Basic operating modes of the device for the presets included in the program.
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Charging mode - “Charge” menu. For batteries with capacities from 7Ah to 12Ah, the IUoU algorithm is set by default. This means:
- First step- charging with a stable current of 0.1C until the voltage reaches 14.6V
- second phase-charging with a stable voltage of 14.6V until the current drops to 0.02C
- third stage- maintaining a stable voltage of 13.8V until the current drops to 0.01C. Here C is the battery capacity in Ah.
- fourth stage- recharging. At this stage, the voltage on the battery is monitored. If it drops below 12.7V, the charge starts from the very beginning.
For starter batteries we use the IUIoU algorithm. Instead of the third stage, the current is stabilized at 0.02C until the battery voltage reaches 16V or after about 2 hours. At the end of this stage, charging stops and recharging begins.
>> Desulfation mode - “Training” menu. Here the training cycle is carried out: 10 seconds - discharge with a current of 0.01C, 5 seconds - charge with a current of 0.1C. The charge-discharge cycle continues until the battery voltage rises to 14.6V. Next is the usual charge.
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The battery test mode allows you to evaluate the degree of battery discharge. The battery is loaded with a current of 0.01C for 15 seconds, then the voltage measurement mode on the battery is turned on.
>> Control-training cycle. If you first connect an additional load and turn on the “Charge” or “Training” mode, then in this case, the battery will first be discharged to a voltage of 10.8 V, and then the corresponding selected mode will be turned on. In this case, the current and discharge time are measured, thus calculating the approximate capacity of the battery. These parameters are displayed on the display after charging is complete (when the message “Battery charged” appears) when you press the “select” button. As an additional load, you can use a car incandescent lamp. Its power is selected based on the required discharge current. Usually it is set equal to 0.1C - 0.05C (10 or 20 hour discharge current).
Charging circuit diagram for 12V battery
Schematic diagram of an automatic car charger
Drawing of an automatic car charger board
The basis of the circuit is the AtMega16 microcontroller. Navigation through the menu is carried out using the buttons " left», « right», « choice" The “reset” button exits any operating mode of the charger to the main menu. The main parameters of charging algorithms can be configured for a specific battery; for this, there are two customizable profiles in the menu. The configured parameters are saved in non-volatile memory.
To get to the settings menu, you need to select any of the profiles and press the “ choice", choose " installations», « profile parameters", profile P1 or P2. Having selected the desired option, click " choice" Arrows " left" or " right» will change to arrows « up" or " down", which means the parameter is ready to change. Select the desired value using the “left” or “right” buttons, confirm with the “ choice" The display will show “Saved”, indicating that the value has been written to the EEPROM. Read more about the setup on the forum.
The control of the main processes is entrusted to the microcontroller. A control program is written into its memory, which contains all the algorithms. The power supply is controlled using PWM from the PD7 pin of the MK and a simple DAC based on elements R4, C9, R7, C11. The measurement of battery voltage and charging current is carried out using the microcontroller itself - a built-in ADC and a controlled differential amplifier. The battery voltage is supplied to the ADC input from the divider R10 R11.
Charging and discharging current are measured as follows. The voltage drop from the measuring resistor R8 through dividers R5 R6 R10 R11 is supplied to the amplifier stage, which is located inside the MK and connected to pins PA2, PA3. Its gain is set programmatically, depending on the measured current. For currents less than 1A, the gain factor (GC) is set equal to 200, for currents above 1A GC=10. All information is displayed on the LCD connected to ports PB1-PB7 via a four-wire bus.
Protection against polarity reversal is carried out on transistor T1, signaling of incorrect connection is carried out on elements VD1, EP1, R13. When the charger is connected to the network, transistor T1 is closed at a low level from the PC5 port, and the battery is disconnected from the charger. It connects only when you select the battery type and charger operating mode in the menu. This also ensures that there is no sparking when the battery is connected. If you try to connect the battery in the wrong polarity, the buzzer EP1 and the red LED VD1 will sound, signaling a possible accident.
During the charging process, the charging current is constantly monitored. If it becomes equal to zero (the terminals have been removed from the battery), the device automatically goes to the main menu, stopping the charge and disconnecting the battery. Transistor T2 and resistor R12 form a discharge circuit, which participates in the charge-discharge cycle of the desulfating charge and in the battery test mode. The discharge current of 0.01C is set using PWM from the PD5 port. The cooler automatically turns off when the charging current drops below 1.8A. The cooler is controlled by port PD4 and transistor VT1.
Resistor R8 is ceramic or wire, with a power of at least 10 W, R12 is also 10 W. The rest are 0.125W. Resistors R5, R6, R10 and R11 must be used with a tolerance of at least 0.5%. The accuracy of the measurements will depend on this. It is advisable to use transistors T1 and T1 as shown in the diagram. But if you have to select a replacement, then you need to take into account that they must open with a gate voltage of 5V and, of course, must withstand a current of at least 10A. For example, transistors marked 40N03GP, which are sometimes used in the same ATX format power supplies, in the 3.3V stabilization circuit.
LCD– WH1602 or similar, on the controller HD44780, KS0066 or compatible with them. Unfortunately, these indicators may have different pin locations, so you may have to design a printed circuit board for your instance
Converting an ATX power supply to a charger
Electrical circuit for modification of standard ATX
It is better to use precision resistors in the control circuit, as indicated in the description. When using trimmers, the parameters are not stable. tested from my own experience. When testing this charger, it carried out a full cycle of discharging and charging the battery (discharging to 10.8V and charging in training mode, it took about a day). The heating of the computer's ATX power supply is no more than 60 degrees, and that of the MK module is even less.
There were no problems with the setup, it started right away, it just needed some adjustment to the most accurate readings. After demonstrating the work of this charging machine to a friend who was a car enthusiast, an application was immediately received for the production of another copy. Author of the scheme - Slon , assembly and testing - sterc .
Discuss the article AUTOMATIC CAR CHARGER
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 a 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 intensify 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.
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 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, as a result of which the likelihood of their failure due to burning is reduced.
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 resulting value is greater or less, this indicates a low battery and the generator device is not operating normally. 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.
Long-term use of the car leads to the fact that the generator stops charging the battery. As a result, the car will no longer start. To revive the car you need a charger. In addition, lead-acid batteries are highly sensitive to temperatures. Therefore, problems may arise with their operation if the temperature outside is sub-zero.
A car charger is not particularly technically complex. To collect it you don’t need to have any highly specialized knowledge, just perseverance and ingenuity. Of course, you will need certain parts, but they can easily be purchased on the radio market for almost nothing.
Types of chargers for cars
Science does not stand still. Technologies are developing at an incredible speed; it is not surprising that transformer chargers are gradually disappearing from the market, and they are being replaced by pulsed and automatic chargers.
The pulse charger for the car is compact in size. His easy to use, and unlike transformer type devices of this class provide a full battery charge. The charging process takes place in two stages: first at constant voltage, then at current. The design consists of similar circuits.
The automatic car charger is extremely easy to use. In fact, this is a multifunctional diagnostic center, which is extremely difficult to assemble on your own.
The most advanced devices of this class will notify you with a signal if the poles are connected incorrectly. Moreover, the power supply will not even start. You cannot ignore the diagnostic functions of the device. It is able to measure battery capacity and even charge level.
Electrical circuits have a timer. Therefore, an automatic car charger allows for various types of charging:
- complete,
- fast,
- restorative.
Once the automatic car charger has finished charging, a beep will sound and the current will automatically stop flowing.
Three ways to make a car charger with your own hands
How to make a charger from a computer block
Old computers are not uncommon. Some people leave them out of a sense of nostalgia, while others hope to use serviceable components somewhere. If you don’t have an old desktop computer at home, it’s okay. Second-hand The power supply can be purchased for 200-300 rubles.
Power supplies from desktop computers are ideal for creating any chargers. The controller used here is the TL494 chip or a similar KA7500 chip.
The power supply for the charger must be 150 W or higher. All wires from sources -5, -12, +5, +12 V are soldered off. The same is done with resistor R1. It needs to be replaced with a trim resistor. In this case, the value of the latter should be 27 Ohms.
The operating diagram of a car charger from a power supply is extremely simple. The voltage from the bus marked at +12 V is transmitted to the upper pin. In this case, pins 14 and 15 are simply cut off due to their uselessness.
Important! The only pin that needs to be left is the sixteenth one. It is adjacent to the main wire. But at the same time it needs to be turned off.
A potentiometer-regulator R10 should be installed on the rear wall of the power supply. You also need to run two cords: one for connecting the terminals, the other for the network. Additionally, you need to prepare a block of resistors. It will allow for adjustments.
To make the block described above, you will need two current measuring resistors. It is best to use 5W8R2J. A power of 5 W is quite enough. The block resistance will be 0.1 Ohm, and the total power will be 10 W.
To configure, you will need a trim resistor. It is attached to the same board. Part of the print track is first removed. This will eliminate the possibility of communication between the case and the main circuit, and will also significantly increase the safety of the car charger.
Before as solder pins 1, 14-16, they must first be tinned. Multi-core thin wires are soldered. Full charge is determined by the open circuit voltage. The standard range is 13.8-14.2 V.
The full charge is set by a variable resistor. It is important that potentiometer R10 is in the middle position. To connect the output to the terminals, special clamps are installed at the ends. It is best to use the crocodile type.
The insulating tubes of the clamps must be made in different colors. Traditionally, red is a plus, blue is a minus. But you can choose any colors you like. This is not important.
Important! If you mix up the wires, it will damage the device.
To save time and money when assembling a charger for a car, you can eliminate the volt and ammeter from the design. The initial current can be set using potentiometer R10. Recommended value is 5.5 and 6.5 A.
Charger from adapter
The best option for creating a car charger is a 12-volt adapter. But when choosing a voltage, you must first consider the battery parameters.
The adapter wire must be cut at the end and exposed. About 5-7 centimeters will be enough for comfortable work. Wires with opposite charges must be laid at a distance of 40 centimeters from each other. A “crocodile” is put on the end of each one.
The clamps are connected to the battery in sequential order. Plus to plus, minus to minus. After that, all you need to do is turn on the adapter. This is one of the simplest schemes for creating a charger for a car with your own hands.
Important! During the charging process, you need to ensure that the battery does not overheat. If this happens, the process must be interrupted immediately to avoid damage to the battery.
Everything ingenious is simple or a car charger made from a light bulb and a diode
Everything you need to create this charger can be found at home. The main element of the design will be an ordinary light bulb. Moreover, its power should not be higher than 200 W.
Important! The more power, the faster the battery will charge.
When charging, some care must be taken. You should not charge a low-capacity battery with a 200-watt light bulb. Most likely this will lead to it simply boiling. There is a simple calculation formula that will help you choose the optimal light bulb power for your battery.
You will also need a semiconductor diode that will conduct electricity in only one direction. It can be made from a regular laptop charger. The final element of the design will be a wire with terminals and a plug.
It is very important to follow safety rules when creating a charger for a car. First, always unplug the circuit before touching any of the elements with your hand. Secondly, all contacts must be carefully isolated. There should be no exposed wires.
When assembling the circuit, all elements are connected in series: lamp, diode, battery. It is important to know the polarity of the diode in order to connect everything correctly. For greater safety, use rubber gloves.
When assembling the circuit, pay special attention to the diode. There is usually an arrow on it that points to the plus. Since it only allows electricity to pass in one direction, this is extremely important. You can use a tester to check the polarity of the terminals.
If everything is configured and connected correctly, the light will light at half a channel. If there is no light, it means you did something wrong or the battery is completely discharged.
The charging process itself takes about 6-8 hours. After this time period, the car charger must be disconnected from the network to avoid overheating of the battery.
If you urgently need to recharge the battery, the process can be accelerated. The main thing is that the diode is powerful enough. You will also need a heater. All elements are connected into one circuit. The efficiency of this charging method is only 1%, but the speed is many times higher.
Results
The simplest car charger can be assembled with your own hands in a few hours. At the same time, a set of necessary materials can be found in every home. More complex devices require more time to create, but they have increased reliability and a good level of security.
How often do car owners fail 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 charging unit or there is a friend with a car nearby who is ready to help start the starter, no special problems are expected.
The situation is much worse if you cannot implement either the first or second option, especially motorists who do not have the opportunity to purchase an expensive factory-made charger suffer from this. But even in this case, you can find a solution if you make a charger for a car battery with your own hands.
Advantages and disadvantages of a homemade device
The main advantage of a homemade charger is its low cost, even if you do not have all the necessary parts, the savings will be noticeable. Also a significant advantage is the ability to use unnecessary instruments and devices as a source of materials for a homemade memory.
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 possible for experienced radio amateurs.
Device settings
As you well know, the entire network in the car is powered by low voltage 12V DC, but the charging level of the car battery should be in the range of 13 to 15V. The charge current at the device output should be about 10% of the power source capacity. If the current is less, the charge will still occur, but the procedure will last much longer. Therefore, the choice of elements for the charger should be based on the operating parameters of the specific model of lead-acid battery and the network to which it will be connected.
What is needed for the memory?
Structurally, the charger includes the following elements:
Rice. 2: Example of setting the adjustment resistor If you are going to charge the battery once, you can use only the first three elements; for constant use it will be more convenient to have at least control devices. But before you put it all together, you need to make sure that the charger's parameters after assembly will meet your needs. The first thing that needs to match is the charger transformer.
If the transformer is not suitable
Not always in a garage or at home you will find just such a transformer that will be powered by 220V and output 13 - 15V at the output terminals. Most 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 machine is used as a 42V power supply, but you want to get 14V for the charger. Therefore, you need to make 31 turns on the charger secondary with 480 turns in the primary. This can be achieved either by reducing the number of turns, removing unnecessary ones, or 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 with a smaller number of turns.
U 1 *I 1 = U 2 *I 2 ,
Where U 1 and U 2 are the voltage on 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 voltage on the secondary winding, the current strength in it will increase proportionally. As a rule, the cross-sectional margin is not enough, so after determining the current strength, a new conductor is selected for it from the data in the table:
Table: selection of cross section, depending on the flowing current
| Copper conductor | Aluminum conductor | ||
| 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 current value at the output of the charger exceeds the required 10% of the battery capacity, a current-limiting resistor must be included in the circuit, the value of which is selected in proportion to the excess current.
The procedure for assembling a charger for a car battery
Depending on the components you have and the battery parameters, the charger assembly will vary significantly. In this example, the manufacturing technology includes the following steps:
But you must start from the parameters of your electric machine. Therefore, if necessary, remove excess windings or insulate their terminals (if any), wind a secondary (if the existing one does not provide the required voltage level in the memory).
Rice. 5: Rewind the windings 
and on the secondary there are pins 9 and 9′.
Rice. 7: connect pins 9 - Solder the power cord leads to terminals 2 and 2′.
Rice. 8: Connect the power cord - Assemble the diode assembly on a textolite plate, as shown in the diagram. Due to intense heat generation due to high charging currents, semiconductor devices are installed on a radiator.
Rice. 9: diode assembly - Connect the bridge to the 12V terminals, in this example these are terminals 10 and 10′. The main elements of the charger are assembled.
Rice. 10: connect pins 10 to the diode bridge - Install an ammeter with a measurement limit of up to 15 A between the diode bridge terminal and the battery terminals.
Rice. 11: connect the ammeter - Connect a current-limiting block of resistors or a switch with a resistance adjustment function to the ammeter circuit; they will allow you to change the value of the charger current. Rice. 13: Connect the voltmeter
To protect the charger, both on the mains side and on the lead battery side, you need to install two fuses. In the example under consideration, a 0.5A fuse is used on the high side of the charger, and a 10A fuse is used in the lead-acid battery charging circuit.
If you have a charger current regulator, you should 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 mains and use the battery for its intended purpose.
Rice. 14: dependence of values on charging time 
