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By Clement
#92337 Hi everyone, so I have a project with ESP8266 that uses ultrasonic sensor to detect water level and a 5V relay module that will be powering a micro submersible DC water pump. Everything works fine without the pump connected to the relay module and I could switch on or off the relay module through Blynk app.

When I connect the pump to the relay module and power it, the ESP8266 keep resetting after a few seconds and the relay keep switching on or off by itself even the water level is low. The LCD display just goes crazy by displaying weird character.

I make sure everything is connected to the common ground and I am powering the entire system with a MB102 module which I suspect it could not deliver enough power to the system and causes resetting of the ESP8266?

Thank you!
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By btidey
#92347 It does sound like a power supply problem.

The module can supply around 700mA but this could be less if powered from USB rather than the power jack.

You need to add up all the potential current drains. It sounds like you have

ESP8266 module. What sort. I assume it is a 5V module like a NodeMCU or Wemos. These need a solid 500mA

5V relay. These can need 75mA but may take a bit more momentarily when switched on.

LCD screen Dependent on size and backlight. Could be around 150mA

Pump? Is that a 5V unit or externally powered. If 5V then it is almost certainly the straw that breaks the camel's back based on above numbers.