Thermometer LED display

[joedupa]

Is there any way to disable the "onboard" LED display for the Mi thermometer devices? I have several sensors that will be buried in the deep freezers and I will be accessing their readings remotely via external ESP controller. The intention is to preserve as much battery energy as possible. Thanks.

[nightshark]

I am interested as well. I have 2 devices in freezers.

[pvvx]

Help solve these problems:

• Disabling the data refresh transmission command on the LCD does not save power.
• There is no documentation for LCD controllers.
• There is no command to switch the controller to low consumption mode.
• LYWSD03MMC uses more than 4 types of LCD controller chips.
• CR2032 are not intended for operation in negative temperatures.
• On sale there are key fobs without LCD display.

To reduce consumption in LYWSD03MMC, there is only one option - mechanical removal of the LCD controller.
Lithium-thionyl chloride battery 14335 2/3AA PC1 Li-SOCl2 3.6 V will work in the thermometer for more than 10 years. Operating temperature range: from -55°С to +90°С.

[joedupa]

Thanks Victor, what is the operating voltage range of the LYWSD03MMC ? The 14335 battery is 3.6V as opposed to 3V CR2032, wouldn't this kill the sensor?

[pvvx]

TLSR8251F512ET24: Supply voltage 1.8 - 3.6V
SHTV3, SHT4x: Supply voltage 1.08 - 3.6V

Didn't do any specific tests.
But during the fuss with them, 5V power was supplied more than once. Nothing happened - they work to this day.
To comply with the documentation, it is possible to include any diode in the power circuit.

[pvvx]

USB powered operation (5V):

I do not recommend repeating, but if desired, it works with a slight increase in the total current consumption ... :)

The reliability of the SoC is sufficient. But it does not withstand the supply of 12V to the GPIO :) This is also checked - that GPIO will no longer work, but the processor itself and the BLE remain working. :)
This is not Espressif with ESP, but Telink... :)

[pvvx]

At 3.6V, something triggers in the chip and the current rises...

[joedupa]

Very informative Victor, thanks again, just ordered a couple of those: https://www.aliexpress.com/item/1005003637299772.html