I'd let it go but I don't want mineseeker to screw up his detector. You can't measure voltage that way. First I taught electricity and electronics. For the fun of it I measured the voltage of a bounty hunter your way. Check the picture. It measured 17 plus volts. The problem is this detector only has one 9V battery for this detector and yet reads 17.27 volts. Rob
I can take the criticism, so don't worry about offending me if you think I'm wrong, I'll be the first to admit that I've been mistaken on more than one occasion.
I agree that putting a voltmeter in series with the circuit is not the way to achieve a proper voltage reading, because the reading is minus the sum of all voltage drops in the circuit(Kirchoff's current law). In this case however, the purpose of the reading is not to accurately determine the voltage, but to see what the voltage is between a broken conductor of the circuit. If a series circuit is broken, obviously the two points become a positive and a negative, and in the case of a power supply circuit, are going to give a reading close to the power supply's source. I can't explain your reading of 17V, I did not have that result in my tests, and with one battery taken out of the circuit, I had a reading of around 9V.
As the picture below shows, I have a reading of 8.7 V between the two positive terminals, if the batteries were wired in parallel, the reading would be zero.
That's my take,
Ed
Electronics school graduate 1974-1976
Journeyman Electrician 1986
Master Electrician (Block & Assoc.) 1988
IMSA certified electronics Bench Technician 1997
Journeyman Technician IBEW Local 53