This may be an odd question, but what should the power consumption be for the axidraw? I run 2 routinely during the day but havent been turning them off at night. Would the idle consumption be enough to raise my energy bill by 40-50 dollars a month for 2 devices? I have had a consistently higher power bill since running them and this seems to be the only change. Would the draw be enough to warrant unplugging them when not in use?
The AxiDraw power supply is 9 V, 1.5 A, or 13.5 W, and usually uses less than that, but can also potentially use slightly more accounting for the inefficiency of the power supply. For two, figure maybe 30 W total? For a full month, 24 hours * 30 days = 720 hours, or 21600 watt-hours at 30 W, 21.6 kWh.
Figuring $0.15 (US average) per kWh, I would estimate that two AxiDraws would together use about $3.25 per month in electricity, assuming that you leave the motors powered on all the time. (Use Extensions>AxiDraw Utilities>Disable XY Motors to disable an AxiDraw, and it will use much less energy.)
I don’t think that this is enough to explain $40-$50 difference. On the other hand, if having them connected is (for example) related to your computer not sleeping, that kind of thing could cause a much larger difference in energy use.