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It seems like my Eneloops doesn't like -20 Celcius

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bingo600:
Fun observation.

It seems like my Eneloops doesn't like -20 Celcius

I have some Temp sensors in the summerhouse, that are fed by 2 x Pana Eneloop (AA)
https://www.amazon.de/dp/B00392XX5U/

I built some Arduino code, that combined with a Hope 868MHz module, keeps track of the temperatures reported from the sensors.
And poll the Arduino (every 5 sec) from a Linux box. I log to CSV every minute - Both Arduino + Linux are inside the summerhouse, kept at 10C.
If the Arduino don't detect a xmission from the temp sensor for 5 minutes , it reports the temperature as 0 degrees, for that sensor. In order to see a "malfunction".

It's quite cold in the summerhouse, and yesterday i noticed the sensor not reporting at several periods.
I actually think the Eneloops stop delivering power, when the temp goes below -19C.

The purple graph is the sensor "outside" by the Grill , the red is inside the (unheated garage).

I looked at the Eneloop DS , and it states they should work down to -20C , and i think i have hit the limit.
Seems like they wake again, when temp reaches around -14C.



I also looked at Alkaline, limit seems to be the same -20C.

Is there any "payable" batteries that works down to -30C ?

/Bingo

Gyro:
EnerSys Cyclon cylindrical SLA cells are perfectly happy at -20'C and rated down to [Edit: -65'C]. The smallest single cell capacity is 2.5Ah. They have very long life compared to normal SLAs.

https://www.enersys.com/en/products/batteries/cyclon/cyclon/

wraper:
-20C is not a hard limit when they suddenly stop working. Most likely there is some problem with the device. Maybe it's not happy with lower voltage.

SiliconWizard:
Yeah what makes you think it's the batteries?

bingo600:
It could just as easy be the sensor that does'nt like the -20C, I agree.
I just assumed (yes i know .....) , that an outdoor sensor was made for outdoor temp's.  :palm:
But maybe not Scandinavian outdoor

Well no biggie

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