12V lead acid battery charger

This project is a charger specially designed for automotive lead-acid batteries 6-QW-105. The maximum charging current is 10A. The charging process is divided into four stages: trickle current, constant current, overcharge and float charging. It can well protect the lead-acid battery. .

Input plus two pads for external transformer, the transformer needs to be prepared by yourself

Output plus two pads for external alligator clips, available at Lichuang Mall

Red LED indicates charging, green LED indicates full charge

The potentiometer samples the input voltage, and the voltage divider needs to be adjusted to 1.205V~~~~

Here R5 and R6 are current sampling resistors. The sum of the resistance values ​​is 12mΩ. The calculation formula is 0.12V in addition to the charging current. The charging current is determined by the battery capacity. You can check it online.

The chip documentation is in the attachment. Those who need it can check it and change the parameters by themselves.

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The input power is a stepped-down alternating current, which is converted into direct current after rectification and filtering.

The main control chip drives the PMOS tube to control the charging current by sampling the battery voltage and charging current, and realizes the switching of different charging stages of the lead-acid battery.

The output inductor, diode and capacitor filter the output PWM wave, similar to the output circuit of a switching power supply.

In fact, the principle of the entire circuit is very similar to that of a switching power supply.