This page has been robot translated, sorry for typos if any. Original content here.

Car Charger

To help motorists

The schemes shown in this section will be useful not only for motorists and will save a lot of money. Of course, some devices can be purchased and industrial manufacturing, but there is not always confidence in the quality of the product purchased. So, for example, commercially available car chargers quite often in fact are not starting because of their low power and without the help of the battery will not be able to perform their task. But it is possible to verify this only some time after the purchase.

There are also many useful electronic devices that our industry does not produce.

STARTING DEVICE

The use of the starting device will be especially useful for motorists involved in the operation of the car in the winter season, as it prolongs the battery life and also allows you to start a cold car in the winter without any problems, even with a not fully charged battery. From experience it is known that at sub-zero temperatures the battery reduces its return by 25 ... 40%. And if it is not fully charged, it will not be able to provide the initial current required for starting the engine to 200 A. This current consumes the starter at the initial moment of spinning the motor shaft (the rated current consumption of the starter is about 80 A, but at the moment of starting it is much larger).

The simplest calculations show that . In order for the starter to work effectively when it is connected in parallel with the battery, it must provide a current of at least 1 DUCHA at a voltage of -10 ... 14 V. At the same time, the rated power of the used network transformer T1 (Fig. 4.1) must be at least 800 W. As is known, the nominal operating power of a transformer depends on the cross-sectional area of ​​the magnetic circuit (iron) at the location of the windings.

The circuit itself is quite simple starter, but requires proper manufacturing network transformer. It is convenient for him to use toroidal iron from any LATRA - thus, the minimum dimensions and weight of the device are obtained. The perimeter of the iron section can be from 230 to 280 mm (it differs for different types of autotransformers).

Before winding the windings, it is necessary to round off the sharp edges with a file on the edges of the magnetic core, after which we wind it with varnished cloth or fiberglass .

The transformer primary winding contains about 260 ... 290 turns of the PEV-2 wire with a diameter of 1.5 ... 2.0 mm (the wire can be of any type with lacquer insulation). Winding is distributed evenly in three layers, with interlayer insulation. After completing the primary winding, the transformer must be turned on and the no-load current measured. It should be 200 ... 380 mA. In this case, there will be optimal conditions for the transformation of power into the secondary circuit. If the current is less, some of the turns need to be rewound, if more is to be done before obtaining the specified value. It should be borne in mind that the relationship between the inductive resistance (and hence the current in the primary winding) and the number of turns is quadratic - even a small change in the number of turns will lead to a significant change in the current of the primary winding.

When the transformer is in idle mode, there should be no heat. The heating of the winding indicates the presence of interturn closures or the forcing and closing of part of the winding through the magnetic circuit. In this case, the winding will have to perform again.

The secondary winding is wound by an insulated stranded copper wire with a cross section of at least 6 square meters. mm (for example, type PVKV with rubber insulation) and contains two windings of 15 ... 18 turns. The secondary windings are wound simultaneously (with two wires), which makes it easy to obtain their symmetry - the same voltage in both windings, which should be in the range of 12 ... 13.8 V at a rated mains voltage of 220 V. It is better to measure the voltage in the secondary winding on a temporarily connected to terminals X2, X3 load resistor with a resistance of 5 ... 10 ohms.

The connection of the rectifier diodes shown in the diagram allows using the metal elements of the starter case not only for fixing the diodes, but also as a heat sink without dielectric shims (plus the diode is connected to the mounting nut).

To connect the starter parallel to the battery, the connecting wires must be insulated and stranded (preferably copper), with a cross section of at least 10 square meters. mm (not to be confused with the diameter). At the ends of the wire, after servicing, the connecting tips are soldered .

The contacts of the switch S 1 must be designed for a current of at least 5 A , for example, type TZ.