Regal 53 SC Owner's Manual page 65

DIRECT CURRENT (12 VOLTS)
Your Regal yacht uses 12 volt DC electricity otherwise
known as direct current. It is called DC because it fl ows
only one way in a circuit. Specifi cally to name a few,
helm gauges, batteries, battery cables, engine electrical
components, engine wiring harnesses, dash switches,
selected lighting, shower sump, bilge pumps, and vacuum
style toilets are all components using a 12 volt DC system.
With the DC system used in the U.S.A the red wire is
designated as the "hot" or conductor wire and the black
wire is referred to as the ground wire. At times other
current carrying wires are color coded such as blue to
identify their use as a low voltage conductor. This is
especially helpful in troubleshooting and adding additional
equipment. Be sure to review the wiring schematics in the
drawing section of the technical chapter.
Direct current is stored in the ship's batteries and produced
through the engine alternators while the engines are
running or by the battery charger at dockside.
The alternators charge the batteries by sending current
through the main distribution panel relays, battery switches
and harnesses to the appropriate battery. Normal DC
voltage is between 12 and 15 volts. Lower or higher
readings could indicate a charging malfunction or a weak
battery.
The Cummins diesel engine alternators used on your
yacht are internally self "excited" and initially produce DC
current around 1200 rpm's.
Current specifi cations for alternator output is between
130 and 160 amps.
Note: The port cranking battery controls the windlass,
port engine and generator.
The starboard cranking battery controls the starboard
engine
The house battery controls a variety of onboard
equipment.
BATTERY (12 VOLTS) DESCRIPTION
On board direct current is stored in the ship's AGM
batteries. There are 2 engine starting batteries (one for
each engine) and a deep cycle "house" battery.
Port Engine Typical
Cranking House Battery
Battery
13
Systems
Starboard Engine
Cranking
Battery