VA and W
UPS boxes show volt-amperes but the load limit is watts: on budget models watts are about 60 % of VA (a 600 VA UPS is about 360 W). Keep 25 % headroom: at the limit a UPS runs hot and the battery drains faster. Runtime is an estimate: lead-acid batteries give far less than their rating when drained fast, and lose another third after 3–4 years.
For Home Assistant, a NAS and the router a clean shutdown matters more than hours of runtime: connect the UPS over USB and set up NUT; the Network UPS Tools add-on shuts Home Assistant down before the battery runs out. Which server to pick: server for HA.
UPS 600–1000 VA: AliExpress
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