Mission Planner displaying battery voltage in AH window without battery connected

I have my pixracer connected to mission planner and I also have it connected via wifi to tower beta on my android phone. I do not have a battery connected but MP shows between 20v and 23v and tower app keeps giving me voice updates of battery capacity left. Is this a known issue? Another problem is that voltage calibration does not seem to work for me. It is always off by about a volt. Does that possibly mean I need to get another PM like a Mauch?