Battery Charger Operating Voltages Puzzling

I was just curious to see what a 12 volt AC battery charger puts out with no connection to a battery I took a digital voltmeter connected it to the clamps it says 10.82 volts and about 9 volts on trickle charge I thought this charger can not be working as this low of voltage would not charge a battery so I hooked it to a battery and shows amps are flowing on the meter and the volts are over 15 this charger only has a transformer and the diodes to change the AC to DC why does it not read on a voltmeter at least 15 volts with no connection?

John

A meter set to volts has a very high internal resistance. I believe its in the million-ohm range.

Never thought about that my have to use VTVM instead.

Depending on the design of the charger, it may not give a representative output voltage measured that way with no load. Best is to connect it to a know good battery, and monitor the voltage.