If I have a USB powered device, could I leave it plugged into a portable power bank (like the kind you charge your phone with) as a power outage backup?
Basically as the title says. We have semi frequent power outages where I live. The noise machine in my daughter's room goes out and wakes her up. If I were to buy a USB powered one, plug it into a power bank like one of those 10000ma ones you get for charging cell phones, would it have continuous power. Basically like a cheap UPS
Most power banks won't output power and charge at the same time.
There are USB "UPS"s that will do that, though. They're typically used to run Raspberry Pi projects and are quite a bit pricier than regular power banks.
General UPS are great of medical/server devices too. You can get a generic one and then use software to disable the beep. It's what they are used for. The batteries are even replaceable.
I was gonna suggest a regular UPS (some have USB ports), but OP said it was for a noise machine/sleeping, so didn't want to recommend something that would start beeping randomly lol.
Yea I've got some Cyberpower UPSs for bigger equipment but it seemed like overkill to add a $100 battery to a $20 noise machine. Plus they're actually pretty noisy on battery mode (they buzz)