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, in which all the algorithms are embedded. 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
If such devices had appeared on stage forty years ago, they would have been booed. Because everyone knew: a real charger is a heavy box with a huge transformer inside, various kinds of twisters, a voltmeter and an ammeter outside. Everything else is not serious.
A modern charger is, as a rule, a rather nice automatic box with a minimum of controls. Or even without them at all. At the same time, for some reason many are very similar to each other. But are they the same at work?
We tested eight devices taken for testing at two temperatures: -10 and +20 ºС. Let us say right away that you should not believe the statements of individual manufacturers regarding performance in severe frosts. Firstly, the intensity of the charging process in the cold drops very much: at -25 ºС, the charging current of the 55th battery will be only 4–6% of the value at plus twenty-five. And attempts to increase the charge voltage are fraught with destruction of the active mass and corrosion of down conductors. Secondly, at lower temperatures the insulation of the power wires of the presented devices hardens and breaks. Thirdly... However, two reasons are quite enough.
We compiled kilograms, millimeters and volts with amperes into a table, and supplemented the photo gallery with comments for each instance. In general, we can say that the devices honestly issue the stated charging programs. The reasons for quibbling were the fuses instead of electronic protection, the lack of clear inscriptions on the body and the inflated price compared to its “colleagues” with approximately equal talents.
8th place
Sweden
Approximate price, rub. 4950 It looks very nice. Everything is intuitively clear, except for the term RECOND: you can’t figure it out without instructions. However, you can do without this mode to restore discharged batteries. There are no complaints about automation and circuitry. In general, everything is excellent, except for the price. Well, no way!7th place
Denmark
Approximate price, rub. 4200 Let us immediately blame you for the lack of inscriptions in Russian. But there is an LED to illuminate the space. The entire process is automatic and does not require intervention. Charging is provided through the cigarette lighter socket. By the way, the product can be hung on the wall if desired. Overall not bad, but the price ruined everything.6th place
Taiwan
Again they offended the Russian language: all the inscriptions on the device are not ours. However, there is nothing to read: I connected it and forgot it. There is protection against polarity reversal, sparking, overcharging and short circuit. But its authors should be ashamed of the shameful unit of measurement of capacity “A/h” in the instructions. That's right: Ah!5th place
, China
Approximate price, rub. 3000 There is a heavy transformer inside. Just don’t believe the inscription on the box: the device is not a launcher at all. Look at the thin wires with “crocodiles” - what a start with them! It’s not for nothing that it is sold on the Internet as a regular charger. It works fine, but I'm not happy with the fuse. And it looks like someone adapted a suitable case for a different filling.4th place
, Russia
Approximate price, rub. 1070 The product is the simplest in appearance and technically uncomplicated. A fuse as protection against incorrect connection is not the most user-friendly solution. There is no recharging mode during storage. But, based on the principle “it couldn’t be simpler,” many will be attracted by the complete lack of bells and whistles. The price, which is several times lower than others, is also an important factor.3rd place
, China
Approximate price, rub. 3220 Perhaps the most presentable look. At least put it under the tree! The pictograms are clear and do not require translation. Works with 6- and 12-volt batteries. “Crocodiles” without wires look funny: the consumer must screw them on himself. There is a “hanger” on the wall for ease of use. But the fuse as “foolproof” is outdated and inconvenient.2nd place
Universal charger device "SOROKIN" 12.94, “made for Russia”
Approximate price, rub. 2000 The cute, foolproof device can work with both 12- and 6-volt batteries. The charge is carried out cyclically, in several stages, and a “desulfation” mode is provided for almost dead batteries. The kit includes various connecting wires, including those for plugging into the cigarette lighter socket. In general, not bad.1 place
Berkut Smart Power SP-8N, China
Approximate price, rub. 2650 The Chinese "Berkut" has become quite comfortable in Russia: even the inscriptions are in Cyrillic. It's simple: turn it on and use it. There is protection, the current is solid, the automation works, there are modes to choose from, the price is average, the appearance is modern. No comments, everything is fine.I tried to insert into the title of this article all the advantages of this scheme, which we will consider, and naturally I did not quite succeed. So let's now look at all the advantages in order.
The main advantage of the charger is that it is fully automatic. The circuit controls and stabilizes the required battery charging current, monitors the battery voltage and when it reaches the desired level, it reduces the current to zero.
What batteries can be charged?
Almost everything: lithium-ion, nickel-cadmium, lead and others. The scope of application is limited only by the charge current and voltage.This will be enough for all household needs. For example, if your built-in charge controller is broken, you can replace it with this circuit. Cordless screwdrivers, vacuum cleaners, flashlights and other devices can be charged with this automatic charger, even car and motorcycle batteries.
Where else can the scheme be applied?
In addition to the charger, this circuit can be used as a charging controller for alternative energy sources, such as a solar battery.The circuit can also be used as a regulated power supply for laboratory purposes with short circuit protection.
Main advantages:
- - Simplicity: the circuit contains only 4 fairly common components.
- - Full autonomy: control of current and voltage.
- - LM317 chips have built-in protection against short circuits and overheating.
- - Small dimensions of the final device.
- - Large operating voltage range 1.2-37 V.
Flaws:
- - Charging current up to 1.5 A. This is most likely not a drawback, but a characteristic, but I will define this parameter here.
- - For currents greater than 0.5 A, it requires installation on a radiator. You should also consider the difference between input and output voltage. The greater this difference is, the more the microcircuits will heat up.
Automatic charger circuit
The diagram does not show the power source, but only the control unit. The power source can be a transformer with a rectifier bridge, a power supply from a laptop (19 V), or a power supply from a telephone (5 V). It all depends on what goals you are pursuing.The circuit can be divided into two parts, each of them functions separately. The first LM317 contains a current stabilizer. The resistor for stabilization is calculated simply: “1.25 / 1 = 1.25 Ohm”, where 1.25 is a constant that is always the same for everyone and “1” is the stabilization current you need. We calculate, then select the closest resistor from the line. The higher the current, the more power the resistor needs to take. For current from 1 A – minimum 5 W.
The second half is the voltage stabilizer. Everything is simple here, use a variable resistor to set the voltage of the charged battery. For example, for car batteries it is somewhere around 14.2-14.4. To configure, connect a 1 kOhm load resistor to the input and measure the voltage with a multimeter. We set the substring resistor to the desired voltage and that’s it. As soon as the battery is charged and the voltage reaches the set value, the microcircuit will reduce the current to zero and charging will stop.
I personally used such a device to charge lithium-ion batteries. It's no secret that they need to be charged correctly and if you make a mistake, they can even explode. This charger copes with all tasks.
To control the presence of charge, you can use the circuit described in this article -.
There is also a scheme for incorporating this microcircuit into one: both current and voltage stabilization. But in this option, the operation is not entirely linear, but in some cases it may work.
Informative video, just not in Russian, but you can understand the calculation formulas.
A very simple charger circuit that uses only one transistor to determine the voltage to automatically disconnect the battery from the network when it is fully charged.
Description of the car battery charger circuit
In the figure we see a simple circuit where one transistor is turned on in its standard operating mode.
The principle of operation of the circuit can be understood from the following points:
- The battery charge is considered complete when the voltage at its terminals reaches 13.5 - 14 volts.
- The shutdown threshold (13.5 - 14 volts) is set by trimming resistor R2 with a connected, fully charged battery. When the voltage at the battery terminals is about 14 volts, transistor T1 will turn on the relay and the charging circuit will be broken.
This automatic car charger is not only easy to make, but also smart enough to take care of the battery's condition and charge it very efficiently.
Parts List:
- R1 = 4.7 kOhm;
- R2 = 10K trimmer;
- T1 = ;
- Relay = 12V, 400 Ohm, SPDT;
- TR1 = secondary winding voltage 14 V, current 1/10 of the battery capacity;
- Diode bridge = for a current equal to the rated current of the transformer;
- Diodes D2 and D3 = 1N4007;
- C1 = 100uF/25V.
From the site administrator
The article is theoretical in nature, in practice I didn't put this diagram together. I recommend paying attention to the following important points:
- The battery is disconnected from the charger when the charging voltage reaches 13.5 - 14 volts. This voltage threshold (tuning resistor R2) must be set with a connected, fully charged battery. If there is no charged battery, then you need to set R2 to the lower (according to the diagram) position, that is, “plant” the base of the transistor on the ground. Then connect the battery and plug in the charger. Next, you need to constantly monitor the charging voltage; when it reaches 13.5 - 14 volts, you need to set R2 to such a position that the relay opens its contacts.
- When the voltage at the battery terminals reaches 13.5 - 14 volts, the device is disconnected from the battery. Then, when the voltage drops to 11.4 volts, charging resumes again. The original article says that such hysteresis is provided by diodes in the emitter of the transistor.
- In the scheme no charging current limitation, therefore, when making this charger, I recommend using a transformer with a power of at least 150 watts, the secondary winding of which is designed for a current of at least 10 amperes. The diode bridge must also correspond to the specified current.
Probably every car enthusiast has at least once encountered the problem of a dead car battery. Even the highest quality and most modern power sources discharge from time to time and require recharging. When purchasing an automatic charger for a car battery, you must carefully study the characteristics of the battery that you plan to charge, and also understand the meaning of the parameters of the device itself.
From the characteristics of a car battery, you need to know the capacity, voltage and type. The vast majority of rechargeable batteries are of the lead-acid type. The exact parameters of the power supply can be found in the documentation for it or directly on the case or label.
Types of devices for charging car batteries
There are two types of chargers on the market: simple pre-chargers (otherwise called “trickle chargers”) and complex pre-chargers. The first are distinguished by the fact that the recharging process takes quite a long time, however, due to the slow rate of recovery of battery energy, it practically does not lose its properties. The latter, as a rule, have a higher price and may have a number of additional features. The device allows recharging in both normal smooth and significantly accelerated modes. Very useful functions of units of this type are: the ability to restore the charge of an almost completely depleted car battery, as well as start the car engine without a battery at all.
Fast charging, available when using jump chargers, by the way, has a rather unfavorable effect on the condition of the car battery and its durability. In view of this, it is not recommended to use the accelerated mode on an ongoing basis unless there is a specific justified need. Under normal conditions, experts recommend recharging with a pre-start device or a start-charging device in low current mode. The slow mode, by the way, provides for automatic regulation of the incoming charging current when the battery is restored. For greater safety, the process occurs as follows: at the beginning of the procedure, the battery is charged with a weak current, which gradually increases and decreases again towards the end of the cycle.
Modern chargers can be programmed to take into account the exact indicators of the battery being charged, eliminating both over- and under-charging of the battery, both options have a detrimental effect on the performance of the devices.
In addition, there are chargers that operate at constant voltage, constant current, and combined. The first two allow you to restore the charge of a car battery quite quickly, however, as already noted, this reduces the resource of the power source. The latter allows you to carry out the procedure without damaging the battery. Rather, this is why almost all modern charging units use combined parameters.
Operating principle of the charger
The operating principle of all devices that are designed to recharge batteries is almost the same. When connected to the network, the device receives 220 V. The voltage and current are adjusted by the device to the proper values, the current is rectified and supplied to the charging power source.
For each type of battery, a certain order and charging method is preferred. For example, experts believe that it is better to recharge lead-acid batteries more often, without allowing them to discharge. Alkaline batteries, due to the fact that they have a “memory effect,” are recommended to be completely discharged. However, both need to be charged to maximum.
Automatic charger
An automatic charger is the best choice for beginners and car enthusiasts who do not want to delve too deeply into the theory of electricity. Devices of this type do not require human intervention; everything happens automatically. Simply connect the unit to the power supply and place the clamps on the terminals of the car battery that needs recharging.
The automatic device independently controls the entire process: it takes into account the charge level, builds a cycle, and controls the course of the procedure. When the charge reaches one hundred percent, the device turns off automatically. Further, if the charger is not disconnected, it continues to monitor the condition of the battery. If its charge drops (due to self-discharge), the sensors will detect this and the automation will turn on again to recharge. Thus, the charge level of the power supply will be constantly maintained at 100%.
Five-stage chargers in automatic mode are capable of:
- recharge to 80% charge level;
- bring charging to the maximum with a decreasing current;
- maintain the battery charge level at 95–100%;
- using the pulse mode of operation to eliminate sulfation of the plates;
- Diagnose the condition of the power supply.
The eight-stage device has wider functionality:
- the charge-discharge method combats sulfation;
- diagnostics;
- recharging up to 80%;
- full recharging with reducing current;
- checking battery self-discharge;
- elimination of electrolyte separation when fully charged;
- maintaining maximum available capacity;
- preventive charging at 95% and above.
Thus, an automatic charger for a car battery has a number of advantages. It is very simple and convenient to use, and does not require special skills and knowledge from the car enthusiast.
