This has been discussed before and many great options are out there, but I wanted to give a firsthand review of one device that is designed specifically to act as a UPS rather than a power bank. The one I got is called “RPi UPS PowerPack” ($16) but I’ve seen it sold under a couple different brands. If you search for “Raspberry Pi UPS” it usually turns up:
It’s designed to provide battery backup for a Raspberry Pi, but it will work for any USB-powered device like a WyzeCam v2. It comes with one 5000mAh lithium battery and has a place to connect a second battery if you need more capacity (you can buy 2 batteries up to 10000mAh each). It has 2 USB ports which may not be useful unless you have two cameras near each other, but if you have a cam and a hotspot at a remote site this can power both for a short time.
I tested it with a WyzeCam v2 and it provided 6.5 hours of continuous recording from a full charge. Once power was restored it took just under 10 hours to fully recharge from the standard Wyze USB power (with a 2A USB charger it might be less) while still powering the cam. I was able to unplug the UPS and move it and the cam around without any interruption to power.
One thing I did find was that if the battery is fully depleted it will not automatically power the camera once power is restored. You need to cycle the power switch on the board off and back on manually. Since most of the power outages in my area are only a few minutes this is not a problem because I don’t expect the battery will ever be depleted, but if you need something for a remote site where you need it to come back up automatically after 6+ hours of no power, you may need a real UPS or at least a second/larger battery.
See these threads for discussions of other DIY and off-the-shelf battery backup solutions: