Loaded voltmeter is one that puts a synthetic load (simulates the receiver and servo loads) on the battery pack. Just hooking a regular voltmeter to the batteries, without some sort of "load", will give you an almost useless reading.

The term ESV for Expanded Scale Voltemeter, is designed for use in RC to check the Receiver and Transmitter batteries. It has an internal "load" (resistive in nature) that simulates the load or the connected components in a typical RC aircraft or other RC application.

Your local hobby shop or mail order shops, like Tower Hobbies, has them. Typical price is about $15.00.

http://www3.towerhobbies.com/cgi-bin...RCH=volt+meter

CGr