Isolating house and reserve batteries on Beneteau 373 - SailNet Community
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post #1 of 4 Old 05-01-2011 Thread Starter
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Isolating house and reserve batteries on Beneteau 373

I'm currently working on updating my electrical system to accommodate new Odyssey batteries. I've looked at a number of threads that talk about the challenge of isolating the house and reserve batteries, but none that are specific to the Beneteau set-up. I'm looking for help with the following questions:

1) how to "unparallel" the two red +ve switches

2) ensuring that all loads are off the reserve battery

3) using the Nav station volt meter for only monitoring the reserve (have Victron 600 monitor for the house system)

Thanks in advance for any responses and advice.
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post #2 of 4 Old 05-01-2011
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By "reserve battery", do you mean a starting battery for the diesel?

What do you mean by the "two +ve switches"? How are they wired now?

Basically, what you're trying to do isn't that hard. You think of them as two completely separate battery banks: house and "reserve". Wire them separately, with their own ON-OFF switches. Connect all charging sources (alternator, battery charger, wind, solar, onboard generator, etc.) to the house batteries.

Then, put a little voltage follower device like the Xantrex EchoCharge or the Balmar DuoCharge between the house and the "reserve" batteries. It will keep the "reserve" battery fully charged automatically.

With more details of your setup, I can be more specific.

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post #3 of 4 Old 05-02-2011
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Beneteaus are wired much differently than most other boats. Instead of a simple 1-2-B switch, they have these two strange red switches, one for each battery bank, and then a common ground switch.

In order to answer the OP questions, he'll have to do a wiring diagram of the boat (start with the factory wiring diagram, then check what is actually ON the boat) and understanding that before making any changes.

There have been a number of good threads here that include wiring diagrams for the more traditional 1-2-B switch and its variations.

There's no need to do #3. I have a Link 2000 which gives me voltage (and a whole lot more) for my two banks, as well as the old analog voltmeter for each individual bank. If you want to, just remove one of the pairs of wires if you have a two bank voltmeter.

As far as #2 is concerned, I would caution you to design a system that allows each bank to start the engine and serve the loads just in case one bank dies catastrophically. Dedicated start engine only reserve banks make little sense. You can do it with switching (multiple switches) or with a simple 1-2-B switch.

Stu Jackson, Catalina 34, 1986, M25 engine, Rocna 10 (22#), Maple Bay, BC, Canada

Last edited by Stu Jackson; 05-03-2011 at 05:02 PM.
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post #4 of 4 Old 05-06-2011
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While you'll have to trace each circuit to be sure, I do not believe they are currently parallel other than for charging purposes. That's why you have two Red + switches, one for the house, the other the engine battery. I suspect B placed isolaters in the circuit which will allow both battery banks to be charged by the same device but not allow them to accidentally drain from each other. Otherwise they're different circuits controlled by the Red + switches. Even if B did not place isolaters in the circuit you still can isolate the banks by flipping off one of the switches, typically the engine start, such as while on the hook. You just have to remember to flip it back on when it comes time to start the engine. Even if you forget to turn it back on the house bank will easily start the engine. B designs a pretty flexible system, not sure why you want to change that.
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