Charger for car batteries

Scheme charger is shown in the relative complexity of chips. Created this just for one condition: to adjust the current should be from 0 to maximum. Usually, even a factory car chargers have the initial leap from 2,5-3 A and to the maximum. In the charger used thermostat, which includes a radiator cooling fan, but it can be deleted. This was done in order to minimize the size of the charger. Charger consists of a control unit and the power section.



Fig.1. Charger for car batteries. Scheme

Control unit.

The voltage from the transformer Trr, approximately 14 V, enters the diode assembly KTS405. Rectified voltage used to power the control circuit D3 and thyristor pulse-forming network management. After a chain of Rp, VD1, R1, R2, and the first element of the chip D1.1, receive signals, roughly the shape. (Figure 2.1).
Then these pulses through R3, D5, C1, R4, converted to a saw, a form of which varies with the R4. (Figure 2.2). Elements chips c D1.2 to D1.4 equalize signal (attached to a rectangular shape) and prevent the influence of the transistor VT1. Ready signal passing through D4, R5 and VT1 comes to managing output thyristor. As a result, the control signal by changing phase thyristor opens at the beginning of each half period, in the middle, in the end, and so forth (Figure 2. 3). Regulation of the full range of smooth.
Nutrition and chip and the transistor VT1 receive from KREN05. (it pyativoltovaya Krenke). For it is necessary to tie a small radiator. Strongly Krenke no heat, but heat dissipation needs, especially in hot weather. Instead of transistor KT315 can apply KT815, but may have to pick up the resistance R5, if not open thyristor.


Fig.2. Charger for car batteries. Diagrams and design of the radiator


It consists of a thyristor D3 and 4-diodes KD213. Diodes D6-D9 are chosen from considerations that are suitable for current and voltage and should not be screwed. They are simply pressed against the radiator metal or plastic plate. The whole thing (including the Thyristor) mounted on a radiator, and under the diodes and thyristors enclose insulating heat-conductive plate. I found a very convenient material in the old burnt-out monitors. He is and the power supply from the computer. At the touch it is like a thin rubber, is used to import equipment. But of course you can use ordinary mica. (Fig.2. 4). In the worst case can be made for each diode and thyristor its own radiator. Then no mica is not needed, but the electrical connection of radiators should not be.


 Consists of 3 windings:
1 - 220 V.
2 - 14 V, to supply management
3 - 21 - 25 V to supply the power section.


Charger for car batteries. PCB<br>

Fig.3. Charger for car batteries. PCB

They check the work as follows: connect to the battery charger instead of a light bulb at 12 V, for example on the dimensions of the car. About the turn R4 brightness light bulbs must be changed from very bright to fully extinguished condition. If the bulb does not burn completely, then reduce the resistance of R5 half (to 50 ohms). If the bulb does not go off completely, then increase the resistance of R5. Add approximately 50-100 ohms.
If the bulb does not burn completely and nothing helps, then peremknite collector and emitter of transistor VT1 resistance of 50 ohms. If the bulb is not lit up - incorrectly assembled power part, if on fire, look for fault in the control circuit.
So, if everything is regulated and lights need to set charge current. The figure is a resistance 2 ohms (wire resistance of nichrome at 2 ohm). First, take the same, but a 3 ohm. Connect the charger and jumper wires short-circuited, which went to the lamp and measure the current (on the ammeter). It should be 8.10 A. If it is more or less, then adjust the current through the wire resistance Rprov. Sam nichrome can be 0,5-0,3 mm in diameter. Remember when this procedure, the resistance of great heats. It runs cooler when charging, but not so much, it's normal. So Make it cool, such as holes in the hull, etc. But fans poiskrit crocodiles will not be equal, sparks arbitrarily, charger, nothing will happen. Strengthen resistance Rprov. better on getinaksovoy (textolite) platform.
And the last - on ventilation. Among the elements KREN12, C2, C3, VT2, R6, R7, R8 collected cooling radiator (mounted assembly). By and large it is not necessary (unless you are doing super mini charger), it's just rage. If you have a heat sink (for example) of the aluminum plate 120 * 120 mm, then this is sufficient for heat dissipation (the area of the factory radiator of this size, even large). But if you really want the fan, put one Krenke at 12 V and connect it to a fan. Otherwise you need to install the sensor transistor VT2. It must be attached to the radiator through the same insulating heat-conductive plate. You can use the CPU fan from the processor 386, or 486. They are almost identical.
All resistance device 0,25 or 0,5 Va. Two trimming by an asterisk. Other denominations listed.
It should be noted that if instead of KD213 diodes will be used D232 or the like, the voltage winding Trr 21 The need to increase to 26-27 V.

Author: Fuganok

Ed. 02.12.09. V. Gainutdinov