The preferred method is to have 1 engine,1 battery switch(1-both-2), 2 starting batteries for each engine.Most companies try to save a buck by using 1 switch(on-off) or twin motors with 1 switch.Bucking alternators are never a good thing.What good are backup systems (twin motors) if you kill all the batteries or both alt`s.
You bought twins for the safety factor of having at least 1 running motor to get back.2 motors = 2 separate wiring systems.With "twins" how many sets of instruments does your boat have . 1 or 2. think about it.If you only have 1 set of gauges for both motors ,how would you know exactly what each motor was doing.
Lets say your 75 miles off shore,Could you have only 1 alt. charging the batteries,and your planning a "overnight" too.You just might.you`d never know because both voltmeter gauges are "wired together".
You`lll be safer wired this way:
#1 position,#1 position =normal setting for both switches
#2 positions jumpered together and go to the + side of the house/ships battery.Also your shore power charger lead is hooked here.
BOTH -BOTH= emergency starting power iincluding the house/ships battery to both engines.
The "house/ships" can be charged buy using the "BOTH " setting of ONE SWITCH ONLY.Either engine has this feature to charge the ships battery or install an isolator on 1 engine to charge the ship battery and not use the switches unless if an emergency.
Remember: The preferred method for the negative cables is a cable from each battery to the engine block and a battery cable between the engine blocks.5 batteries and a lousy connection still give you "0"
You bought twins for the safety factor of having at least 1 running motor to get back.2 motors = 2 separate wiring systems.With "twins" how many sets of instruments does your boat have . 1 or 2. think about it.If you only have 1 set of gauges for both motors ,how would you know exactly what each motor was doing.
Lets say your 75 miles off shore,Could you have only 1 alt. charging the batteries,and your planning a "overnight" too.You just might.you`d never know because both voltmeter gauges are "wired together".
You`lll be safer wired this way:
#1 position,#1 position =normal setting for both switches
#2 positions jumpered together and go to the + side of the house/ships battery.Also your shore power charger lead is hooked here.
BOTH -BOTH= emergency starting power iincluding the house/ships battery to both engines.
The "house/ships" can be charged buy using the "BOTH " setting of ONE SWITCH ONLY.Either engine has this feature to charge the ships battery or install an isolator on 1 engine to charge the ship battery and not use the switches unless if an emergency.
Remember: The preferred method for the negative cables is a cable from each battery to the engine block and a battery cable between the engine blocks.5 batteries and a lousy connection still give you "0"