Connected UPS to Mac Pro with USB cable, and now LOAD shown is 20W Less!

[Anonymous user]

I have a BR1500LCD (from 2009).

Today, for the first time, I tried connecting the data cable from the UPS to my Mac Pro.

Before I connected the cable, the Load shown on the UPS LCD hovered around 185 Watts.
After I connected the cable, it hovers around 165 Watts - 20 Watts less!
I confirmed this by repeatedly unplugging/plugging in the data cable.

What's going on? Does it mean that the load really does decrease when the data line is connected, or is there a bug in the UPS firmware?
Is the UPS getting some power from the Mac via the USB?

Another question:
While I was exploring the new UPS options in the Mac's System Preferences/Energy Saver panels, I noticed that the UPS battery level started to decrease. It continued to decrease to about 90% within an hour, then started to increase again, and reached 100%.
During this time the UPS was connected to mains, and there was no outage. What was happening during this time? Why did the battery level change?

[Anonymous user · Accepted solution]

With nothing connected to my APC Back UPS 1300 XS LCD the load shoots up to over 100 and eventually drops to 71 when connecting the data USB cable to an XP laptop. Seems very wrong.