Two-channel charger-discharge device. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Two-channel charger-discharge device. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Chargers, batteries, galvanic cells

Comments on the article

Batteries in cars are used in a mixed mode of operation:

when starting the engine, they consume a significant starting current;
during the trip, the batteries are charged from the generator with a small current in the buffer mode.

If the car's automation is faulty, the charging current may be insufficient or excessive and lead to overcharging. Crystallization of the plates, increased charge voltage and insufficient capacity are the hallmarks of such a battery. It is practically impossible to restore its normal operation directly from a car generator. For this, chargers are used.

Some vehicles use two batteries with a common voltage of 24 V.

They have different discharge currents due to the fact that the entire load with a voltage of 12 V is connected to the first battery (TV, radio, etc.). which is powered by a battery in the parking lot and on the road, and the second is loaded only during the start of the starter and the heating of the candles in the diesel engine. Charging a circuit of two batteries connected in series often leads to undercharging one and overcharging the second. It is necessary to restore such batteries with a separate charger with the ability to control the charge current of each battery.

Good results in restoring the performance of batteries are obtained when the charging current alternates cyclically with a small discharge current.

Such a need prompted the creation of a two-channel charger-discharge device with separate adjustment of the charge and discharge current. The discharge current when charging with an asymmetric current should be no more than 1/5 of the charge current.

Manufacturers' instructions often state that the battery must be discharged before charging. to form plates.

It is desirable to carry out control discharge with a current of 0,05C (C is the battery capacity) for 20 hours. For example, with a battery capacity of 50 A, the discharge current is 2,5 A per hour.

The proposed device allows the molding of plates of two batteries simultaneously with separate installation of the discharge and charging current.

(click to enlarge)

The device is based on current amplifiers based on powerful field-effect transistors VT1 and VT2.

Optocouplers VU1, VU2 are installed in the feedback circuits, which protect transistors from overload. At higher charge currents, the effect of filter capacitors C4 C5 is minimal, and a current is supplied to the batteries, which is close in shape to the current after a half-wave rectifier (pulses with a duration of 5 ms with a pause of 5 ms).

Such a current, as proven by practice, accelerates the recovery of battery plates. Capacitors C2 and C3, when switching diodes VD1 and VD2, create an additional current pulse.

The current control circuits of both channels are formed by dividers R2-R3 and R5-R6, respectively. They are powered by parametric voltage regulators R1-VD3 and R4-VD4. Resistors R7, R8 in the gate circuits of field-effect transistors VT1, VT2 limit the gate current to a safe value.

Phototransistors of optocouplers VU1, VU2 form controlled voltage dividers. The control voltages are removed from resistors R11 and R12 in the drain circuits VT1, VT2 and are fed through the limiting resistors R9, R10 to the optocoupler LEDs.

With an increase in voltage drops across resistors R11, R12 due to an increase in charging or discharging currents in excess of the established limits, the LEDs of the optocouplers light up, the phototransistors open and reduce the voltage supplied to the gates of the transistors, thereby limiting the currents in the drain circuits.

For visual control of charge and discharge currents, ammeters RA1, RA2 with internal shunts of 10 A are installed. The charge or discharge mode in the first channel is set by switch SA1, in the second - SA2. LEDs HL1, HL2 indicate the correct polarity of connecting batteries to the charging circuit.

The power transformer T1 is not critical in terms of power.

You can use power transformers types TN59.TN63, CCI. The manufactured device uses a transformer from an old tube TV, the secondary winding of which is rewound with a wire with a cross section of 4 mm2 and provides a voltage of 2x16.18 V. Resistors R13, R14 are made of pieces of nichrome 1,8 mm and 100 mm long, fixed as a mandrel on PEV-50 resistors. Field-effect transistors are mounted for cooling on separate radiators.

Batteries are connected to the charger-discharge device with stranded wires with a cross section of 2,5 ... 4 mm2 in vinyl insulation with crocodile clips. After connecting the battery, the mode switch (SA1 or SA2) is set to discharge mode.

The current regulator sets the discharge current within the required limits. After the discharge current drops to zero after 6 hours, the mode switch is switched to the charge mode and the recommended value of the charging current is set by the current regulator. After 10 ... 6 hours, the current should drop to the recharge value.

Then it is recommended to re-discharge (10 hours, up to a voltage of at least 1,9 V per cell) and re-charge (10 hours). The good condition of the battery allows it to be restored in one cycle.

Charging-discharging cycles are recommended after long-term storage of the battery, long-term operation, etc.

Authors: V.Konovalov, A.Vanteev, Creative laboratory "Automation and telemechanics", Irkutsk

See other articles Section Chargers, batteries, galvanic cells.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive

Xiaomi Smart Cat Eye 1S 06.04.2022

Xiaomi has introduced the Smart Cat Eye 1S, a smart peephole for doors with a 5-inch screen.

Smart Cat Eye 1S received a built-in camera with FHD resolution. With its help, you can see in high resolution everything that happens in front of the door of our house. 160 degree camera angle and f/2.0 aperture.

The 5-inch internal LCD panel displays everything captured by the "smart eye".

In addition to this, Xiaomi Smart Cat Eye 1S has a large 8000mAh battery. It won't need to be charged for several months. Also included is a small button that works as an internal call.

Since this is a product with Wi-Fi technology, we can also view what is happening from our smartphone, as well as make two-way calls with the one who presses the button.

The price of the device is 90 euros.

Other interesting news:

▪ Lightning prediction

▪ Climbers harm nature

▪ Heated microphone

▪ We have right-handedness from fish

▪ Cookies in orbit

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Mobile communications. Article selection

▪ article Do not renounce, loving. Popular expression

▪ article What are bacteria? Detailed answer

▪ article Organization of control over the state of labor protection in the organization

▪ article Water pump control device. Encyclopedia of radio electronics and electrical engineering

▪ superman article. Focus Secret

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews