Battery Selector Switch

Calhere

Petty Officer 2nd Class
Joined
Jun 17, 2008
Messages
123
So I am thinking I installed my switch wrong, anyone got one of those niffty generic charts.
 

drewpster

Commander
Joined
Oct 17, 2006
Messages
2,059
Re: Battery Selector Switch

post 1- to battery one positive

post 2- to battery two positive

Com (common)- to all loads- power out to boat
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Battery Selector Switch

Here ya go!

StandardBatterySwitchWiring.jpg
 

Godfirst

Petty Officer 1st Class
Joined
Aug 11, 2008
Messages
228
Re: Battery Selector Switch

Hi It looks like all the questions were a answered.
 

Calhere

Petty Officer 2nd Class
Joined
Jun 17, 2008
Messages
123
Re: Battery Selector Switch

actually from the switch do I wire directly into the fuse block or from the ignition, the person I bought the boat from had it wired into the ignition first with an inline 30 amp fuse
 

waterone1@aol.com

Lieutenant Junior Grade
Joined
Oct 10, 2004
Messages
1,235
Re: Battery Selector Switch

Wait a minute guy's.........I think we need more info here. What engine, inboard or outboard ? Are you replacing a switch or adding one ? These are wired differently for larger boats with I/O's than smaller boats with outboards.
 

Calhere

Petty Officer 2nd Class
Joined
Jun 17, 2008
Messages
123
Re: Battery Selector Switch

It is a 1962 Dorset Cabin Cruiser 17 1/2 http://www.vintageglassboats.com/dorsett20.html with a 75HP Evinrude Starflight V, im replacing the entire electrical it has a switch on it but the guy i bought it from wired the switch to the ignition with an inline fuse(30 AMPs), then the fuse block from the ignition im trying to find out was that the right way or if not what is the right way.
 

drewpster

Commander
Joined
Oct 17, 2006
Messages
2,059
Re: Battery Selector Switch

What you need to do is figure out where the main power for your boat comes from. In the case of my outboard boat there are two wires that feed power to the boat. One is the main positive battery cable. The big battery cable is used to feed power to the starter. The other smaller main power feed (10ga.) that connects on the battery side of the starter solenoid. From the solenoid it runs up through the switch harness to the ignition switch. I have a small fuse panel that powers nav lights and do-dads from that connection at the switch.
In my case, all that I needed to do was to disconnect the battery cable from its original place at the battery and reconnect it to the COM post on my battery switch. All of the boat's power comes from the main battery cable.
The battery switch is there to serve two functions. One is to provide a means of keeping a fresh battery. The other is to provide a means of turning off all power. So the point is to find out where main power comes from and connect it to the COM post on the switch. (the only exception being an electric bilge pump circuit in a boat that stays in the water)

In my case the fuse panel is powered from the ignition switch post where a constant hot wire comes from the start solenoid. The panel gets constant power directly from the battery via this connection regardless of ignition switch position. (ignition switch does not have a accessory position) There is a 30 amp fuse back at the solenoid that protects the wire from the solenoid, to the ignition switch, and to the fuse panel. I can get away with this because my fuse panel only powers a few small things. The small hot post on the ignition switch merely serves as a connection point. If I were to add more accessories that draw more amps (stereo, spot light, radar, rocket launcher, sea whiz, ray gun ect.) I would move the fuse panel connection point from the ignition switch positive to a buss bar to accommodate more amp load. Some boats come with this type of system already installed. Look for a common connection point, or buss, that powers everything. This buss will most likely have a constant hot wire of some kind that either connects at the battery side of the starter solenoid, at a buss back at the engine somewhere, or directly to the battery positive separate from the starter cable. In any case this power feed should also connect at the COM post of the battery switch.
Hope this helps.:redface:
 

Calhere

Petty Officer 2nd Class
Joined
Jun 17, 2008
Messages
123
Re: Battery Selector Switch

Ok sorry guys so I am a lot new at this please forgive me,

So heres what I intend on powering on the boat from the fuse block a sony cd player nothing fancy just so I can listen to the game while I fish. my gauges (fuel, speed (light only), voltmeter (light only), and hour meter), running lights, and a fish finder, and a small cabin light.

So to re phrase my question with all the things above can I wire the fuse block though the ignition or though the switch?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Battery Selector Switch

Let's clear up a few things first. Most boats have not one, but two basic electrical circuits. The engine is one one electrical system that in a one battery system, is powered by that single battery. The boat itself, separate from the engine, may or may not have a feed directly from the battery to the fuse or circuit breaker panel. Regardless of the single or dual electrical system, anything you want active only when the key is in the RUN position, MUST be wired through the ignition switch. Gauges are the primary load for that circuit. Everything else can be wired into the boat harness and would not be affected by the ignition switch. So when you add a dual battery switch, nothing changes in that regard. The pupose of the switch is to ensure you are not left stranded by a dead battery. OFF is exactly that, both batteries and the loads they feed are turned off. In the BAT 1 position, battery #1 is the source of all power -- whether starting or house loads. Same applies in BAT #2. BOTH means that both batteries are powering the loads. When the engine is running whatever battery you have selected will be charging. How you wire the switch is a matter of preference. But the COM (common) terminal is output of the switch so whatever you connect there is affected by the switch setting. So the short answer to your last question is you need to do both. The COM terminal feeds the +12V bus on the fuse panel. The ignition switch feeds the instruments and anything else you want controlled in the RUN position. You can certainly power the fuse panel from the ignition switch but then you need to have the key in the RUN position all the time, regardless what you want on. That is not a good scheme.
 

Beefer

Lieutenant Commander
Joined
Aug 4, 2008
Messages
1,737
Re: Battery Selector Switch

Absolutely nothing to do with the meat-n-potatoes of this thread, but that's a cool boat! Any interior photos? :D
 

Calhere

Petty Officer 2nd Class
Joined
Jun 17, 2008
Messages
123
Re: Battery Selector Switch

Yea i like it alot but thinking of selling it when im done fixing it because the wife will only let me have one boat and well this one aint that good for fishing.
 

waterone1@aol.com

Lieutenant Junior Grade
Joined
Oct 10, 2004
Messages
1,235
Re: Battery Selector Switch

This is a little off from what I normally deal with. My suggestion would be to have everything that is engine related before the switch, and all accessories and boat related, after the switch.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Battery Selector Switch

Then why have the switch -- the engine harness is a multi-wire harness and can suffer the same electrical issues the "after the switch" circuits can have. One of the main purposes of the switch is to prevent electrical issues when the boat is unattended so with that scheme the engine and it's harness would remain active even though the battery switch is OFF. The ONLY thing that should be unswitched is the auto bilge pump and a security system is you have one.
 

drewpster

Commander
Joined
Oct 17, 2006
Messages
2,059
Re: Battery Selector Switch

I think it is important to note the reasons for having a battery switch. I have read many posts and responses in these forums. It is common that the original reasons for having the switch gets muddled, or even completely overlooked.

A battery switch obviously serves as a convenient way to turn on and off main power to the boat. It also serves as a means of selecting a second battery. Having a second battery has obvious benefits. Other reasons for having the switch are less obvious but no less beneficial.
One very important reason for having a main power switch is that it provides battery isolation in the event of a battery failure. Boats vibrate and pound around allot more than cars. This makes batteries more prone to internal damage. If one of your batteries fails you can simply switch to the other battery. If a major failure occurs and one of your batteries starts to get hot, you can shut off all power drawing from it and possibly prevent a fire. This is also a good reason that your batteries should not be placed close together or in the same box. Separate them if you have the room. This safety feature also holds true for failures you may have down stream of the switch. If a short occurs, and a fuse fails, any wires on that circuit will overheat and burn. This can burn into other wires causing shorts in a domino effect. Without a battery switch there would be no way to kill the power and stop the short. So safety is a good reason for having the switch even on a single battery setup.
Another reason for having the main switch would be to prevent parasitic drain. Most people think that if all the boat's switches and the ignition is off the battery should have zero drain. The truth is, all electrical systems will have some degree of parasitic drain on the battery. The moist marine environment is enough to cause problems. Couple parasitic drain with radio memory and your boat's battery will die much faster while the boat is in the slip or sitting on the trailer for weeks at a time. All of the boat's power should route through the switch so that it is completely isolated. The only exception would be an electric bilge pump for boat's kept in a slip. In that case, the bilge circuit should be direct to the battery and independently protected with its own fuse. To keep the battery charged, and the bilge working, an automatic onboard charger will also be needed for a boat moored in a slip. A main battery switch provides an easy way to shut everything down without having to dig around in the battery box disconnecting cables.
Another question concerned how many circuits should route through the ignition switch. Most marine ignition switches do not provide a accessory position like the one in your car. One reason for this is that it provides a passive safety feature by isolating the start/ ignition circuits from the rest of the electrics. In fact, it is also a good idea to physically route the start and ignition wires away from other circuits through the boat. In the event of a short leading to burned wires it is far less likely that the essential start/ ignition wires will be damaged and far more likely that the engine will start and run. Isolating the start/ run circuit will also help to prevent damage to sensitive computers and circuitry in modern marine engines. Even small outboards have some form of electronic control built into them these days. It is important to plan ahead for possible failures in your electrical system in all cases. Think in terms of what can happen instead of what simply will work. You will be safer and more likely to prevent a problem as big as this:
Boat20fire.jpg
:eek:
 
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