ESP32 electronic load meter

The DC electronic load meter based on ESP32 has high-precision voltage and current measurement display, input overvoltage and overcurrent reverse connection protection, independent battery power supply, CH224K fast charging, temperature measurement, serial port download communication and other functions

Measurement : Measured by INA226 to ensure high accuracy

Constant current : The TLC2272 operational amplifier collects the alloy resistor voltage amplification and compares it with the TL431 quasi-voltage adjustable resistor voltage divider to control the MOS to achieve constant current (I was originally planning to engage in numerical control, but the ESP32 ADC and DAC are not good)

Input : 7.62-2P terminal block / TYPE-C/DC5.0 three interfaces + TYPE-C interface for independent battery power supply and communication

Output : 5.0-3P terminal block (which can be output or used as a MOS expansion interface) / TYPE-C / USB-A three interfaces

Display: Using 0.96-inch TFT color screen

Heat dissipation : Use Jinbao pure copper radiator (no problem at 120W, but a little hot). Pay attention to the model.

Disadvantages : There is something wrong with the fan control and it cannot be controlled to stop rotating. The NTC resistor cannot measure the accurate temperature of the radiator.

Software : A simple program developed based on the Arduino framework

MOS: Two high-power TO-247 package MOS are used in parallel and more MOS can be expanded using the output 3P interface.

The maximum input voltage is 30V, the maximum input current is 20A, and the maximum input power should not exceed 120W for long-term operation (excluding external measurement)

When making external measurements, it is recommended to slide the potentiometer to 0V and turn off the load discharge function.