Self-made 12 volt battery charger detailed steps

1, 1, charging voltage 2, charging current

Second, select the rated power, voltage and current of the transformer

Third, the necessary rectification, current limiting, and voltage stabilizing circuit components must reach the maximum index of the voltage and current being loaded.

For the battery, the charger was the first to use a transformer charger. However, transformer chargers are rarely used because they are too bulky, bulky, low in cost, and low in charging efficiency. Widely used is the electronic charger. The charger input AC voltage is about 220V, the output terminal is connected to the battery, and its charging mode;

First, intermittent charging and compensation are performed by charging a large current pulse; secondly, maintaining a constant charging voltage and current to the charged battery by constant current and constant voltage floating charge. The charger has output short circuit protection, output over voltage, over current protection and overshoot protection to ensure battery life.

Due to the development of fast charging technology, the concept of the fast charging performance of the traditional lead-acid battery has been changed. Experiments have shown that most VRLA batteries can withstand rapid charging, and reasonable fast charging is not only harmless but also beneficial for extending battery life.

The circuit is shown in Figure 4-8. FU is a short-circuit protection tube, LED1 is the power supply indication, adjusting RP1 can change the output voltage of ICl, the center end of RP2 provides a reference voltage for the positive phase input terminal of voltage comparator IC2, R3 is the charging current sampling resistor, and VD can prevent the battery Discharge, LED2 is the state of charge indication, C1, C2 are used to prevent pulse interference.

The control principle of automatic stop charging is that the charging current is gradually reduced as the charging progresses, and the voltage drop on R3 is also reduced. If it is less than the set value on RP2, the relationship between the level of pin 2 of IC2 and the level of pin 3 is changed from high to low, and the output of pin 6 is changed from high level to low level, VD is reverse biased, charging The current drops to zero, at this point, because there is no voltage drop on R3. Change the 6 pin of IC2 to keep low level, LED2 light means that the battery is fully charged.

Components can be selected as shown in Figure 4-8. A heat sink should be installed on the IC1. The IC2 does not have to use the LM741. Other units of single or multiple op amps are also available.

The debugging process is as follows: first do not install IC2, do not connect the battery, adjust RPl. Make the output voltage of ICl 8.5V. Disconnect the power supply, install IC2, and connect two fully charged battery packs. Restore the power supply, adjust RP2 so that LED2 will not emit light until it starts to emit light, and fix RPl and RP2.