Regal 26 EXPRESS Owner's Manual page 61

Systems
DIRECT CURRENT (12 VOLTS)
Your Regal boat uses 12 volt DC electricity otherwise
known as direct current. It is called DC because it flows
only one way in a circuit. Specifically 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
toilets are all components using a 12 volt DC system.
In the DC system used in the United States 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 alternator while the engine is running
or by the battery charger at dockside.
The alternator charges 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 engine alternator used on your boat is internally self
"excited" and produce DC current at idle. Normal stern
drive alternator output would be around 105 amps.
Typical battery set-up includes:
The port battery is normally used to start the engine.
The starboard battery is the "house" battery and it controls
many component functions.
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