XIAO ESP32C6 SHT41 Temperature and Humidity Sensor with Battery

This is like the One Button Remote but with a SHT41 Temperature and Humidity sensor by Adafruit.
The SHT45 has a bit higher precision and can be use too. I know Yellow isn't the best color but I wanted to try it. I use a Pro PLA but regular PLA should be fine too.

The insert has changed to hold the SHT4x from Adafruit but the ones in the picture are a clone. I would recommend the Adafruit ones for better quality. I just got the clones because it was faster to get.

The case has been slightly modified to add another hole to the other side of the USB opening. On the XIAO ESP32C6 they put the charging light on the other side from the XIAO ESP32C3 and even though there are buttons in the way you can still see it.
With the Yellow case you can see it blinking without the hole. It's somewhat transparent.
I made the Hole bigger for the Sensor than what is shown in the picture. Instead of 5mm it's 8mm to give more air to get in though I've haven't had any problems with the small hole.

Electronic Parts:
1 - Seeed Studio XIAO ESP32C6
1 - Adafruit Sensirion SHT41 Temperature & Humidity Sensor - STEMMA QT / Qwiic Product ID: 5776
2 - 220K 1/4w 1% Resistors (Used to get battery voltage)
1 - 15k 1/4w 1% Resistor
1 - 10k 1/4w 1% Resistor
1 - Adafruit Lithium Ion Polymer Battery - 3.7v 500mAh Product ID: 1578
1 - Pre-Crimped 2-pin JST-PH connector with silicon wire (Optional) (https://www.amazon.com/Connector-SIM-NAT-connectors-Inductrix/dp/B08SC3F658)
A couple pieces of solid 22 AWG wire for Board to Board connections.

Construction Notes: 
The ESP32C6 has a built in antenna so unless you need more range it should be good.

I did have to remove the Resistor for the LED on the SHT41 and the SHT45 has it too to save on battery power.
It is right next to the left connector to the left of the yellow capacitor. It's tiny so I took my soldering iron with a very fine tip and put a little solder on it and heated up both sides till I could drag it to the top where there are no components to get in the way. Just be careful not to mess anything else up and take your time.

Danger Warning
Lithium Ion Polymer Batteries can be dangerous. Do not short out the battery. If you get the Pre-Crimped cable for the battery make sure that the wires match the color on the battery. Just hold it together like your going to plug it in and check. Mine was not correct. The Pre-Crimped cable is great because you can switch the Red and Black wires in the connector if needed and you are not directly soldering the battery to the ESP32C3 which would be a bad idea anyway.
As with any battery and devices like many ESP32 and other boards that have a battery socket soldered to the board always check the polarity before plugging it in.
From Adafruit Website about this battery.
The included protection circuitry keeps the battery voltage from going too high (over-charging) or low (over-use) which means that the battery will cut out when completely dead at 3.0V. It will also protect against output shorts. However, even with this protection, it is very important that you only use a LiIon/LiPoly constant-voltage/constant-current charger to recharge them and at a rate of 500mA or less. We suggest our Micro Lipo charger, which has a 100mA default rate. You can also set the Micro Lipo to 500mA rate for a faster charge.

I did the project code using Visual Studio Code and pioarduino to use the latest version of Arduino core for the ESP32 (version 3).
The project code can be found here: https://github.com/jaseiffert/XIAO_SHT4x_Temp_Sensor_With_Battery

Operation
The XIAO will wake up every x minutes and transmit the data to the MQTT Server setup in Home Assistant.
The Home Assistant Configuration will be with the code on Github when it's ready.

Charging on the XIAO ESP32C6 is a bit different than the C3, the LED will blink until it is charged then it will go off when charged.
It is also on the opposite side than the C3 so it's on the right side looking at the USB Port.

Please let me know if I missed any information.

Updates
2025/09/01 - Added three pictures of the case in Polymaker PLA Pro Polymaker Teal. It looks great! I think the problem with the Yellow is that the print is not very thick so the Yellow is a bit transparent. I've printed other things in the same Polymaker PLA Pro Yellow that were thicker and it looked Yellow and looked great. It also shows the larger Air hole in the cover.

I also put up the code for the project on Github. To make things easier there are two files you need to change in the includes folder. One secrets.h which holds the user id and password for different things and the configuration.h file that configures the other setting for the program.

Also because this uses a wake up timer which makes it hard to reprogram the ESP32C6 I also added a GPIO Wake up pin D2. Take a jumper wire and put it from ground to D2, the 3rd pin down from the USB on the side that doesn't have the power pins. It will wake up but won't run any code to go back to sleep. Then you can upload any changes. Once it is restarted it will go back to normal operation and sleep.

I also uploaded a picture with a red oval to show the resistor that needs to be removed from the SHT4x board to disable the LED on it.

2025/09/10 - Updated HA Yaml file on Github and added unit_of_measurement to several sensors. I tried that once before but maybe I did something wrong because it accepted it now. Values such as Temperature, Humidity, and WiFi Signal now show the correct type of measurement. Voltage always seemed to work. Updated HA Card showing measurement values now.

Print Settings

• Printer brand:

VoronDesign

• Printer:

Voron2 350

• Rafts:

No

• Supports:

No

• Resolution:

0.4 nozzle .2 layer height

• Infill:

I Did 30%, 20% is probably fine.

• Filament brand:

Polymaker PLA Pro

• Filament color:

Yellow