Here is the link that explains everything including the 10 hour battery backup it includes. Click the Details tab and the. Specs of the hub.
I will just include it here for you.
Wyze Sense v2 Hub
White base with grey speaker top
Dimensions (H x W x D)
4.5” x 4” x 1” / 114.3 x 101.6 x 25.4 mm
Built-in rechargeable battery
Battery backup life: 10 hours
Battery cell composition: 18650
Battery power: 3.7 V, 2600 mAh
Battery weight: 11.5 g
Number of battery Cells: 1
Personally, even if it is on battery, the last thing I am going to do is keep refreshing the app to watch the power level go down. If it’s plugged in, I know I have battery backup if the power is removed. If yours just shuts off, maybe the plug came loose or something. As another user just included photos of the inside the hub, the battery looks to be easily replaced. Also a new firmware version is available, so try and update it. I know a relatives I ordered talks and says it’s running on battery backup where mine does not. I preordered mine back in December 2020 and ordered theirs in April. I am assuming a different hardware or firmware version. At the end of the day, I still believe this is a reasonably priced alarm and zero complaints with Wyze’s first attempt.