Troubleshooting ESP Power Issue with NPK Sensor and DC Converters

Using Arduino Project Guidance
1

I'm working on an ESP project where I need to read data from an NPK sensor with an RS485 interface, which requires a power supply of 5-24 volts. I am using a single 18650 battery to power the entire system. Here is the setup:

  1. Power Source: 18650 battery (maximum voltage of 3.7V).
  2. Voltage Conversion:
  • Step-up Converter: Increases the voltage to 12V to power the NPK sensor.
  • Step-down Converter: Lowers the voltage from 12V to 5V to power the ESP.

The Issue

When I turn on the system, the LED on the ESP lights up but is very dim. If I disconnect the ESP, power up the system, wait a few seconds for the step-down converter to stabilize at 5V, and then reconnect the ESP, it works fine.

My Questions

  • Why is the ESP's LED dim when I power up the system initially?
  • How can I solve this issue to ensure the ESP powers up correctly without needing to disconnect and reconnect it?

I tried using an RC delay circuit to delay the start of the ESP. I used a 10 kΩ resistor and a 1 µF capacitor, but I noticed that the voltage after the resistor drops to 0.88V. So my esp never power up
This my schema...Any suggestion how i can make running this system.?
Screenshot 2024-08-07 083342

2

Can't understand 'voltage after the resistor', when esp32 powerup with faint led check 12V stepup output voltage and stepdown 5V output voltage with multimeter ( maybe one of the two is in 'protection'.).
Also you could use an esp32 board with battey input connection ( to spare the stepdown and the power issue ).
Several Lilygo/ttygo boards have a battery connector, and also firebeetle ones

3

Voltage out of the the 2 stepup and stepdown are correct that why i dont understand why the esp not power up

4

Yes, strange, sometime when power does not rise 'fast enough' the processor can't reset correctly ( even if there is a brown-out protection circuit ).
If you have a scope try verifyng the power 'voltage profile'.
You could also trying increasing the capacitor on the reset pin so that it exit reset after power is stable over 3V