Doorbell dual T8213 issue: wired to 24V 30VA transformator shut down due to empty battery

i bought a Doorbell Dual (T8213) last november which has a battery, but can also be wired
the situation at home was that I had not installed a doorbell before, so there were no wires or chime.

To not charge the baterry every now and then, I wired the doorbell to a transformer, 24V 30VA from brand EZVIZ, cable/wire is 10 meters
Product sheet:变压器-Datasheet.pdf?ver=94569&_gl=1*ceemof*_ga*MTY1MDU0NzY3NC4xNjc0OTMzMjUx*_ga_GFXNRVT2BW*MTY3NDkzMzEyMy4xLjEuMTY3NDkzMzI2OC40Mi4wLjA.
I do use Homebase2 and a eufy chime in the power outlet in my home situation.

Today i got to know, that my doorbell is shut down, due to low/empty battery. A message is shown in the android app. I did not get a notification.

Everytime i opened the android app, i saw the icon that it is wired connected. Never got to know things were not working fine. So i was very surprised that my doorbell is not working anymore.

Ok, temperatures the recent days outdoors were little lower, due to winter. About -2 degrees celsius at nights and +1 Celsius dayover. So, within ranges that the doorbell should work fine, in my opinion. In december it were 2 weeks with temperatures at around -10 Celsius at nights, and 0 celsius dayover. Also not temperatures to make the device stop to work.

My android app showing:

does my doorbell dual need the be replaced by a new device? Is it dead? Or will it get back on again when temperatures rise? It there a wiring problem, or transformer issue? It cant be that my device goes offline with longer periode of low temperatures (some periode around 0 degrees celsius, should not be a problem to keep de battery charged).

Today, day over, temperature is about 0-2 degrees Celsius.
I saw a message in the app, that due to low temperatures, the battery is instable.

So the device, the doorbell dual, is not resisted to low temperatures. Very bad for a outdoors device. I call it malfunctioning.

I can understand this, not/bad working in low temperatures, when they are -10 degrees or lower, for days. But these temperatures we are having now, should be peanuts for my doorbell.

Worst buy ever.

Eufy battery powered gear, like any other non-heated lithium battery gear, doesn’t charge below 0C. This is because it will destroy the batteries. That fact is called out on the spec sheet for the device. It will operate below 0 C, but unless you have fully charged batteries before the temps drop, you will have to remove the device and warm it up before charging in lower temps.