A voltmeter will tell you NOTHING. This is because a voltmeter draws almost ZERO current, and will show a reading at very very low leakage current. Hell try this:
Find one of your cars with a little dirty battery. This might be tough in the modern day and age. Stick one probe of your voltmeter on the hot post of the battery, then probe around different spots on top of the battery CASE
If there's enough moisture and dirt on there, YOU WILL get a voltage reading.
That is WHY some of my posts are this involved. You must measure CURRENT, not voltage.
