Battery powered outdoor sensor drops connection in cold weather

[Atesz]

Hi,

I have a battery powered sensor to measure and report the outside temp and hum, utilizing a pro mini 3.3, powered fro step up booster, nRF24L01+ directly from battery + battery voltage sensing resistor pair plus the DTH22.

I have noticed that when the battery is around 2.6V (2x AA ~ 50% bettery 1.9-3.3) then under 4°C the sensor lost the connection to the gateway. However bringing inside after a few minutes the node come back, and the voltage jumps to 75-78%.

Any of you experienced similar behavior ? Is this expected ? How can I insulate efficiently the batteries ?

Many thanks any comment, advice in advance

Attila

[sundberg84]

@Atesz Yes, I have. I dont know why but changing the capacitor on the radio for a new one helped me this time.

[mfalkvidd]

see also https://forum.mysensors.org/topic/5826/nrf24-problems-with-cold-temperatures/

[Takero]

Insert an delay between sends will help to refresh the load in the capacitor. I prefer to wait for 100ms before send a new message. And increase the capacitor. My Sensor (not battery) works fine until -15°C.

[Atesz]

@mfalkvidd IIIIInteresting topic....Thanks for sharing !

[Atesz]

@Takero Good idea, I will implement it ! Thanks !