All motorists have found themselves in such an unpleasant situation. There are two options: start the car with a charged battery from a neighbor’s car (if the neighbor doesn’t mind), in the jargon of car enthusiasts this sounds like “lighting a cigarette.” Well, the second way out is to charge the battery.

When I found myself in this situation for the first time, I realized that I urgently needed a charger. But I didn’t have an extra thousand rubles to buy charger. I found it on the Internet simple diagram and decided to assemble the charger on my own.

I simplified the transformer circuit. Windings from the second column are indicated with a stroke.

F1 and F2 are fuses. F2 is needed to protect against short circuit at the output of the circuit, and F1 – from excess voltage in the network.

Description of the assembled device

Here's what I got. It looks so-so, but most importantly it works.

Transformer

Now let's talk about everything in order. A power transformer of the TS-160 or TS-180 brand can be obtained from old black-and-white Record TVs, but I didn’t find one and went to a radio store. Let's take a closer look.

Here are the petals where the leads of the transformer windings are soldered.

And here right on the transformer there is a sign indicating which petals have what voltage. This means that if we apply 220 Volts to petal No. 1 and 8, then on petals No. 3 and 6 we will get 33 Volts and a maximum load current of 0.33 Ampere, etc. But we are most interested in windings No. 13 and 14. On them we can get 6.55 Volts and a maximum current of 7.5 Amperes.

In order to charge the battery, we just need a large amount of current. But we don’t have enough voltage... The battery produces 12 Volts, but in order to charge it, the charging voltage must exceed the battery voltage. 6.55 Volts will not work here. The charger should give us 13-16 Volts. Therefore, we resort to a very cunning solution.

As you noticed, the transformer consists of two columns. Each column duplicates another column. The places where the winding leads come out are numbered. In order to increase the voltage, we simply need to connect two windings in series. To do this, we connect windings 13 and 13′ and remove the voltage from windings 14 and 14′. 6.55 + 6.55 = 13.1 Volts. This is the alternating voltage we will get.

Diode bridge

In order to rectify the alternating voltage, we use a diode bridge. We assemble a diode bridge using powerful diodes, because a decent amount of current will pass through them. To do this, we will need D242A diodes or some others designed for a current of 5 Amperes. A direct current of up to 10 Amps can flow through our power diodes, which is ideal for our homemade charger.

You can also separately buy a diode bridge as a ready-made module. The KVRS5010 diode bridge, which can be bought on Ali at this link or in the nearest radio store

A fully charged battery has low voltage. As it charges, the voltage across it becomes higher and higher. Consequently, the current in the circuit at the very beginning of charging will be very large, and then it will decrease. According to the Joule-Lenz Law, when the current is high, the diodes will heat up. Therefore, in order not to burn them, you need to take heat from them and dissipate it in the surrounding space. For this we need radiators. As a radiator, I disassembled a non-working computer power supply, cut a tin into strips and screwed a diode onto them.

Ammeter

Why is there an ammeter in the circuit? In order to control the charging process.

Don't forget to connect the ammeter in series with the load.

When the battery is completely discharged, it begins to consume (I think the word “eat” is inappropriate here) current. It consumes about 4-5 Amps. As it charges, it uses less and less current. Therefore, when the arrow of the device shows 1 Ampere, the battery can be considered charged. Everything is ingenious and simple :-).

Crocodiles

We remove two crocodiles for the battery terminals from our charger. When charging, do not confuse the polarity. It's better to mark them somehow or take different colors.

If everything is assembled correctly, then on the crocodiles we should see this kind of signal shape (in theory, the tops should be smoothed out, since it’s a sinusoid), but is that something you can present to our electricity provider))). Is this your first time seeing something like this? Let's run here!

Constant voltage pulses charge the battery better than pure voltage D.C.. How to obtain pure direct current from alternating current is described in the article How to obtain direct current from alternating voltage.

Conclusion

Don't be lazy to modify your device fuses. Fuse ratings on the diagram. Do not check the voltage on the charger crocodiles for a spark, otherwise you will lose the fuse.

Attention! The circuit of this memory is intended for fast charging your battery in critical cases when you urgently need to go somewhere in 2-3 hours. Do not use it for everyday use, as it charges at maximum current, which is not the best charging mode for your battery. When overcharging, the electrolyte will begin to “boil” and toxic fumes will begin to be released into the surrounding area.

Those who are interested in the theory of chargers (chargers), as well as the circuits of normal chargers, then be sure to download this book on this link. It can be called the bible on chargers.

Buy a car charger

Aliexpress has really good and smart chargers that are much lighter than ordinary transformer chargers. Their price averages from 1000 rubles.

The simplest and cheapest switch is two diodes connected in an “OR” circuit. The load connected to each power source (battery and adapter) through separate Schottky diodes is powered by the source whose voltage is higher.

The disadvantage of this approach is the power dissipation (PD = Ibatt × Vdiode) and voltage drop (Vdiode = 350 mV at 0.5 A for the PMEG2010AEH diode) when the battery is connected to the load. These losses are not particularly significant if high-voltage multi-cell batteries are used. But for a single-cell Li+ or two-cell NiMH battery, power losses and voltage drop across the diodes cannot be neglected.

An alternative to diodes can be charger chips that have a POK output (POK - “Power OK”), for example the MAX8814 chip, which switches loads with a voltage drop of only 45 mV at a current of 0.5 A (Fig. 1), which gives a gain compared to 305 mV diodes. Power losses in such circuits are 152.5 mW (175 mW - 22.5 mW) less than in circuits with diode “OR”. At lower currents, the circuit's performance becomes even better. So, with a load current of 100 mA, for example, the voltage drop across the diode is 270 mV, and on transistors of an alternative circuit it is only 10 mV.

This circuit switches the load without any involvement of the microcontroller or system program. When the load is powered by batteries and Vdc In is disabled, the POK output of the U1 chip high voltage. In this case, the load is connected to the battery through Q4 and Q3. Node 1 receives battery voltage through R2, and transistors Q1 and Q2 are turned off. When Vdc In is connected to a constant voltage source, Q1 and Q2 remain off for a while thanks to capacitor C1, which increases the voltage at node 1 to Vbatt + Vdc.

High voltage appears at the gates of Q1 and Q2 immediately after Vdc is applied. To prevent the possibility of damage to the POK pin, transistor Q5 is added as a source follower. The gate of Q5 is supplied with battery voltage and the POK pin will not exceed this voltage. When the voltage at the POK pin drops, current begins to flow through Q5, the voltage at the gates of Q1 and Q2 goes low, and transistors Q1 and Q2 turn off. Vdc In is connected to the load, and U1 begins to charge the battery. C1 and R1 create a slight delay to allow Q3 to turn off completely and avoid uncontrolled current flowing to the battery.

If you disable external source DC voltage from Vdc In, the POK pin will go into a high impedance state and battery current will flow through the internal diode of transistor Q3. The load voltage will be equal to Vbatt - Vdiode. Due to the battery voltage applied to the gate, Q5 will be open until POK reaches a level sufficient to connect the load through Q4 and Q3. Rice. Figure 2 illustrates the behavior of this circuit when the load is switched from a constant voltage source to the battery and then back to a constant voltage source.

By changing the circuit, you can use charge control chips that do not have a POK output, for example, the MAX1507 (Fig. 3). A signal similar to POK can be generated by a comparator (U3) comparing Vdc In with the battery voltage. The response of such a circuit is very similar to the response of the original circuit (Fig. 4).

Desulfating scheme charger devices proposed by Samundzhi and L. Simeonov. The charger is made using a half-wave rectifier circuit based on diode VI with parametric voltage stabilization (V2) and a current amplifier (V3, V4). The H1 signal light lights up when the transformer is connected to the network. The average charging current of approximately 1.8 A is regulated by selecting resistor R3. The discharge current is set by resistor R1. The voltage on the secondary winding of the transformer is 21 V (amplitude value 28 V). The voltage on the battery at the rated charging current is 14 V. Therefore, the charging current of the battery occurs only when the amplitude of the output voltage of the current amplifier exceeds the battery voltage. During one period of alternating voltage, one pulse is formed charger then during time Ti. Radomkrofon circuits The battery discharge occurs during the time Tz = 2Ti. Therefore, the ammeter shows the average importance charger current, equal to approximately one third of the amplitude value of the total charger and discharge currents. You can use the TS-200 transformer from the TV in the charger. The secondary windings are removed from both coils of the transformer and a new winding consisting of 74 turns (37 turns on each coil) is wound with PEV-2 1.5 mm wire. Transistor V4 is mounted on a radiator with an effective surface area of ​​​​approximately 200 cm2. Details: Diodes VI type D242A. D243A, D245A. D305, V2 one or two zener diodes D814A connected in series, V5 type D226: transistors V3 type KT803A, V4 type KT803A or KT808A. When setting up...

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Charger being considered car batteries manufactured on the basis of a converter for powering 12V halogen lamps of the TASCHIBRA type. Converters of this type are often found on sale among electrical products. TASCHIBR is distinguished by fairly good reliability and preservation of performance at negative ambient temperatures.

This device is made on the basis of a self-oscillating converter with a conversion frequency of approximately 7 to 70 kHz, which depends on the resistance of the converter connected to the output active load. As the load power increases, the conversion frequency increases. Interesting feature TASCHIBR is a disruption of generation when the load increases beyond the permissible limit, which can be a kind of protection against short circuit. Let me make a reservation right away that I was not going to consider options for the so-called “rework” or “refinement” of these converters, which is described in some publications. I propose to use TASCHIBR "as is" with the exception, perhaps, of increasing the number of turns of the secondary winding, which is necessary in order to ensure the charging current of the desired value

As is known, to ensure the required charging current, a voltage of at least 15-16 V must be generated on the secondary winding.

The picture shows that the existing white secondary winding wire was used as additional turns. For a 50 W converter it was enough to add 2 turns to the secondary winding. In this case, it is necessary to ensure that the direction of winding is carried out in the direction (i.e., consistent) of the existing winding, in other words, that the magnetic flux of the newly appearing turns coincides in direction with the magnetic flux of the “native” secondary winding of TASHIBR, designed to power 12V halogen lamps and located on top of the primary at 220V.

The bridge rectifier is made from Schottky diodes such as 1N5822. It is possible to use domestic high-speed diodes, for example KD213.

The optimal charging process is based on limiting both the charging current and the voltage level at the battery terminals. Let's set a current of approximately 1.5 A and a voltage of no more than 14.5V. The control circuit shown in Fig. 1 has the characteristics under consideration. The key element of the circuit is a triac V type BT134-600, switched on by an optosimistor MOS3083. The current limitation is formed by the voltage drop across resistor R2 with a resistance of 1 Ohm and a dissipation power of 2 W. When the voltage drop across it exceeds 1-1.5 V, transistor VT2 opens and bypasses the LED of the optosimistor VD5, interrupting the power supply to the TASCHIBR. If it is necessary to increase the charging current level, for example to 3 - 4 A, it is necessary to reduce the resistance of resistor R2 accordingly, paying attention to the choice of the required dissipation power for this resistor. As the battery charges, the voltage at its terminals approaches 14.5V. Current begins to flow through the zener diode VD3, which causes transistor VT3 to open. At the same time, the VD4 LED begins to flicker, signaling the end of the charging process, and a current begins to flow through the VD2 diode, opening the VT2 transistor, which leads to the locking of the triac V. To indicate the fact of the opening of the triac, a transistor switch VT1 with a VD1 LED in the circuit of its collector is used . This transistor must be germanium, due to the small voltage drop across the optosimistor LED (about 1V).

Disadvantages of the charger of this type It should be noted that its performance depends on the voltage level on the battery, since, obviously, the circuit initially receives power from battery, which to ensure the operation of the circuit should not fall below 6V. However, due to the rarity similar cases- you can put up with this. If forced charging is necessary, you can install an additional SW button, as shown in the diagram, by pressing which you can bring the battery voltage to the required level.

The charger was made in a single copy. Printed circuit board was not developed. The device is mounted in a machine housing of a suitable size.

List of radioelements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
VT1	Bipolar transistor	MP37B	1			To notepad
VT2	Bipolar transistor	BC547C	1			To notepad
VT3	Bipolar transistor	BC557B	1			To notepad
V	Triac	BT134-600	1			To notepad
VD1	Light-emitting diode	ARL-3214UGC	1			To notepad
VD2	Rectifier diode	1N4148	1			To notepad
VD3	Zener diode	D814D	1			To notepad
VD4	Light-emitting diode	ARL-3214URC	1			To notepad
VD5	Optosimistor	MOC3083	1			To notepad
D1	Schottky diode	1N5822	4	Diode bridge		To notepad
C1	Electrolytic capacitor	470 µF	1			To notepad
C2	Capacitor	1 µF	1			To notepad
F1	Fuse	1A	1			To notepad
R1, R3	Resistor	820 Ohm	2			To notepad
R2	Resistor	1 ohm	1	2W		To notepad
R4, R5	Resistor	6.8 kOhm	2

I made this charger to charge car batteries, output voltage 14.5 volts, maximum charge current 6 A. But it can also charge other batteries, such as lithium-ion ones, since the output voltage and output current can be adjusted within a wide range. The main components of the charger were purchased on the AliExpress website.

These are the components:

You will also need an electrolytic capacitor 2200 uF at 50 V, a transformer for the TS-180-2 charger (see how to solder the TS-180-2 transformer), wires, a power plug, fuses, a radiator for the diode bridge, crocodiles. You can use another transformer with a power of at least 150 W (for a charging current of 6 A), the secondary winding must be designed for a current of 10 A and produce a voltage of 15 - 20 volts. The diode bridge can be assembled from individual diodes designed for a current of at least 10A, for example D242A.

The wires in the charger should be thick and short. The diode bridge must be mounted on a large radiator. It is necessary to increase the radiators of the DC-DC converter, or use a fan for cooling.

Charger assembly

Connect the cord with power plug and fuse to primary winding transformer TS-180-2, install the diode bridge on the radiator, connect the diode bridge and the secondary winding of the transformer. Solder the capacitor to the positive and negative terminals of the diode bridge.

Connect the transformer to a 220 volt network and measure the voltages with a multimeter. I got the following results:

1. The alternating voltage at the terminals of the secondary winding is 14.3 volts (mains voltage 228 volts).
2. The constant voltage after the diode bridge and capacitor is 18.4 volts (no load).

Using the diagram as a guide, connect a step-down converter and a voltammeter to the DC-DC diode bridge.

Setting the output voltage and charging current

There are two trimming resistors installed on the DC-DC converter board, one allows you to set the maximum output voltage, the other allows you to set the maximum charging current.

Plug in the charger (nothing is connected to the output wires), the indicator will show the voltage at the device output and the current is zero. Use the voltage potentiometer to set the output to 5 volts. Close the output wires together, use the current potentiometer to set the short circuit current to 6 A. Then eliminate the short circuit by disconnecting the output wires and use the voltage potentiometer to set the output to 14.5 volts.

This charger is not afraid of a short circuit at the output, but if the polarity is reversed, it may fail. To protect against polarity reversal, a powerful Schottky diode can be installed in the gap in the positive wire going to the battery. Such diodes have a low voltage drop when connected directly. With such protection, if the polarity is reversed when connecting the battery, no current will flow. True, this diode will need to be installed on a radiator, since a large current will flow through it during charging.

Suitable diode assemblies are used in computer units nutrition. This assembly contains two Schottky diodes with a common cathode; they will need to be paralleled. For our charger, diodes with a current of at least 15 A are suitable.

It must be taken into account that in such assemblies the cathode is connected to the housing, so these diodes must be installed on the radiator through an insulating gasket.

It is necessary to adjust the upper voltage limit again, taking into account the voltage drop across the protection diodes. To do this, use the voltage potentiometer on the DC-DC converter board to set 14.5 volts measured with a multimeter directly at the output terminals of the charger.

How to charge the battery

Wipe the battery with a cloth soaked in soda solution, then dry. Remove the plugs and check the electrolyte level; if necessary, add distilled water. The plugs must be turned out during charging. No debris or dirt should get inside the battery. The room in which the battery is charged must be well ventilated.

Connect the battery to the charger and plug in the device. During charging, the voltage will gradually increase to 14.5 volts, the current will decrease over time. The battery can be conditionally considered charged when the charging current drops to 0.6 - 0.7 A.