How to hook up a dual battery switch?

I have been researching the best way to hook up a dual battery switch. I noticed that people sometimes recommend hooking the negatives of the two batteries together while others dont. Why do some people hook up the negatives together and what is the benefits of doing so. I have a Guest Dual Battery Switch 3101 with a Battery 1, Battery 2, and Feeder connection on the back of it. From my reading am I suppose to hook up positive (from battery 1) to "batt 1" on switch and positive (from battery 2) to "batt 2" on switch? Where do I find the feeder cable? Should it be a cable that is currently on my starting battery (battery 1)? Some people also speak of a common connector on the switch, I do not have this connection...Do I suppose to have a common connector? Also how will the switch crank the motor? Is there a cable that goes to the starter or motor that needs to be on the switch? And once I get this switch installed properly, will it hurt to start the motor on battery 1 and then switch it over to battery 2 or both while the motor is running? I know that I shouldn't turn the switch off while the motor is running but can I change batteries on the switch? Thanks in advance.

Re: How to hook up a dual battery switch?

Moving to Electrics, Electronics and Trolling Motors (not engine)

Re: How to hook up a dual battery switch?

Your switch probably has 3 posts on the back, otherwise it's just a battery disconnect which will not work for what you are trying to do..

If your switch has a OFF 1 - 2 - Both setting it will have 3 terminals or posts on the back. The common that people refer to is the 3rd post. You connect the positive of batt #1 to terminal #1, positive of batt #2 to terminal #2 and then whatever was connected to battery #1's positive post (ie your starter/accessory circuits) should be connected to terminal #3 or the common.

This will allow you to use battery #1, #2 or both for cranking/charging, you can ONLY switch between the batteries when the engine is running IF you have a switch that is designed to be "make before break" meaning it makes the connection you are switching to before it breaks the connection it already has. (Consult the manual that came with the switch for clarification)

As for the grounds the simplest thing to do is tie the ground from your new battery to battery #1's ground, otherwise you will need to run the ground from your new battery to the engine block (or wherever your ground is presently connected to battery #1)

I hope this is clear enough if not feel free to ask more questions!

Re: How to hook up a dual battery switch?

I do have 3 posts (batt1, batt2, and feeder). Are you saying to take all the wires that was on batt1 positive and put on the "feeder" post? Also if my switch is not a break before connect, how would I ever be able to charge both batteries if I can not change the switch to "Both" while the engine is running. I have a starter battery and a deep cycle battery. The deep cycle battery runs my stereo equipment (amp) and trolling motor. The amp and trolling motor is connected directly to the deep cycle battery. I want to be able to charge this battery without draining battery #1. What is the best way to wire this setup to my switch? I know there are different ways to do this using different equipment, but I want to use what I have (switch). Also how would you use the settings, i.e. start engine with switch in batt #1 position, switch over to both to charge both batteries, and while sitting in water switch to battery #1 to prevent drain? When would I ever need to select battery #2 on the switch?

I have the following switch: http://www.boatersland.com/gue3101.html

Re: How to hook up a dual battery switch?

If your switch isnt make before break you cant switch while the engine is running it without possibly ruining something. If it isn't take it back and get a new one. Otherwise you just need to hook your trolling motor/stereo up to batt #2 and use batt #1 for cranking.

If this is on a boat with an outboard you won't be able to charge both batteries at the same time with the both setting because your outboard wont put out enough to charge both at once.

My suggestion is to use batt #1 to crank, switch to #2 to charge it while underway. Troll/radio/whatever on batt #2. If you ever have a problem cranking you can always use the both setting.

You might want to consider a onboard charger that you connect when you get back home to keep your batteries fully charged for your next outing.

Re: How to hook up a dual battery switch?

I have an 3.0L I/O. My switch is this one http://www.boatersland.com/gue3101.html I don't think it is a break before make type switch. So I won't be able to switch it to both to charge battery#2. Will it hurt just to start the motor in the "both" selection and will it drain both batteries if I leave it in "both" with the engine off if a battery is weaker than the other. Not being able to switch over to "batt#2" or "both" with the engine running makes no sense to me. Why would they design a switch to charge both batteries, but you can't switch it over to charge both batteries???

Re: How to hook up a dual battery switch?

Run a search for battery switches and you'll eventually find a bunch of different threads where I recommend using the Blue Sea add-a-battery set up. One, Two, Both switches stink and aren't very reliable especially if you're boat stays in a mooring where charging the batteries is not convenient.

Re: How to hook up a dual battery switch?

http://63.136.217.17/switches.html

According to guest's webpage your switch is make before break, so you can hook it up and switch it to any position except OFF while the engine is running.

Guest Battery Switches Features

* Heavy-duty copper sweep contacts.
* Positive click-stop on all positions.
* Built-in skirt protects connections.
* "Make before break" contacts allow selection of all positions except "off" while engine is running.
* Alternator Field Disconnect (AFD) models allow selection of any position, including "off", without damage to alternator or electrical system.
* For 6, 12, 24 and 32 volt systems.
* Marine UL Listed.*
* Momentary ratings are for five minutes continuous.
* 1 year limited warranty.

Your model is not a AFD model:
Model 2110, 2100, 2300A, 3100 and 3200 switches feature an alternator field disconnect which interrupts the alternator field when the switch is turned to the "off" position, thus preventing electrical surges in the armature circuit which might burn out the alternator diodes or ancillary equipment. Models 2101, 3101, 2111, and 3201 do not include this feature and should never be turned to the "off" position with the engine running.

Re: How to hook up a dual battery switch?

playyas4u said:

Also how would you use the settings, i.e. start engine with switch in batt #1 position

Click to expand...

YES

switch over to both to charge both batteries

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YES

and while sitting in water switch to battery #1 to prevent drain?

Click to expand...

YES

When would I ever need to select battery #2 on the switch?

Click to expand...

Only if battery #1 died or some other emergency starting need.

The big thing here is you have to remember to always do these things... If you don't you could be stuck with dead batteries anyways. The blue sea add-a-battery is by far the simplest solution. It looks cool too!

Re: How to hook up a dual battery switch?

Do you have any more pics of setup? Im trying to install a amp and sub/Component spks. But need some ideas!