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Holcom, 1) A generator works cuz youre rotating a coil of wire (Armatue) inside a Magnetic Field (Field). 2) When current flows through a wire, a magnetic field is created whose North/South Magnetic Polarity is dependant upon the direction of the current flow. 3) The North/South magnetic polarity of the magnetic field in which the coil of wire (Armature) rotates, determines the direction of curent flow in that coil of wire when a load is attached. 4) You "Polarize" the Generator (NOT the VR) by grounding the Gens Field post and then flashing voltage to the Armature post (where Field windings are also internally connected on Class A Systems). This draws Field current which imparts residual magnetism (via the electromagnetic field created around current flow in a wire) into the soft iron poles which has that certain and correct North/South magentic polarity. THEREFORE When you Polarize a Generator you impart residual magnetism into the soft iron field poles having the correct N/S magnetic polarity so the Generator will cause current flow and charge the battery in the right direction and electrical polarity. When the Gen first starts to turn and before the Battery gets connected to it (via the cutout relay inside the VR between its BAT and ARM terminals) it generates electricity in the correct electrical polarity so as to charge (pump current into battery) and NOT discharge (draw current out of battery) Some VR's are bi polar and work at either polarity (if wired correct) while others may not. I have read the direction of current flow determines the coatings on the relay contacts and while they can work regardless, they last longer if current flow is in the direction they were designed for. Clear as mud????? ?? John T Nordhoff in Indiana, retired electrical engineer
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