We tested the peak power consumption of the NAS at the wall during a run of CrystalDiskMark 5.0.2 as this version of the benchmark runs the read and write benchmark suites separately, so it's easier to monitor what power the device is using during each function.
The official power consumption figures for the DS119j are 5.01W in HDD hibernation and 10.04W when being accessed. These figures are with a 1TB WD Red (WD10EFRX) installed in the NAS. The 4TB Seagate IronWolf we used for testing the DS119J may be much bigger in capacity than the WD10EFRX but its average active power rating is a little lower than the WD drive, 4.8W against the 5.7W of the Red drive.