T&T: Alternator Ground

[Mark Richter]

Jack,
It is good practice to add an alternator ground wire, the same size (or
larger) as the hot starter lead.  It should run to the engine ground cable
on the starter/solenoid.

The purpose of this ground wire is to minimize the alternator current
running through the engine block.  Sometimes engine corrosion issues can be
caused by this uncontrolled currrent passing through the block from the
alternator to the starter motor.  This is a larger issue for alternators
which charge large house banks.  A battery used solely for engine starting
doesn't need much charging, so relatively little current is passing through
the engine block.

Mark Richter, m/v Winnie the Pooh
homeport Ortona, FL; lying Staten Island, NY and southbound
Mark's Mobile Marine, electrical system design, installation and repair