Dual Battery Connection

[tholmes3]

Re: Dual Battery Connection

Right, so if you have two batteries connected in parallel and they are fully charged when you depart, you should have ample power to run 2 boats off your system set up for 1. It seems that would just insure you more time. But, as you have said, if you simply have an extra battery on hand, then you can connect it via jumper cables or do a swap on the water. The only think that worries me is if you have a spare battery just sitting, it will go bad, and keeping it fully charged is one thing, but it is better for these batteries to be used some and then charged back up to capactiy. Regardless, having an extra battery will not hurt, its all in how you connect it.

 

[JRJ]

Re: Dual Battery Connection

A loose extra battery and jumper cables just isn't the way to go if you have room for a perminent mount and a switch.

 

[Boatin Bob]

Re: Dual Battery Connection

Thomas..if you are going the 2 battery parallel route with no switch, isolator or combiner then you really should use 2 of the same batteries, same size and age as they will constantly try to equalize each other so if one cell were to go a little bad the bad battery will always pull from the good one to try and equalize possibly killing both batteries. The way you want to do it theoretically works great in a perfect world but do any of us live in one?

 

[tholmes3]

Re: Dual Battery Connection

I think I have decided on an Isolator/conbiner switch. But I am confused as to exactly how to connect it. Is the following correct?<br /><br />+ from bat 1 to connection for bat 1 on switch<br />+ from bat 2 to connection for bat 1 on switch<br />+ from bat 1 and + from bat 2 to connection for both on switch<br /><br />Then where do the leads from the boat connect? to the switch or to one of the batteries? I have heard of not using the negative (ground) lead, but this does not make sense. It would seem that I would connect the - terminals of the batteries together?<br /><br />Also, how would I connect my maintainer/charger? Do I need two?

 

[Boatin Bob]

Re: Dual Battery Connection

Not trying to confuse you more but have a look at this link as it shows the basic wiring for a few different scenario's, there is a link at the bottom of page 1 to take you to page 2. Battery Schematics

 

[JRJ]

Re: Dual Battery Connection

Good job Boatin Bob, even I could follow it

 

[tholmes3]

Re: Dual Battery Connection

That did help. I am doing the setup with two batteries and a selector switch. But, how do I install the battery maintainer/charger? From the looks of it, I would set the switch to off while the boat is sitting and have two maintainers. But, how could I wire it to have only one charger/maintainer?

 

[Reel Poor]

Re: Dual Battery Connection

The batteries in my tracker are connected in paralell and charged through an isolator. Then I installed a Marine Priority Start on my starting battery. No switches to contend with. Works great. With this set-up I get dual battery power untill the priority start sences a voltage drop at my starting battery.

 

[cuzner]

Re: Dual Battery Connection

Hey Tommy, confused yet? Its a lot simpler than it sounds. I would suggest with the equiptment you already have plus a battery switch (isolater) follow the instructions with the switch to instal ( make sure you proper guage wire to do this!!!!), and with your ( I'm assuming its a 1 bank charger)charger you can either use it to charge one battery only, or wire it the way had planed, and leave battery switch in "both" position to charge.<br /><br /> Jim

 

[tholmes3]

Re: Dual Battery Connection

I have the Blue Seas 9001e switch. I believe one is supposed to connect the positive terminal of bat 1 to connection 1 and the positive terminal of bat 2 to connection 2; next one is supposed to connect the positive lead from the boat to the "common" connection. What I do not understand is what to do with the negative lead from the boat and the negative terminals of both batteries (ground both of the batteries to each other and the negative lead?)...?<br /><br />Also, as for the charger/maintainer, could I connect the positive to the "common" connection and the negative to one of the batteries and then set the switch on Both, so both batteries are charges by the maintainer?

 

[Reel Poor]

Re: Dual Battery Connection

Each battery should have an individual ground lead that terminates on the engine block.<br /><br />I cant answer question about that particular switch. Switches are made different. Some are designed to be charged through, even in the off position, others have different configurations. <br /><br />The ground lead from the charger should terminate on a ground buss and not at the battery. If the wiring is done properly the only thing that will be connected to the batteries will be the large battry cables, positive terminals to your switch and negitive leads to the enging block. Every thing else connects to the switch (or a fused power buss) or a ground buss.

 

[tholmes3]

Re: Dual Battery Connection

This is the link to the instructions for the switch. I have the 9001e.<br /><br /> https://myeporia.eporia.com/resources/company_57/6900.pdf <br /><br />Ok. So as for the ground buss, I would connect the negative lead fromt he engine to that, correct, and how do I go about setting that up?<br /><br />For each battery having a ground lead terminating a the engine block, how do I do that? Going through the hull will be quite difficult. I can't just connect the negative terminals together and then to the negativer terminal lead from the boat?

 

[Reel Poor]

Re: Dual Battery Connection

It looks like a pretty simple diagram.<br />

<br /><br />The engine block itself can be your ground buss (named in the drawing as "Negative Ground Buss").<br />Another note, the positive terminal on your starter can replace the positive buss shown in the drawing. In other words, you dont need an "actuall buss bar" as pictured in the drawing.<br /><br />

origionally posted by Thomas Holmes<br /><br />I can't just connect the negative terminals together and then to the negativer terminal lead from the boat?

You can do it that way, but the most benefit from dual batteries will come from terminating each battery negative lead to the engine block.<br /><br />I hope this helps.

 

[tholmes3]

Re: Dual Battery Connection

Remember I have the 9001e. So, essentially I connect the positive terminals of the batteries to the switch, then the positive lead from the BOAT to the common?<br /><br />As for the negative terminals from teh batteries, I should try to run them to the engine. But what about the loose cable in the battery bay that is black (negative) and comes from the boat?<br /><br />Also, what will change if i simply connect the negative terminals of the batteries both to that negative lead from the boat? Will it prohibit the use of the switch? Will it harm the batteries?<br /><br />This is how i see hooking it up in my situation:<br /><br />+ terminal lead from the boat (that was connected to the one and only battery in the old set up) connects to the "common" connection.<br /><br />+ terminal from bat 1 connects to connection 1<br />+ terminal from bat 2 connects to connection 2<br /><br />-terminal from bat 1 and 2 connect to the terminal lead from the boat (that was connected to the one and only batter in the old set up).<br /><br />Now, as for the charger/maintainer (it seems we keep forgetting it!) What should I do?<br /><br />I see my options as being one of the following:<br /><br />1) connect a charger/maintainer to each battery with the switch in the OFF position.<br /><br />2) Connect the positive terminal of the charger/maintainer to the "common" connection and the negative from the charger/maintainer with the cluster of negative terminal leads from the batteries and the terminal lead from the boat?<br />-This seems plausible since the alternator is set to charge both batteries thorough the "common" connection when the switch is set to both... Is this correct?<br /><br />I have edited the diagram to show how i have it in mind, but how do I add pictures?

 

[imported_Curmudgeon]

Re: Dual Battery Connection

Take it to a professional before it gets really, really expensive.

 

[Reel Poor]

Re: Dual Battery Connection

Originally posted by Thomas Holmes:<br /> Remember I have the 9001e. So, essentially I connect the positive terminals of the batteries to the switch, then the positive lead from the BOAT to the common?<br /><br />As for the negative terminals from teh batteries, I should try to run them to the engine. But what about the loose cable in the battery bay that is black (negative) and comes from the boat?<br /><br />Also, what will change if i simply connect the negative terminals of the batteries both to that negative lead from the boat? Will it prohibit the use of the switch? Will it harm the batteries?<br /><br />This is how i see hooking it up in my situation:<br /><br />+ terminal lead from the boat (that was connected to the one and only battery in the old set up) connects to the "common" connection.<br /><br />+ terminal from bat 1 connects to connection 1<br />+ terminal from bat 2 connects to connection 2<br /><br />-terminal from bat 1 and 2 connect to the terminal lead from the boat (that was connected to the one and only batter in the old set up). <br /><br />Correct<br /><br /> Now, as for the charger/maintainer (it seems we keep forgetting it!) What should I do?<br /><br />I see my options as being one of the following:<br /><br />1) connect a charger/maintainer to each battery with the switch in the OFF position.<br /><br />2) Connect the positive terminal of the charger/maintainer to the "common" connection and the negative from the charger/maintainer with the cluster of negative terminal leads from the batteries and the terminal lead from the boat?<br />-This seems plausible since the alternator is set to charge both batteries thorough the "common" connection when the switch is set to both... Is this correct? <br /><br />Either will work. Although it is not ideal. The problem with this setup is that the charger/maintainer tries to charge both batteries at the same rate,(unless its a dual bank charger) even if one of the batteries is in a full state of charge. Possiable premature battery failure could occur due to over charging fully charged battery or under charging low battery.<br /><br />I have edited the diagram to show how i have it in mind, but how do I add pictures?

Let us know how it goes, or if you still have questions.

 

[tholmes3]

Re: Dual Battery Connection

So, connecting both batteries' negative terminals to the negative terminal lead from the boat will not cause any problems? What could potentially happen?<br /><br />And as for the charger, what would you suggest?<br /><br />Tommy

 

[Reel Poor]

Re: Dual Battery Connection

If by "negative terminal lead from the boat" you mean the ground cable that terminates at the engine, you are correct.<br /><br />As for the charger something like this, or equivilant, as long as it is designed for charging/maintaining two batteries. <br /><br />Battery Charger

 

[tholmes3]

Re: Dual Battery Connection

I already own 2, 2amp chargers, would it be fine to connect one to each battery. I would assume to set the switch to off. is this correct?

 

[Reel Poor]

Re: Dual Battery Connection

That would be correct.<br /><br />Keep in mind that a dead 80 amp hour battery would take 40 hours to recharge with that charger.