I'm pretty certain any UPS in a working order should not have an issue staying for an hour at 5W load. A 5W load for an hour is just a 5Wh capacity. That's no

I'm pretty certain any UPS in a working order should not have an issue staying for an hour at 5W load. A 5W load for an hour is just a 5Wh capacity. That's nothing. A 16in MacBook Pro has a 100Wh battery. Vertiv Liebert PST5-660MT120, rated 660VA/400W, retailing at $77 USD on Amazon, https://www.amazon.com/dp/B07BXZPF99 https://www.amazon.com/dp/B07BXZPF99, is supposed to last "2 min" at full load, "7 min" at half-load, per Amazon listing. However, looking closer at the specs in the listing's User Manual in PDF, https://m.media-amazon.com/images/I/B14RNuD0LXS.pdf https://m.media-amazon.com/images/I/B14RNuD0LXS.pdf: 10% — 56; 20% — 28; 25% — 13; 30% — 14; 40% — 11; 50% — 7.5; … 100% — 2. But what's 10%? A 10% of 400W is 40W. A load of 4W would then be a load of 1% of capacity that would be like 560 minutes (9.33 hours) if we extrapolate. So, my guess is, at a 5W load, a device can easily last about 5 hours or more, on an average UPS that's in good working order. I think the biggest problem may be, that it'd be consuming less than 5W during sleep, and could be deemed as parasitic load, and thus the UPS could actually turn itself off, to avoid wasting the energy, thinking that it's unloaded.