Homemade charger for a car battery. DIY car battery charger from a computer power supply

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 D.C.. 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. They operate on a similar principle automatic devices for charging. 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.

There are a lot of people in Lately request to write an article or film a video review about the simple charger for a car battery. I decided to write an article and film a video so that questions related to charging car batteries would not arise.

At the same time, users are asked to provide the design of the simple option. Of course, on a quick fix You can make a charger for a car, but without galvanic isolation from a 220 Volt network, this is very dangerous and it is not advisable to always charge the battery with such a charge (we will quickly consider a general collection of chargers in the next article).

Most cheap block power supply is definitely an electronic transformer. Now in stores such a 60-80 watt unit costs only one dollar. 60 watts is quite a lot of power, it turns out to be about 4-5 Amperes of current at a voltage of 14 Volts - it’s quite possible to charge the battery!

The electronic transformer has no protection, so do not short-circuit the output wires, otherwise it will be bad (in best case scenario cotton, at worst - shrapnel wounds with serious consequences).

• The second drawback is that the unit does not turn on without an output load.
• The third disadvantage is output voltage variable - 15 kHz
• The fourth drawback is that the output voltage is 8-10 Volts, which is not enough to charge a car battery.

These problems can be fixed in half an hour. First, let's add protection from short circuit and a system for turning on the unit without an output load, and also increase the output voltage to 14 Volts.

We need wirewound resistor 3-10 Ohms, the higher the rating, the lower the protection operation current, I advise you to use a 3-6 Ohms resistor.

We take a 0.8mm wire, fold it into 4 cores and wind a new winding on the transformer frame. The winding consists of 12-14 turns.

After that, we wind a separate winding in the same direction - only 3 turns with 0.8 mm wire (the wire is not critical -0.4-0.8 mm).

We look at the transformer board and find the OS transformer ( Feedback). It is in the form of a small ring and consists of 3 independent windings - 2 of them are the base windings of transistors, 3 turns each winding. The third winding, the OS winding, consists of only one turn. We unsolder this winding and replace it with a jumper. Next, on the same ring we wind 2 turns of 0.8mm wire and connect the OS resistor in series; we make the connection according to the photo.

Everything is ready - this modification has implemented short-circuit protection at the output, increased the output voltage of the block and the block is now turned on without an output load. All that remains is to add a diode rectifier and a smoothing capacitor after the rectifier. It is advisable to assemble a full-fledged diode bridge from KD213 diodes, but of course any other ones are possible pulse diodes with a current of at least 4-5 A, preferably 10 Amperes or more.

Electrolyte at 1000 uF (You can use 470-2200 uF, or you can remove it altogether)

The output voltage is about 14.5 Volts. We connect the unit to a 220 Volt network and measure the voltage. Next we connect the battery to charge BUT! necessarily through an ammeter. If the current is more than 4 Amps, then we connect a 5-10 watt resistor with a resistance of 0.5-2.2 Ohms in series to one of the power buses (plus or minus) - the resistor must be selected until we get a charge current of about 4A (3. 5-4A). This is necessary so that the unit does not overload and fail.

Finally, some safety tips.

Always connect the electronic transformer to a 220 Volt network in series through a 220 Volt 40-100 watt incandescent lamp, this will avoid explosions if installed incorrectly.

Do not short-circuit the output wires of the electronic transformer. During tests, do not touch the device board when the transformer is connected to a 220 Volt network. Be extremely careful during testing to avoid tragic consequences.

In the video clip he spoke in detail about the rework, if anyone is too lazy to read the article, but is still interested, then watch the video - see you again on the pages of the site - AKA KASYAN

Every owner of a used car is faced with the need to recharge the battery. In addition, batteries are often used as a backup (or main) source of electricity in a garage, barn, or country house without a centralized electricity supply.

To restore the battery charge, you can purchase a ready-made one; there is no shortage of options.

Used to charge car battery

However, many home craftsmen prefer to make their own. If you have a radio engineering background, you can calculate the circuit yourself. And for the majority of hobbyists who know how to hold a soldering iron in their hands, we offer a couple of simple designs.

First of all, let's decide which batteries you need to charge. Typically these are acidic starter batteries, used in cars.

Such a battery can be purchased inexpensively at a car store, or you can use an old one left over from replacing it in your car. a used one may not be able to work as a starter, but it’s easy to connect a lighting device (especially LED) or a radio in the country to it.

How to correctly calculate a homemade charger?

The first rule that needs to be learned is the value of the charge voltage.
Lead-acid batteries have an operating voltage of 12.5 volts. But to charge, you need to apply a voltage in the range of 13.9 - 14.4 volts. Accordingly, the charger must be made with exactly these output parameters.

The next quantity is power.
More precisely, the current strength at which there will be no voltage drop at the output terminals of the charger. If you do not plan to charge batteries with a capacity of more than 65 Ah, a stable current of 12 A is sufficient.

Important! This value must be provided by the output stage of the charger; the current at the 220 volt input will be several times less.

A low-power charger can also charge high-capacity batteries. It will just take much more time.

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 alternating current of the 220 V network, lowers it and converts it into direct current with a voltage of up to 14 V, that is, 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 transforming it with alternating current permanently performed by another element of the device - 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 feature 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.

I made this charger to charge car batteries, the output voltage is 14.5 volts, the maximum charge current is 6 A. But it can also charge other batteries, for example 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 TS-180-2 transformer, 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. AC voltage at terminals secondary winding 14.3 volts (mains voltage 228 volts).
2. 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. 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 used in computer power supplies. 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.