I have a VX4400 and two batteries to go with it. A standard capacity and an extended capacity. I don't put the phone on charger, but I just exchane the battery when battey gauge gets to one bar. Well lately I noticed the gauge is acting up. It shows 75% charge (3 bars), then suddenly drops to 25% when I make a call and after the short call, it returns to 75%. Is using extended and standard capacity alternatingly confusing the battery status calibration within the phone or is the battery charge information located within the battery monitor chip inside the pack?