Useful battery powered PoE Gigabit adapter tested with ThermoView 30 and 40 plus SV600
These devices are marketed as mini UPS devices for routers or CCTV cameras.
There is one version described as (useable search term):
UPS Uninterrupted Power Supply 8000mAh 29.6Wh 60W 48V 5V 9V 12V 5.5x2.5mm POE
Special note: EU and US versions are essentially the same, just with a different power chord.
All version have 110-240V AC input (for charging).