Review on 🔋 Powerful Vertiv Liebert PSI5 1500VA Lithium-Ion UPS: Reliable 13500W 120V Mini Tower Line Interactive AVR with UPS Lithium Battery Backup - Single Phase (PSI5-1500MT120LI) by Boss Spangler

This UPS is installed in my rack and is working fine so far. I was expecting to be able to just plug it into my Linux system via USB and control it with NUT (Network UPS Tools). However, this UPS is not supported by NUT. Argh. In case you're wondering, it uses a removable 48V, 5Ah/240Wh LiFePO battery. Big, but not that big: my $150 "solar generator" (which can be used as a UPS in a pinch) has a capacity of 333Wh (it's LiFePO if you're wondering), it's still going to be heavy . The AVR functions work, but let the voltage vary quite a bit (at least +/- 15V) before changing the transformer windings to compensate. My old AVR UPS had much more precise control (keeping voltage within +/- 10V). Don't be fooled by the name "PSI5" and the expansion port on the back, this device cannot be configured with runtime expansion. Battery pack (not that it was ever advertised as a support). I fell for this train of thought, although I thought I had done enough research beforehand (read wrong datasheet). It turns out that none of the lithium-ion versions of the PSI5 series support external batteries (which makes sense, but I was still hoping). If you remove the expansion port cover, you will see that there is no port inside. My UPS came with the battery attached, which I found strange. But everything works. It arrived with 60% charge. Was it really worth the extra cost? May be. I'm still a little annoyed that it's not supported by the UPS Network Tools (NUT), but maybe that's about to change.