GASOLINE ENGINE 8.1 S INBOARD MODELS
Page 18 of 58
Battery
IMPORTANT: Boating industry standards (BIA, ABYC), federal standards and Coast
Guard regulations must be adhered to when installing a battery. Be sure the battery
cable installation meets the pull test requirements and that positive battery terminal
is properly insulated in accordance with regulations.
IMPORTANT: Engine electrical system is negative (–) ground. It is recommended
(required in some states) that battery be installed in an enclosed case. Refer to
regulations for your area.
Select a battery that meets all of the following specifications:
• 12-volt marine type.
• Tapered post connector or side terminal connectors. Do not use a battery with wing nut
connectors.
• Reserve battery capacity rating of at least:
Engine (cyl./type)
cid (l)
Minimum Required Cranking
Battery Size
V8 MPI 496 (8.1) 650 cca/825 mca/150Ah
MULTIPLE EFI ENGINE BATTERY PRECAUTIONS
NOTE: All references to EFI models apply to EFI and MPI Engines. The following precau-
tions apply to all EFI models.
NOTE: All references to ECM apply to all engine control modules
Situation
Alternators: Alternators are designed to charge the battery that supplies electrical power
to the engine that the alternator is mounted on. When batteries for two different engines are
connected, one alternator will supply all of the charging current for both batteries. Normally,
the other engine’s alternator will not be required to supply any charging current.
EFI Electronic Control Module (ECM): The ECM requires a stable voltage source. During
multiple engine operation, an onboard electrical device may cause a sudden drain of voltage
at the engine’s battery. The voltage may go below the ECM’s minimum required voltage.
Also, the alternator on the other engine may now start charging. This could cause a voltage
spike in the engine’s electrical system.
In either case, the ECM could shut off. When the voltage returns to the range that the ECM
requires, the ECM will reset itself. The engine will now run normally. This ECM shut down
usually happens so fast that the engine appears to have an ignition miss.
Recommendations
Batteries: Boats with multi-engine EFI power packages require each engine be connected
to its own battery. This ensures that the engine’s Electronic Control Module (ECM) has a
stable voltage source.
Battery Switches: Battery switches should always be positioned so each engine is running
off its own battery. DO NOT operate engines with switches in BOTH or ALL position. In an
emergency, another engine’s battery can be used to start an engine with a dead battery.
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