of the charger (points A and B, connector XI) through a DC milliammeter connected in series, which after long-term use has turned itself off due to a discharged battery, and by selecting the resistance of resistor R2, a current of 100 mA is set.
For this purpose, it is convenient to use a dial milliameter with a total deflection current of 100 mA; it is undesirable to use a digital tester due to the inertia of reading and displaying readings.
After this (having previously disconnected the charger from the AC mains), the emitter of transistor VT3 is unsoldered from other elements of the circuit and instead of a “dead” battery, a normally charged battery is connected to points A and B on the circuit (for this, the batteries are swapped in the same phone). Now, by selecting the resistance of resistors R5 and R6, LED HL2 is lit.
After this, the emitter of transistor VT3 is connected back to other elements of the circuit.

About details
Transformer Tr1 is any, designed for power supply from a 220V 50 Hz network and a secondary winding producing a voltage of 10 - 12V.
Transistors VT1, VT2 type KT315B - KT315E, KT3102A - KT3102B, KT503A - KT503V, KT3117A or similar in electrical characteristics.
Transistor VT3 - from the KT801, KT815, KT817, KT819 series with any letter index. There is no need to install this transistor on the heat sink.
All fixed resistors (except R2) are of type MLT-0.25, MF-25 or similar, R2 - 1 W.
Oxide capacitor C1 type K50-24, K50-29 or similar for an operating voltage of at least 25V.
LEDs HL1, HL2 type AL307BM or others (to indicate status in different colors), designed for a current of 5-12 mA.
Diode bridge VD1 - any of the KTs402, KTs405, KTs407 series.
Zener diode VD2 determines the voltage at which the charging current of the device will decrease to almost zero. In this embodiment, a zener diode with a stabilization (opening) voltage of 4.5-4.8V is required. The zener diode indicated in the diagram can be replaced with a KS447A or made up of two zener diodes at a lower voltage, connecting them in series. In addition, the threshold for automatically turning off the device charging mode can be adjusted by changing the resistance of the voltage divider, consisting of resistors R5 and R6.

Source:

Kashkarov A.P. “Electronic homemade products” - St. Petersburg: BHV-Petersburg, 2007, p.32.

http://istochnikpitania.ru/index.files/Electronic_sxem.files/Electronic_sxem45.htm

Simple charger circuits.

Now on the market there are many complex devices for charging batteries with currents of various shapes and amplitudes with charging process control systems, however, in practice, experiments with various charger circuits lead us to a simple conclusion that everything is much simpler.

A charging current of 10% of the battery capacity is suitable for both NiCd and Li-Ion batteries. And in order to fully charge the battery, it needs to be given a charging time of about 10 - 12 hours.

For example, when we need to charge a AA battery at 2500 mA, we need to select a current of 2500/10 = 250 mA and charge it with it for 12 hours.

Diagrams of several such chargers are shown below.:

A device that does not contain a transformer shown in Fig. 2, allows you to charge both one battery and a battery of several battery cells, while the charging current changes slightly.

Diodes KD105 or similar are used as diodes D1 - D7. LED D8 - AL307 or similar, desired color. Diodes D1 - D4 can be replaced with a diode assembly. Resistor R3 selects the required brightness of the LED. The capacity of capacitor C1, which sets the required charging current, is calculated by the formula:

C1= 3128/A,
A = V - R2,
V = (220 - Ueds) / J: Where: C1 in uF; Ueds - voltage on the battery in V ; J is the required charging current in A.

For example, let's calculate the capacitor capacity for charging a battery of 8 batteries with a capacity of 700mAh.

The charging current (J) will be 0.1 battery capacity - 0.07A, Ueds 1.2 x 8 =9.6 V.

Therefore, V = (220 - 9.6) / 0.07 = 3005.7, then A = 3005.7 - 200 = 2805.7.

The capacitance of the capacitor will be C1 = 3128 / 2805.7 = 1.115 µF, the closest value is 1 µF.

The operating voltage of the capacitor must be at least 400 V . The power dissipation of resistor R2 is determined by the magnitude of the charging current. For a charging current of 0.07A it will be 0.98 W (P= JxJxR). We select a resistor with a power dissipation of 2 W.

The charger is not afraid of short circuits. After assembling the charger, you can check the charging current by connecting an ammeter instead of the battery.

If the battery is connected with incorrect polarity, then even before the charger is connected to the electrical network, the D8 LED will light up.

After connecting the device to the electrical network, the LED signals the passage of charging current through the battery.

Shown in Fig. 3, the device allows you to charge simultaneously four D-0.26 batteries with a current of 26 mA for 12...14 hours.

Fig.3

Excess voltage of the 220V network is extinguished due to the reactance of capacitors (Xc).

Using this electrical circuit and knowing the charge current (Iz) recommended for a specific type of battery, using the formulas below, you can determine the capacitance of capacitors C1, C2 (in total C = C1 + C2) and select the type of zener diode VD2 so that its stabilization voltage exceeds the voltage charged batteries approximately 0.7V.

The type of zener diode depends only on the number of simultaneously charged batteries, for example, to charge three D-0.26 or NKGTs-0.45 cells, it is necessary to use a VD2 zener diode of type KS456A. An example calculation is given for D-0.26 batteries with a charging current of 26 mA.

The charger uses resistors of the MLT or C2-23 type, capacitors C1 and C2 of the K73-17V type for an operating voltage of 400V. Resistor R1 can have a nominal value of 330...620 kOhm; it ensures the discharge of capacitors after the device is turned off.

You can use any LED HL1, provided you select resistor R3 so that it glows bright enough. The VD1 diode matrix is replaced by four KD102A diodes.

The presence of voltage in the charging circuit is indicated by the HL1 LED, the VD3 diode allows you to prevent the battery from being discharged through the charger circuits when it is disconnected from the 220V network.

When charging NKGTs-0.45 batteries with a current of 45 mA, resistor R3 must be reduced to a value at which the LED glows at full brightness.

The charger circuit (Fig. 4) is designed to charge batteries of the NKGTs-0.45 (NKGTs-0.5) type. The charge is carried out with a current of 40...45 mA during one half-wave of the mains voltage; during the second half-wave, the diode is closed and no charging current is supplied to element G1.

Rice. 4

To indicate the presence of mains voltage, a miniature lamp HL1 type SMH6.3-20 or similar is used.

If the devices are assembled correctly, no configuration is required. We calculate the capacitance of the capacitor using the formula: C1 (in µF) = 14.8 * charging current (in A)

If you need a current of 2A, then 14.8*2=29.6 µF. We take a capacitor with a capacity of 30 μF and get a charge current of 2 Amperes. Resistor to discharge the capacitor.

The charger circuit shown in the following figure is a simple current stabilizer. The charging current is regulated using a variable resistor in the range from 10 to 500 mA.

The device can use any diodes capable of withstanding the charging current.

The supply voltage should be 30% greater than the maximum voltage of the battery being charged.

Since all of the above schemes do NOT exclude the possibility of the battery receiving an excess charge, when using such devices it is necessary to control the charging time, which should not exceed 12 hours.

Device for charging small batteries

At today's prices, you can literally go broke powering small-sized equipment from galvanic cells and batteries. It is more profitable to spend one time and switch to using batteries. In order for them to serve for a long time, they must be used correctly: not discharge below the permissible voltage, charge with a stable current, and stop charging on time. But if the user himself has to monitor the fulfillment of the first of these conditions, then it is advisable to assign the fulfillment of the other two to the charger. This is exactly the device that is described in the article.

During development, the task was to construct a device with the following characteristics:

wide intervals of change in charging current and automatic charging stop voltage (APC). providing charging of both individual batteries used to power small-sized equipment, and batteries composed of them with a minimum number of mechanical switches;
close-to-uniform scales of the regulators, allowing you to set the charging current and voltage of the APC with acceptable accuracy without any measuring instruments;
high stability of the charging current when the load resistance changes;
relative simplicity and good repeatability.

The described device fully meets these requirements. It is intended for charging batteries D-0.03, D-0.06. D-0.125, D-0.26, D-0.55. TsNK-0.45, NKGTs-1.8, their imported analogues and batteries composed of them. Up to the set threshold for switching on the APP system, the battery is charged with a stabilized current, independent of the type and number of elements, and the voltage on it gradually increases as it charges. After the system is triggered, the previously set constant voltage is stably maintained on the battery, and the charging current decreases. In other words, the battery does not recharge or discharge, and it can remain connected to the device for a long time.

The device can be used as a power supply for small-sized equipment with adjustable voltage from 1.5 to 13 V and protection against overload and short circuit in the load.

The main technical characteristics of the device are as follows:

charging current at the limit "40 mA" - 0...40, at the limit "200 mA" - 40...200 mA;
instability of the charging current when the load resistance changes from 0 to 40 Ohms - 2.5%;
The limits for regulating the response voltage of the automatic protection system are 1.45... 13 V.

The schematic diagram of the device is shown in Fig. 1.

A current source on the transistor \L"4 is used as a charging current stabilizer. Depending on the position of the switch SA2, the load current In is determined by the ratios: IN = (UB - UBE)/R10 and IN = (UB - UBE)/(R9 + R10 ), where UБ is the voltage at the base of transistor VT4 relative to the positive bus, V; UBE is the voltage drop at its emitter junction, V; R9, R10 are the resistances of the corresponding resistors, Ohm.

From these expressions it follows that. changing the voltage at the base of transistor VT4 with variable resistor R8. the load current can be adjusted over a wide range. The voltage across this resistor is maintained by a constant zener diode VD6, the current through which, in turn, is stabilized by field-effect transistor VT2. All this ensures the instability of the charging current specified in the technical specifications. The use of a voltage-controlled stable current source made it possible to change the charging current down to very small values, to have a close to uniform scale of the current regulator (R8) and to simply switch the limits of its regulation.

APZ system. triggered after reaching the maximum permissible voltage on the battery or battery, includes a comparator on the op-amp DA1, an electronic switch on the transistor VT3, and a zener diode VD5. current stabilizer on transistor VT1 and resistors R1 - R4. The HL1 LED serves as an indicator of charging and its completion.

When a discharged battery is connected to the device, the voltage on it and the non-inverting input of the op-amp DA1 is less than the exemplary one on the inverting one, which is set by variable resistor R3. For this reason, the voltage at the output of the op-amp is close to the voltage of the common wire, transistor VT3 is open, a stable current flows through the battery, the value of which is determined by the positions of the variable resistor R8 slider and switch SA2.

As the battery charges, the voltage at the inverting input of op-amp DA1 increases. The voltage at its output also increases, so transistor VT2 leaves the current stabilization mode, VT3 gradually closes and its collector current decreases. The process continues until then. until the zener diode VD6 ceases to stabilize the voltage across resistors R7, R8. As this voltage decreases, transistor VT4 begins to close and the charging current quickly decreases. Its final value is determined by the sum of the self-discharge current of the battery and the current flowing through resistor R11. In other words, from this moment on, the charged battery maintains the voltage set by resistor R3, and the current necessary to maintain this voltage flows through the battery.

The HL1 LED indicates that the device is connected to the network and two phases of the charging process. In the absence of a battery, resistor R11 is set to a voltage determined by the position of the slider of variable resistor R3. Very little current is required to maintain this voltage, so HL1 glows very dimly. At the moment the battery is connected, the brightness of its glow increases to maximum, and after the automatic protection system is activated at the end of charging, it abruptly decreases to the average between those mentioned above. If desired, you can limit yourself to two levels of glow (weak, strong), for which it is enough to select resistor R6.

The device parts are mounted on a printed circuit board, the drawing of which is shown in Fig. 2. It is made by cutting through foil and is designed for the installation of permanent resistors MLT, trimmer (wire) PPZ-43. capacitors K52-1B (C1) and KM (C2). Transistor VT4 is installed on a heat sink with an effective thermal dissipation area of 100 cm2. Variable resistors R3 and R8 (PPZ-11 group A) are fixed on the front panel of the device and are equipped with scales with corresponding marks.

(click to enlarge)

Switches SA1 and SA2 are of any type; however, it is desirable that the contacts used as SA2 be designed for switching current of at least 200 mA.

Network transformer T1 must provide an alternating voltage of 20 V on the secondary winding at a load current of 250 mA.

Field-effect transistors KP303V can be replaced with KP303G - KP303I, bipolar KT361V - with transistors of the KT361 series. KT3107, KT502 with any letter index (except A), and KT814B - on KT814V, KT814G, KT816V, KT816G. Zener diode D813 (VD5) must be selected with a stabilization voltage of at least 12.5 V. Instead, it is permissible to use D814D or any two low-power zener diodes connected in series with a total stabilization voltage of 12.5... 13.5 V. It is possible to replace PPZ-11 ( R3, R8) with variable resistors of any type of group A, and PPZ-43 (R10) with a tuned resistor of any type with a dissipation power of at least 3 W.

Setting up the device begins with selecting the brightness of the HL1 LED. To do this, switch switches SA1 and SA2, respectively, to the “13 V” and “40 mA” positions. and the variable resistor R8 slider is in the middle, connect a resistor with a resistance of 50... 100 Ohms to sockets XS1 and XS2 and find this position for the resistor R3 slider. in which the brightness of the HL1 glow changes. Increasing the difference in the brightness of the glow is achieved by selecting resistor R6.

Then the boundaries of the regulation intervals for the charging current and voltage of the automatic protection zone are set. By connecting a milliammeter with a measurement limit of 200...300 mA to the output of the device. move the slider of resistor R8 to the lower (according to the diagram) position, and switch SA2 to the “200 mA” position. By changing the resistance of the tuning resistor R10, the device needle is deflected to 200 mA. Then move the R8 slider to the upper position and select the resistor R7 to achieve a reading of 36...38 mA. Finally, switch SA2 to the “40 mA” position. return the slider of the variable resistor R8 to the lower position and select R9 to set the output current within 43...45 mA.

To adjust the boundaries of the APZ voltage regulation interval, switch SA1 is set to the “13 V” position, and a DC voltmeter with a measurement limit of 15...20 V is connected to the output of the device. By selecting resistors R1 and R4, readings of 4.5 and 13 V are achieved at the extremes positions of the resistor R3. After this, moving SA1 to the “4.5 V” position, in the same positions of the R3 slider, set the instrument arrow to the 1.45 and 4.5 V marks by selecting resistor R2.

During operation, the APZ voltage is set at the rate of 1.4... 1.45 V per battery being charged.

After such modification, when the set value of the APZ voltage is reached, the HL1 LED will go out and the charging current through the battery will completely stop. As a result, the voltage across it will begin to drop, so the current stabilizer will turn on again and the HL1 LED will light up. In other words, when the set voltage is reached, HL1 will begin to blink, which is sometimes more visual than a certain average brightness. The nature of the battery charging process remains unchanged in both cases.

Power supplies

N. HERTZEN, Berezniki, Perm region.
Radio, 2000, No. 7

During development, the task was to construct a device with the following characteristics:

Wide intervals of change in charging current and voltage automatically stop charging (APC). providing charging of both individual batteries used to power small-sized equipment, and batteries composed of them with a minimum number of mechanical switches;
- close to uniform scales of the regulators, allowing you to set the charging current and voltage of the APP with acceptable accuracy without any measuring instruments;
- high stability of the charging current when the load resistance changes;
- relative simplicity and good repeatability.

Described Charger fully meets these requirements. It is intended for charging D-0.03 batteries. D-0.06. D-0.125. D-0.26. D-0.55. TsNK-0.45. NKGC-1.8. their imported analogues and batteries made from them. Up to the set threshold for switching on the APP system, the battery is charged with a stabilized current, independent of the type and number of elements, and the voltage on it gradually increases as it charges. After the system is triggered, the previously set constant voltage is stably maintained on the battery, and the charging current decreases. In other words, the battery does not recharge or discharge, and it can remain connected to the device for a long time.

The device can be used as a power supply for small-sized equipment with adjustable voltage from 1.5 to 13 V and protection against overload and short circuit in the load.

The main technical characteristics of the device are as follows:

Charging current at the limit "40 mA" - 0...40, at the limit "200 mA" - 40...200 mA;
- instability of the charging current when the load resistance changes from 0 to 40 Ohms - 2.5%;
- the limits of regulation of the APP response voltage are 1.45... 13 V.

Charger circuit

A current source on the transistor \L"4 is used as a charging current stabilizer. Depending on the position of the switch SA2, the load current In is determined by the ratios: I N = (U B - U BE)/R10 and I H = (U B - U BE )/(R9 + R10), where U B is the voltage at the base of transistor VT4 relative to the positive bus, V; U BE is the voltage drop at its emitter junction, V; R9, R10 are the resistances of the corresponding resistors, Ohms.

The device parts are mounted on a printed circuit board, the drawing of which is shown in Fig. 2. It is made by cutting through foil and is designed for the installation of permanent resistors MLT, trimmer (wire) PPZ-43. capacitors K52-1B (C1) and KM (C2). Transistor VT4 is installed on a heat sink with an effective thermal dissipation area of 100 cm 2. Variable resistors R3 and R8 (PPZ-11 group A) are fixed on the front panel of the device and are equipped with scales with corresponding marks.

Switches SA1 and SA2 are of any type; however, it is desirable that the contacts used as SA2 be designed for switching current of at least 200 mA.

Network transformer T1 must provide an alternating voltage of 20 V on the secondary winding at a load current of 250 mA.

Field-effect transistors KPZZV can be replaced with KPZZG - KPZOZI, bipolar KT361V - with transistors of the KT361 series. KT3107, KT502 with any letter index (except A), and KT814B - to KT814V. KT814G. KT816V. KT816G. Zener diode D813 (VD5) must be selected with a stabilization voltage of at least 12.5 V. Instead, it is permissible to use D814D or any two low-power zener diodes connected in series with a total stabilization voltage of 12.5... 13.5 V. It is possible to replace PPZ-11 (R3. R8) with variable resistors any type of group A, and PPZ-43 (R10) - a tuned resistor of any type with a dissipation power of at least 3 W.

During operation, the APZ voltage is set at the rate of 1.4... 1.45 V per battery being charged.

If the device is not intended to be used to power radio equipment, the indication of the end of charging by the extinguishing of the LED can be replaced by its blinking, for which it is enough to introduce hysteresis into the comparator - supplement the device with resistors R12, R13 (Fig. 3). and remove resistor R6. After such modification, when the set value of the APZ voltage is reached, the HL1 LED will go out and the charging current through the battery will completely stop. As a result, the voltage across it will begin to drop, so the current stabilizer will turn on again and the HL1 LED will light up. In other words, when the set voltage is reached, HL1 will begin to blink, which is sometimes more visual than a certain average brightness. The nature of the battery charging process remains unchanged in both cases.

Every car owner needs a battery charger, but it costs a lot, and regular preventive trips to a car service center are not an option. Battery service at a service station takes time and money. In addition, with a discharged battery, you still need to drive to the service station. Anyone who knows how to use a soldering iron can assemble a working charger for a car battery with their own hands.

A little theory about batteries

Any battery is a storage device for electrical energy. When voltage is applied to it, energy is stored due to chemical changes inside the battery. When a consumer is connected, the opposite process occurs: a reverse chemical change creates voltage at the terminals of the device, and current flows through the load. Thus, in order to get voltage from the battery, you first need to “put it down,” that is, charge the battery.

Almost any car has its own generator, which, when the engine is running, provides power to the on-board equipment and charges the battery, replenishing the energy spent on starting the engine. But in some cases (frequent or difficult engine starts, short trips, etc.) the battery energy does not have time to be restored, and the battery is gradually discharged. There is only one way out of this situation - charging with an external charger.

How to find out the battery status

To decide whether charging is necessary, you need to determine the state of the battery. The simplest option - “turns/does not turn” - is at the same time unsuccessful. If the battery “doesn’t turn”, for example, in the garage in the morning, then you won’t go anywhere at all. The “does not turn” condition is critical, and the consequences for the battery can be dire.

The optimal and 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 voltage on the terminals of the battery disconnected from the load (!) 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, the “car battery” (especially a maintenance-free one) will fail.

Correct 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 realistic and not particularly difficult. To do this, you need to have basic knowledge of electrical engineering and be able to hold a soldering iron in your hands.

Simple 6 and 12 V device

This scheme is the most basic and budget-friendly. Using this charger, you can efficiently charge any lead-acid battery with an operating voltage of 12 or 6 V and an electrical capacity of 10 to 120 A/h.

The device consists of a step-down transformer T1 and a powerful rectifier assembled using 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 circuit of the primary winding of the transformer. Thanks to the multiple “weight” of each switch, various combinations allow you to stepwise adjust the charging current in the range of 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 required, 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. To monitor the voltage on the battery, use a voltmeter PU1, the charging current is monitored using an ammeter PA1.

The design can use any power transformer with a power of about 300 W, including homemade ones. It should produce a voltage of 22–24 V on the secondary winding at a current of up to 10–15 A. 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 are suitable. D214 or D242 are suitable. They should be installed through insulating gaskets on a radiator with a dissipation area of at least 300 cm2.

Capacitors C2-C5 must be non-polar paper with an operating voltage of at least 300 V. Suitable, for example, are MBChG, KBG-MN, MBGO, MBGP, MBM, MBGCh. Similar cube-shaped capacitors were widely used as phase-shifting capacitors for electric motors in household appliances. A DC voltmeter of type M5−2 with a measurement limit of 30 V was used as PU1. 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 adjustment. 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 the charging currents using an ammeter.

With continuously adjustable current

Using this scheme, it is more difficult to assemble a charger for a car battery with your own hands, but it can be repeated and also does not contain scarce parts. With its help, it is possible to charge 12-volt batteries with a capacity of up to 120 A/h, the charge current is smoothly regulated.

The battery is charged using a pulsed current; a thyristor is used as a regulating element. In addition to the knob for smoothly adjusting the current, this design also has a mode switch, when turned on, the charging current doubles.

The charging mode is controlled visually using the RA1 dial gauge. 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 is an indicator lamp. 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 on the secondary winding of 18–24 V at a current of up to 15 A. If you don’t have a suitable device at hand, you can make it yourself from any network transformer with a power of 250–300 W. To do this, wind all windings from the transformer except the mains winding, and wind one secondary winding 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 dispersion area of at least 200 sq. cm. The power installation of the device is done with wires of minimal 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 withstanding 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, monitoring 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 the characteristics of the device will be decent. With its help, batteries are charged with a current of up to 10 A, adjusting the current and charge voltage. The only condition is that the power supply is desirable on the TL494 controller.

For creating DIY car charging from a computer power supply you will have to assemble the circuit shown in the figure.

Step by step steps required to finalize the operation will look like this:

Bite off all the power bus wires, with the exception of the yellow and black ones.
Connect the yellow and separately black wires together - these will be the “+” and “-” chargers, 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 power supply casing - these are the controls for regulating the voltage and charging current, respectively.
Using a suspended installation, assemble the circuit shown in the figure above.

If the installation is done correctly, then the modification is complete. All that remains is to equip the new charger with a voltmeter, an ammeter and wires with alligator clips for connecting to the battery.

In the design it is possible to use any variable and fixed resistors, except for the current resistor (the lower one in the circuit with a nominal value of 0.1 Ohm). Its power dissipation is at least 10 W. 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 10 A shunt from a Chinese digital tester or a C5-16MV resistor. Another option is two 5WR2J resistors connected in parallel. Such resistors are found 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 Extend battery life and maintain your health:

The question of creating a simple battery charger with your own hands has been clarified. Everything is quite simple, all you have to do is stock up on the necessary tools and you can safely get to work.