ESP32 Forum

Hi everyone,

I'm fairly new to electronics, and this is my first ESP32 project, so I'd really appreciate some advice.

I'm building a water level monitoring system for my home's rooftop water tank. The idea is to use an ESP32 to read a water level sensor and send the readings over Wi-Fi to the Blynk app. I also want Blynk to notify me when the tank is nearly empty or completely full.

Current setup
ESP32 development board
Water level sensor
Blynk IoT
3.7V Nokia Li-ion battery
MT3608 boost converter

The sensor is connected like this:

VCC → ESP32 3.3V
GND → ESP32 GND
Signal → GPIO35

The electronics will eventually be placed inside a waterproof enclosure on the rooftop.

The issue I'm facing

My original plan was to power the ESP32 using the 3.7V battery with the MT3608 boosting it to 5V, then connect the boost converter's output to the ESP32 VIN pin.

The strange part is:

The ESP32 works perfectly from USB.
It also powers on when connected directly to the Nokia battery.
But as soon as I use the MT3608, the ESP32 won't power on at all.

I connected everything as follows:

Battery + → VIN+
Battery - → VIN-
VOUT+ → ESP32 VIN
VOUT- → ESP32 GND

I've double-checked the wiring, tried adjusting the potentiometer on the MT3608 in both directions, and still nothing. Unfortunately, I don't have a multimeter, so I can't measure the output voltage to see whether the module is actually working.

Advice I've received

Some people have suggested that I should forget about the boost converter altogether and instead power the ESP32 from a regulated 3.3V supply. Others have recommended using a wall adapter instead of batteries.

The problem is that this project will be installed on the rooftop, and there isn't an electrical outlet available there, so using an AC adapter isn't really an option.

My questions
Does this sound like a faulty MT3608, or is there something obvious I might be overlooking?
If you were building a battery-powered ESP32 project like this, how would you power it?
Would you recommend a 3.3V regulator, a buck/boost converter, a different battery, or something else?
Would adding a small solar panel make more sense for a project that's going to stay on the roof?
Any suggestions for protecting the electronics from rain, heat, and long-term outdoor exposure?

Since I'm still learning, I'd also appreciate it if you could explain why you recommend a particular solution. I'm trying to understand the design choices instead of just copying a circuit.

Thanks in advance for your help!

On your immediate problem - does the ESP32 boot after you manually reset it by pressing the reset button?

On the larger problem So the issue is that if you want to run on batteries without having to charge or replace your batteries every day, you need something that on average uses very little power. You do that by limiting the time it's active (measuring water level, sending data via WiFi) and making sure the time it's not active is as low-power as possible - you'd put the ESP32 into deep sleep, for example, which only drains a a couple of uA meaning the battery isn't slowly sucked empty.

Issue is that the rest of your components also use power, and if you don't pick them properly, they can drain the battery all by themselves. For instance, your setup uses an MT3608 plus whatever LDO is on your ESP32 board (likely some LM1117 variant). Those can eat up at least a handful of mA; roughly stated, divide you battery capacity by that and you know how many hours you'll be able to get even when your ESP does nothing at all.

Generally, for low power use, you either want a board that's optimized for battery use (those usually have a connector for a battery on the PCB) or you can roll your own.

what water level sensor are you using?
have a look at https://forum.arduino.cc/t/data-logging ... 1449369/22 which uses a Heltec WiFi LoRa V4 with a SR04M ultrasonic sensor
data is transmitted over LoRaWAN ever 10 minutes with the Heltec V4 being in deep sleep between transmissions - taking a current of 15microAmps (normal operation 60mAmps)