Mercury Racing 500R Operation And Maintenance Manual page 105

• Refer to NMMA, ABYC, and U.S. Coast Guard boating standards and
regulations for complete guidelines.
BATTERY CABLE RECOMMENDATIONS
Refer to NMMA, ABYC, and U.S. Coast Guard boating standards and
regulations for complete guidelines.
IMPORTANT: Solder the terminals to the cable ends to ensure good electrical
contact. Use electrical grade (resin flux) solder only. Acid flux solder may cause
corrosion and a subsequent failure.
1. Measure the length of the positive (+) battery cable.
2. Measure the length of the negative (–) battery cable.
3. Using the total cable length and the chart below, determine what gauge of
wire to use for both cables.
NOTE: Place the battery as close to the engine as possible.
Total Cable Length (a + b)
Minimum
–
7.4 m (24.3 ft)
12.2 m (40.0 ft)
15.2 m (49.9 ft)
19.6 m (64.3 ft)
PREFERRED CHARGING CIRCUIT
Modify the charging circuit so that both engines charge the auxiliary battery
but also isolate the auxiliary battery from the port and starboard engine start
batteries. This configuration provides enough current to operate the boat's
accessories and still have current available to start the engines.
Positive battery terminals: Boats with multiengine EFI power packages
require that each engine has its positive battery cable connected to its own
battery. This ensures that the engine's propulsion control module (PCM) has a
stable voltage source.
Negative battery terminals: Connect all negative battery cables at one
source.
Auxiliary batteries: To ensure proper charging, properly switch or isolate
single engine applications. In multiengine applications, do not consider the
auxiliary battery as another engine's battery. Use proper switching or isolation
of the auxiliary battery to ensure proper charging and separation of engine's
positive battery cables.
eng
MAINTENANCE
Maximum
7.4 m (24.3 ft)
12.2 m (40.0 ft)
15.2 m (49.9 ft)
19.6 m (64.3 ft)
24.4 m (80.0 ft)
95
Minimum Cable Size
21.2 mm² (2 AWG)
33.6 mm² (2 AWG)
42.4 mm² (1 AWG)
53.5 mm² (0 AWG)
67.7 mm² (00 AWG)