Connecting a voltmeter

[Dave Fain <kc3565l@sprintmail.com>]

After fixing a charging problem on my 1973 GT6, I installed a Smiths voltmeter 
I had lying around to help keep an eye on things.  I have it connected to the 
hot side of the ignition switch.  Is this OK or should it be switched so it 
only works when the engine is on?  I kind of like the idea of knowing what 
condition the battery is in before I hit the starter.  Is this going to cause a 
drain on the battery?
Dave