We make our own chargers for car batteries. A simple homemade charger for car batteries with your own hands The simplest charger using an adapter

Very often, especially in the cold season, car enthusiasts are faced with the need to charge a car battery. It is possible, and advisable, to purchase a factory Charger, better charging and starting for use in the garage.

But, if you have electrical engineering skills and certain knowledge in the field of radio engineering, then you can make a simple charger for a car battery with your own hands. In addition, it is better to prepare in advance for the possible event that the battery suddenly discharges far from home or a place where it is parked and serviced.

General information about the battery charging process

Charging a car battery is necessary when the voltage drop across the terminals is less than 11.2 Volts. Despite the fact that the battery can start the car engine even with such a charge, during long-term parking at low voltages, plate sulfation processes begin, which lead to loss of battery capacity.

Therefore, when wintering a car in a parking lot or garage, it is necessary to constantly recharge the battery and monitor the voltage at its terminals. More the best option– remove the battery, put it in a warm place, but still do not forget about maintaining its charge.

The battery is charged using constant or pulsed current. In the case of charging from a constant voltage source, a charge current equal to one tenth of the battery capacity is usually selected.

For example, if the battery capacity is 60 Amp-hours, the charging current should be selected at 6 Amp. However, research shows that the lower the charge current, the less intense the sulfation processes.

Moreover, there are methods for desulfating battery plates. They are as follows. First, the battery is discharged to a voltage of 3 - 5 Volts with high currents of short duration. For example, such as when turning on the starter. Then there is a slow full charge with a current of about 1 Ampere. Such procedures are repeated 7-10 times. There is a desulfation effect from these actions.

Desulfating pulse chargers are practically based on this principle. The battery in such devices is charged with pulsed current. During the charging period (several milliseconds), a short discharge pulse of reverse polarity and a longer charging pulse of direct polarity are applied to the battery terminals.

It is very important during the charging process to prevent the effect of overcharging the battery, that is, the moment when it is charged to ultimate voltage(12.8 - 13.2 Volts depending on the type of battery).

This can cause an increase in the density and concentration of the electrolyte, irreversible destruction of the plates. This is why factory chargers are equipped with electronic system control and shutdown.

Schemes of homemade simple chargers for a car battery

Protozoa

Let's consider the case of how to charge a battery using improvised means. For example, a situation when you left your car near your house in the evening, forgetting to turn off some electrical equipment. By morning the battery was discharged and would not start the car.

In this case, if your car starts well (with half a turn), it is enough to “tighten” the battery a little. How to do it? First, you need a constant voltage source ranging from 12 to 25 volts. Secondly, restrictive resistance.

What can you recommend?

Nowadays, almost every home has a laptop. The power supply of a laptop or netbook usually has output voltage 19 Volts, current not less than 2 amperes. The external pin of the power connector is minus, the internal pin is positive.

As a limiting resistance, and it is mandatory!!!, you can use the car's interior light bulb. You can, of course, have more power from turn signals or even worse stops or dimensions, but there is a possibility of overloading the power supply. The simplest circuit is assembled: minus the power supply - light bulb - minus the battery - plus the battery - plus the power supply. In a couple of hours the battery will be charged enough to start the engine.

If you don’t have a laptop, you can pre-purchase a powerful rectifier diode on the radio market with a reverse voltage of more than 1000 Volts and a current of 3 Amperes. It is small in size and can be put in the glove compartment for an emergency.

What to do in an emergency?

Conventional lamps can be used as a limiting load incandescent at 220 Volt. For example, a 100 Watt lamp (power = voltage X current). Thus, when using a 100-watt lamp, the charge current will be about 0.5 Ampere. Not much, but overnight it will give 5 Amp-hours of capacity to the battery. Usually it is enough to crank the car starter a couple of times in the morning.

If you connect three 100-watt lamps in parallel, the charging current will triple. You can charge your car battery almost halfway overnight. Sometimes they turn on an electric stove instead of lamps. But here the diode may already fail, and at the same time the battery.

In general, this kind of experiments with direct charging of the battery from the network AC voltage 220 volt extremely dangerous. They should only be used in extreme cases when there is no other option.

From computer power supplies

Before you start making your own charger for a car battery, you should evaluate your knowledge and experience in the field of electrical and radio engineering. In accordance with this, select the complexity level of the device.

First of all, you should decide on the element base. Very often, computer users are left with old system units. There are power supplies there. Along with the +5V supply voltage, they contain a +12 Volt bus. As a rule, it is designed for current up to 2 Amperes. This is quite enough for a weak charger.

Video - step-by-step instruction on the manufacture and diagram of a simple charger for a car battery from computer unit power supply:

But 12 volts is not enough. It is necessary to “overclock” it to 15. How? Usually using the "poke" method. Take a resistance of about 1 kiloOhm and connect it in parallel with other resistances near the microcircuit with 8 legs in the secondary circuit of the power supply.

Thus, the transmission coefficient of the circuit is changed feedback, respectively, and the output voltage.

It’s difficult to explain in words, but usually users succeed. By selecting the resistance value, you can achieve an output voltage of about 13.5 Volts. This is enough to charge a car battery.

If you don’t have a power supply at hand, you can look for a transformer with a secondary winding of 12 - 18 Volts. They were used in old tube televisions and other household appliances.

Now such transformers can be found in used uninterruptible power supplies; you can buy them for pennies at secondary market. Next, we begin manufacturing the transformer charger.

Transformer chargers

Transformer chargers are the most common and safe devices widely used in automotive practice.

Video - a simple charger for a car battery using a transformer:

The most simple circuit transformer charger for a car battery contains:

• network transformer;
• rectifier bridge;
• restrictive load.

A large current flows through the limiting load and it gets very hot, so to limit the charging current, capacitors are often used in the primary circuit of the transformer.

In principle, in such a circuit you can do without a transformer if you choose the capacitor wisely. But without galvanic isolation from the network alternating current such a circuit will be dangerous from the point of view of electric shock.

More practical charger circuits for car batteries with regulation and limitation of charge current. One of these schemes is shown in the figure:

You can use the rectifier bridge of a faulty car generator as powerful rectifier diodes by slightly reconnecting the circuit.

More complex pulse chargers with desulfation function are usually made using microcircuits, even microprocessors. They are difficult to manufacture and require special installation and configuration skills. In this case, it is easier to purchase a factory device.

Safety requirements

Conditions that must be met when using a homemade car battery charger:

• The charger and battery must be located on a fireproof surface during charging;
• when using simple chargers, it is necessary to use personal protective equipment (insulating gloves, rubber mat);
• when using newly manufactured devices, constant monitoring of the charging process is necessary;
• the main controlled parameters of the charging process are current, voltage at the battery terminals, temperature of the charger body and battery, control of the boiling point;
• When charging at night, it is necessary to have residual current devices (RCDs) in the network connection.

Video - diagram of a charger for a car battery from a UPS:

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Comments on the article:

Lyokha

The information presented here is certainly interesting and informative. As a former radio engineer of the Soviet school, I read it with great interest. But in reality, now even “desperate” radio amateurs are unlikely to bother searching for circuit diagrams for a homemade charger and later assembling it with a soldering iron and radio components. Only radio fanatics will do this. It’s much easier to buy a factory-made device, especially since the prices, I think, are affordable. As a last resort, you can turn to other car enthusiasts with a request to “light up”, fortunately, now there are plenty of cars everywhere. What is written here is useful not so much for its practical value (although that too), but for instilling interest in radio engineering in general. After all, most modern children not only cannot distinguish a resistor from a transistor, but they won’t be able to pronounce it the first time. And this is very sad...

Michael

When the battery was old and half-dead, I often used a laptop power supply to recharge. I used an unnecessary old one as a current limiter. back light with four 21 Watt bulbs connected in parallel. I control the voltage at the terminals, at the beginning of charging it is usually about 13 V, the battery greedily eats up the charge, then the charging voltage increases, and when it reaches 15 V, I stop charging. It takes half an hour to an hour to reliably start the engine.

Ignat

I have a Soviet charger in my garage, it’s called “Volna”, made in ’79. Inside is a hefty and heavy transformer and several diodes, resistors and transistors. Almost 40 years in service, and this despite the fact that my father and brother use it constantly, not only for charging, but also as a 12 V power supply. And now, indeed, it’s easier to buy a cheap Chinese device for five hundred square meters than to bother with soldering iron And on Aliexpress you can even buy it for one and a half hundred, although it will take a long time to send it. Although I liked the option from the computer power supply, I have a dozen old ones lying around in the garage, but they work quite well.

San Sanych

Hmmm. Of course, the Pepsicol generation is growing... :-\ The correct charger should produce 14.2 volts. No more and no less. With a greater potential difference, the electrolyte will boil, and the battery will swell so that it will then be problematic to remove it or, conversely, not to install it back in the car. With a smaller potential difference, the battery will not charge. The most normal circuit presented in the material is with a step-down transformer (first). In this case, the transformer must produce exactly 10 volts at a current of at least 2 amperes. There are plenty of these on sale. It is better to install domestic diodes - D246A (must be installed on a radiator with mica insulators). At worst - KD213A (these can be glued to an aluminum radiator with superglue). Any electrolytic capacitor with a capacity of at least 1000 uF for an operating voltage of at least 25 volts. Strongly large capacitor It’s also not needed, since due to the ripples of the under-rectified voltage we get the optimal charge for the battery. In total we get 10 * root of 2 = 14.2 volts. I myself have had such a charger since the days of the 412th Muscovite. Not killable at all. 🙂

Kirill

In principle, if you have the necessary transformer, it is not so difficult to assemble a transformer charger circuit yourself. Even for me, not a very big specialist in the field of radio electronics. Many people say, why bother if it’s easier to buy. I agree, but it’s not about the final result, but about the process itself, because it’s much more pleasant to use a manufactured thing with my own hands than purchased. And most importantly, if this homemade product breaks down, then the one who assembled it knows his battery charger thoroughly and is able to fix it quickly. And if a purchased product burns out, then you still need to dig around and it’s not at all a fact that a breakdown will be found. I vote for self-built devices!

Oleg

In general, I think that the ideal option is a charger industrial production, that’s why I have this and carry it in my trunk all the time. But in life situations are different. Once I was visiting my daughter in Montenegro, and there they generally don’t carry anything with them and rarely do anyone even have one. So she forgot to close the door at night. The battery is drained. No diode at hand, no computer. I found a Boschevsky screwdriver with 18 volts and 1 ampere current. So I used his charger. True, I charged it all night and periodically checked for overheating. But she couldn’t stand it, in the morning they started her with half a kick. So there are many options, you have to look. Well, regarding homemade chargers, as a radio engineer I can only recommend transformer ones, i.e. isolated via the network, they are safe compared to capacitors, diodes with a light bulb.

Sergey

Charging the battery with non-standard devices can lead to either complete irreversible wear or a decrease in guaranteed operation. The whole problem is connecting homemade products, so that the rated voltage does not exceed the permissible one. It is necessary to take into account temperature differences and this is a very important point, especially in winter time. When we decrease by a degree, we increase it and vice versa. There is an approximate table depending on the type of battery - it is not difficult to remember. Another important point is that all measurements of voltage and, of course, density are made only when the engine is cold, with the engine not running.

Vitalik

In general, I use the charger extremely rarely, maybe once every two or three years, and only when I go away for a long time, for example in the summer for a couple of months to the south to visit relatives. And so basically the car is in operation almost every day, the battery is charged and there is no need for such devices. Therefore, I think that buying for money something that you practically never use is not very smart. The best option is to assemble such a simple craft, say from a computer power supply, and let it lie around, waiting in the wings. After all, the main thing here is not to fully charge the battery, but to cheer it up a little to start the engine, and then the generator will do its job.

Nikolai

Just yesterday we recharged the battery using a screwdriver charger. The car was parked outside, the frost was -28, the battery was spun a couple of times and stopped. We took out a screwdriver, a couple of wires, connected it, and after half an hour the car started up safely.

Dmitriy

A ready-made store charger is of course an ideal option, but who wants to use their own hands, and considering that you don’t have to use it often, you don’t have to spend money on the purchase and do the charging yourself.
A homemade charger should be autonomous, not require supervision or current control, since we charge most often at night. In addition, it must provide a voltage of 14.4 V and ensure that the battery is turned off when the current and voltage exceed the norm. It should also provide protection against polarity reversal.
The main mistakes that “Kulibins” make are connecting directly to a household electrical network, this is not even a mistake, but a violation of safety regulations, the next limiting the charging current is by capacitors, and it’s also more expensive: one bank of capacitors 32 uF at 350-400 V (less than that is not possible) will cost like a cool branded charger.
The easiest way is to use a computer switching power supply (UPS), it is now more affordable than a hardware transformer, and you don’t need to do separate protection, everything is ready.
If you don't have a computer power supply, you need to look for a transformer. A power supply with filament windings from old tube TVs - TS-130, TS-180, TS-220, TS-270 - is suitable. They have plenty of power behind their eyes. You can find an old TN filament transformer at the car market.
But all this is only for those who are friends with electricians. If not, don’t bother - you won’t do the exercises that meet all the requirements, so buy ready-made ones and don’t waste time.

Laura

I got a charger from my grandfather. Since Soviet times. Homemade. I don’t understand this at all, but when my friends see it, they click their tongues in admiration and respect, saying, this is a thing “for centuries.” They say it was assembled using some lamps and still works. True, I practically don’t use it, but that’s not the point. Everyone criticizes Soviet technology, but it turns out to be many times more reliable than modern technology, even homemade ones.

Vladislav

In general, a useful thing in the household, especially if there is a function for adjusting the output voltage

Alexei

Neither use nor collect homemade exercises Somehow I’ve never tried it, but I can quite imagine the principle of assembly and operation. I think that homemade products are no worse than factory ones, it’s just that no one wants to tinker, especially since store-bought ones are quite affordable.

Victor

In general, the schemes are simple, there are few parts and they are accessible. Adjustment can also be done if you have some experience. So it's quite possible to collect. Of course, it is very pleasant to use a device assembled with your own hands)).

Ivan

The charger is, of course, a useful thing, but now there are more interesting specimens on the market - their name is start-chargers

Sergey

There are a lot of charger circuits and as a radio engineer I have tried many of them. Until last year, I had a scheme that worked for me since Soviet times and it worked perfectly. But one day (through my fault) the battery completely died in the garage and I needed a cyclic mode to restore it. Then I didn’t bother (due to lack of time) with creating a new circuit, but just went and bought it. And now I carry a charger in the trunk just in case.

Automatic devices are simple in design, but very reliable in operation. Their design was created using a simple design without unnecessary electronic additions. They are designed for simple charging batteries of any vehicles.

Pros:

1. The charger will last for many years with proper use and proper maintenance.

Minuses:

1. Lack of any protection.
2. Eliminating discharge mode and the possibility of reconditioning the battery.
3. Heavy weight.
4. Quite a high cost.

Consists of classic charger of the following key elements:

1. Transformer.
2. Rectifier.
3. Adjustment block.

Such a device produces direct current at a voltage of 14.4V, not 12V. Therefore, according to the laws of physics, it is impossible to charge one device with another if they have the same voltage. Based on the above, the optimal value for such a device is 14.4 Volts.

The key components of any charger are:

• transformer;
• mains plug;
• fuse (provides protection against short circuit);
• wire rheostat (adjusts the charging current);
• ammeter (shows the strength of electric current);
• rectifier (converts alternating current to direct current);
• rheostat (regulates current and voltage in the electrical circuit);
• bulb;
• switch;
• frame;

Wires for connection

To connect any charger, as a rule, red and black wires are used, red is positive, black is negative.

When choosing cables to connect the charging or starting device, it is necessary to choose a cross-section of at least 1 mm2.

Attention. Further information is provided for informational purposes only. Whatever you want to bring to life, you do at your own discretion. Incorrect or inept handling of certain spare parts and devices will cause them to malfunction.

Having looked at the available types of chargers, let’s move on directly to making them ourselves.

Charging the battery from the computer power supply

To charge any battery, 5-6 ampere hours is enough, this is about 10% of the capacity of the entire battery. Any power supply with a capacity of 150 W or more can produce it.

So, let's look at 2 ways to make your own charger from a computer power supply.

Method one

For manufacturing you need the following parts:

• power supply, power from 150 W;
• resistor 27 kOhm;
• current regulator R10 or resistor block;
• wires with a length of 1 meter;

Work progress:

1. To start we will need to disassemble the power supply.
2. We extract wires we do not use, namely -5v, +5v, -12v and +12v.
3. We replace the resistor R1 to a pre-prepared 27 kOhm resistor.
4. Removing the wires 14 and 15, and 16 we simply turn off.
5. From the block we bring out the power cord and wires to battery.
6. Install the current regulator R10. In the absence of such a regulator, it is possible to make homemade block resistors. It will consist of two 5 W resistors, which will be connected in parallel.
7. To set up the charger, We install a variable resistor in the board.
8. To exits 1,14,15,16 We solder the wires and use a resistor to set the voltage to 13.8-14.5V.
9. At the end of the wires connect the terminals.
10. We delete the remaining unnecessary tracks.

Important: stick to complete guide, the slightest deviation can lead to burnout of the device.

Method two

To manufacture our device using this method, you will need a slightly more powerful power supply, namely 350 W. Since it can output 12-14 amps which will satisfy our needs.

Work progress:

1. In computer power supplies The pulse transformer has several windings, one of them is 12V, and the second is 5V. To make our device, you only need a 12V winding.
2. To start our block you will need to find the green wire and connect it to the black wire. If you use a cheap Chinese unit, there may be a gray wire instead of a green one.
3. If you have an old power supply and with a power button, the above procedure is not needed.
4. Further, we make 2 thick busbars from the yellow and black wires, and cut off the unnecessary wires. A black tire will be a minus, a yellow one will be a plus.
5. To improve reliability Our device can be swapped. The fact is that the 5V bus has a more powerful diode than the 12V.
6. Since the power supply has a built-in fan, then he is not afraid of overheating.

Method three

For manufacturing we will need the following parts:

• power supply, power 230 W;
• board with TL 431 chip;
• resistor 2.7 kOhm;
• resistor 200 Ohm power 2 W;
• 68 Ohm resistor with a power of 0.5 W;
• resistor 0.47 Ohm power 1 W;
• 4-pin relay;
• 2 diodes 1N4007 or similar diodes;
• resistor 1kOhm;
• bright LED;
• wire length of at least 1 meter and cross-section of at least 2.5 mm 2, with terminals;

Work progress:

1. Desoldering all wires except 4 black and 2 yellow wires, since they carry power.
2. Close the contacts with a jumper, responsible for overvoltage protection so that our power supply does not turn off due to overvoltage.
3. We replace it on a board with a TL 431 chip built-in resistor for a 2.7 kOhm resistor, to set the output voltage to 14.4 V.
4. Add a 200 Ohm resistor with a power of 2 W per output from the 12V channel, to stabilize the voltage.
5. Add a 68 Ohm resistor with a power of 0.5 W per output from the 5V channel, to stabilize the voltage.
6. Solder the transistor on the board with the TL 431 chip, to eliminate obstacles when setting the voltage.
7. Replace the standard resistor, in the primary circuit of the transformer winding, to a 0.47 Ohm resistor with a power of 1 W.
8. Assembling a protection scheme from Not correct connection to the battery.
9. Unsolder from the power supply unnecessary parts.
10. We output necessary wires from the power supply.
11. Solder the terminals to the wires.

For ease of use of the charger, connect an ammeter.

The advantage of this homemade device is the inability to recharge the battery.

The simplest device using an adapter

Now consider the case when there is no unnecessary power supply available, our battery is dead and needs to be charged.

Every good owner or fan of all kinds of electronic devices has an adapter for recharging autonomous equipment. Any 12V adapter can be used to charge a car battery.

The main condition for such charging is that the voltage supplied by the source is no less than that of the battery.

Work progress:

1. Necessary cut off the connector from the end of the adapter wire and peel off the insulation at least 5 cm.
2. Since the wire goes double, it is necessary to divide it. The distance between the ends of the 2 wires must be at least 50 cm.
3. Solder or tape to the ends of the terminal wire for secure fixation on the battery.
4. If the terminals are the same, then you need to take care of putting insignia on them.
5. The biggest disadvantage of this method consists of constant monitoring of the temperature of the adapter. Since if the adapter burns out, it can render the battery unusable.

Before connecting the adapter to the network, you must first connect it to the battery.

Charger made from a diode and a household light bulb

Diode is a semiconductor electronic device that is capable of conducting current in one direction and has a resistance equal to zero.

The charging adapter for the laptop will be used as a diode.

To manufacture this type of device, we will need:

• charging adapter for laptop;
• bulb;
• wires from 1 m long;

Each car charger produces about 20V voltage. Since the diode replaces the adapter and passes voltage only in one direction, it is protected from short circuits that can occur if connected incorrectly.

The higher the power of the light bulb, the faster the battery charges.

Work progress:

1. To the positive wire of the laptop adapter We connect our light bulb.
2. From a light bulb we throw the wire to the positive.
3. Disadvantage from the adapter directly connect to the battery.

If connected correctly, our light bulb will glow because the current at the terminals is low and the voltage is high.

Also, you need to remember that correct charging provides an average current of 2-3 amperes. Connecting a high-power light bulb leads to an increase in current strength, and this, in turn, has a detrimental effect on the battery.

Based on this, you can connect a high-power light bulb only in special cases.

This method involves constantly monitoring and measuring the voltage at the terminals. Overcharging the battery will produce excessive amounts of hydrogen and may damage it.

When charging the battery in this way, try to stay near the device, since leaving it temporarily unattended can lead to failure of the device and the battery.

Checking and setting

To test our device, you must have a working car light bulb. First, using a wire, we connect our light bulb to the charger, remembering to observe the polarity. We plug in the charger and the light comes on. Everything is working.

Each time, before using a homemade charging device, check its functionality. This check will eliminate all possibilities of damaging your battery.

How to charge a car battery

Quite a large number of car owners consider charging the battery a very simple matter.

But in this process there are a number of nuances on which the long-term operation of the battery depends:

Before you put the battery on charge, you need to carry out a number of necessary actions:

1. Use chemical resistant gloves and goggles.
2. After removing the battery carefully inspect it for signs of mechanical damage and traces of liquid leakage.
3. Unscrew the protective caps, to release the generated hydrogen, to avoid boiling the battery.
4. Take a close look at the liquid. It should be transparent, without flakes. If the liquid is dark in color and there are signs of sediment, seek professional help immediately.
5. Check fluid level. Based on current standards, there are marks on the side of the battery, “minimum and maximum,” and if the fluid level is below the required level, it must be refilled.
6. Flood Only distilled water is needed.
7. Don't turn it on charger into the network until the crocodiles are connected to the terminals.
8. Observe polarity when connecting alligator clips to the terminals.
9. If during charging If you hear boiling sounds, then unplug the device, let the battery cool down, check the fluid level and then you can reconnect the charger to the network.
10. Make sure that the battery is not overcharged, since the condition of its plates depends on this.
11. Charge the battery only in well-ventilated areas, as toxic substances are released during the charging process.
12. Electrical network must have installed circuit breakers that turn off the network in the event of a short circuit.

After you charge the battery, over time the current will drop and the voltage at the terminals will increase. When the voltage reaches 14.5V, charging should be stopped by disconnecting from the network. When the voltage reaches more than 14.5 V, the battery will begin to boil and the plates will become free of liquid.

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 condition of the battery. The simplest option - “turns/does not turn” - is at the same time unsuccessful. If the battery doesn’t turn on, 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 in electrical engineering and be able to hold a soldering iron.

Simple 6 and 12 V device

This scheme is the most basic and budget-friendly. With this charger you can efficiently charge any lead battery with an operating voltage of 12 or 6 V and an electrical capacity from 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 shifters for electric motors. household appliances. A voltmeter is used as PU1 direct current type M5−2 with a measurement limit of 30 V. 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. Besides the pen smooth adjustment current, this design also has a mode switch, when turned on, the charging current doubles.

The charging mode is controlled visually by pointer device RA1. 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 suitable device If you don’t have it 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 letters V-H. 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 car charging do it yourself 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:

1. Bite off all the power bus wires, with the exception of the yellow and black ones.
2. Connect the yellow and separately black wires together - these will be the “+” and “-” chargers, respectively (see diagram).
3. Cut all traces leading to pins 1, 14, 15 and 16 of the TL494 controller.
4. 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.
5. 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 available in pulse blocks 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 necessary tool and you can safely get to work.

The article will tell you how to make your own homemade Schemes you can use absolutely any, but the simplest manufacturing option is to remake a computer power supply. If you have such a block, it will be quite easy to find a use for it. For food motherboards voltages of 5, 3.3, 12 Volts are used. As you understand, the voltage of interest to you is 12 Volts. The charger will allow you to charge batteries whose capacity ranges from 55 to 65 Ampere-hours. In other words, it is enough to recharge the batteries of most cars.

General view of the diagram

To make the alteration, you need to use the diagram presented in the article. made with your own hands from the power supply of a personal computer, allows you to control the charging current and voltage at the output. It is necessary to pay attention to the fact that there is protection against short circuit - a 10 Ampere fuse. But it is not necessary to install it, since in most power supplies personal computers There is protection that turns off the device in the event of a short circuit. Therefore, charger circuits for batteries from computer power supplies are able to protect themselves from short circuits.

The PSI controller (designated DA1), as a rule, is used in the power supply of two types - KA7500 or TL494. Now a little theory. Can the computer's power supply charge the battery normally? The answer is yes, since lead batteries in most cars have a capacity of 55-65 Ampere-hour. And for normal charging it needs a current equal to 10% of the battery capacity - no more than 6.5 Amperes. If the power supply has a power of over 150 W, then its “+12 V” circuit is capable of delivering such current.

Initial stage of remodeling

To replicate a simple homemade battery charger, you need to slightly improve the power supply:

1. Get rid of all unnecessary wires. Use a soldering iron to remove them so as not to interfere.
2. Using the diagram given in the article, find a constant resistor R1, which must be unsoldered and in its place install a trimmer with a resistance of 27 kOhm. A constant voltage of “+12 V” must subsequently be applied to the upper contact of this resistor. Without this, the device will not be able to operate.
3. The 16th pin of the microcircuit is disconnected from the minus.
4. Next, you need to disconnect the 15th and 14th pins.

It turns out to be quite simple and homemade. You can use any circuits, but it’s easier to make it from a computer power supply - it’s lighter, easier to use, and more affordable. When compared with transformer devices, the mass of the devices differs significantly (as do the dimensions).

Charger adjustments

The back wall will now be the front; it is advisable to make it from a piece of material (textolite is ideal). On this wall it is necessary to install a charging current regulator, indicated in the diagram R10. It is best to use a current-sensing resistor as powerful as possible - take two with a power of 5 W and a resistance of 0.2 Ohm. But it all depends on the choice of battery charger circuit. Some designs do not require the use of high-power resistors.

When connecting them in parallel, the power is doubled, and the resistance becomes equal to 0.1 Ohm. On the front wall there are also indicators - a voltmeter and an ammeter, which allow you to monitor the relevant parameters of the charger. To fine-tune the charger, a trimming resistor is used, with which voltage is supplied to the 1st pin of the PHI controller.

Device requirements

Final assembly

Multi-core thin wires must be soldered to pins 1, 14, 15 and 16. Their insulation must be reliable so that heating does not occur under load, otherwise the homemade car charger will fail. After assembly you need to install trimmer resistor voltage is about 14 Volts (+/-0.2 V). This is the voltage that is considered normal for charging batteries. Moreover, this value must be in the mode idle move(without connected load).

You must install two alligator clips on the wires that connect to the battery. One is red, the other is black. These can be purchased at any hardware or auto parts store. This is how you get a simple homemade charger for a car battery. Connection diagrams: black is attached to the minus, and red to the plus. The charging process is completely automatic, no human intervention is required. But it is worth considering the main stages of this process.

Battery charging process

During the initial cycle, the voltmeter will show a voltage of approximately 12.4-12.5 V. If the battery has a capacity of 55 Ah, then you need to rotate the regulator until the ammeter shows a value of 5.5 Amperes. This means that the charging current is 5.5 A. As the battery charges, the current decreases and the voltage tends to a maximum. As a result, at the very end the current will be 0 and the voltage will be 14 V.

Regardless of the selection of circuits and designs of chargers used for manufacturing, the operating principle is largely similar. When the battery is fully charged, the device begins to compensate for the self-discharge current. Therefore, you do not risk the battery overcharging. Therefore, the charger can be connected to the battery for a day, a week, or even a month.

If you don't have measuring instruments, which it would not be a shame to install in the device, you can refuse them. But for this it is necessary to make a scale for the potentiometer - to indicate the position for the charging current values ​​​​of 5.5 A and 6.5 A. Of course, the installed ammeter is much more convenient - you can visually observe the process of charging the battery. But a battery charger, made with your own hands without the use of equipment, can be easily used.

The simplest charger for car and motorcycle batteries usually consists of a step-down transformer and a full-wave rectifier connected to its secondary winding. A powerful rheostat is connected in series with the battery to set the required charging current. However, this design turns out to be very cumbersome and excessively energy-intensive, and other methods of regulating the charging current usually complicate it significantly.

In industrial chargers, KU202G thyristors are sometimes used to rectify the charging current and change its value. It should be noted here that the forward voltage on the switched-on thyristor with a high charging current can reach 1.5 V. Because of this, they become very hot, and according to the passport, the temperature of the thyristor body should not exceed +85°C.

In such devices, it is necessary to take measures to limit and temperature stabilize the charging current, which leads to their further complexity and cost.

The relatively simple charger described below has wide limits for regulating the charging current - practically from zero to 10 A - and can be used to charge various starter batteries of 12 V batteries.

The device (see diagram) is based on a triac regulator with additionally introduced low-power diode bridge VD1-VD4 and resistors R3 and R5.

After connecting the device to the network at its positive half-cycle (plus on the top wire in the diagram), capacitor C2 begins to charge through resistor R3, diode VD1 and series-connected resistors R1 and R2. With a negative half-cycle of the network, this capacitor is charged through the same resistors R2 and R1, diode VD2 and resistor R5. In both cases, the capacitor is charged to the same voltage, only the charging polarity changes.

As soon as the voltage on the capacitor reaches the ignition threshold of the neon lamp HL1, it lights up, and the capacitor is quickly discharged through the lamp and the control electrode of the triac VS1. In this case, the triac opens. At the end of the half-cycle, the triac closes. The described process is repeated in each half-cycle of the network.

It is well known, for example, that controlling a thyristor using a short pulse has the disadvantage that with an inductive or high-resistance active load, the anode current of the device may not have time to reach the holding current value during the action of the control pulse. One of the measures to eliminate this drawback is to connect a resistor in parallel with the load.

In the described charger, after turning on the triac VS1, its main current flows not only through primary winding transformer T1, but also through one of the resistors - R3 or R5, which, depending on the polarity of the half-cycle mains voltage alternately connected in parallel to the primary winding of the transformer with diodes VD4 and VD3, respectively.

The powerful resistor R6, which is the load of the rectifier VD5, VD6, also serves the same purpose. In addition, resistor R6 generates discharge current pulses, which extend the battery life.

The main unit of the device is transformer T1. It can be made on the basis of a laboratory transformer LATR-2M by insulating its winding (it will be the primary) with three layers of varnished cloth and winding a secondary winding consisting of 80 turns of insulated copper wire with a cross-section of at least 3 mm² with a tap from the middle. The transformer and rectifier can also be borrowed from a power source of suitable power. At self-production transformer, you can use the following calculation method - in this case, the voltage on the secondary winding is set to 20 V at a current of 10 A.

Capacitors C1 and C2 - MBM or others for a voltage of at least 400 and 160 V, respectively. Resistors R1 and R2 are SP 1-1 and SPZ-45, respectively. Diodes VD1-VD4 -D226, D226B or KD105B. Neon lamp HL1 - IN-3, IN-ZA; It is advisable to use a lamp with electrodes of the same design and size - this will ensure symmetry of the current pulses through the primary winding of the transformer.

KD202A diodes can be replaced with any of this series, as well as with D242, D242A or others with an average direct tone of at least 5 A. The diode is placed on a duralumin heat-sinking plate with a useful dissipation surface area of ​​at least 120 cm². The triac should also be mounted on a heat sink plate with approximately half the surface area. Resistor R6 - PEV-10; it can be replaced with five MLT-2 resistors connected in parallel with a resistance of 110 Ohms.

The device is assembled in a durable box made of insulating material (plywood, textolite, etc.). Ventilation holes should be drilled in its upper wall and bottom. The placement of parts in the box is arbitrary. Resistor R1 (charging current) is mounted on the front panel, a small arrow is attached to the handle, and a scale is attached under it. Circuits carrying load current must be made with MGShV brand wire with a cross-section of 2.5-3 mm².

When setting up the device, first set the required charging current limit (but not more than 10 A) with resistor R2. To do this, connect a battery to the output of the device through a 10 A ammeter, strictly observing the polarity. The slider of resistor R1 is moved to the highest position according to the diagram, resistor R2 - to the lowest position, and the device is connected to the network. By moving the slider of resistor R2, the required value of the maximum charging current is set.

The final operation is to calibrate the scale of resistor R1 in amperes using a standard ammeter.

During the charging process, the current through the battery changes, decreasing by about 20% toward the end. Therefore, before charging, set the initial battery current slightly higher than the nominal value (about 10%).

The end of charging is measured by the density of the electrolyte or with a voltmeter - the voltage of the disconnected battery should be in the range of 13.8-14.2 V.

Instead of resistor R6, you can install a 12 V incandescent lamp with a power of about 10 W, placing it outside the housing. It would show the connection of the charger to the battery and at the same time illuminate the work area.