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Author Topic:   Installing battery switch: Dual motor/dual battery
littleblue posted 08-09-2005 12:28 AM ET (US)   Profile for littleblue   Send Email to littleblue  
I already looked up the dual battery article in the reference section but had a question. My boat has two battery's and two motors. Basically I want to use the "new" dual battery configuration. Is there anything I should check to make sure this configuration will work/not work?
Also, there should only be one set of wires going from one of the batteries up to the console right? (asking about the current settings, not after the switch is installed)
Last question: There is a small box, same color as the hull on the starboard side of the boat, above the splashwell w/ some wires going to it. It also has a small silver button on top. What is this box for?
jimh posted 08-10-2005 12:01 AM ET (US)     Profile for jimh  Send Email to jimh     
The molded box in desert tan gelcoat is a cover that houses the circuit breaker that protects the conductor from the battery to the console. This is the main house circuit breaker.
littleblue posted 08-10-2005 04:19 AM ET (US)     Profile for littleblue  Send Email to littleblue     
So all I need to do is bridge the two negative terminals w/ battery wire. There should already be a negative wire going from one of the batteries to the "house circuit". Add a positive wire to each battery and then connect the corresponding positive wires to the 1 and 2 spot on the switch. Find the other positive lead and connect that to the "both" switch. Is this correct?

Sorry, for the redundency. I don't want to screw anything up.

Bulldog posted 08-10-2005 05:47 PM ET (US)     Profile for Bulldog  Send Email to Bulldog     
What? I'm not sure what you mean by the new dual battery setup. I assume you are talking about using a 1-2-both-off battery switch to power your "house" circuits. I don't think it wold be a problem with a 1-2-off switch , but that both postion can really cause a problem and possibly a fire if used! Consider that most "house" circuits use about a #6 or #8 wire good for about 45 amps or so, if you put your house selector switch in both you will be tying the batteries together and if you did this during a condition that one battery was drained and tried to start a engine , all the motor starting current will be going through that cross connection you made, not good! My problems I have had with both of my twin engine boats is having the house battery drained down by leaving something on by mistake, then not being able to start that engine, my first boat , a Sea Ray , had an emergency start system whit a momentary switch that controlled a starter solenoid wired between the two batteries, I would start the one engine up, then hit the switch while cranking the second engine , once running I would let off the switch, worked great! The system I had was on a 1989 boat from the factory, and I'm putting this on my boat this winter, but my engines are 1987 motors, there could be a potential problem with some newer motors, that would maybe require you to start the dead battery engine first...Jack
jimh posted 08-10-2005 06:05 PM ET (US)     Profile for jimh  Send Email to jimh     
The diagram in the Reference Section shows the circuit wiring with enough detail for most people who are familiar with electrical wiring to accomplish an installation on a small boat. If you need more help with the primary battery distribution wiring on your boat, I suggest you get someone to assist you in person. I do not think it is possible to communicate sufficient information via this forum to teach proper electrical wiring installation techniques. It requires more hands-on learning and direct observation.
jimh posted 08-10-2005 06:11 PM ET (US)     Profile for jimh  Send Email to jimh     

Wiring of low-voltage/high-current circuits can be hazardous because of the extremely high short circuit current capacity that exists when working with large batteries. All the information provided is believed to be accurate and representative of techniques and practices in common use in the marine applications described. Examine any wiring carefully for proper configuration before applying power. Low-voltage/high-current short circuits can produce extremely rapid heating and can be dangerous. Never wear a ring or metal jewelry when working with high-current sources like storage batteries.

Bulldog posted 08-12-2005 09:16 AM ET (US)     Profile for Bulldog  Send Email to Bulldog     
You sound like you are doing ok with this, I have checked the reference section and yes to running the wires from each battery to the #1 and #2 terminals on switch , also yes to running a "jumper between the battery negative, all of the above mentioned wiring needs to be the same size as you battery to engine cables! The wire from your fuse box will go to the third terminal bost I believe it is "C". This seems like a simple safe effective way to do things...............Jack

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