DIY car battery charger repair

In detail: DIY repair of a car battery charger from a real master for the site my.housecope.com.

The correct operation of some types of car batteries requires periodic maintenance: recharging and adding electrolyte. Of course, now in stores you can choose batteries that do not need supervision at all, but the cost of such devices is quite high. Therefore, experienced drivers, for whom the car is a common technique, purchase standard rechargeable batteries and regularly recharge them with a special device.

However, like any other electrical equipment, this device can break down and then the car battery charger needs to be repaired. This can be done both independently and by handing over the "charger" to professionals.

Now there are several types of devices on the market, which differ not only in name and price, but also in the principle of operation. The division takes place in two planes: a design feature and a work feature.

In the first case, there are:

Transformer. Here, the design is based on a transformer that lowers the voltage to the desired level so that the battery can be charged. Such devices are quite reliable and charge the car battery well. However, they are rather cumbersome.
Pulse. Here, the work is provided by a pulse converter, which is considered less reliable. But the obvious advantage of such devices is their low weight and dimensions.

With regard to the principles of operation of chargers for vehicle batteries, the division goes into two categories:

Video (click to play).

Charging and pre-starting devices. Easily recognized by the thin wires that must connect the terminals of the charging equipment and the terminals of the battery itself. Effectively recharges or fully charges the battery and can be used even if the vehicle's battery is still connected to the vehicle. Convenience is pretty obvious.
Starting and charging devices. They are recognized by the presence of thicker wires connecting the battery and the charger. They can work in two different modes, which are switched by a special toggle switch. In one mode, the "charger" delivers the maximum current. In another, it is used for automated charging. Such devices can only be used with a battery that is disconnected from the car. If you forget about it, you can burn many different fuses of the onboard system, or even a few important parts.

It must be understood that this is an electrical device that is assembled according to a certain scheme in order to perform its function. And the more powerful and high-quality the device, the more functions it has, the more complex the scheme of work. Therefore, without knowledge of electronics, without understanding the theory of work, it is not worth disassembling and repairing the battery charger.

However, sometimes a small self-repair is still possible. Especially if a relatively simple transformer-type device has failed. Let's see how it looks from the inside. To do this, just take a screwdriver, unscrew the bolts and remove the top cover. Under it you can see:

Power transformer. Allows you to give the output different values and voltage range.
Galent switch. Allows the user to adjust the voltage.
Ammeter. Monitors the current.
Diode bridge. These are four diodes combined together. Responsible for rectifying current from AC to DC.
Fuse. Certain protection against power surges.

What can you check with little understanding of electronics?

Secondly, for devices that are used quite often and intensively, often the wires simply leave the connection points. It is necessary to carefully examine the insides of the device, and check that the fastening of the wiring is sufficiently reliable. If a torn wire is found during visual inspection, then it must be soldered in place. Thirdly, sometimes in cheap "chargers" plastic is used where it does not fit well. For example, once it was necessary to repair a charger for a car battery, inside which a diode bridge was screwed to a plastic stand. Naturally, the plastic eventually melted and the diode bridge moved away from the heat sink plate.

This is where the possibilities of self-repair for a simple layman, as a rule, end.

If the knowledge in electronics is deeper and there is an understanding of how to use testing devices, then you can go further.

We check the incoming voltage. We go along the power wire and find the place where it is connected to the power transformer. In this place we measure the voltage, thereby excluding malfunctions of the power cable and fuse.
Checking the output voltage. Now we act from the other side - we look at where the wires going towards the battery are connected. Switch the multimeter to DC current mode and check the voltage. Most likely, there will already be problems here.
We check the performance of the diodes and the galent switch. To do this, it is necessary to measure the voltage at the input of the diode bridge. Depending on the result of measurements in this place, the conclusion will be obtained - the switch is faulty, or the diodes are faulty. In the second case, you will have to unscrew the entire bridge and check each diode separately. As soon as it becomes clear which one is not working properly, it will be necessary to replace it with a whole one.

In general, a diagram of its operation is attached to each battery charger. People who can read the diagram and understand the general principles of the system functioning, in some cases will be able to independently repair the "charger" of the battery.

If there is no certain knowledge in electronics, then it is not worth doing such work. This is not only a risk to the performance of the charging devices, but also a health risk. It is much easier to contact a professional electrician, who will certainly deal with the problem faster and better.

During long-term operation, the battery loses its charge, therefore it is important to periodically perform maintenance (especially the battery is vulnerable in winter) and properly charge your car battery.
To date, there are a large number of battery chargers on the market, which can be divided into two large groups: transformer and impulse. The first is based on the simplest transformer and rectifier, the second is based on a less cumbersome, but more reliable pulse converter.
As with any device, the battery charger fails and requires repair. This is manifested primarily in the fact that the car battery is not charged from the charger.

Battery voltage check

If the voltage of the charger is below 13 V, or it "jumps", then the electrical appliance is definitely broken.

You need to connect the battery to the charger and measure the voltage. It is measured on the clips (crocodiles) coming from the device using a multimeter. The ideal voltage is 14.4 V. If the voltage of the charger is below 13 V, or it "jumps", then the electrical appliance is definitely broken.
Serviceability can also be checked by the current in the circuit. To do this, connect the fully discharged battery to the charger through a multimeter (that is, insert a multimeter between the crocodile and the battery terminal).The current supplied to the battery should be 10% of the capacity of this battery. If the reading is different, the car battery charger is not working.

Checking the charger with an incandescent light bulb

Instead of a battery, any 12 V device, for example, a light bulb, can be connected to a charged device. If it is on, then the charger is working; if it is off, then, accordingly, no.

There may be several reasons: improper battery charging, damage to wires, malfunction of one of the working elements, loss of current at a certain stage.
To determine what kind of malfunctions of the car battery charger are taking place, you need to disconnect the device from the power supply and disassemble it. To do this, unscrew the screws with a simple screwdriver and remove the cover. The transformer type charger will have the following composition:

Before repairing the charger, you must disconnect it from the mains and disassemble it.

Checking the car battery charger

First of all, you should check the fastening of the wires, often it is enough to solder the wire in place and the charger will work.

First of all, you should check the fastening of the wires. If any of them is weakened or completely cut off, then you just need to solder the wire in place. In this case, repairs will be simple and cheap.
If the wiring is in place and there are no other connection defects (it happens that some connecting plastic parts are melted, in this case they should be replaced with new ones, or the elements must be fixed in another way), then we proceed to checking the device components separately.
Let's check the voltage at the input, namely along the wire to the junction with the power transformer. In the event that it is inconsistent or absent, we are dealing with a malfunction of the power supply circuit. Let's check the fuse, in order for it to work, power must be present at both terminals. If deficiencies are identified in this area, then we eliminate them (we change the fuse, or the wiring or plug).

Checking the power transformer of the charger

Next, we check the power transformer. To do this, you need to measure the voltage at the output terminals of the transformer. If absent, replace it with a new one; if present, check the wafer switch. The galette switch should be diagnosed in its different positions, and replaced if there is no power at the output (in this case, there must be power at the input).

Monolithic diode bridges cannot be repaired and are completely replaced.

To test the diode bridge, you need to apply voltage to the charger. If the element is serviceable, then the current will be present both at the input to the diode bridge and at the output from it. If this is not the case, then each diode in the bridge is checked. Normal operation of a diode is characterized by a small resistance on the one hand and almost infinite on the other.
We calculate the faulty diodes, remove them, install new ones. By the way, monolithic diode bridges cannot be repaired and are completely changed.
If the previous checks did not reveal any defects in the operation of the charger, then proceed to the examination of the ammeter. When the device is connected to the plus and minus, there is no voltage, and the connected terminals of the ammeter output voltage at the output - this is a sure sign of ammeter breakdown.

In general, it is not so difficult to repair a charger and find out why the battery is not taking charge from the charger. But if you do not have good knowledge of electrical engineering and are not confident in your abilities, then it would be advisable to entrust this work to specialists.

To recharge the battery, a special device is used, which, like any other electrical equipment, can fail.By following step-by-step instructions, repairing your car battery charger is easy at home.When eliminating battery charging breakdowns, simple safety measures must be taken into account:

Do not short-circuit the contact probes on the device. This could cause a short circuit and fire the device. The main board of the charger will fail and it will not be possible to restore it.

When dismantling the battery, it is not allowed to short-circuit the positive and negative terminals connected to the battery. This will cause a short circuit in the on-board network, which will lead to catastrophic consequences. A breakdown of the electronic control unit and even failure of all electrical equipment may occur.

If the car owner will restore the operation of the charger on his own, it is necessary to carefully approach the choice of component parts. It is not allowed to use components that do not correspond to those installed on the board. This can lead not only to damage to the charger itself, but also to the failure of the battery.

When checking the charger after repair, the battery will need to be recharged. In carrying out this task, it is imperative to unscrew the plugs on the banks of the device if the battery is serviced. Otherwise, the electrolyte solution may boil. In theory, a battery explosion could occur.

User Alexey Techmaster spoke in detail about the precautions, as well as the repair of charging equipment for the car battery.For diagnostics, the storage battery is connected to the charger and the voltage is measured. The measurement procedure is performed on the terminal clamps that go from the on-board network to the battery. A multimeter is used for measurement. Ideally, this value should be about 14.4 volts.. If the operating parameter during diagnostics showed less than 13 volts or the voltage jumps, but the battery is working, then the charger must be repaired. You can check it by measuring the magnitude of the current in the electrical circuit.To carry out diagnostics, it is necessary to connect the discharged battery to the charger through the tester. The multimeter terminals are installed between the terminal clip and the battery contact itself. The amount of current that is supplied to the battery should be about 10% of the total battery capacity. If the obtained values do not correspond to the norm, then the memory is inoperative and must be changed or repaired.In the absence of a tester, it is allowed to diagnose the charger according to a different scheme. Instead of a multimeter, a conventional lamp designed to operate on a 12-volt network will be used. The connection of the light source is carried out in the same way. If, as a result of the connection, the lamp lights up, this indicates the correct operation of the charger. If the light source does not turn on, the charger must be repaired.To diagnose this component, it is necessary to apply voltage to the charging equipment. If the diode bridge is inoperative, then the current can be seen both at the output and at the input. Otherwise, diagnostics of each diode element of the component is performed. If the diodes are operational, then the resistance value on the one hand will be minimal, and on the other hand, it will tend to infinity. Inoperative diode elements must be removed and replaced with new ones.If the previous diagnostic steps have not yielded results, an ammeter operation check is performed. A simple option to make sure that the device is working is to connect the terminal clamps to each other. If, as a result of the actions performed, voltage appeared, but before that it was absent, then the ammeter must be replaced or repaired.The Maysternya TV channel spoke in detail about the diagnostics of car charging equipment in garage conditions.Reasons why the device breaks down:

Errors while charging the battery. The technical parameters of this task may not have been met.

Damage to the conductors coming from the charger or disconnection of the contact elements.

One of the components of the charging equipment has broken. The problem may lie in the operation of the ammeter, safety element or diode bridge.

The problem lies in the leakage of current at a particular stage in its transmission.

The zxDTSzx channel presented detailed instructions for diagnosing a battery charger, and also talked about the main causes of device malfunctions.A simple car battery charger repair can only be done by disassembling the equipment and diagnosing each item.The procedure for checking and restoring operability should be started after disconnecting the charger from the network. The cover is carefully dismantled, for this self-tapping screws are unscrewed with a screwdriver, after which the diagnostics of electrical circuits is performed. When the contact elements are weakened, they are re-soldered using a conventional soldering iron.Sometimes the problem lies in the failure or melting of plastic joints between the components of the equipment. Then the replacement of damaged parts is carried out independently using a soldering iron and scrap materials. If the electrical circuits and contacts on the connections are intact, then the remaining parts of the device are subject to diagnosis.Using a multimeter, it is necessary to check the voltage level at the beginning of the power line, at the input. The operating parameter is measured along the conductor from the place where the cable is connected to the transformer device.If there is no voltage or its jumps are observed, then it is diagnosed:

Safety element. Voltage must be present on both sides of the part, at two terminals. If problems are observed, the part must be replaced.

Electric circuit and plug for integrity. The voltage measurement procedure is similar. If there are problems, then the failed elements change.

Diagnostics of the transformer device is performed. The voltage is measured, if it is present, then the transformer unit is working, if not, then the diagnostics of the wafer switch is performed. When the switching device is inoperative, the output voltage on the line will not be at the output, but it will be present at the input.

The Maysternya TV channel spoke in more detail about the diagnostics of safety parts, the transformer device and other elements of the board, as well as the repair of ROMs.After troubleshooting the wiring, transformer mechanism and fuse, the repair procedure will have a number of features: Image - DIY car battery charger repair

The user Nikolay Tyani-Tolkai presented a visual instruction on how to independently detect malfunctions in the operation of the charging equipment and eliminate them.

Car battery chargers (ROMs) are abundant in the consumer market. However, any of them may eventually break down during operation. Therefore, car owners need to know how to carry out simple repairs to car battery chargers. Of course, a lot depends on the degree of damage: if it is the simplest one, there are elements that you can repair yourself.

All chargers, based on the principle of operation, are divided into two types: impulse and transformer e. The impulse device works due to the presence of a impulse current converter in it. And inside the transformer charging there is a simple transformer with a rectifier, due to which the ROM weighs more and looks more cumbersome than the pulse one. Pulse-type devices are considered more reliable in operation, but transformer ones are easier to maintain and repair.

If you decide to charge the car battery at home, but are in doubt about your charger, this article is for you. A simple check determines the quality and health of its work.

One way is to connect it to the battery and measure the voltage readings with a multimeter. The optimal U in this case is 14 V, it is allowed a little higher, up to 14.4 V. If U is less than 13 V, or the multimeter detects its jumps, then there is definitely a malfunction, and it is necessary to carry out one or another repair of the starting-charger.

If you do not have a battery at hand, you can check the performance of the charger with a simple electric lamp designed for U 12 V. If, when connected to it, the light starts to light up, charging is working normally, and if the light does not light up, the device should be repaired.

The main causes of battery ROM breakdown in cars can be as follows:

the battery was charged incorrectly ;
"The contacts are loose" or the wires themselves are damaged ;
the diode bridge, fuse, ammeter, or another component of the ROM could fail ;
possible loss of current at a certain stage of its transfer .

You can try to carry out a simple repair of the car charger and, using the example of a transformer-type power supply, consider how this should be done.

Before carrying out any actions with the ROM, be sure to disconnect it from the network. Carefully remove the cover with a screwdriver and first check the integrity of the wiring. It is possible that the matter is in the weakening of contacts, and then the problems can be solved independently using a simple soldering iron.

It happens that some of the plastic connections between the component parts of the charger break or melt. In this case, you can also replace them yourself using a soldering iron and suitable tools at hand.

If all wires and connections are in place, all other elements of the ROM should be checked in turn ... First of all, a multimeter checks the voltage level at the beginning of the electrical circuit, at the input. U is measured across the wire up to where the wire connects to the transformer itself.

If U jumps or does not exist at all, then it is checked:

fuse (U must be on both sides, on one terminal and on the other, and if there are problems, the fuse is replaced);
wiring and plug (U is checked according to the same principle, if there are problems, one or the other is replaced);
checking the transformer itself (measurements of U, if any - the transformer is in good order, if not, you need to check the wafer switch);
if the switch is faulty, the output U will be absent, but present at the input .

If there is a desire and ability to diagnose a diode bridge, it must be borne in mind that diode bridges can be both monolithic and with the possibility of replacing one faulty diode with another. Monolithic bridges in the event of a malfunction are removed and replaced entirely. As for the voltage supply to the bridge to check its normal operation, U is supplied to the ROM. If the bridge is working properly, no current will be lost either at the input or at the output. If the current does not flow at one of these stages, then you need to separately check each diode, identify the faulty one and replace it.

For a more accurate diagnosis of a breakdown, if nothing was revealed during previous checks, you should check the ammeter. If, when checking the voltage in the ammeter, it is absent, and when its terminals are connected to each other, U appears, then the ammeter is broken, and it is time to repair it.

Thus, it is possible to carry out fault diagnosis and simple repair of chargers for car lead-acid batteries on our own. But when the battery does not charge due to a malfunction of the device, and the motorist does not have the necessary skills in the field of electronics, or it was not possible to fix the ROM himself, it would be best to contact the specialists. As a last resort, you can try to charge the battery without a charger.

Well, it will also be interesting for DIYers of all trades to learn how to make a do-it-yourself battery plug for a battery.

They brought me to make a completely new factory-made car battery charger. It did not work at all for a long time ...The reason is simple - the diode bridge on the heat sink plate (radiator) was screwed to a plastic stand, which melted from heating. As a result, the diode bridge moved away from the heat sink plate, overheated and failed. We fasten the diode bridge to the heat sink plate (radiator), and then the latter to the charger body. I did not find such a powerful diode bridge and assembled a diode bridge from diodes D242 - D248.I used radiators from old color TVs, which are in line scan (transistors KT838, KT846). Two diodes, in which the anodes are soldered together, screwed through insulating mica, I took in the same place from under the transistors.By the way, the switch for selecting the charging mode is designed for a current of 2A, but in reality it switches up to 10A. Therefore, it is better to replace it with a more powerful one.The charger circuit is simple - a transformer, a diode bridge. The current is regulated by a quenching resistance of nichrome through the switch, protection against short-circuits and polarity reversals - an automatic fuse.A. Zotov, Volgograd region

Diy welding machine from television transformers

Old tube TVs have not been used for a long time. The powerful power transformers used in them can be useful for the manufacture of power supplies, chargers, starters, or by connecting several transformers, you can even assemble a small welding machine!

On the drive2 website, you can find not a single activation of various functions in MediaNav, among other things, in other blocks too.

Owners of petrol versions of Renault cars, complete with standard autostart and MediaNav, were more fortunate - from the factory they have a BIC 283468105R unit installed in their car, which switches two car buses: CAN1 and CAN2, transmitting data from the on-board computer and ambient temperature to the MediaNav screen.

Below is a simple diagram for automatically keeping the battery charged. The circuit does not contain expensive and scarce parts. Simple and inexpensive charger for 12V, 7 Ah lead-acid batteries. Can also be used to charge car batteries and emergency lighting systems, etc.

The universal charger is a small box that can be placed on a 220V socket and has flexible spring contacts with adjustable size. Under them, you can insert a mobile battery with any current (within reason) and any distance between the contact pads.

At the bottom of the charging case there are four LEDs that show the presence of a 220V network, the battery is connected, the process of charging it - the red LED is blinking, and some other function.

All modes are controlled by a small chip - a charge processor. Naturally, it cannot be replaced. In extreme cases, it can simply be excluded by letting the charging current through a small resistor directly to the battery.

The problem was that if there was a network, the corresponding LED was on, there was no charging process, which could be verified by connecting a milliammeter to the battery break. We open the case and conduct an inspection. As you can see, the switching power supply itself is a complete copy of a standard charger with a 13001 transistor.

Next, the received 9V through the C8550 transistor goes to the battery. the amount of charging current, as well as the duration of the cycle, is determined and controlled by the chip.

Of course, if the problem is in the microcircuit, then all that remains is to supply these 9V directly through a small current-limiting resistor, but fortunately, the semiconductor test revealed the hero of the occasion - it turned out to be a controlled S8550 transistor.

It is unclear what burned it - the output may be closed for a long time, but after replacing it with a new similar transistor, everything worked fine. Testing for several hours showed that all modes were working properly and the battery was disconnected at the end of the cycle.

The charging current has a value of about 80-100mA and after a certain time (when the voltage on the battery reaches the required voltage), the charge stops and the corresponding LED lights up. I think every radio master should have such a useful device, since there is no need to search for native memory devices even for the most exotic lithium-ion batteries of Chinese mobile phones.

Failure of a charger for charging starter batteries is unpleasant news for any car enthusiast. Today's article is devoted to the repair of the VZVU OTRE-6,3P-12/6 rectifier charging-recovery device.

The device described below is of very good quality for its time. Made in 1988, it worked without any problems until recently.

Modes of charging the battery, its training (alternately charge-discharge) and active load - in other words, a conventional power supply unit for connecting a carrier, an electro-vulcanizer, etc. - and are now in great demand by any car enthusiast.

After checking the fuse, we begin the repair by studying the circuit.

The middle part, which includes five transistors, is a time relay and transistor switches for thyristor control, which operate the device in the “Relay” mode. This node is made on a separate board.

The second board contains a unit for adjusting the charging current (lower part) and controlling the thyristors, which determine the magnitude of this current. On the same board there are thyristors, which ensure the operation of the device in the "Relay" mode, and an automatic protection unit on transistors VT1 and VT2 ..

When inspecting the car charger for external damage, a broken wire was found, we solder it in place.

We turn on the device, the “Network” lamp is on, but there is no voltage at the terminals in all modes, there is no charge.

Having checked the diodes VD1 and VD2 (D242), we turn to the thyristors VS1 and VS2 (KU202G).

As you can see in the photo, the thyristor passes current in one direction.

Broken thyristors can also be detected using a tester, but to detect broken thyristors, you will have to assemble at least the simplest probe to test thyristors.

One of the thyristors of the automation also turned out to be faulty.

After checking all semiconductor devices, we check the electrolytic capacitors for capacity loss and increased leakage current.

Strange, but in this particular case, in 26 years of work, none of them failed.

We assemble the charger and turn it on - the device works only in the “Active load” mode. We continue to study the scheme.

Since the charge current is adjustable, the adjustment unit is beyond suspicion.

When the S1 toggle switch is on (“Charge - Active load” in the “Active load” position), the collector and emitter terminals of the VT1 transistor are closed, thereby disabling the automatic protection unit on the VT1 and VT2 transistors. Since the collector-emitter junction does not open when the toggle switch is off, the elements VT1, VT2 and C2 should be checked first.

After repeated checks of the parts VT1, VT2, VS3, VS4 and C2, a malfunction of VT2 was revealed - when dialing, it behaved as if it were in good condition, but the emitter junction was cut off under voltage.

Now, when turned on, the device started working in all modes.

It remains only with resistor R13 to adjust the discharge time in the “Relay” mode within 10-15 seconds.

Instead of a constant resistor R18 in earlier copies, a trimmer was installed, if it is present, you can correct the charge time with it within 1.5-2 minutes.

After assembly, we check the charger again.

As stated, the discharge time is 15 seconds.

... and the charge time is one and a half minutes.

The result of the repair is three faulty thyristors, one KT361 transistor and a working charger that will last for more than one year.

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

And the longer the battery lasts, the more often it needs to be charged in order to recharge.

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

However, they all do the same job - they convert an alternating voltage of 220V to a constant voltage of 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, their high cost can be noted, and the more sophisticated the device, the higher the price.

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

Yes, a home-made device will not look as presentable as a purchased one, but after all, its task is to charge the battery, and not "show off" on the 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.

Next, we will consider several schemes for battery chargers that can be created from old electrical appliances or electronic components.

The first will be the scheme, perhaps the simplest, and almost any motorist can handle it.

To manufacture the simplest charger, you need only two components - a transformer and a rectifier.

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

That is, often a 60 Ah battery is used on passenger cars, based on this, the current output from the device should be at the level of 6 A. At the same time, the voltage is 13.8-14.2 V.

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

The schematic diagram of the charger from the TV looks like this.

Often, a TS-180 transformer was installed on such TVs. 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 need to make a serial connection of the windings. The convenience of working with such a transformer is that each of the winding terminals has its own designation.

For serial connection of the secondary winding, it is necessary to connect pins 9 and 9 'together.

And to the terminals 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 serial connection it is necessary to connect pins 1 and 1 'together. The wires with a plug for connecting to the network must be soldered to pins 2 and 2 '. This completes the work with the transformer.

Next, you need to make a diode bridge. This will require 4 diodes capable of operating with a current of 10 A and above. For these purposes, diode bridges D242 or analogs D246, D245, D243 are suitable.

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

Don't forget about the fuses. It is recommended to install one of them on the "positive" terminal from the diode bridge. This fuse must be rated for a maximum current of 10 A. A second fuse (0.5 A) must be installed at terminal 2 of the transformer.

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

Sometimes it happens that the current strength 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" excess current strength.

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

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

Alteration of the transformer is reduced to the complete removal of the secondary winding, and the winding of 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 readings of the voltmeter, it is determined what voltage at the output these 10 turns provide.

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

Well, then everything is done as described above - a diode bridge is made, all the constituent elements are connected and the operability is checked.

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 the base.

It is imperative to mark where the "positive" wire, and where - the "negative", so as not to "re-positive", and not to disable the device.

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

For the manufacture of the device, units with a capacity of at least 200 watts of AT or ATX models, which are controlled by a TL494 or KA7500 controller, are suitable. It is important that the power supply is fully functional. The ST-230WHF model from old PCs has shown itself not badly.

A fragment of the 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 kΩ trimmer resistor, two 5 W resistors (5WR2J) and a resistance of 0.2 Ohm or one C5-16MV.

The initial stage of work is reduced to disconnecting all unnecessary, which are the wires "-5 V", "+5 V", "-12 V" and "+12 V".

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

Terminal 16 of the controller must be disconnected from the common wire, and also the connections of terminals 14 and 15 must be cut.

A potentiometer-regulator (in the diagram - R10) must be installed in the rear wall of the power supply case. It must be installed on an insulating plate so that it does not touch the block body.

Through this wall, you should also bring out the wiring for connecting to the network, as well as wires for connecting the battery.

To ensure the convenience of adjusting 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 10 W at the output with a resistance of 0.1 Ohm.

Next, the manufactured board is installed in the case and all terminals are connected according to the diagram.

Then you should check the correctness of the connection of all outputs and the operability of the device.

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

For this, the potentiometer knob must be set to the middle position.After that, the open circuit voltage should be set on the trimming resistor at the level of 13.8-14.2 V.

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

As the battery is charged, the voltage will increase to the value set on the trimmer. As soon as the voltage reaches this value, the current will begin to decrease.

If all the operating parameters converge and the device is working normally, all that remains is to close the case 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 the voltage stabilization mode. That is, recharging the battery is completely excluded.

For the convenience of work, you can additionally equip the device with a voltmeter and ammeter.

These are just a few types of chargers that can be made at home from available tools, although there are much more options.

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

If you have experience in the manufacture of such devices, share it in the comments, many will be very grateful for that.

Video (click to play).