Any boat wiring/mechanical experts?

[Wes Davis]

Currently I have a two battery system with a 1-2-both switch, isolator and wired in 110 charger. I would like to eliminate the switch. I want to have a cranking battery dedicated to the motor only and a deep cycle battery dedicated to lighting and accessories only. When the motor is running I want both batteries to be charged by the alternator. When the boat is plugged in at the dock I want both batteries to be charged by the 110 charger. The isolator needs to be installed to prevent one battery from discharging into the second battery in case of a failure. Can anyone put me together a simple wiring diagram or give me a better option for what I am looking for. Keep in mind I want to eliminate the switch.

 

[Scott Tanner]

My dad did this years ago... you need to put a large diode across the battery terminals on the rear on the 1-2 battery switch, so that the aux battery gets charged from the engine and charger while the switch is on 'engine'. the diode capacity should equal the amp rating of the charger. when you start, the engine battery gets used. the aux battery can be wired to all of your accessories. HTH

 

[Kevin Palmer]

What ST describes is the way I would as well if I was going to do this.



I am curious though, why do you want to take what I would call a back-up battery out of the loop.



By that, your out there fishing or whatever, decide to start the motor so you can go home, for whatever reason the "dedicated" battery is dead/defective/weak or whatever. You will not be able to start the motor.



In its present wired configuration you will be able to use the other battery as the main and or as a booster and thus will be able to start the motor.



What is your thought process of eliminating a potential life saver when you need to start the motor and won't be able to????



Just curious....

 

[Scott Tanner]

by leaving the 1-2 switch intact, you can still have a backup battery.... just switch the 1-2 switch to the aux or the both position..... of course, this only works well if both batteries and the charging/starting system is in top condition...

 

[Robert Thomas]

Don't know if you have an outboard motor or inboard. If it's an outboard motor only charge one battery at a time when charging from the motor.

 

[Wes Davis]

Coastie my thought process was I would have a cheap set of jumpers in the boat. If either of my batteries had a catastrophic failure I could jump from the good battery. I like to fish at night with lots of lights and the stereo going and this would be my deep cycle battery. I want it to stay isolated from the starting battery so I always have that starting power but I want both batteries to receive the charge when the engine is running. Does this make sense or am I still not looking at this right?

 

[Bill Ellis]

Read this article and see if it helps. Looks like a battery integrator, rather than an isolator, is what you need. Check it out.

 

[Wes Davis]

My motor is a 1979 Chevy 350. Can one of you gurus tell me the wiring path on how the power gets from my alternator back to recharge the batteries. There is no wire going directly from the alternator to the battery so it must take some path unknown to me. Does it go to the starter and connect with the main positive battery cable there?

 

[Wes Davis]

Todd Z, Coastie? I know one of you guys can help me with this.

 

[Kevin Palmer]

There are diodes and rectifiers within the alternator that create the voltage that runs through the wires and charge the battery. The same wires that feed the ground and positive system are the same wires that will also feed the charge.



In most cases, there will be at least one other red wire of heavy guage, (bot as big as the battery cable) that run to and from the alternator, it is this wire that charges the battery.



Why it does not discharge when things are off is because of the diodes. They are a one-way electronic gate.



I am pretty sure if you want to do what you suggest above, all you have to do is simply put the battery switch over to whatever number is the deep cycle battery. This way you are only running your electronics on that battery. When it comes time to start the motor, I suggest you switch it to Both or at least the other fully charges battery as you will need some cranking power to turn the motor over.



Make sense???