I have small project using ESP32 devkit V1 and I will use a flow meter that have a operating voltage of 3.5V and a turbidity sensor that have a 5v operating voltage. It is okay to use a 9v battery or what can you suggest type of battery to power this project? I prefer an external battery because I'm planning to mount it in a plastic blue container of water And also I'm planning to use it send data to Web server like an monitoring system.
ESP32 device:
Water flow sensor:
Turbidity sensor:
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What type of 9V battery do you have in mind ?
Is it a PP3 like this by any chance ?
Yes, a PP3 type can you recommend a good external battery because I’m planning to mount the system in a blue plastic container. Thank you in advance.
PP3 is never a good choice, especially so with blue plastic containers.
Try with 3x 1.5v batteries in series, power esp32 VIN and turbidity sensor from that 4.5v and flow sensor from esp32 3.3v pin.
@daaveeee1
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Please post the data sheets for your devices so that we can determine the best power options for you.
the LilyGo ESP32 T Beam has a built in 18650 battery holder.
ESP32 Specs— This board has the same data sheet with the DO IT EPS32 Devkit board Version 1.
Water flow sensor specs——
I cant find the data sheet of this particular sensor but I tried it to plug in a 5v pin in my Arduino Uno and surprisingly it worked.
I recommend using a 3.7V Li-ion battery with a 5V boost converter and run everything from 5V. However, the ESP32 I/Os are 3.3V so you will need to use some type of voltage level converters on the flow meter and turbidity meter outputs. A simple resistive voltage divider should work. 2.2K and 3.9K ohms would be good.
You have choosen for a board that is not designed for battery power. There are plenty of ESP32 offerings with battery connection and even with built-in chargers,
but your board is not one of them.
The easy way out is to connect the USB lead to a cellphone powerbank and be done with it.
Leo..
Thank you!
Can i rely on a on-board voltage regulator of ESP32 or I need to use a resistor?
A cellphone powerbank is basically a 3.7volt LiPo battery with charger, battery management (protection), 5volt boost converter and USB socket in a neat case.
No other parts needed. You already have the USB lead.
You could make that yourself, likely for a higher price, but why.
A simple 5Ah model could run your board for 36 hours. 10Ah for 72hours, etc.
Leo..
Which is more cost-effective, a powerbank or a li-on 18650 battery with 3000mAh?
That depends on where you purchase it and what you pay. Also quality will enter into the equation as well.
A resistor and a voltage regulator are not the same thing. Yes, you can rely on the on-board regulator if you stay within the specs.
It depends on the powerbank.
Battery-less powerbanks (for an 18650 cell) can be bought for about $5.
There are a lot of fake 18650 cell out there, claiming to be 3Ah or more.
I bought a 5Ah power bank locally for $15, that runs an ESP32 board for about two days.
Leo..
I use the cheapest USB powerbanks I can find. My logic is that the cheap ones won’t have minimum power limit circuitry that could make them not work with arduino. If the current is too low, some of them won’t turn on.
Which is a problem when powering an Uno/Nano etc.
But that likely won't happen with a big-board ESP32, that already draws 100mA doing nothing.
As long as you don't do something silly as using sleep modes.
Sleep modes would be better with a board designed for battery power.
Leo..
