Auto charger for all types of battery circuits. Charger for car batteries

Compliance with the operating mode of rechargeable batteries, and in particular the charging mode, guarantees their trouble-free operation throughout their entire service life. Batteries are charged with a current, the value of which can be determined by the formula

where I is the average charging current, A., and Q is the nameplate electric capacity of the battery, Ah.

A classic charger for a car battery consists of a step-down transformer, a rectifier and a charging current regulator. Wire rheostats (see Fig. 1) and transistor current stabilizers are used as current regulators.

In both cases, these elements generate significant thermal power, which reduces the efficiency of the charger and increases the likelihood of its failure.

To regulate the charging current, you can use a store of capacitors connected in series with the primary (mains) winding of the transformer and acting as reactances that dampen excess network voltage. A simplified version of such a device is shown in Fig. 2.

In this circuit, thermal (active) power is released only on the diodes VD1-VD4 of the rectifier bridge and the transformer, so the heating of the device is insignificant.

The disadvantage in Fig. 2 is the need to provide a voltage on the secondary winding of the transformer one and a half times greater than the rated load voltage (~ 18÷20V).

The charger circuit, which provides charging of 12-volt batteries with a current of up to 15 A, and the charging current can be changed from 1 to 15 A in steps of 1 A, is shown in Fig. 3.

It is possible to automatically turn off the device when the battery is fully charged. It is not afraid of short-term short circuits in the load circuit and breaks in it.

Switches Q1 - Q4 can be used to connect various combinations of capacitors and thereby regulate the charging current.

The variable resistor R4 sets the response threshold of K2, which should operate when the voltage at the battery terminals is equal to the voltage of a fully charged battery.

In Fig. Figure 4 shows another charger in which the charging current is smoothly regulated from zero to the maximum value.

The change in current in the load is achieved by adjusting the opening angle of the thyristor VS1. The control unit is made on a unijunction transistor VT1. The value of this current is determined by the position of the variable resistor R5. The maximum battery charging current is 10A, set with an ammeter. The device is provided on the mains and load side with fuses F1 and F2.

A version of the charger printed circuit board (see Fig. 4), 60x75 mm in size, is shown in the following figure:

In the diagram in Fig. 4, the secondary winding of the transformer must be designed for a current three times greater than the charging current, and accordingly, the power of the transformer must also be three times greater than the power consumed by the battery.

This circumstance is a significant drawback of chargers with a current regulator thyristor (thyristor).

Note:

The rectifier bridge diodes VD1-VD4 and the thyristor VS1 must be installed on radiators.

It is possible to significantly reduce power losses in the SCR, and therefore increase the efficiency of the charger, by moving the control element from the circuit of the secondary winding of the transformer to the circuit of the primary winding. such a device is shown in Fig. 5.

In the diagram in Fig. 5 control unit is similar to that used in the previous version of the device. SCR VS1 is included in the diagonal of the rectifier bridge VD1 - VD4. Since the current of the primary winding of the transformer is approximately 10 times less than the charging current, relatively little thermal power is released on the diodes VD1-VD4 and the thyristor VS1 and they do not require installation on radiators. In addition, the use of an SCR in the primary winding circuit of the transformer made it possible to slightly improve the shape of the charging current curve and reduce the value of the current curve shape coefficient (which also leads to an increase in the efficiency of the charger). The disadvantage of this charger is the galvanic connection with the network of elements of the control unit, which must be taken into account when developing a design (for example, use a variable resistor with a plastic axis).

A version of the printed circuit board of the charger in Figure 5, measuring 60x75 mm, is shown in the figure below:

Note:

The rectifier bridge diodes VD5-VD8 must be installed on radiators.

In the charger in Figure 5 there is a diode bridge VD1-VD4 type KTs402 or KTs405 with the letters A, B, C. Zener diode VD3 type KS518, KS522, KS524, or made up of two identical zener diodes with a total stabilization voltage of 16÷24 volts (KS482, D808 , KS510, etc.). Transistor VT1 is unijunction, type KT117A, B, V, G. The diode bridge VD5-VD8 is made up of diodes, with a working current not less than 10 amperes(D242÷D247, etc.). The diodes are installed on radiators with an area of ​​at least 200 sq.cm, and the radiators will become very hot; a fan can be installed in the charger case for ventilation.

Many car enthusiasts know very well that in order to extend the life of the battery, it is required periodically from the charger, and not from the car’s generator.

And the longer the battery life, the more often it needs to be charged to restore charge.

You can't do without chargers

To perform this operation, as already noted, chargers operating from a 220 V network are used. There are a lot of such devices on the automotive market, they may have various useful additional functions.

However, they all do the same job - convert alternating voltage 220 V into direct voltage - 13.8-14.4 V.

In some models, the charging current is manually adjusted, but there are also models with fully automatic operation.

Of all the disadvantages of purchased chargers, one can note their high cost, and the more sophisticated the device, the higher the price.

But many people have a large number of electrical appliances at hand, the components of which may well be suitable for creating a homemade charger.

Yes, a homemade device will not look as presentable as a purchased one, but its task is to charge the battery, and not to “show off” on a shelf.

One of the most important conditions when creating a charger is at least basic knowledge of electrical engineering and radio electronics, as well as the ability to hold a soldering iron in your hands and be able to use it correctly.

Memory from a tube TV

The first scheme will be, perhaps the simplest, and almost any car enthusiast can cope with it.

To make a simple charger, you only need two components - a transformer and a rectifier.

The main condition that the charger must meet is that the current output from the device must be 10% of the battery capacity.

That is, a 60 Ah battery is often used in passenger cars; based on this, the current output from the device should be 6 A. The voltage should be 13.8-14.2 V.

If someone has an old, unnecessary tube Soviet TV, then it is better to have a transformer than not to find one.

The schematic diagram of the TV charger looks like this.

Often, a TS-180 transformer was installed on such televisions. Its peculiarity was the presence of two secondary windings, 6.4 V each and a current strength of 4.7 A. The primary winding also consists of two parts.

First you will need to connect the windings in series. The convenience of working with such a transformer is that each of the winding terminals has its own designation.

To connect the secondary winding in series, you need to connect pins 9 and 9\’ together.

And to pins 10 and 10\’ - solder two pieces of copper wire. All wires that are soldered to the terminals must have a cross-section of at least 2.5 mm. sq.

As for the primary winding, for a series connection you need to connect pins 1 and 1\'. Wires with a plug for connecting to the network must be soldered to pins 2 and 2\’. At this point, work with the transformer is completed.

The diagram shows how the diodes should be connected - the wires coming from pins 10 and 10\', as well as the wires that will go to the battery, are soldered to the diode bridge.

Don't forget about fuses. It is recommended to install one of them on the “positive” terminal of the diode bridge. This fuse must be rated for a current of no more than 10 A. The second fuse (0.5 A) must be installed at terminal 2 of the transformer.

Before starting charging, it is better to check the functionality of the device and check its output parameters using an ammeter and voltmeter.

Sometimes it happens that the current is slightly higher than required, so some install a 12-volt incandescent lamp with a power of 21 to 60 watts in the circuit. This lamp will “take away” the excess current.

Microwave oven charger

Some car enthusiasts use a transformer from a broken microwave oven. But this transformer will need to be redone, since it is a step-up transformer, not a step-down transformer.

It is not necessary that the transformer be in good working order, since the secondary winding in it often burns out, which will still have to be removed during the creation of the device.

Remaking the transformer comes down to completely removing the secondary winding and winding a new one.

An insulated wire with a cross-section of at least 2.0 mm is used as a new winding. sq.

When winding, you need to decide on the number of turns. You can do this experimentally - wind 10 turns of a new wire around the core, then connect a voltmeter to its ends and power the transformer.

According to the voltmeter readings, it is determined what output voltage these 10 turns provide.

For example, measurements showed that there is 2.0 V at the output. This means that 12V at the output will provide 60 turns, and 13V will provide 65 turns. As you understand, 5 turns adds 1 volt.

It is worth pointing out that it is better to assemble such a charger with high quality, then place all the components in a case that can be made from scrap materials. Or mount it on a base.

Be sure to mark where the “positive” wire is and where the “negative” wire is, so as not to “over-plus” and damage the device.

Memory from the ATX power supply (for prepared ones)

A charger made from a computer power supply has a more complex circuit.

For the manufacture of the device, units with a power of at least 200 Watts of the AT or ATX models, which are controlled by a TL494 or KA7500 controller, are suitable. It is important that the power supply is fully operational. The ST-230WHF model from old PCs performed well.

A fragment of the circuit diagram of such a charger is presented below, and we will work on it.

In addition to the power supply, you will also need a potentiometer-regulator, a 27 kOhm trim resistor, two 5 W resistors (5WR2J) and a resistance of 0.2 Ohm or one C5-16MV.

The initial stage of work comes down to disconnecting everything unnecessary, which are the “-5 V”, “+5 V”, “-12 V” and “+12 V” wires.

The resistor indicated in the diagram as R1 (it supplies a voltage of +5 V to pin 1 of the TL494 controller) must be unsoldered, and a prepared 27 kOhm trimmer resistor must be soldered in its place. The +12 V bus must be connected to the upper terminal of this resistor.

Pin 16 of the controller should be disconnected from the common wire, and you also need to cut the connections of pins 14 and 15.

You need to install a potentiometer-regulator in the rear wall of the power supply housing (R10 in the diagram). It must be installed on an insulating plate so that it does not touch the block body.

The wiring for connecting to the network, as well as the wires for connecting the battery, should also be routed through this wall.

To ensure ease of adjustment of the device, from the existing two 5 W resistors on a separate board, you need to make a block of resistors connected in parallel, which will provide an output of 10 W with a resistance of 0.1 Ohm.

Then you should check the correct connection of all terminals and the functionality of the device.

The final work before completing the assembly is to calibrate the device.

To do this, the potentiometer knob should be set to the middle position. After this, the open circuit voltage should be set on the trimmer resistor at 13.8-14.2 V.

If everything is done correctly, then when the battery starts charging, a voltage of 12.4 V with a current of 5.5 A will be supplied to it.

As the battery charges, the voltage will increase to the value set on the trim resistor. As soon as the voltage reaches this value, the current will begin to decrease.

If all operating parameters converge and the device operates normally, all that remains is to close the housing to prevent damage to the internal elements.

This device from the ATX unit is very convenient, because when the battery is fully charged, it will automatically switch to voltage stabilization mode. That is, recharging the battery is completely excluded.

For convenience of work, the device can be additionally equipped with a voltmeter and ammeter.

Bottom line

These are just a few types of chargers that can be made at home from improvised materials, although there are many more options.

This is especially true for chargers that are made from computer power supplies.

If you have experience in making such devices, share it in the comments, many would be very grateful for it.

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 of 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.

The classic charger consists 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 short circuit protection);
• 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 a charger or starting device, you must select 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 the battery.
6. Install the current regulator R10. In the absence of such a regulator, you can make a homemade resistor block. 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: adhere to the complete instructions, 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 incorrect 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 such a 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 proper charging requires 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.

Important. Never overcharge your battery as this may cause it to lose capacity and become damaged.

Sometimes it happens that the battery in the car runs out and it is no longer possible to start it, since the starter does not have enough voltage and, accordingly, current to crank the engine shaft. In this case, you can “light it” from another car owner so that the engine starts and the battery starts charging from the generator, but this requires special wires and a person willing to help you. You can also charge the battery yourself using a specialized charger, but they are quite expensive and you don’t have to use them very often. Therefore, in this article we will take a detailed look at the homemade device, as well as instructions on how to make a charger for a car battery with your own hands.

Homemade device

Normal battery voltage when disconnected from the vehicle is between 12.5 V and 15 V. Therefore, the charger must produce the same voltage. The charge current should be approximately 0.1 of the capacity, it can be less, but this will increase the charging time. For a standard battery with a capacity of 70-80 Ah, the current should be 5-10 amperes, depending on the specific battery. Our homemade battery charger must meet these parameters. To assemble a charger for a car battery, we need the following elements:

Transformer. Any old electrical appliance or one purchased on the market with an overall power of about 150 watts is suitable for us, more is possible, but not less, otherwise it will get very hot and may fail. It’s great if the voltage of its output windings is 12.5-15 V and the current is about 5-10 amperes. You can view these parameters in the documentation for your part. If the required secondary winding is not available, then it will be necessary to rewind the transformer to a different output voltage. For this:

Thus, we found or assembled the ideal transformer to make our own battery charger.

We will also need:

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:

1. We create a homemade battery charging circuit. In our case it will look like this:
   
2. We use transformer TS-180-2. It has several primary and secondary windings. To work with it, you need to connect two primary and two secondary windings in series to obtain the desired voltage and current at the output.
   
   
3. Using a copper wire, we connect pins 9 and 9’ to each other.
   
4. On a fiberglass plate we assemble a diode bridge from diodes and radiators (as shown in the photo).
   
5. We connect pins 10 and 10’ to the diode bridge.
6. We install a jumper between pins 1 and 1’.
   
7. Using a soldering iron, attach a power cord with a plug to pins 2 and 2’.
8. We connect a 0.5 A fuse to the primary circuit, and a 10-amp fuse to the secondary circuit, respectively.
9. We connect an ammeter and a piece of nichrome wire into the gap between the diode bridge and the battery. One end of which is fixed, and the other must provide a moving contact, thus the resistance will change and the current supplied to the battery will be limited.
10. We insulate all connections with heat shrink or electrical tape and place the device in the housing. This is necessary to avoid electric shock.
11. We install a moving contact at the end of the wire so that its length and, accordingly, the resistance are maximum. And connect the battery. By decreasing or increasing the length of the wire, you need to set the desired current value for your battery (0.1 of its capacity).
12. During the charging process, the current supplied to the battery will itself decrease and when it reaches 1 ampere, we can say that the battery is charged. It is also advisable to directly monitor the voltage on the battery, but to do this it must be disconnected from the charger, since when charging it will be slightly higher than the actual values.

The first start-up of the assembled circuit of any power source or charger is always carried out through an incandescent lamp if it lights up at full intensity - either there is an error somewhere, or the primary winding is short-circuited! An incandescent lamp is installed in the gap of the phase or neutral wire feeding the primary winding.

This circuit of a homemade battery charger has one big drawback - it does not know how to independently disconnect the battery from charging after reaching the required voltage. Therefore, you will have to constantly monitor the readings of the voltmeter and ammeter. There is a design that does not have this drawback, but its assembly will require additional parts and more effort.

A visual example of the finished product

Operating rules

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