Two batteries or one???

brokemerc

Petty Officer 1st Class
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Nov 13, 2007
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I have a 1995 Bayliner Capri 1854 open bow fish and ski with the Mercruiser 3.0 I/O. Question is the boat came to me with two batteries which I'm about to replace, the boat has a trolling motor (original equipment) I'm thinking one of the batteries is for the trolling motor?? I'm getting rid of the trolling motor and have been researching weather or not I will still need two batteries?? Anyone know?? Also shouldn't these batteries be in some sort of battery box??
 

JB

Honorary Moderator Emeritus
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Mar 25, 2001
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45,907
Re: Two batteries or one???

If you have no troller the main reason for the second (deep cycle) battery is not there. On the other hand if you have lots of electronics, like a high power music system, that you may run with the engine off then stay with two. . . one starting and one deep cycle.
 

jtexas

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Oct 13, 2003
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8,646
Re: Two batteries or one???

re battery boxes.......not required long as they're tied down securely & not placed where something can fall on 'em.
 

drewpster

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Oct 17, 2006
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Re: Two batteries or one???

Ahhh, another of my favorite subjects. This follows JB's post.
If it were my boat I would use the second battery as a backup battery. I would use one as the primary starting battery. And I would use the other battery to power everything else while the engine is off.
That way you always have a fresh starting battery substantially reducing the risk of a dead battery when your miles from help. (less required swimming)
You can use a manual battery switch or an automatic one to pick which battery you want to use.
You may want to check your system close. It may already be setup to do this. See a 1-2-both battery switch anywhere?
 

brokemerc

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Nov 13, 2007
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233
Re: Two batteries or one???

Thanks to all for the info. Yes there is some kind of switch mounted to a charge guage where you can switch between battery 1 & 2 but I thought switching would just tell you what the charge is not totally switch boat power from one to the other???? The panel also tells you hours..
 

ted655

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Oct 21, 2003
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252
Re: Two batteries or one???

.Install a bank switch
 

brokemerc

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Nov 13, 2007
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233
Re: Two batteries or one???

The only problem I see with the two battery theory is that everything I need to operate needs to be used with the engine running, I troll and fish with the engine running and utilize the Radio, Fish finders, VHF, ect.. Now if I were to keep the trolling motor and use it then I could see switching to a deep cycle battery for that and the radio, fish finder ect. I'm thinking i'll just run off one battery and keep a second just in case, and then swap the wires if needed.. I was at advance auto and they carry a Marine Deep Cycle (500cca) which I would think would do the trick.. Any thoughts.. Thanks.
 

brokemerc

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Nov 13, 2007
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233
Re: Two batteries or one???

I'm learning more and more about this charging system I have on the boat. I have two large wires that come off my alternator and hook into this small maybe 3 inch by 3 inch blue electrical box with cooling fins,, seems this is actually an isolator.. From there the wires run to the battery guage and meter which has a switch that says battery 1 or battery 2.. I won't be using the trolling motor which I assume the battery 2 position is for, so what do you think, I could just hook up the two batteries and use battery 2 position for a back up???
 

PondTunes

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Jun 7, 2007
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387
Re: Two batteries or one???

Brokemerc: "I won't be using the trolling motor which I assume the battery 2 position is for, so what do you think, I could just hook up the two batteries and use battery 2 position for a back up???"

The small switch at the dash is probably ONLY for the meter it doesn't do any actual switching of the electrical loads from battery to battery. The way it sounds like it was set up is that only the trolling motor was connected to battery #2, it was kept charged using the isolator and everything else ran off battery #1.

The blue box should be an isolator and it will automatically keep the battery #2 charged.. All you would need to do is add a OFF-1-2-BOTH switch if there isn't one present. It would replace your master disconnect (if so equipped) and allow you to select battery #2 in the event of battery #1 being dead. All you should need to do is install the OFF-1-2-BOTH switch and connect a lead from battery #2 to position #2 on the Switch. Then leave the switch in #1 all the time, the only time you would need to switch to 2 or both is in the event of problem.

I wrote a fairly lengthy post about switches and battery setups here:
http://forums.iboats.com/showthread.php?t=228575

***EDIT*** I updated the post with a drawing that I think matches your setup..
 

brokemerc

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Nov 13, 2007
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233
Re: Two batteries or one???

Yes I'm pretty sure your correct as the switch is spring loaded to center and allows you to toggle up to check the charge on either battery 1 or 2. Any suggestions on a good place to purchase the switch you refered to? I also just pulled the fuel sending unit to allow me to drain the gas tank,, any ideas on a new gasket for the sending unit? It appears to be in pretty good shape but it's probably 12 years old and typically fuel leaks are a bad thing.... Thanks..
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Two batteries or one???

Make the gasket from gasket material available at most auto stores. As for the OFF-1-BOTH-2 switch, they are available right here on iBoats. Click the Marine Store button right under the red iBoats.com logo at the top of the page.
 
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