Its explained here http://talk.maemo.org/showpost.php?p...&postcount=846. BME can turn off device before calibration complete but AFAIK Pali's BME replacement have different voltage threshold and it working better.
Still you need avoid high pick current which could lead to decrease voltage and cause turn off.
I am not sure about display and vdq issue but turning it on lead to ~10mA -> 200mA so voltage can drop.
I have never serious problems with battery calibration. With stock BME I just disable it and leave phone with display on and low brightness until it shutdown. Similar with bme replacement but I don't need to disable anything. Try 2 or 3 times and there is no way it will not work.