Battery problems are not that uncommon. To restore functionality, additional charging is necessary, but normal charging costs a lot of money, and it can be done from available “trash.” The most important thing is to find a transformer with the required characteristics, and making a charger for a car battery with your own hands takes just a couple of hours (if you have all the necessary parts).
The battery charging process must follow certain rules. Moreover, the charging process depends on the type of battery. Violations of these rules lead to a decrease in capacity and service life. Therefore, the parameters of a car battery charger are selected for each specific case. This opportunity is provided by a complex charger with adjustable parameters or purchased specifically for this battery. There is a more practical option - making a charger for a car battery with your own hands. To know what parameters should be, a little theory.
Types of battery chargers
Battery charging is the process of restoring used capacity. To do this, a voltage is supplied to the battery terminals that is slightly higher than the operating parameters of the battery. Can be served:
- D.C. The charging time is at least 10 hours, during this entire time a fixed current is supplied, the voltage varies from 13.8-14.4 V at the beginning of the process to 12.8 V at the very end. With this type, the charge accumulates gradually and lasts longer. The disadvantage of this method is that it is necessary to control the process and turn off the charger in time, since when overcharging the electrolyte may boil, which will significantly reduce its working life.
- Constant pressure. When charging with a constant voltage, the charger produces a voltage of 14.4 V all the time, and the current varies from large values in the first hours of charging to very small values in the last. Therefore, the battery will not be recharged (unless you leave it for several days). The positive aspect of this method is that the charging time is reduced (90-95% can be reached in 7-8 hours) and the battery being charged can be left unattended. But such an “emergency” charge recovery mode has a bad effect on service life. With frequent use of constant voltage, the battery discharges faster.
In general, if there is no need to rush, it is better to use DC charging. If you need to restore battery functionality in a short time, apply constant voltage. If we talk about what is the best charger to make for a car battery with your own hands, the answer is clear - one that supplies direct current. The schemes will be simple, consisting of accessible elements.
How to determine the necessary parameters when charging with direct current
It has been experimentally established that charge car lead acid batteries(most of them) required current that does not exceed 10% of the battery capacity. If the capacity of the battery being charged is 55 A/h, the maximum charge current will be 5.5 A; with a capacity of 70 A/h - 7 A, etc. In this case, you can set a slightly lower current. The charge will continue, but more slowly. It will accumulate even if the charge current is 0.1 A. It will just take a very long time to restore the capacity.
Since the calculations assume that the charge current is 10%, we obtain a minimum charge time of 10 hours. But this is when the battery is completely discharged, and this should not be allowed. Therefore, the actual charging time depends on the “depth” of the discharge. You can determine the depth of discharge by measuring the voltage on the battery before charging:
To calculate approximate battery charging time, you need to find out the difference between the maximum battery charge (12.8 V) and its current voltage. Multiplying the number by 10 we get the time in hours. For example, the voltage on the battery before charging is 11.9 V. We find the difference: 12.8 V - 11.9 V = 0.8 V. Multiplying this figure by 10, we find that the charging time will be about 8 hours. This is provided that we supply a current that is 10% of the battery capacity.
Charger circuits for car batteries
To charge batteries, a 220 V household network is usually used, which is converted to reduced voltage using a converter.
Simple circuits
The simplest and most effective way is to use a step-down transformer. It is he who lowers 220 V to the required 13-15 V. Such transformers can be found in old tube TVs (TS-180-2), computer power supplies, and found at flea market “ruins”.
But the output of the transformer produces an alternating voltage that must be rectified. They do this using:
The above diagrams also contain fuses (1 A) and measuring instruments. They make it possible to control the charging process. They can be excluded from the circuit, but you will have to periodically use a multimeter to monitor them. With voltage control this is still tolerable (just attach probes to the terminals), but it is difficult to control the current - in this mode the measuring device is connected to an open circuit. That is, you will have to turn off the power every time, put the multimeter in current measurement mode, and turn on the power. disassemble the measuring circuit in reverse order. Therefore, using at least a 10 A ammeter is very desirable.
The disadvantages of these schemes are obvious - there is no way to adjust the charging parameters. That is, when choosing an element base, choose the parameters so that the output current is the same 10% of the capacity of your battery (or a little less). You know the voltage - preferably within 13.2-14.4 V. What to do if the current turns out to be more than desired? Add a resistor to the circuit. It is placed at the positive output of the diode bridge in front of the ammeter. You select the resistance “locally”, focusing on the current; the power of the resistor is larger, since excess charge will be dissipated on them (10-20 W or so).
And one more thing: a do-it-yourself car battery charger made according to these schemes will most likely get very hot. Therefore, it is advisable to add a cooler. It can be inserted into the circuit after the diode bridge.
Adjustable circuits
As already mentioned, the disadvantage of all these circuits is the inability to regulate the current. The only option is to change the resistance. By the way, you can put a variable tuning resistor here. This will be the easiest way out. But manual current adjustment is more reliably implemented in a circuit with two transistors and a trimming resistor.
The charging current is changed by a variable resistor. It is located after the composite transistor VT1-VT2, so a small current flows through it. Therefore, the power can be about 0.5-1 W. Its rating depends on the selected transistors and is selected experimentally (1-4.7 kOhm).
Transformer with a power of 250-500 W, secondary winding 15-17 V. The diode bridge is assembled on diodes with an operating current of 5A and higher.
Transistor VT1 - P210, VT2 is selected from several options: germanium P13 - P17; silicon KT814, KT 816. To remove heat, install on a metal plate or radiator (at least 300 cm2).
Fuses: at the input PR1 - 1 A, at the output PR2 - 5 A. Also in the circuit there are signal lamps - the presence of a voltage of 220 V (HI1) and a charging current (HI2). Here you can install any 24 V lamps (including LEDs).
Video on the topic
DIY car battery charger is a popular topic for car enthusiasts. Transformers are taken from everywhere - from power supplies, microwave ovens... they even wind them themselves. The schemes being implemented are not the most complex. So even without electrical engineering skills you can do it yourself.
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 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.
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.
In electrical engineering, batteries are usually called chemical current sources that can replenish and restore spent energy through the application of an external electric field.
Devices that supply electricity to the battery plates are called chargers: they bring the current source into working condition and charge it. To properly operate batteries, you need to understand the principles of their operation and the charger.
How does a battery work?
During operation, a chemical recirculated current source can:
1. power the connected load, for example, a light bulb, motor, mobile phone and other devices, using up its supply of electrical energy;
2. consume external electricity connected to it, spending it to restore its capacity reserve.
In the first case, the battery is discharged, and in the second, it receives a charge. There are many battery designs, but their operating principles are common. Let us examine this issue using the example of nickel-cadmium plates placed in an electrolyte solution.
Low battery
Two electrical circuits operate simultaneously:
1. external, applied to the output terminals;
2. internal.
When a light bulb is discharged, a current flows in the external circuit of the wires and filament, generated by the movement of electrons in the metals, and in the internal part, anions and cations move through the electrolyte.
Nickel oxides with added graphite form the basis of the positively charged plate, and cadmium sponge is used on the negative electrode.
When the battery is discharged, part of the active oxygen of the nickel oxides moves into the electrolyte and moves to the plate with cadmium, where it oxidizes it, reducing the overall capacity.
Battery charge
The load is most often removed from the output terminals for charging, although in practice the method is used with a connected load, such as on the battery of a moving car or a mobile phone on charge, on which a conversation is taking place.
The battery terminals are supplied with voltage from an external source of higher power. It has the appearance of a constant or smoothed, pulsating shape, exceeds the potential difference between the electrodes, and is directed unipolarly with them.
This energy causes current to flow in the internal circuit of the battery in the direction opposite to the discharge, when particles of active oxygen are “squeezed out” from the cadmium sponge and through the electrolyte enter their original place. Due to this, the spent capacity is restored.
During charge and discharge, the chemical composition of the plates changes, and the electrolyte serves as a transfer medium for the passage of anions and cations. The intensity of the electric current passing in the internal circuit affects the rate of restoration of the properties of the plates during charging and the speed of discharge.
Accelerated processes lead to rapid release of gases and excessive heating, which can deform the structure of the plates and disrupt their mechanical condition.
Too low charging currents significantly lengthen the recovery time of used capacity. With frequent use of a slow charge, sulfation of the plates increases and capacity decreases. Therefore, the load applied to the battery and the power of the charger are always taken into account to create the optimal mode.
How does the charger work?
The modern range of batteries is quite extensive. For each model, optimal technologies are selected, which may not be suitable or may be harmful to others. Manufacturers of electronic and electrical equipment experimentally study the operating conditions of chemical current sources and create their own products for them, differing in appearance, design, and output electrical characteristics.
Charging structures for mobile electronic devices
The dimensions of chargers for mobile products of different power differ significantly from each other. They create special operating conditions for each model.
Even for batteries of the same type AA or AAA sizes of different capacities, it is recommended to use their own charging time, depending on the capacity and characteristics of the current source. Its values are indicated in the accompanying technical documentation.
A certain part of chargers and batteries for mobile phones are equipped with automatic protection that turns off the power when the process is complete. However, monitoring their work should still be carried out visually.
Charging structures for car batteries
Charging technology should be observed especially precisely when using car batteries designed to operate in difficult conditions. For example, in cold winters, they need to be used to spin the cold rotor of an internal combustion engine with thickened lubricant through an intermediate electric motor—the starter.
Discharged or improperly prepared batteries usually do not cope with this task.
Empirical methods have revealed the relationship between the charging current for lead acid and alkaline batteries. It is generally accepted that the optimal charge value (ampere) is 0.1 the capacity value (ampere hours) for the first type and 0.25 for the second.
For example, the battery has a capacity of 25 ampere hours. If it is acidic, then it must be charged with a current of 0.1∙25 = 2.5 A, and for alkaline - 0.25∙25 = 6.25 A. To create such conditions, you will need to use different devices or use one universal one with a large amount functions.
A modern charger for lead acid batteries must support a number of tasks:
control and stabilize the charge current;
take into account the temperature of the electrolyte and prevent it from heating more than 45 degrees by stopping the power supply.
The ability to carry out a control and training cycle for a car's acid battery using a charger is a necessary function, which includes three stages:
1. fully charge the battery until it reaches maximum capacity;
2. ten-hour discharge with a current of 9÷10% of the nominal capacity (empirical dependence);
3. recharge a discharged battery.
When carrying out CTC, the change in electrolyte density and the completion time of the second stage are monitored. Its value is used to judge the degree of wear of the plates and the duration of the remaining service life.
Chargers for alkaline batteries can be used in less complex designs, because such current sources are not so sensitive to undercharging and overcharging conditions.
The graph of the optimal charge of acid-base batteries for cars shows the dependence of the capacity gain on the shape of the current change in the internal circuit.
At the beginning of the charging process, it is recommended to maintain the current at the maximum permissible value, and then reduce its value to the minimum for the final completion of the physicochemical reactions that restore capacity.
Even in this case, it is necessary to control the temperature of the electrolyte and introduce corrections for the environment.
The complete completion of the charging cycle of lead acid batteries is controlled by:
restore the voltage on each bank to 2.5÷2.6 volts;
achieving maximum electrolyte density, which ceases to change;
the formation of violent gas evolution when the electrolyte begins to “boil”;
achieving a battery capacity that exceeds by 15÷20% the value given during discharge.
Battery charger current forms
The condition for charging a battery is that a voltage must be applied to its plates, creating a current in the internal circuit in a certain direction. He can:
1. have a constant value;
2. or change over time according to a certain law.
In the first case, the physicochemical processes of the internal circuit proceed unchanged, and in the second, according to the proposed algorithms with a cyclic increase and decrease, creating oscillatory effects on anions and cations. The latest version of the technology is used to combat plate sulfation.
Some of the time dependences of the charge current are illustrated by graphs.
The lower right picture shows a clear difference in the shape of the output current of the charger, which uses thyristor control to limit the opening moment of the half-cycle of the sine wave. Due to this, the load on the electrical circuit is regulated.
Naturally, many modern chargers can create other forms of currents not shown in this diagram.
Principles of creating circuits for chargers
To power charger equipment, a single-phase 220 volt network is usually used. This voltage is converted into a safe low voltage, which is applied to the battery input terminals through various electronic and semiconductor parts.
There are three schemes for converting industrial sinusoidal voltage in chargers due to:
1. use of electromechanical voltage transformers operating on the principle of electromagnetic induction;
2. application of electronic transformers;
3. without the use of transformer devices based on voltage dividers.
Inverter voltage conversion is technically possible, which has become widely used for frequency converters that control electric motors. But, for charging batteries this is quite expensive equipment.
Charger circuits with transformer separation
The electromagnetic principle of transferring electrical energy from the primary winding of 220 volts to the secondary completely ensures the separation of the potentials of the supply circuit from the consumed circuit, eliminating its contact with the battery and damage in the event of insulation faults. This method is the safest.
The power circuits of devices with a transformer have many different designs. The picture below shows three principles for creating different power section currents from chargers through the use of:
1. diode bridge with a ripple-smoothing capacitor;
2. diode bridge without ripple smoothing;
3. a single diode that cuts off the negative half-wave.
Each of these circuits can be used independently, but usually one of them is the basis, the basis for creating another, more convenient for operation and control in terms of the output current.
The use of sets of power transistors with control circuits in the upper part of the picture in the diagram allows you to reduce the output voltage at the output contacts of the charger circuit, which ensures regulation of the magnitude of direct currents passed through the connected batteries.
One of the options for such a charger design with current regulation is shown in the figure below.
The same connections in the second circuit allow you to regulate the amplitude of the ripples and limit it at different stages of charging.
The same average circuit works effectively when replacing two opposite diodes in the diode bridge with thyristors that equally regulate the current strength in each alternating half-cycle. And the elimination of negative semi-harmonics is assigned to the remaining power diodes.
Replacing the single diode in the bottom picture with a semiconductor thyristor with a separate electronic circuit for the control electrode allows you to reduce current pulses due to their later opening, which is also used for various methods of charging batteries.
One of the options for such a circuit implementation is shown in the figure below.
Assembling it with your own hands is not difficult. It can be made independently from available parts and allows you to charge batteries with currents of up to 10 amperes.
The industrial version of the Electron-6 transformer charger circuit is made on the basis of two KU-202N thyristors. To regulate the opening cycles of semiharmonics, each control electrode has its own circuit of several transistors.
Devices that allow not only charging batteries, but also using the energy of the 220-volt supply network to parallel connect it to starting the car engine are popular among car enthusiasts. They are called starting or starting-charging. They have even more complex electronic and power circuitry.
Circuits with electronic transformer
Such devices are produced by manufacturers to power halogen lamps with a voltage of 24 or 12 volts. They are relatively cheap. Some enthusiasts are trying to connect them to charge low-power batteries. However, this technology has not been widely tested and has significant drawbacks.
Charger circuits without transformer separation
When several loads are connected in series to a current source, the total input voltage is divided into component sections. Due to this method, dividers work, creating a voltage drop to a certain value on the working element.
This principle is used to create numerous RC chargers for low-power batteries. Due to the small dimensions of the component parts, they are built directly inside the flashlight.
The internal electrical circuit is completely housed in a factory-insulated housing, which prevents human contact with the network potential during charging.
Numerous experimenters are trying to implement the same principle for charging car batteries, proposing a connection scheme from a household network through a capacitor assembly or an incandescent light bulb with a power of 150 watts and passing current pulses of the same polarity.
Similar designs can be found on the sites of do-it-yourself experts, praising the simplicity of the circuit, the cheapness of parts, and the ability to restore the capacity of a discharged battery.
But they are silent about the fact that:
open wiring 220 represents ;
The filament of the lamp under voltage heats up and changes its resistance according to a law unfavorable for the passage of optimal currents through the battery.
When switched on under load, very large currents pass through the cold thread and the entire series-connected chain. In addition, charging should be completed with small currents, which is also not done. Therefore, a battery that has been subjected to several series of such cycles quickly loses its capacity and performance.
Our advice: do not use this method!
Chargers are created to work with certain types of batteries, taking into account their characteristics and conditions for restoring capacity. When using universal, multifunctional devices, you should choose the charging mode that optimally suits a particular battery.
An automatic car battery charger consists of a power supply and protection circuits. You can assemble it yourself if you have electrical installation skills. During assembly, both complex electrical circuits and simpler versions of the device are designed.
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Requirements for homemade chargers
In order for the charger to automatically restore the car’s battery, strict requirements are imposed on it:
- Any simple modern memory device must be autonomous. Thanks to this, the operation of the equipment does not have to be monitored, in particular if it operates at night. The device will independently control the operating parameters of voltage and charge current. This mode is called automatic.
- The charging equipment must independently provide a stable voltage level of 14.4 volts. This parameter is necessary to restore any batteries operating in a 12-volt network.
- The charging equipment must ensure irreversible disconnection of the battery from the device under two conditions. In particular, if the charge current or voltage increases by more than 15.6 volts. The equipment must have a self-locking function. To reset the operating parameters, the user will have to turn off and activate the device.
- The equipment must be protected from overvoltage, otherwise the battery may fail. If the consumer confuses the polarity and incorrectly connects the negative and positive contacts, a short circuit will occur. It is important that charging equipment provides protection. The circuit is supplemented with a safety device.
- To connect the charger to the battery, you will need two wires, each of which must have a cross-section of 1 mm2. An alligator clip must be installed on one end of each conductor. On the other side, split tips are installed. The positive contact must be made in a red sheath, and the negative contact in a blue sheath. For a household network, a universal cable equipped with a plug is used.
If you completely make the device yourself, failure to comply with the requirements will harm not only the charger, but also the battery.
Vladimir Kalchenko spoke in detail about the modification of the charger and the use of wires suitable for this purpose.
Automatic charger design
The simplest example of a charger structurally includes the main part - a step-down transformer device. This element reduces the voltage parameter from 220 to 13.8 volts, which is required to restore the battery charge. But the transformer device can only reduce this value. And the conversion of alternating current to direct current is carried out by a special element - a diode bridge.
Each charger must be equipped with a diode bridge, since this part rectifies the current value and allows it to be divided into positive and negative poles.
In any circuit, an ammeter is usually installed behind this part. The component is designed to demonstrate current strength.
The simplest designs of chargers are equipped with pointer sensors. More advanced and expensive versions use digital ammeters, and in addition to them, the electronics can be supplemented with voltmeters.
Some device models allow the consumer to change the voltage level. That is, it becomes possible to charge not only 12-volt batteries, but also batteries designed to operate in 6- and 24-volt networks.
Wires with positive and negative terminals extend from the diode bridge. They are used to connect equipment to the battery. The entire structure is enclosed in a plastic or metal case, from which comes a cable with a plug for connecting to the electrical network. Also, two wires with a negative and positive terminal clamp are output from the device. To ensure safer operation of the charging equipment, the circuit is supplemented with a fusible safety device.
User Artem Kvantov clearly disassembled the proprietary charging device and talked about its design features.
Automatic charger circuits
If you have skills in working with electrical equipment, you can assemble the device yourself.
Simple circuits
These types of devices are divided into:
- devices with one diode element;
- equipment with a diode bridge;
- devices equipped with smoothing capacitors.
Circuit with one diode
There are two options here:
- You can assemble a circuit with a transformer device and install a diode element after it. At the output of the charging equipment, the current will be pulsating. Its beats will be serious, since one half-wave is actually cut off.
- You can assemble the circuit using a laptop power supply. It uses a powerful rectifying diode element with a reverse voltage of more than 1000 volts. Its current must be at least 3 amperes. The outer terminal of the power plug will be negative and the inner terminal will be positive. Such a circuit must be supplemented with a limiting resistance, which can be used as a light bulb to illuminate the interior.
It is permissible to use a more powerful lighting device from a turn signal, side lights or brake lights. When using a laptop power supply, this may cause it to overload. If a diode is used, then an incandescent lamp of 220 volts and 100 watts must be installed as a limiter.
When using a diode element, a simple circuit is assembled:
- First comes the terminal from a 220-volt household outlet.
- Then - the negative contact of the diode element.
- The next one will be the positive terminal of the diode.
- Then a limiting load is connected - a lighting source.
- Next will be the negative terminal of the battery.
- Then the positive terminal of the battery.
- And the second terminal for connecting to a 220-volt network.
When using a 100-watt light source, the charging current will be approximately 0.5 amperes. So in one night the device will be able to transfer 5 A/h to the battery. This is enough to turn the vehicle's starter mechanism.
To increase the indicator, you can connect three 100-watt lighting sources in parallel; this will replenish half the battery capacity overnight. Some users use electric stoves instead of lamps, but this cannot be done, since not only the diode element will fail, but also the battery.
The simplest circuit with one diode 
Electrical diagram for connecting the battery to the network
Circuit with diode bridge
This component is designed to “wrap” the negative wave upward. The current itself will also pulsate, but its beats are much less. This version of the scheme is used more often than others, but is not the most effective.
You can make a diode bridge yourself using a rectifying element, or purchase a ready-made part.
Electrical circuit of a charger with a diode bridge
Circuit with smoothing capacitor
This part should be rated for 4000-5000 uF and 25 volts. A direct current is generated at the output of the resulting electrical circuit. The device must be supplemented with 1 ampere safety elements, as well as measuring equipment. These parts allow you to control the battery recovery process. You don’t have to use them, but then you will need to connect a multimeter periodically.
While monitoring voltage is convenient (by connecting terminals to probes), monitoring current will be more difficult. In this operating mode, the measuring device will have to be connected to an electrical circuit. The user will need to turn off the power from the network each time and put the tester in current measurement mode. Then turn on the power and disassemble the electrical circuit. Therefore, it is recommended to add at least one 10 amp ammeter to the circuit.
The main disadvantage of simple electrical circuits is the lack of ability to adjust the charging parameters.
When selecting the element base, you should select operating parameters so that the output current is 10% of the total battery capacity. A slight decrease in this value is possible.
If the resulting current parameter is greater than required, the circuit can be supplemented with a resistor element. It is installed on the positive output of the diode bridge, immediately before the ammeter. The resistance level is selected in accordance with the bridge used, taking into account the current indicator, and the power of the resistor should be higher.
Electrical circuit with a smoothing capacitor device
Circuit with the ability to manually adjust the charge current for 12 V
To make it possible to change the current parameter, it is necessary to change the resistance. A simple way to solve this problem is to install a variable trimmer resistor. But this method cannot be called the most reliable. To ensure higher reliability, it is necessary to implement manual adjustment with two transistor elements and a trimming resistor.
Using a variable resistor component, the charging current will vary. This part is installed after the composite transistor VT1-VT2. Therefore, the current through this element will be low. Accordingly, the power will also be small, it will be about 0.5-1 W. The operating rating depends on the transistor elements used and is selected experimentally; the parts are designed for 1-4.7 kOhm.
The circuit uses a 250-500 W transformer device, as well as a secondary winding of 15-17 volts. The diode bridge is assembled on parts whose operating current is 5 amperes or more. Transistor elements are selected from two options. These can be germanium parts P13-P17 or silicon devices KT814 and KT816. To ensure high-quality heat removal, the circuit must be placed on a radiator device (at least 300 cm3) or a steel plate.
At the output of the equipment, a safety device PR2 is installed, rated at 5 amperes, and at the input - PR1 at 1 A. The circuit is equipped with signal light indicators. One of them is used to determine the voltage in a 220 volt network, the second is used to determine the charging current. It is allowed to use any lighting sources rated for 24 volts, including diodes.
Electrical circuit for a charger with manual adjustment function
Over-reversal protection circuit
There are two options for implementing such a memory:
- using relay P3;
- by assembling a charger with integral protection, but not only from overvoltage, but also from overvoltage and overcharging.
With relay P3
This version of the circuit can be used with any charging equipment, both thyristor and transistor. It must be included in the cable break through which the battery is connected to the charger.
Scheme for protecting equipment from reverse polarity on relay P3
If the battery is not connected to the network correctly, the VD13 diode element will not pass current. The electrical circuit relay is de-energized and its contacts are open. Accordingly, current will not be able to flow to the battery terminals. If the connection is made correctly, the relay is activated and its contact elements are closed, so the battery is charged.
With integrated overvoltage, overcharge and overvoltage protection
This version of the electrical circuit can be built into an already used homemade power source. It uses the slow response of the battery to a voltage surge, as well as relay hysteresis. The voltage with the release current will be 304 times less than this parameter when triggered.
An AC relay is used with an activation voltage of 24 volts, and a current of 6 amperes flows through the contacts. When the charger is activated, the relay turns on, the contact elements close and charging begins.
The voltage parameter at the output of the transformer device drops below 24 volts, but at the output of the charger there will be 14.4 V. The relay must maintain this value, but when an extra current appears, the primary voltage will drop even more. This will turn off the relay and break the charging circuit.
The use of Schottky diodes in this case is impractical, since this type of circuit will have serious disadvantages:
- There is no protection against voltage surges across the contact if the battery is completely discharged.
- There is no self-locking of the equipment. As a result of exposure to extra current, the relay will turn off until the contact elements fail.
- Unclear operation of equipment.
Because of this, adding a device to this circuit to adjust the operating current does not make sense. The relay and transformer device are precisely matched to each other so that the repeatability of the elements is close to zero. The charging current passes through the closed contacts of relay K1, which reduces the likelihood of their failure due to burning.
Winding K1 must be connected according to a logical electrical circuit:
- to the overcurrent protection module, these are VD1, VT1 and R1;
- to the surge protection device, these are elements VD2, VT2, R2-R4;
- as well as to the self-locking circuit K1.2 and VD3.
Circuit with integrated protection against overvoltage, overcharge and overvoltage
The main disadvantage is the need to set up a circuit using a ballast load, as well as a multimeter:
- Elements K1, VD2 and VD3 are desoldered. Or you don’t have to solder them during assembly.
- The multimeter is activated, which must be configured in advance to measure a voltage of 20 volts. It must be connected instead of winding K1.
- The battery is not connected yet; a resistor device is installed instead. It should have a resistance of 2.4 ohms for a charge current of 6 A or 1.6 ohms for 9 amperes. For 12 A, the resistor should be rated at 1.2 Ohms and no less than 25 W. The resistor element can be wound from a similar wire that was used for R1.
- A voltage of 15.6 volts is supplied to the input from the charging equipment.
- The current protection should operate. The multimeter will show voltage since the resistance element R1 is selected with a slight excess.
- The voltage parameter is reduced until the tester shows 0. The output voltage value must be recorded.
- Then part VT1 is desoldered, and VD2 and K1 are installed in place. R3 must be placed in the lowest position in accordance with the electrical diagram.
- The voltage of the charging equipment increases until the load reaches 15.6 volts.
- Element R3 rotates smoothly until K1 is triggered.
- The charger voltage is reduced to the value that was previously recorded.
- Elements VT1 and VD3 are installed and soldered back. After this, the electrical circuit can be checked for functionality.
- A working but dead or undercharged battery is connected through an ammeter. A tester must be connected to the battery, which is pre-configured to measure voltage.
- The test charge must be carried out with continuous monitoring. At the moment when the tester shows 14.4 volts on the battery, it is necessary to detect the content current. This parameter should be normal or close to the lower limit.
- If the content current is high, the charger voltage should be reduced.
Automatic shutdown circuit when the battery is fully charged
The automation must be an electrical circuit equipped with a power supply system for an operational amplifier and a reference voltage. For this, a DA1 class 142EN8G stabilizer board for 9 volts is used. This circuit must be designed so that the output voltage level remains virtually unchanged when measuring the board temperature by 10 degrees. The change will be no more than hundredths of a volt.
In accordance with the description of the circuit, the automatic deactivation system when the voltage increases by 15.6 volts is done on half of the A1.1 board. Its fourth pin is connected to the voltage divider R7 and R8, from which a reference value of 4.5V is supplied. The operating parameter of the resistor device sets the activation threshold of the charger to 12.54 V. As a result of using the diode element VD7 and part R9, it is possible to provide the desired hysteresis between the activation and shutdown voltages of the battery charge.
Electrical circuit of the charger with automatic deactivation when the battery is charged
The description of the action of the scheme is as follows:
- When a battery is connected, the voltage level at the terminals of which is less than 16.5 volts, a parameter is set at the second terminal of circuit A1.1. This value is enough for the transistor element VT1 to open.
- This detail is being discovered.
- Relay P1 is activated. As a result, the primary winding of the transformer device is connected to the network through a block of capacitor mechanisms via contact elements.
- The process of replenishing the battery charge begins.
- When the voltage level increases to 16.5 volts, this value at output A1.1 will decrease. The decrease occurs to a value that is not enough to maintain the transistor device VT1 in the open state.
- The relay is switched off and contact elements K1.1 are connected to the transformer unit through the capacitor device C4. With it, the charge current will be 0.5 A. In this state, the equipment circuit will operate until the voltage on the battery drops to 12.54 volts.
- After this happens, the relay is activated. The battery continues to charge at the user-specified current. This circuit implements the ability to disable the automatic adjustment system. For this purpose, switching device S2 is used.
This operating procedure for an automatic charger for a car battery helps prevent its discharge. The user can leave the equipment turned on for at least a week, this will not harm the battery. If the voltage in the household network is lost, when it returns, the charger will continue to charge the battery.
If we talk about the principle of operation of the circuit assembled on the second half of the A1.2 board, then it is identical. But the level of complete deactivation of charging equipment from the power supply will be 19 volts. If the voltage is less, at the eighth output of board A1.2 it will be sufficient to hold the transistor device VT2 in the open position. With it, current will be supplied to relay P2. But if the voltage is more than 19 volts, then the transistor device will close and the contact elements K2.1 will open.
Required materials and tools
Description of parts and elements that will be required for assembly:
- Power transformer device T1 class TN61-220. Its secondary windings must be connected in series. You can use any transformer whose power is no more than 150 watts, since the charging current is usually no more than 6A. The secondary winding of the device, when exposed to an electric current of up to 8 amperes, should provide a voltage in the range of 18-20 volts. If a ready-made transformer is not available, parts of similar power can be used, but the secondary winding will need to be rewinded.
- Capacitor elements C4-C9 must comply with the MGBC class and have a voltage of at least 350 volts. Any type of device can be used. The main thing is that they are intended to operate in alternating current circuits.
- Any diode elements VD2-VD5 can be used, but they must be rated for a current of 10 amperes.
- Parts VD7 and VD11 are flint impulse.
- Diode elements VD6, VD8, VD10, VD5, VD12, VD13 must withstand a current of 1 ampere.
- LED element VD1 - any.
- As a VD9 part, it is allowed to use a device of class KIPD29. The main feature of this light source is the ability to change color if the polarity of the connection is changed. To switch the light bulb, contact elements K1.2 of relay P1 are used. If the battery is being charged with the main current, the LED lights up yellow, and if the recharging mode is turned on, it turns green. It is possible to use two devices of the same color, but they must be connected correctly.
- Operational amplifier KR1005UD1. You can take the device from an old video player. The main feature is that this part does not require two polar power supplies; it can operate at a voltage of 5-12 volts. Any similar spare parts can be used. But due to different numbering of pins, it will be necessary to change the design of the printed circuit.
- Relays P1 and P2 must be designed for voltages of 9-12 volts. And their contacts are designed to operate with a current of 1 ampere. If devices are equipped with several contact groups, it is recommended to solder them in parallel.
- Relay P3 is 9-12 volts, but the switching current will be 10 amperes.
- Switching device S1 must be designed to operate at 250 volts. It is important that this element has enough switching contact components. If the adjustment step of 1 ampere is not important, then you can install several switches and set the charge current to 5-8 A.
- Switch S2 is designed to deactivate the charge level control system.
- You will also need an electromagnetic head for a current and voltage meter. Any type of device can be used, as long as the total deviation current is 100 µA. If not voltage is measured, but only current, then a ready-made ammeter can be installed in the circuit. It must be rated to operate with a maximum continuous current of 10 amps.
User Artem Kvantov spoke in theory about the circuit of the charging equipment, as well as the preparation of materials and parts for its assembly.
Procedure for connecting the battery to chargers
The instructions for turning on the charger consist of several steps:
- Cleaning the battery surface.
- Removing plugs for filling liquid and monitoring the electrolyte level in jars.
- Setting the current value on the charging equipment.
- Connecting the terminals to the battery with correct polarity.
Surface cleaning
Guidelines for completing the task:
- The car's ignition is turned off.
- The hood of the car opens. Using appropriately sized wrenches, disconnect the clamps from the battery terminals. To do this, you do not need to unscrew the nuts; they can be loosened.
- The fixing plate that secures the battery is dismantled. This may require a socket or sprocket wrench.
- The battery is dismantled.
- Its body is cleaned with a clean rag. Subsequently, the lids of the cans to fill the electrolyte will be unscrewed, so the weight must not be allowed to get inside.
- A visual diagnosis of the integrity of the battery case is performed. If there are cracks through which electrolyte leaks, it is not advisable to charge the battery.
User Battery Technician talked about cleaning and flushing the battery case before servicing it.
Removing Acid Fill Plugs
If the battery is serviceable, you need to unscrew the caps on the plugs. They can be hidden under a special protective plate; it must be removed. To unscrew the plugs, you can use a screwdriver or any metal plate of the appropriate size. After dismantling, it is necessary to evaluate the electrolyte level; the liquid should completely cover all the cans inside the structure. If it is not enough, then you need to add distilled water.
Setting the charge current value on the charger
The current parameter for recharging the battery is set. If this value is 2-3 times greater than the nominal value, then the charging procedure will occur faster. But this method will lead to a decrease in battery life. Therefore, you can set this current if the battery needs to be recharged quickly.
Connecting the battery with correct polarity
The procedure is performed like this:
- Clamps from the charger are connected to the battery terminals. First the connection is made to the positive terminal, this is the red wire.
- The negative cable does not need to be connected if the battery remains in the car and has not been removed. This contact can be connected to the vehicle body or to the cylinder block.
- The plug from the charging equipment is inserted into the socket. The battery begins to charge. The charging time depends on the degree of discharge of the device and its condition. The use of extension cords is not recommended when performing this task. Such a wire must be grounded. Its value will be sufficient to withstand the current load.
The VseInstrumenti channel talked about the features of connecting a battery to a charger and observing polarity when performing this task.
How to determine the degree of battery discharge
To complete the task you will need a multimeter:
- The voltage value is measured on a car with the engine turned off. The vehicle's electrical network in this mode will consume part of the energy. The voltage value during measurement should correspond to 12.5-13 volts. The tester leads are connected with correct polarity to the battery contacts.
- The power unit is started, all electrical equipment must be turned off. The measurement procedure is repeated. The working value should be in the range of 13.5-14 volts. If the value obtained is greater or less, this indicates a discharge of the battery and the operation of the generator device is not in normal mode. An increase in this parameter at low negative air temperatures cannot indicate battery discharge. It is possible that at first the resulting indicator will be higher, but if over time it returns to normal, this indicates efficiency.
- The main energy consumers are turned on - the heater, radio, optics, rear window heating system. In this mode, the voltage level will be in the range from 12.8 to 13 volts.
The discharge value can be determined in accordance with the data given in the table.
How to calculate the approximate battery charging time
To determine the approximate recharging time, the consumer needs to know the difference between the maximum charge value (12.8 V) and the current voltage. This value is multiplied by 10, resulting in the charging time in hours. If the voltage level before recharging is 11.9 volts, then 12.8-11.9 = 0.8. By multiplying this value by 10, you can determine that the recharging time will be approximately 8 hours. But this is provided that a current of 10% of the battery capacity is supplied.
There are a huge number of circuits and designs that will allow us to charge a car battery; in this article we will consider only a few of them, but the most interesting and the simplest possible
As the basis for this car charger, let's take one of the simplest circuits that I could dig up on the Internet; first of all, I liked the fact that the transformer can be borrowed from an old TV
As I said above, I took the most expensive part of the charger from the power supply of the Record TV; it turned out to be the TS-160 power transformer, which was especially pleasing; it had a sign displaying all possible voltages and currents. I chose a combination with the maximum current, that is, from the secondary winding I took 6.55 V at 7.5 A
But as you know, charging a car battery requires 12 volts, so we simply connect two windings with the same parameters in series (9 and 9" and 10 and 10"). And at the output we get 6.55 + 6.55 = 13.1 V AC voltage. To straighten it, you will need to assemble a diode bridge, but given the high current strength, the diodes should not be weak. (You can see their parameters in). I took the domestic D242A diodes recommended by the circuit
From the electrical engineering course we know that a discharged battery has a low voltage, which increases as it charges. Based on the current strength at the beginning of the charging process, it will be very high. And a large current will flow through the diodes, which will cause the diodes to heat up. Therefore, in order not to burn them, you need to use a radiator. The easiest way to use a radiator is to use the case of a non-working power supply from a computer. Well, to understand at what stage the battery is charging, we use an ammeter that we connect in series. When the charging current drops to 1A, we consider the battery to be fully charged. Do not remove the fuse from the circuit, otherwise when the secondary winding closes (which can sometimes happen when one of the diodes short-circuits), your power transformer will shut down
The simple homemade charger discussed below has large limits for regulating the charging current up to 10 A, and does an excellent job of charging various starter batteries of batteries designed for a voltage of 12 V, i.e. it is suitable for most modern cars.
The charger circuit is made on a triac regulator, with an additional diode bridge and resistors R3 and R5.
Device operation When power is applied at a positive half-cycle, capacitor C2 is charged through the circuit R3 - VD1 - R1 and R2 - SA1. With a negative half-cycle, capacitor C2 is charged through diode VD2; only the charging polarity changes. When the threshold charge level is reached, a neon lamp flashes on the capacitor, and the capacitor is discharged through it and the control electrode of the VS1 smistor. In this case, the latter will open for the remaining time until the end of the half-period. The described process is cyclical and is repeated every half-cycle of the network.
Resistor R6 is used to generate discharge current pulses, which increases battery life. The transformer must provide a voltage on the secondary winding of 20 V at a current of 10 A. The triac and diodes must be placed on the radiator. It is advisable to place resistor R1 regulating the charging current on the front panel.
When setting up the circuit, first set the required charging current limit with resistor R2. A 10A ammeter is inserted into the open circuit, then the handle of the variable resistor R1 is set to the extreme position, and the resistor R2 to the opposite position, and the device is connected to the network. By moving knob R2, set the required value of the maximum charging current. Finally, the scale of resistor R1 is calibrated in amperes. It must be remembered that when charging a battery, the current through it decreases by an average of 20% by the end of the process. Therefore, before starting the operation, you should set the initial current slightly higher than the rated value. The end of the charging process is determined using a voltmeter - the voltage of the disconnected battery should be 13.8 - 14.2 V.
Automatic car charger- The circuit turns on the battery for charging when its voltage drops to a certain level and turns it off when it reaches the maximum. The maximum voltage for acid car batteries is 14.2...14.5 V, and the minimum permissible during discharge is 10.8 V
Automatic voltage polarity switch for charger- designed for charging twelve-volt car batteries. Its main feature is that it allows connecting a battery with any polarity.
Automatic charger- The circuit consists of a current stabilizer on transistor VT1, a control device on comparator D1, thyristor VS1 for fixing the state and key transistor VT2, which controls the operation of relay K1
Restoring and charging a car battery- Restoration method with “asymmetrical” current. In this case, the ratio of charging and discharging current is selected to be 10:1 (optimal mode). This mode allows you not only to restore sulfated batteries, but also to carry out preventive treatment of serviceable ones.
Method for restoring acid batteries using alternating current- The technology for restoring lead batteries with alternating current allows you to quickly reduce the internal resistance to the factory value, with slight heating of the electrolyte. The positive half-cycle of the current is used completely when charging batteries with slight operating sulfation, when the power of the charging current pulse is sufficient to restore the plates.
If you have a gel battery in your car, the question will arise as to how to charge it. Therefore, I propose this simple circuit on the L200C chip, which is a conventional voltage stabilizer with a programmable output current limiter. R2-R6 - Current setting resistors. It is advisable to place the microcircuit on a radiator. Resistor R7 adjusts the output voltage from 14 to 15 volts.
If you use diodes in a metal case, then they do not need to be installed on the radiator. We select a transformer with an output voltage on the secondary winding of 15 volts.
A fairly simple circuit designed for a charging current of up to ten amperes, copes well with batteries from a Kamaz vehicle.
Lead-acid batteries are very critical to operating conditions. One of these conditions is the charging and discharging of the battery. Excessive charge leads to boiling of the electrolyte and destructive processes in the positive plates. These processes are enhanced if the charging current is high
Several simple circuits for charging car batteries are considered.
The circuit of an automatic charger for car batteries described in this article allows you to charge the battery in a car in automatic mode, i.e. the circuit will automatically turn off the battery at the end of the charging process.
Sometimes there is a need to charge the battery far from a quiet and cozy garage, but there is no charging. It doesn’t matter, let’s try to mold it from what was. For example, for the simplest charging we need an incandescent light bulb and a diode.
You can take any incandescent lamp, but with a voltage of 220 volts, but the diode must be powerful and designed for a current of up to 10 Amps, so it is best to install it on a radiator.
To increase the charge current, the lamp can be replaced with a more powerful load, for example an electric heater.
Below is a diagram of a slightly more complex charger circuit, the load of which is a boiler, electric stove, or the like.
The diode bridge can be borrowed from an old computer power supply. But do not use Schottky diodes, although they are quite powerful, their reverse voltage is about 50-60 Volts, so they will burn out immediately.