Qingping CGDK2 - Missing LCD information when placed outside

[suschmania]

Hi there, Since 3 days I am using the QIngping CGDK2 sensors with the Firmware version 3.7. One sensor is placed in livingroom, the other one outside in a "wind and rain protected" area below the roof.

Over night the sensor outside looses the "power" (?) to display the values on the LCD display. At the beginning they are very less visible and at the next morning nothing is visible anymore. Bringing it inside does not help, the display can be reactivated only when taking out the battery and wait 2-3 minutes. I read the values via bluetooth and they are still transferred, so internally the device still works.

I think the battery has too less power? We are talking here about ~ 5°C at night with humidity of 70 - 80 % max.

Can I increase the battery power to the display that it stays active?

Attached some infos from the sensor:

Status: Hardware Version: CGDK2 2.1.0, Software Version: 3.7
Vbat: 2955 mV , Temp: 23.12°C, Humi: 46.78%, ID: 11258, Reed switch counter: 0, flg: 0x05:r1/t0

data.csv

I also have a MHO-C401 with an E-Ink display. Maybe this is better for outside usage?

Any help welcome, thank you :)

[mr-sneezy]

Not sure if this means much, but I've had one of the old square sensors inside my fridge for at least 9 months on the original battery, and the LCD is quite readable. Perhaps try a new battery before anything else....

[suschmania]

Thank you.

Is there a difference in my case when i switch the Option "Sensor in "LowPower mode"? I wil ltry to use a different battery (even this is close to be fully charged).

[pvvx]

Yes, the LCD driver chip in the CGDK2 has this behavior. When the power is reduced or the temperature is low, the microcircuit loses its initialization ... Submission of new initialization commands does not result in operability. There is no solution yet.

Is there a difference in my case when i switch the Option "Sensor in "LowPower mode"?

For the SHTV3 sensor, this lowers its resolution and consumption. (SHTV3 sensor is used in CGDK2) The SHTV3 sensor does not automatically go into low power mode and during operation it is required to wake up and put the sensor to sleep with I2C commands between measurements. For the SHTV3, the reduction in consumption when the "low power mode" is turned on does not justify a decrease in the quality of the readings.

For the SHT4x sensor in "low power mode", the algorithm changes to: read the last measurement and start a new measurement. We receive data with a delay of the set measurement period, but the consumption is reduced. Without "LowPower Mode" in one cycle, the program starts the measurement, waits for readiness and reads the data, which consumes more power. The SHT4x sensor automatically goes into sleep mode after a measurement and remembers the last measurement. If the delay in readings from the sensor is not critical, then with SHT4x it is better to enable "low power mode".

[pvvx]

The datasheet for the LCD controller chip BU9792 has a Vdd (power) parameter from 2.5 to 5.5 V (+25С), which is not enough for this application. https://datasheet4u.com/datasheet-parts/BU9792FUV-datasheet.php?id=705112

[suschmania]

Thank you for the answer! Today night the sensor kept active, I was able to read the display this morning. Yesterday I changed the lowpower mode (turned it off). I thought that I should use this one compared to the other models, as it was the only one that goes down to - 10 C in its range. The other sensors starting from 0 in their specifications.

But these negative values are a bit senseless when the LCD display can't stay active... Anyway :)

[pvvx]

Since the beginning of December, LYWSD03MMC has been working outdoors. The temperature was below -27C. So far everything is working fine...

[suschmania]

Today night it happened again. So i think I will go for a LYWSD03MMC

[suschmania]

After 1 week of using the LYWSD03MMC everything is working how it should. The Qingping is used in the sleeping room now.