I'm looking at an Eaton 5SC750 UPS and the runtimes seem pretty low compared with APC. The Eaton has two 12V 7Ah batteries according to Eaton. Since the 5SC is sinewave output, I'm comparing it with a sinewave out APC BR1500MS2 which also has two batteries, although those seem to be 9Ah.
This datasheet claims 105W load on the Eaton lasts 36 minutes:https://www.eaton.com/content/dam/eaton/products/backup-power-ups-surge-it-power-distribution/backup-power-ups/eaton-5sc-ups/eaton-5sc-ups-technical-specifications-tn153004en.pdf
If I enter 105W into the APC product page it claims 70 minutes!
https://www.apc.com/us/en/product/BR1500MS2/apc-backups-pro-1500va-900w-tower-120v-10x-nema-515r-outlets-avr-usb-type-a-+-c-ports-lcd-user-replaceable-battery/That is very close to 2X the runtime, with not even a 30% advantage in battery capacity. What is going on here? Is APC lying? I do have a dual-battery APC unit but it's not sinewave, and the display claims 80 minutes with a load in the low 80s of watts. I haven't tested it that far, but it seems comparable with the BR100MS2.
I called Eaton and the guy didn't have a good answer but I admit this is only something the engineers there could answer.
On a side note, 24V at 9Ah is 216W-hours and makes either UPS appear to have a very low conversion efficiency.