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Author Topic:   Single engine/ dual battery setup
Sal A posted 06-02-2005 08:03 AM ET (US)   Profile for Sal A   Send Email to Sal A  
I have read this reference article, and found it clear, concise, and very helpful:

I would like to know your thoughts on what would be best for me and my usage. I have a 190 Nantucket with a Yamaha F150, currently a single battery (Perko on /off switch in console... you can see the set up on the webpage in my profile). I would like dual batteries for safety primarily. I don't troll too long, and my electronics on the boat are limited to Garmin 188, and a VHF. I guess I'd like to have two charged batteried in the console, with a switch between them, and that I'd alternatively switch between the two batteries each time I go out; I can't think why I would use the two batteries in parallel. Would you weigh in? Thanks in advance.....


jimh posted 06-02-2005 08:15 AM ET (US)     Profile for jimh  Send Email to jimh     
The simplest approach:

--Two identical batteries
--New OFF-1-BOTH-TWO switch

This is shown in the article with the illustration Single Engine/Dual Battery. That is how my boat is currently set up.

There are many possible modifications. I can't really describe them without making a few new diagrams to illustrate. In general, I'd say about 95-percent of all boats with a single engine and two batteries are wired as described above.

Backlash posted 06-02-2005 08:34 AM ET (US)     Profile for Backlash  Send Email to Backlash     

I have a single engine dual battery setup on my boat contolled by a Guest (OFF-1-BOTH-2) SmartSwitch. When crusing, I typically alternated between batteries, so one battery is always fully charged. I do not use one battery for starting and one for the electronics. I also have 2 identical combination starting/deep cycle batteries.

I also have a Guest 2-bank battery charger wired into the shore power as well as to a Marinco #150BBI Onboard Charger Inlet mounted in the splash well. A standard extension cord is plugged into this to charge the batteries when the boat is sitting on the trailer at home.

This setup has worked well for the past 12 years.


Sal A posted 06-03-2005 08:42 AM ET (US)     Profile for Sal A  Send Email to Sal A     
Thank you.
Liteamorn posted 06-04-2005 08:23 AM ET (US)     Profile for Liteamorn  Send Email to Liteamorn     
Always run one battery at a time. If you have one bad battery it will kill the second. The only time you should use the "both" setting on the switch is a last ditch effort to start the engine, which will probably be futile anyway because if you managed to drain two batteries that engine isn't going to start anway.
andygere posted 06-04-2005 02:08 PM ET (US)     Profile for andygere  Send Email to andygere     
Better solution: Install a battery switch cluster that has a built in voltage sensing relay (VSR). When you start up your boat, put the start and house switches to the *on* position. Now, go boating, and forget about fussing with the battery switch for the rest of the day. When the alternator on your motor develops 13.7 volts, the relay closes, and both batteries are charged. When you stop the motor, and the voltage drops below 12.7 volts, the relay opens, and the house battery and start battery are automatically isolated. Go ahead and run your house loads all day, and the start battery is never drained, and you don't have to remember to fuss with the switch every time you stop and start the boat. If your start battery does somehow get weak, you can parallel the batteries simply by turning the parallel switch to *on*, effectively jump starting the start battery with the house battery. I installed this system in my Outrage 22 Cuddy this winter, and have been very pleased with the construction and performance of this device.

Eddie Mucciolo posted 06-04-2005 05:26 PM ET (US)     Profile for Eddie Mucciolo  Send Email to Eddie Mucciolo     
Good stuff Andy. Thank you!
jimh posted 06-05-2005 12:28 PM ET (US)     Profile for jimh  Send Email to jimh     
The system described by Andy, and using the components manufactured by BEP, is a good design. Were I about to re-wire my boat and buy all new switch gear, I would probably install something like that--maybe exactly that. And having done that, then I would buy new batteries--one a staring battery and one a deep-cycle.

But, like the traveler in Robert Frost's poem, that is a road untaken. I left it for another day. Maybe in a couple of years when I need new batteries and have everything else working to perfection.

Sal--Some outboard motors have dual charging outputs that are isolated. If your Yamaha F150 has this, you could connect both batteries to the engine for charging. Check with your Yamaha dealer to see if that is available.

jimh posted 07-17-2005 06:00 PM ET (US)     Profile for jimh  Send Email to jimh     
[Moved from another area.]
dcritch posted 07-23-2005 12:02 PM ET (US)     Profile for dcritch  Send Email to dcritch     
Are there any issues to be aware of when switching from one battery to the other when my 90 optimax is running. In reading the various posts and reading my optimax manual I,ve decided to add another interstate cranking battery identical to the one that came with the boat. This is to facilitate the use of electric down riggers and always have a back up battery. I don't always pull the boat out at the end of the day (keep it on a buoy)so I need to recharge underway. I havn,t decided how to manage the batteries yet but was concerened about any problems related to switching from one to the other or to "both" while under power.

JOHN W MAYO posted 07-23-2005 11:14 PM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
Do not the unit to OFF when the motor is running.
Stop by where they sell them and you can read a good page or two about instalation, how to operate, and what not to do.

Good units, I have a Perko and it does fine.

I have only run it in Both when I had an two old week batteries to start it, and a couple of time to start the engine when a retifier went bad.

jimh posted 07-23-2005 11:36 PM ET (US)     Profile for jimh  Send Email to jimh     
Most of the OFF-1-BOTH-2 switches are built to be make-before-break type switches. If that is true of your switch, as long as you don't move through the OFF position you should be fine operating the switch while the engine is running. Well, fine unless one of the batteries is really a dead short or close to it. That said, I actually do try to avoid having to move the switch while the engine is running, just in case....
dcritch posted 07-24-2005 11:51 AM ET (US)     Profile for dcritch  Send Email to dcritch     
John and jimh

Thanks for the advice. I did go on line to download operating insructions and my switch does have "make before break" feature. I think I'll put my current yr old battery in another boat and buy two new ones for my 170.


JOHN W MAYO posted 07-30-2005 12:18 PM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
New Batteries are cheap for what great problems you can have if they do not work if you have the extra cash for them. I also carry a jumper battery as back up for the back up battery.

Normally I use one battery about 1/2 the trip, the switch to the other.

Perko makes 2 types of switches, The cheaper one does fine and is what I have. You do not have to do extra wireing as with the more expensive one.

kimbajmann posted 11-24-2008 11:15 AM ET (US)     Profile for kimbajmann  Send Email to kimbajmann     
Ok, does it matter if I do one starter and one deep cycle or do they both need to be matching? I got a starter battery from a local place and was wondering if I should just grab another matching one or return this for two deep cycle batteries.

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