How to make a battery charger. Homemade car charger from parts from old devices

This Charger I made it for charging 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:

Still needed electrolytic capacitor 2200 uF at 50 V, transformer for the TS-180-2 charger (see how to solder the TS-180-2 transformer), wires, power plug, fuses, 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 mains plug and a fuse to the primary winding of the transformer TS-180-2, install diode bridge to 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:

The alternating voltage at the terminals of the secondary winding is 14.3 volts (mains voltage 228 volts).
Constant pressure after the diode bridge and capacitor 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

The DC-DC converter board has two trimmer resistor, 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 output of the device, and the current equal to zero. Use the voltage potentiometer to set the output to 5 volts. Connect the output wires to each other, set the current using the current potentiometer short circuit 6 A. Then eliminate the short circuit by disconnecting the output wires and using the voltage potentiometer, 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 parallelized. 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.

Automotive on-board network until the power plant starts up and supplies power accumulator battery. But she herself electrical energy does not produce. The battery is simply a container for electricity, which is stored in it and, if necessary, given to consumers. Afterwards, the expended energy is restored due to the operation of the generator, which produces it.

But even constant recharging of the battery from a generator is not able to completely restore the expended energy. This requires periodic charging from external source, not the generator.

Design and principle of operation of the charger

Chargers are used to produce. These devices operate from a 220 V network. In fact, the charger is a conventional electrical energy converter.

It takes the 220 V alternating current, lowers it and converts it into D.C. voltage up to 14 V, that is, up to the voltage that the battery itself produces.

Currently in production a large number of all kinds of chargers - from primitive and simple ones to devices with big amount all kinds of additional functions.

Chargers are also sold, which, in addition to possibly recharging the battery installed on the car, can also start power plant. Such devices are called charging and starting devices.

There are also autonomous charging and starting devices that can recharge the battery or start the engine without connecting the device itself to a 220 V network. Inside such a device, in addition to equipment that converts electrical energy, there is also one, which makes such a device autonomous, although the battery of the device is also After each release of electricity, charging is required.

Video: How to make a simple charger

As for conventional chargers, the simplest of them consists of only a few elements. The main element of such a device is a step-down transformer. It lowers the voltage from 220 V to 13.8 V, which is the most optimal for charging the battery. However, the transformer only lowers the voltage, but converting it from alternating current to direct current is performed by another element of the device - a diode bridge, which rectifies the current and divides it into positive and negative poles.

Behind the diode bridge, an ammeter is usually included in the circuit, which shows the current strength. The simplest device uses a dial ammeter. In more expensive devices, it can be digital, and in addition to the ammeter, a voltmeter can also be built-in. Some chargers have the ability to select voltage; for example, they can charge both 12-volt and 6-volt batteries.

Wires with “positive” and “negative” terminals come out of the diode bridge, which connect the device to the battery.

All this is enclosed in a housing, from which comes a wire with a plug for connecting to the network, and wires with terminals. To protect the entire circuit from possible damage, a fuse is included in it.

In general, this is the entire circuit of a simple charger. Charging the battery is relatively simple. The terminals of the device are connected to the discharged battery, but it is important not to mix up the poles. The device is then connected to the network.

At the very beginning of charging, the device will supply voltage with a current of 6-8 amperes, but as charging progresses, the current will decrease. All this will be displayed on the ammeter. If the battery is fully charged, the ammeter needle will drop to zero. This is the entire process of charging the battery.

The simplicity of the charger circuit makes it possible to manufacture it yourself.

Making your own car charger

Now let's look at the simplest chargers that you can make yourself. The first will be a device that schematic diagram very similar to what was described.

The diagram shows:
S1 - power switch (toggle switch);
FU1 - 1A fuse;
T1 - transformer TN44;
D1-D4 - diodes D242;
C1 - capacitor 4000 uF, 25 V;
A - 10A ammeter.

So, to make a homemade charger you will need a step-down transformer TS-180-2. Such transformers were used on old tube TVs. Its peculiarity is the presence of two primary and secondary windings. Moreover, each of the secondary output windings has 6.4 V and 4.7 A. Therefore, in order to achieve the 12.8 V necessary for charging the battery, which this transformer is capable of, you need to produce serial connection these windings. For this, a short wire with a cross-section of at least 2.5 mm is used. sq. The jumper connects not only the secondary windings, but also the primary ones.

Video: The simplest battery charger

Next, you will need a diode bridge. To create it, 4 diodes are taken, designed for a current of at least 10 A. These diodes can be fixed on a textolite plate, and then they can be connected correctly. Wires are connected to the output diodes, which the device will connect to the battery. At this point, the assembly of the device can be considered complete.

Now about the correctness of the charging process. When connecting a device to a battery, do not reverse the polarity, otherwise you can damage both the battery and the device.

When connecting to a battery, the device must be completely de-energized. You can turn it on only after connecting it to the battery. It should also be disconnected from the battery after disconnecting from the network.

A heavily discharged battery cannot be connected to the device without a means that reduces the voltage and current, otherwise the device will supply a high current to the battery, which can damage the battery. An ordinary 12-volt lamp, which is connected to the output terminals in front of the battery, can act as a reducing agent. The lamp will light up when the device is operating, thereby partially absorbing the voltage and current. Over time, after the battery is partially charged, the lamp can be removed from the circuit.

When charging, you need to periodically check the state of charge of the battery, for which you can use a multimeter, voltmeter or load plug.

A fully charged battery, when checking the voltage on it, should show at least 12.8 V, if the value is lower, it is required further charging, to bring this indicator to the desired level.

Video: DIY car battery charger

Because the this scheme It does not have a protective case; you should not leave the device unattended during operation.

And even if this device does not provide the optimal 13.8 V output, it is quite suitable for recharging the battery, although after about two years of using the battery, you will still need to charge it with a factory device that provides everything optimal parameters to charge the battery.

Transformerless charger

The design is interesting in design homemade device, which does not have a transformer. His role in this device performs a set of capacitors designed for a voltage of 250 V. There must be at least 4 such capacitors. The capacitors themselves are connected in parallel.

A resistor is connected in parallel to the set of capacitors, designed to suppress the residual voltage after disconnecting the device from the network.

Next, you will need a diode bridge to operate with a permissible current of at least 6 A. It is connected to the circuit after a set of capacitors. And then the wires that will connect the device to the battery are connected to it.

Every motorist sooner or later has problems with the battery. I did not escape this fate either. After 10 minutes of unsuccessful attempts to start my car, I decided that I needed to purchase or make my own charger. In the evening, after checking out the garage and finding a suitable transformer there, I decided to do the charging myself.

There, among the unnecessary junk, I also found a voltage stabilizer from an old TV, which, in my opinion, would work wonderfully as a housing.

Having scoured the vast expanses of the Internet and really assessed my strengths, I probably chose the most simple diagram.

After printing out the diagram, I went to a neighbor who is interested in radio electronics. Within 15 minutes, he collected the necessary parts for me, cut off a piece of foil PCB and gave me a marker for drawing circuit boards. Spending about an hour, I drew reasonable fee(spacious installation dimensions of the case allow). I won’t tell you how to etch the board, there is a lot of information about this. I took my creation to my neighbor, and he etched it for me. In principle, you could buy circuit board and do everything on it, but as they say to a gift horse...
Having drilled all the necessary holes and displayed the pinout of the transistors on the monitor screen, I took up the soldering iron and after about an hour I had a finished board.

A diode bridge can be purchased on the market, the main thing is that it is designed for a current of at least 10 amperes. I found D 242 diodes, their characteristics are quite suitable, and I soldered a diode bridge on a piece of PCB.

The thyristor must be installed on a radiator, since it gets noticeably hot during operation.

Separately, I must say about the ammeter. I had to buy it in a store, where the sales consultant also picked up the shunt. I decided to modify the circuit a little and add a switch so that I could measure the voltage on the battery. Here, too, a shunt was needed, but when measuring voltage, it is connected not in parallel, but in series. The calculation formula can be found on the Internet, I’ll add that great importance has the power dissipation of shunt resistors. According to my calculations, it should have been 2.25 watts, but my 4-watt shunt was heating up. The reason is unknown to me, I don’t have enough experience in such matters, but having decided that I mainly needed the readings of an ammeter, and not a voltmeter, I decided on it. Moreover, in voltmeter mode the shunt noticeably warmed up within 30-40 seconds. So, having collected everything I needed and checked everything on the stool, I took up the body. Having completely disassembled the stabilizer, I took out all its contents.

Having marked the front wall, I drilled holes for variable resistor and a switch, then a drill small diameter I drilled holes around the circumference for an ammeter. Sharp edges were finished with a file.

After racking my brains a bit over the location of the transformer and radiator with thyristor, I settled on this option.

I bought a couple more crocodile clips and everything is ready to charge. The peculiarity of this circuit is that it only works under load, so after assembling the device and not finding voltage at the terminals with a voltmeter, do not rush to scold me. Just hang at least a car light bulb on the terminals, and you will be happy.

Take a transformer with a voltage on the secondary winding of 20-24 volts. Zener diode D 814. All other elements are indicated in the diagram.

Not every car owner has a charger for car battery. Many people do not consider it necessary to purchase such a unit, believing that they will not need it. However, as practice shows, at least once in his life every driver finds himself in a situation where he needs to drive, but...

It is not necessary to purchase a new factory charger; you can make one yourself from, for example, old electrical appliances. There are many options for creating your own car chargers, but most of them have significant drawbacks.

The transformer used is type TN61-22, the windings are connected in series. Coefficient useful action charging is no less than 0.8, current is no more than 6 amperes, so a transformer with a power of 150 watts is perfect. The transformer winding must provide a voltage of up to 20 volts with a current of up to 8 amperes. With absence finished model you can take any transformer required power and reel in the secondary treatment. To calculate the number of turns, use a calculator specially designed for this, which can be found on websites on the Internet.
Suitable capacitors are from the MBGC series, designed for a current voltage of at least 350 volts. If the capacitor supports operation with alternating current, then it is suitable for creating a charger.
Absolutely any diodes will do, but they must be rated for a current of up to 10 amperes.
An analogue of AN6551 - KR1005UD1 can be selected as an operational amplifier. This is exactly the model that was previously inserted into VM-12 tape recorders. It is very good in that it does not require bipolar power supply or correction circuits during operation. KR1005UD1 operates with voltage fluctuations of more than 7 V. In general, this model can be replaced by any similar one. For example, it could be LM158, LM358 and LM258, but then you will have to change the printed circuit board design.
Any electromagnetic head, for example M24, is suitable for measuring voltage and current. If voltage indicators do not interest you, then simply install an ammeter that is designed for direct current. Otherwise, the voltage is controlled with a tester or multimeter.

The video shows the creation of a car charger:

Checking and setting

In the case when all the elements are in working order and the assembly occurred without errors, the circuit should work immediately. And the car owner only needs to set the voltage threshold using a resistor. When charging reaches this device, it will switch to low current mode.

Adjustment is carried out at the time of charging. But it’s probably better to insure yourself: set up and test protection and regulation schemes. From measuring instruments To do this, you will need a multimeter or tester designed to work with constant voltage.

How to charge the assembled device

There are certain rules that must be followed when using a homemade car charger.

It is important, even before charging, to clean it of dust and dirt. Then wipe with a soda solution to remove acid residues. If there are acid particles on the battery, the soda will begin to foam.

The plugs for filling acids in the battery must be unscrewed. This is done so that the gases formed in the battery have the opportunity to escape. Then you should check the quantity: if the level is less than optimal, add distilled water.

After this, use the switch to set a certain charge current reading, connect assembled device, taking into account the polarity. Accordingly, the positive charging terminal should be connected to the positive terminal of the battery. Keeping the switch in the lower position will cause the device's arrow to indicate the current voltage. The voltmeter begins to display current voltage at the same time.

If it has a capacity of 50 Ah, for this moment If it is charged to 50%, then you should first set the current to 25 amperes, gradually reducing it to zero. Automatic charging devices operate on a similar principle. They help charge your car battery to 100%. True, such devices are very expensive. With timely charging, such an expensive device is not needed.

To summarize, we can say that, even using used parts from old devices, you can assemble a pretty decent charger for a car battery. If you don’t have the ability to do this yourself, then you can always find such a craftsman in every garage cooperative. And it will certainly cost significantly less than buying a new factory device.

A homemade charger can come in handy if your battery runs out and you don’t have a normal electrical appliance at hand. Making it yourself is quite simple, you just need to have a few basic elements of the chain. Next, we will take a detailed look at the homemade device, as well as instructions on how to make a battery charger with your own hands.

Homemade device

So, to assemble the charger we need the following elements:

Power transformer. A part from an old TV would be ideal. Usually transformers TS-180-2 are installed, so we will consider it in the article.
Fiberglass plate.
D242A diodes – 4 pcs., you can use products of other markings, but they must be rated for a current of more than 10 A.
Radiators for the diode - 4 pcs., area 25 cm 2 (or better 32 cm 2).
Demountable electrical plug.
Copper wires with a cross section of no less than 2.5 mm 2
10 A and 0.5 A fuse.
Soldering iron.

Having prepared all the materials, you can proceed to the process of assembling the car charger itself.

Assembly technology

To make a charger for a car battery with your own hands, you need to follow the step-by-step instructions:

Creating a diagram homemade charging for battery. In our case it will look like this:
We remove the secondary windings of the TV transformer (the primary must be left) and connect them in series in the circuit. As a result, you should get 12.8 V at the output, because The voltages of the secondary windings are 6.4 V and 4.7 V.
Using a copper wire, we connect pins 9 and 9’ to each other.
On a fiberglass plate we assemble a diode bridge from diodes and radiators (as shown in the photo).
We connect pins 10 and 10’ to the diode bridge.
We connect the primary windings of the TS-180-2 television transformer in series.
We install a jumper between pins 1 and 1’.
We attach to pins 2 and 2’ using a soldering iron power cord with a fork.
We connect a 0.5 A fuse to the primary circuit, and a 10-amp fuse to the secondary circuit, respectively.
We limit the charging current by connecting a 12-volt light bulb to the neutral conductor gap, in series with the battery itself. The power should vary between 21-60 W.

A visual example of the finished product

Operating rules

The disadvantage of a homemade 12V battery charger is that after fully charged battery automatic shutdown the device does not occur. That is why you will have to periodically glance at the scoreboard in order to turn it off in time. Another important nuance– checking the charger “for spark” is strictly prohibited.

Additional precautions include:

when connecting the terminals, make sure not to confuse “+” and “-”, otherwise a simple homemade battery charger will fail;
connection to the terminals should only be made in the off position;
The multimeter must have a measurement scale greater than 10 A.