For car batteries, as industrial designs are quite expensive. And you can make such a device yourself pretty quickly, and from scrap materials that almost everyone has. From the article you will learn how to make your own chargers at minimal cost. Two designs will be considered - with and without automatic regulation of the charge current.
The basis of the charger is a transformer
In any charger, you will find the main component - a transformer. It is worth noting that there are diagrams of devices built according to a transformerless circuit. But they are dangerous because there is no protection against mains voltage. Therefore, an electric shock may be obtained during manufacture. Transformer circuits are much more efficient and simpler, they have a galvanic isolation from the mains voltage. To make a charger, you need a powerful transformer. It can be found by disassembling an unusable microwave oven. However, spare parts from this electrical appliance can be used to make a do-it-yourself battery charger.
In old tube TVs, transformers TS-270, TS-160 were used. These models are perfect for designing a charger. It turns out to be even more efficient to use them, since they already have two 6.3 volt windings. And from them you can collect current up to 7.5 amperes. And when charging car battery a current equal to 1/10 of the capacity is required. Therefore, with a battery capacity of 60 Ah, you need to charge it with a current of 6 amperes. But if there are no windings that satisfy the condition, you will need to make it. And now about how to make a homemade car charger as quickly as possible.
Rewinding transformer
So, if you decide to use a converter from a microwave oven, then you need to remove the secondary winding. The reason lies in the fact that these are step-up transformers, they convert the voltage to a value of about 2000 volts. The magnetron needs a 4000 volt power supply, so a doubling circuit is used. You will not need such values, so mercilessly get rid of the secondary winding. Instead, wind a wire with a cross section of 2 sq. mm. But you don't know how many turns are needed? You need to find out, you can use it in several ways. And this must be done when making a do-it-yourself battery charger.
The simplest and most reliable is experimental. Wrap the ten turns of the wire you will be using. You clean its edges and plug in the transformer. Measure the voltage on the secondary winding. Let's say these ten turns give out 2 V. Therefore, 0.2 V (one tenth) is collected from one turn. You need at least 12 V, and it is better if the output is a value close to 13. One volt will give five turns, now you need 5 * 12 = 60. The desired value is 60 turns of wire. The second method is more complicated, you will have to count the cross section of the magnetic circuit of the transformer, you need to know the number of turns of the primary winding.
Rectifier unit
We can say that the simplest home-made chargers for car batteries consist of two nodes - a voltage converter and a rectifier. If you do not want to spend a lot of time on assembly, then you can use a half-wave scheme. But if you decide to assemble the charger, as they say, conscientiously, then it is better to use the pavement. It is advisable to choose diodes with a reverse current of 10 amperes or higher. They usually have a metal body and fastening with a nut. It is also worth noting that each semiconductor diode should be installed on a separate heatsink to improve cooling of its body.
Small modernization
However, you can stop there, a simple homemade charger is ready to use. But it can be supplemented with measuring instruments. Having collected all the components in a single case, securely fixing them in their places, you can also do the design of the front panel. Two devices can be placed on it - an ammeter and a voltmeter. With their help, you can monitor the charging voltage and current. If you wish, install an LED or an incandescent lamp, which you connect to the rectifier output. With the help of such a lamp, you will see if the charger is plugged in. Supplement with a miniature circuit breaker if necessary.
Automatic regulation of charging current
Good results are shown by home-made chargers for car batteries that have an automatic current adjustment function. Despite their apparent complexity, these devices are very simple. True, some components are required. The circuit uses current stabilizers, for example LM317, as well as its analogs. It is worth noting that this stabilizer has earned the trust of radio amateurs. It is reliable and durable, its characteristics are superior to domestic counterparts.
In addition to it, you will also need an adjustable zener diode, for example TL431. All microcircuits and stabilizers used in the design must be mounted on separate radiators. The principle of operation of the LM317 is that the "excess" voltage is converted into heat. Therefore, if you have not 12 V, but 15 V from the rectifier output, then the "extra" 3 V will go to the radiator. Many do-it-yourself car battery chargers are made without strict outer shell requirements, but it is better if they are enclosed in an aluminum case.
Conclusion
At the end of the article, I would like to note that a device such as a car charger needs high-quality cooling. Therefore, it is necessary to provide for the installation of coolers. It is best to use those that are mounted in computer power supplies. Just pay attention to the fact that they need a 5 volt power supply, not 12. Therefore, you will have to supplement the circuit, introduce a 5 volt voltage regulator into it. There is much more to be said about chargers. The auto charger circuit is simple to repeat and will be useful in any garage.
Homemade battery chargers usually have a very simple design, and in addition to that, increased reliability just because of the simplicity of the circuit. Another plus from making charging with your own hands is the relative cheapness of the components and, as a result, the low cost of the device.
Why is a prefabricated structure better than a purchased one?
The main task of such a technique is to maintain the charge at the required level. battery car if necessary. If the battery is discharged near the house, where there is the necessary device, then there will be no problems. Otherwise, when there is no suitable equipment for powering the battery, and there are not enough funds either, you can assemble the device with your own hands.
The need to use auxiliary means to recharge the car's battery is primarily due to low temperatures in the cold season, when a half-discharged battery is the main, and sometimes not at all solvable problem, unless the battery is recharged in time. Then homemade chargers for powering car batteries will be a salvation for users who do not plan to invest in such equipment, at least for the time being.
Operating principle
Up to a certain level, the car battery can be powered from the vehicle, or more precisely, from an electric generator. After this node, a relay is usually installed, which is responsible for setting the voltage to no more than 14.1V. In order for the battery to charge to the limit, a higher value of this parameter is required - 14.4V. Accordingly, batteries are used to accomplish such a task.
The main components of this device are a transformer and a rectifier. As a result, a constant current with a voltage of a certain value (14.4V) is supplied to the output. But why is there a run-up with the voltage of the battery itself - 12V? This is done in order to ensure the ability to charge the battery discharged to a level when the value of this battery parameter was equal to 12V. If charging is characterized by the same parameter value, then, as a result, powering the battery will become a difficult task.
We watch the video, the simplest device for charging the battery:
But there is a nuance here: a slight excess of the battery voltage level is not critical, while a significantly overestimated value of this parameter will have a very bad effect in the future on the battery's performance. The principle of operation that distinguishes any, even the simplest charger for powering a car battery, is to increase the resistance level, which will lead to a decrease in the charging current.
Accordingly, the higher the voltage value (tends to 12V), the lower the current. For normal operation of the battery, it is advisable to set a certain value of the charge current (about 10% of the capacity). In a hurry, it is tempting to change the value of this parameter to a larger one, however, this is fraught with negative consequences for the battery itself.
What is required to make a battery?
The basic elements of a simple design are a diode and a heater. If you connect them correctly (in series) to the battery, you can achieve what you want - the battery will be charged in 10 hours. But for those who like to save electricity, such a solution may not be suitable, because the consumption in this case will be about 10 kW. The operation of the resulting device is characterized by low efficiency.
Basic elements of a simple design
But to create a suitable modification, it will be necessary to slightly modify individual elements, in particular, the transformer, the power of which should be at the level of 200-300 W. If you have old technology, this part from a regular tube TV will do. A cooler is useful for organizing the ventilation system, it is best if it comes from a computer.
When a simple do-it-yourself battery charger is created, a transistor and a resistor also act as the main elements. To adjust the work of the structure, you will need a compact outside, but quite roomy metal case, a good option is a box from the stabilizer.
In theory, even a novice radio amateur who has not previously encountered complex circuits can assemble this kind of technique.
Diagram of a simple device for charging a battery
The main difficulty lies in the need to modify the transformer. At this power level, the windings are characterized by low voltage indicators (6-7V), the current will be 10A. Usually, however, a voltage of 12V or 24V is required, depending on the type of storage battery. To obtain such values at the output of the device, it is necessary to provide a parallel connection of the windings.
Phased assembly
A homemade charger for powering a car battery begins with the preparation of the core. Winding the wire onto the windings is performed with maximum sealing, it is important that the turns fit snugly against each other, and there are no gaps left. We must not forget about the insulation, which is installed at intervals of 100 turns. The cross-section of the wire of the primary winding is 0.5 mm, the secondary one is from 1.5 to 3.0 mm. Considering that at a frequency of 50 Hz, 4-5 turns can provide a voltage of 1V, respectively, about 90 turns are required to obtain 18V.
Next, a diode of suitable power is selected to withstand the loads supplied to it in the future. The best option is the generator diode of the car. To eliminate the risk of overheating, it is necessary to ensure effective air circulation inside the housing of such a device. If the box is not perforated, take care of this before starting assembly. The cooler must be connected to the charger output. Its main task is to cool the diode and the transformer winding, which is taken into account when choosing a site for installation.
Watching the video detailed instructions for manufacturing:
A simple charger circuit for powering a car battery also contains a variable resistor. For the charging to function normally, it is necessary to obtain a resistance of 150 ohms and a power of 5 watts. The KU202N resistor model meets these requirements more than others. You can choose a different option, but its parameters should be similar in value to those indicated. The purpose of the resistor is to regulate the voltage at the output of the device. The KT819 transistor model is also the best option from a number of analogues.
Evaluation of efficiency, cost
As you can see, if you need to assemble a homemade charger for a car battery, its circuit is more than simple to implement. The only difficulty is the arrangement of all the elements and their installation into the case with subsequent connection. But such work can hardly be called laborious, and the cost of all the parts used is extremely low.
Some of the details, and, perhaps, all of them will probably be found at home, for example, a cooler from an old computer, a transformer from a tube TV, an old case from a stabilizer. As for the degree of efficiency, such self-assembled devices do not have a very high efficiency, however, as a result, they still cope with their task.
Watching the video useful tips specialist:
Thus, large investments in the creation of a homemade charger are not required. On the contrary, all the elements cost very little, which favorably sets off this solution in comparison with a device that can be purchased ready-made. The scheme considered above is not very efficient, but its main plus is a charged car battery, albeit after 10 hours. You can improve this option or consider many others proposed for implementation.
The need to charge the battery arises for many motorists. Some use branded chargers for these purposes, others use homemade chargers made at home. How to make and how to properly charge the battery with such a device? We will discuss this below.
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The design and principle of operation of the charger
A simple charger is a device used to recharge a battery. The essence of the functioning of any charger is that this device allows you to convert the voltage from a 220 volt household network into the voltage required for. Today there are many types of charger, but at the heart of any device are two main components - a transformer device, as well as a rectifier (the author of a video on how to choose a device for charging is the Accumulator channel).
The process itself consists of several stages:
- when the battery is recharged, the charging current parameter decreases, and the resistance level increases;
- at the moment when the voltage parameter approaches 12 volts, the charging current level reaches zero - at this moment the battery will be fully charged, and the charger can be turned off.
Instructions for making a simple charger with your own hands
If you want to make a charger for a 12 volt or 6 volt car battery, then we can help you with this. Of course, if you have never encountered such a need before, but want to get a functional device, then it is better to purchase an automatic one. After all, a homemade car battery charger will not have the same features as a branded device.
Tools and materials
So, to make a do-it-yourself battery charger, you need the following items:
- soldering iron with consumables;
- textolite plate;
- a wire with a plug for connecting to a household network;
- radiator from the computer.
Depending on, in addition, an ammeter and other components can be used that allow for correct charging and control of the charge. Of course, to make a car charger, you also need to prepare a transformer unit and a rectifier for charging the battery. By the way, the case itself can be taken from an old ammeter. The ammeter case has several holes to which you can connect the necessary elements. If you do not have an ammeter, then you can find something similar.
Photo gallery "Getting ready for assembly"
Stages
To build a DIY car battery charger, do the following:
- So, first you need to work with the transformer. We will show an example of making a homemade charger with a TS-180-2 transformer device - such a device can be removed from an old tube TV. Such devices are equipped with two windings - primary and secondary, and at the output of each secondary component, the current is 4.7 amperes, and the voltage is 6.4 volts. Accordingly, a homemade charger will produce 12.8 volts, but for this, the windings must be connected in a sequential manner.
- To connect the windings, you need a cable with a cross-section of less than 2.5 mm2.
- Using a jumper, both secondary and primary components must be connected.
- Then you will need a diode bridge, for its arrangement, take four diode elements, each of which must be designed to work in conditions of a current of at least 10 amperes.
- The diodes are fixed on the textolite plate, after which they will need to be connected correctly.
- Cables are connected to the output diode components, with the help of which the homemade charger will be connected to the battery. To measure the voltage level, you can additionally use an electromagnetic head, but if you are not interested in this parameter, you can install an ammeter designed for direct current. After completing these steps, the do-it-yourself charger will be ready (the author of the video about the manufacture of the device, the simplest in its design, the Soldering Iron TV channel).
How to charge the battery with a homemade charger?
Now you know how to make a charger for your car at home. But how to use it correctly so that it does not affect the service life of a charged battery?
- When connecting, always observe the polarity so as not to confuse the terminals. If you make a mistake and confuse the terminals, you will simply "kill" the battery. So always the positive wire from the charger is connected to the positive of the battery, and the negative to the negative.
- Never try to test a battery for a spark - despite the fact that there are many recommendations on the Internet regarding this, in no case should you short-circuit the wires. This will negatively affect the operation of the charger and the battery itself in the future.
- When the device is connected to the battery, it must be disconnected from the mains. The same goes for turning it off.
- When making and assembling the charger, and during its use, always be careful. To avoid injury, always follow safety precautions, in particular when working with electrical components. In the event that mistakes are made during manufacturing, this can cause not only injury to a person, but also failure of the battery as a whole.
- Never leave a working charger unattended - you need to understand that this is a homemade device and anything can happen in its operation. When recharging, the device with the battery must be kept in a ventilated area, as far as possible from explosive materials.
Video "An example of assembling a homemade charger with your own hands"
The video below shows an example of assembling a homemade charger for a car battery for more complex pattern with basic recommendations and advice (the author of the video is the AKA KASYAN channel).
How often are car owners unable to start a four-wheeled pet due to lack of charge in the battery? Of course, if this incident happened in the garage near the charger or there is a friend with a car nearby who is ready to help start the starter, no special problems are foreseen.
The situation is much worse if you cannot implement either the first or the second option, especially motorists who are unable to purchase an expensive factory-made charger suffer from this. But in this case, you can find a solution if you make a do-it-yourself car battery charger.
Advantages and disadvantages of a homemade device
The main advantage of a homemade charger is its cheapness, even if you do not have all the necessary parts, the savings will be tangible. Also a significant plus is the ability to use unnecessary devices and devices as a source of materials for a homemade charger.
The disadvantages of homemade battery charging include imperfection in operation. Alas, the model cannot turn off on its own when the maximum charge is reached, so you will have to control this process or supplement the invention with homemade automation, which is within the power of experienced radio amateurs.
Device parameters
As you well know, the entire network in the car is powered by a low voltage of 12V direct current, but the charge level of the car battery must be between 13 and 15V. The charge current at the output of the device should be about 10% of the capacity of the power supply. If the current turns out to be less, the charge will still occur, but the procedure will take much longer. Therefore, the choice of elements for the charger should be based on the operating parameters of a specific model of lead-acid batteries and the network to which it will be connected.
What do you need for a memory?
Structurally, the charger includes the following elements:
Rice. 2: Example of setting the control resistor If you are going to charge the battery once, you can use only the first three cells; for constant use it will be more convenient to have at least control devices. But before putting it all together, you need to make sure that the charger parameters after assembly will suit your needs. The first thing that needs to be matched is the charger transformer.
If the transformer is not suitable
Not always in the garage or at home you will find just such a transformer that will be powered by 220V and output at the output terminals 13-15V. Most of the models used in everyday life do have a 220V primary coil, but the output can be of any value. To fix this, you will need to make a new secondary.
First, recalculate the transformation ratio using the formula: U 1 / U 2 = N 1 / N 2,
N 1 and N 2 - the number of turns in the primary and secondary, respectively.
For example, an electric car is used as a 42V power supply, and you want a 14V charger for the charger. Therefore, at 480 turns in the primary, you need to make 31 turns on the secondary of the charger. This can be achieved both by reducing the number of turns, removing unnecessary ones, and by winding a new one. But the first option is not always suitable, since the cross section of the transformer winding may not withstand the current strength with a smaller number of turns.
U 1 * I 1 = U 2 * I 2,
Where U 1 and U 2 are the voltage across the primary and secondary windings, I 1 and I 2 are the current flowing in the primary and secondary.
As you can see, with a decrease in the number of turns and the voltage on the secondary winding, the current in it will increase proportionally. As a rule, the cross-sectional margin is not enough, therefore, after determining the current strength, a new conductor is selected for it from the table data:
Table: selection of cross-section, depending on the flowing current
| Copper conductor | Aluminum conductor | ||
| Cross section
lived. mm 2 |
Current, A | Section of veins. mm 2 | Current, A |
| 0,5 | 11 | — | — |
| 0,75 | 15 | — | — |
| 1 | 17 | — | — |
| 1.5 | 19 | 2,5 | 22 |
| 2.5 | 27 | 4 | 28 |
| 4 | 38 | 6 | 36 |
| 6 | 46 | 10 | 50 |
| 10 | 70 | 16 | 60 |
| 16 | 80 | 25 | 85 |
If the calculated value of the current at the output of the charger exceeds the required 10% of the battery capacity, a current-limiting resistor is necessarily included in the circuit, the value of which is selected in proportion to the excess current.
Car Battery Charger Assembly Procedure
Depending on the components you have and the parameters of the battery, the assembly of the charger will differ significantly. In this example, the manufacturing technology includes the following stages:
But you must start from the parameters of your electric machine... Therefore, if necessary, remove excess windings or insulate their terminals (if any), wind up the secondary (if the existing one does not give the required voltage level in the charger).
Rice. 5: rewind windings 
and on the secondary terminals 9 and 9 ′.
Rice. 7: connect pins 9 - Solder the leads of the power cord to terminals 2 and 2 '.
Rice. 8: plug in the power cord - Assemble the diode assembly on a textolite plate, as shown in the diagram. Due to the intense heat generation due to high charging currents, semiconductor devices are installed on a radiator.
Rice. 9: diode assembly - Connect the bridge to 12V pins, in this example terminals 10 and 10 '. The main elements of the charger are assembled.
Rice. 10: connect pins 10 to diode bridge - Install an ammeter with a measurement limit of up to 15 A. between the output of the diode bridge and the battery terminals.
Rice. 11: connect the ammeter - Connect a current-limiting resistor unit or a switch with a resistance adjustment function to the ammeter circuit, they will allow you to change the value of the charger's current. Rice. 13: connect a voltmeter
To protect the charger, both on the mains side and on the lead battery side, two fuses must be installed. In the example under consideration, a 0.5A fuse is used on the high side of the charger, and a 10A fuse in the lead-acid battery charging circuit.
If there is a current regulator of the charger, start charging from the minimum value on the ammeter and gradually increase it to the required value. When a sufficient amount of charge has accumulated in the battery, the ammeter will show about 1A, after which you can safely disconnect the charger from the network and use the battery for its intended purpose.
Rice. 14: dependence of quantities on charging time Related Videos
Good day, gentlemen, radio amateurs! In this article I want to describe the assembly of a simple charger. Even quite simple, because it does not contain anything superfluous. After all, often by complicating the scheme, we reduce its reliability. In general, a couple of options for such simple car chargers will be considered here, which can be soldered to anyone who has at least once repaired a coffee grinder or changed a switch in the corridor)) From my own experience, I can assume that it will be useful to everyone who has at least something to do with technology or electronics. For a long time I had an idea to assemble the simplest charger for the battery of my motorcycle, since the generator sometimes simply cannot cope with charging the latter, it is especially difficult for him on a winter morning when he needs to start it from the starter. Of course, many will say that it is much easier with a kick starter, but then the battery can be thrown out altogether.
The electrical circuit of a homemade charger
What is needed to charge the battery? A stable current source that does not exceed a certain safe value. In the simplest case, it will be an ordinary mains transformer. It should deliver on the secondary the current that is needed for a standard charging mode (1/10 of the battery capacity). And if at the beginning of the charging cycle the load begins to draw a current of a larger value, there will be a voltage drop on the output winding of the transformer, which means the current will decrease. There are two options for rectifiers:
The latter circuit will allow you to change the value of the charging current by changing the voltage on the battery. If you do not trust the transformer, then the function of the current stabilizer can be assigned to an ordinary 12 volt car light bulb.
In general, I decided for myself to make the charging quite powerful, as I took the TS-160 transformer from the Soviet tube TV as a basis, rewound it to fit my needs, the output came out with 14 volts per 10 amperes, which allows charging a battery of a sufficiently large capacity, including any automobile ones.
Charger case
The body was assembled from zinc sheet, as I wanted to make it as simple as possible. 
A hole for the fan was cut out at the back of the case, for greater reliability I decided to add active cooling, and the valves accumulated, even if they do not lie idle.
Then he began to make the filling, screwed on the transformer, took the diode bridge with a margin too - KRVS-3510
, since they don't cost much:
In the front panel I made a hole for a voltmeter, I also screwed a socket for crocodiles.
It turned out just what I wanted, simple and reliable. This unit is mainly used to charge the battery and power 12 volt LED strips.
Well, as a last resort for tuning automotive converters. And so that there was less interference, after the bridge, I put a pair of capacitors with a total capacity of about 5 thousand microfarads.
Outwardly, of course, it could have been done more accurately, but the main thing here is reliability, the next in line is the laboratory power supply, in which I will embody all my design skills. All the best, I was with you Columnist!.)
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