Any car enthusiast knows how much trouble a battery that does not work in normal mode can cause. Guaranteed trouble-free, he can work for at least 5 years, provided that the driver constantly monitors his condition. But situations when the storage battery (accumulator battery) ceases to perform its functions occur quite often. There can be quite a few reasons, ranging from malfunctions in the car's power supply system and ending with a long downtime of a car in difficult weather conditions, most often in the cold.
Content
- Types of chargers
- Main selection criteria
- Charger classification
- Transformer chargers
- Pulse devices
-
Comparison of memory of different classes
- Transformer chargers
- Impulse chargers
Therefore, motorists who do not want to spend money in special service centers should approach the choice of recharging the battery with great responsibility.
Types of chargers
Before purchasing a charger (charger), a motorist should know that trade offers storage devices of two main types:
- charging and pre-starting devices;
- charging and starting chargers.
The first type is intended only for recharging batteries.
When connecting the battery terminals with wires with clamp-type clamps to the output of the device, the battery is recharged.
Using the charging and starting chargers, it is possible to carry out both conventional recharging of the battery and starting the engine by rotating the starter without connecting the battery.
Main selection criteria
Operating parameters can be used as criteria. These include:
- maximum output voltage;
- maximum load current.
The maximum voltage for charging 12-volt acid batteries (taking into account the voltage drop across the wires and terminals of the battery) is 15.5 V. When choosing such a charger at the end of charging, the battery voltage will be about 14.5 V.
The maximum current is selected based on the nominal capacity of the battery.
For acid batteries, there is a simple relationship between them:
Imax = 0.1 C nom.
For alkaline batteries:
Imax = 0.25 Sleep.
C nom - battery power, expressed in Ampere-hours (Ah).
Choosing a charger with Imax = 10A, you can charge any car battery.
Charger classification
The memory can be classified according to circuit solutions, according to the element base used in their design, according to the principles of converting alternating current into direct current. Based on this, two groups of battery charging devices can be distinguished:
- transformer charger;
- impulse charging devices.
The devices of the first group use a powerful power transformer.
In pulse charging devices, the mains current is converted into a sequence of high-frequency pulses.
Transformer chargers
Powerful electronic components are used in transformer storage devices. They can withstand overloads (within reasonable limits), cope with situations of erroneous connection to the battery terminals. This type of homemade charger does not always contain all the components necessary for stable and safe charging of batteries. Required components of the charging circuit include:
- transformer power supply;
- charging current stabilizer;
- current regulator of the battery charge;
- short circuit protection device;
- parameter display devices.
In simple "homemade" products, the current regulator is often manually controlled wire rheostats, lamps of the low and high beam of the car, which bark to some extent the property thermoresistances. With an increase in the current through the spiral of the lamp, its resistance increases. Thus, the magnitude of the current is, as it were, maintained at a constant level. On the elements of such circuits, a large thermal power is released. The efficiency of these chargers is low. Elements of devices assembled according to such schemes are fire hazardous, and their reliability leaves much to be desired.
Some circuits use a set of capacitors of different capacities. They are manually switched on in turn in series with the primary winding of the step-down transformer. Having a capacitive resistance, they lower the value of the input voltage. The voltage in the lowering winding of the transformer and the value of the battery charge current decrease. The heating of the elements in these circuits is less, and their efficiency increases.
The diodes in the rectifier bridge must be matched to the value of the battery charging current. The current through them must be greater than the maximum charging current. They are usually installed on metal plate radiators, which remove excess heat from the diodes and prevent them from overheating.
More advanced designs provide the ability to automatically disconnect them from the load when the battery is fully charged. Such circuit solutions allow not to be afraid of breaks in the load circuit and short circuits in it.
In "advanced" circuits, thyristors are used to regulate the charging current. The voltage at the control electrode, which determines the degree of opening of the device, through which the charging current flows, is manually set by the variable resistor of the circuit. Its axis is brought out to the front panel of the charger.
The indicator devices for charging parameters are dial ammeters connected in series to the load circuit and voltmeters that monitor the voltage at the terminals of the storage batteries. In the latest models of memory, pointer indicators are gradually replaced by digital ones. The circuit becomes more complicated, since it is necessary to power the electronic indication elements as well.
The automatic charger circuit for 12 V batteries allows you to connect the charger to the network when connecting wires with clamps to the battery. At the end of the charge, when the current decreases to the value of the circuit comparator operation, the relay contacts open, the LED signals the end of the charging process and the charger is disconnected from the mains voltage.
Pulse devices
Devices of this class, like transformer chargers, set themselves the task of restoring the operability of storage batteries when they are partially or completely discharged. But the circuit solutions used in them are based on the use of a modern base.
In order to get rid of powerful power step-down transformers, in pulsed memory devices, an alternating mains voltage (50 Hertz) is converted into an alternating voltage of a high-frequency pulse form. This high-frequency voltage using a pulse transformer is brought to the values required for charging the battery. Then it is straightened and filtered. The conversion frequency is usually about 50 kilohertz, the size of the transformer, which mainly determines the size of the device, is minimized.
Increased requirements in a pulse-type memory are imposed on the level of interference created by the generators of these devices. For these purposes, high-frequency chokes are used in the circuits. The transformers are made in the form of windings on ferrite rings. Pulse diodes are small in size.
If we represent the general diagram of the device in the form of separate components, then it will include:
- network rectifier unit;
- converter block;
- pulse transformer;
- charging control unit;
- parameter indication devices.
In pulse chargers, you can use one of the following methods to restore battery performance:
- direct current;
- constant voltage;
- in a combined way.
The latter of them allows using both the first and the second methods at different stages of the process. When the battery is discharged, it is necessary to recharge it with a constant current up to a certain limit. After that, the voltage stabilization mode is turned on with a decreasing charge current.
Impulse chargers can be divided, in turn, into manual chargers that require self-regulation. voltages and currents, automatic, in which the process is controlled by software, and semiautomatic devices.
Comparison of memory of different classes
It should be noted that both one and the other battery charging devices have a number of advantages and disadvantages. Having considered each class and comparing them with each other, you can come to the final conclusion about the purchase of a particular device.
Transformer chargers
Among the advantages of transformer memory are the following: simplicity of design, which can be repeated by a radio amateur not very high class, time-tested reliability, availability of circuit elements, lack of network and radio interference.
Among the shortcomings, it can be noted: significant weight and dimensions, low efficiency due to losses in the metal cores of transformers.
Impulse chargers
The advantages of these devices are: low weight due to the lack of iron of network transformers and radiators of power elements, high (up to 98%) efficiency, large tolerances for the frequency and voltage of the supply network, a large number of protection elements and automation of the charging process Battery.
The disadvantages include the following: lack of galvanic isolation from the supply network, the presence of a wide range of harmonics, requiring additional circuit solutions to suppress them.
Gradually, an increasing number of motorists seeking to protect themselves from unpleasant situations associated with battery malfunctions are choosing pulse class chargers.
