Battery selector switch on O'Day 27

[lisap]

Hi folks,

I'm the proud new owner of a 1978 O'Day 27. I'm hoping to add a second battery to the boat soon but I'm struggling to understand how to connect it.

Currently the battery selector has the three posts wired as follows:

Post 1 (immediately behind #1 on the switch) - to the single battery
Post 2 (immediately behind #2 on the switch) - to the starter
Post 3 (immediately behind both on the switch) - has 3 small wires, I'm assuming alternator, circuit breaker panel and ??. They disappear into the hull and I haven't figured out where they go yet.

The diagrams I've seen imply that the new battery should be on #2 and everything else (starter, circuit breaker, alternator) should go on the 3rd post. Things currently seem to work fine and everything turns on when the switch is on #1 so I'm nervous about rearranging the wiring without understanding how it works.

Thanks,

Lisa

 

[lisap]

I forgot to mention. This boat has the Yanmar 8HP diesel engine.

Lisa

 

[Panta Rei]

Hi folks,

I'm the proud new owner of a 1978 O'Day 27. I'm hoping to add a second battery to the boat soon but I'm struggling to understand how to connect it.

Currently the battery selector has the three posts wired as follows:

Post 1 (immediately behind #1 on the switch) - to the single battery
Post 2 (immediately behind #2 on the switch) - to the starter
Post 3 (immediately behind both on the switch) - has 3 small wires, I'm assuming alternator, circuit breaker panel and ??. They disappear into the hull and I haven't figured out where they go yet.

The diagrams I've seen imply that the new battery should be on #2 and everything else (starter, circuit breaker, alternator) should go on the 3rd post. Things currently seem to work fine and everything turns on when the switch is on #1 so I'm nervous about rearranging the wiring without understanding how it works.

Thanks,

Lisa

First off:
What are you hoping to accomplish?
Add a second battery to you first battery to get more cranking power?
Add a second battery so you can use the new battery for house loads saving the original battery for starting the engine?
or other (please explain)

Are you having trouble starting the engine?

 

[jibes138]

do a search on battery selector switch connections and you will get a wiring diagram. I just posted one a week ago for another boater. Very simple, nothing to be afraid of. You should have a "c" terminal that things connect to, so when on Bat 1 it sends power to C, when on Bat 2 it send power to C, when on Both it sends power to C. C should feed the panel positive bus, and the starting circuit. Good luck.

 

[SEMIJim]

Hi folks,

I'm the proud new owner of a 1978 O'Day 27. I'm hoping to add a second battery to the boat soon but I'm struggling to understand how to connect it.

Currently the battery selector has the three posts wired as follows:

Post 1 (immediately behind #1 on the switch) - to the single battery
Post 2 (immediately behind #2 on the switch) - to the starter
Post 3 (immediately behind both on the switch) - has 3 small wires, I'm assuming alternator, circuit breaker panel and ??.

This does not make sense, unless it's a single-circuit switch (has only two positions: ON and OFF) and the 3rd post is the alternator field disconnect (AFD) connection, but I don't get why that would have three wires on it--unless they used the AFD connection for the house wiring connection, too. (I'll explain AFD below.)

So my first question is an easy one: How many positions does your battery switch have? Perhaps you could post a picture of the connections you're describing, above?

They disappear into the hull and I haven't figured out where they go yet.

Obviously you're going to have to figure that out

The diagrams I've seen imply that the new battery should be on #2 and everything else (starter, circuit breaker, alternator) should go on the 3rd post.

A traditional two-battery system has one switch with four positions: OFF, 1, BOTH, 2. Essentially the user determines how the batteries are used. As often as not, they just get switched to BOTH and left there. (This is a bad practice, as you can have a dying battery and not know it.) One battery hooks to one large post, for the "1" position; the other battery to the large "2" position post, and the starter and everything else to the large "C" (common) post. Whichever battery/batteries you select runs everything. Switch may or may not have a smaller alternator field disconnect (AFD) connection.

Things currently seem to work fine and everything turns on when the switch is on #1 so I'm nervous about rearranging the wiring without understanding how it works.

Good thinking

Let's start with figuring out what you have. Next we find out how you'll be using the boat and what your budget is for this project. Then we can come up with some suggestions.

Now, the AFD: Most alternators cannot tolerate having the battery removed from the system while they're running. If that happens, the regulator "thinks" the battery level is really, really low and needs lots and lots of charging voltage. So if somebody accidentally switches off the battery while the engine is running, the regulator sends the alternator's output voltage to the heavens and things fry. Usually "just" the alternator itself. (But anything connected to the alternator can also go.) So some battery switches have an alternator field disconnect function that, if connected properly, essentially shuts down the alternator output if the switch is turned off.

I suppose you could use the AFD connection to power other things, but I suspect that part of the switch is not designed for very much load, so I don't know as that's a wise idea.

Jim

 

[Stu Jackson]

Lisa, be careful about those posts and assuming that they are behind the switch positions on the face of the switch. http://c34.org/bbs/index.php/topic,6911.0.html

You can find out what they do by turning the switch to a position and removing either the wire behind the switch or from the battery to see whether or not things turn off - turn your interior lights on and do that.

West Marine Advisors have a very good section on electrical issues: http://www.westmarine.com/webapp/wc...51&catalogId=10001&page=West-Advisor-Articles One of them includes "Adding a Second Battery" - just scroll down to electrical.

I'd forget about the AFDs mentioned earlier, most boat switches do NOT have them and it is confusing the issue. For figuring out how to wire your boat and alternator output, try the reading the links in that article from our C34 Forum.

Good luck.

 

[lisap]

Hi all,

Thanks for the help. I think Stu got it. The posts don't match front to back and they aren't labelled. I brought my multimeter and figured out what was what. The post behind #2 is really the "C " post.

I'll check out all the great links.

Lisa

Lisa, be careful about those posts and assuming that they are behind the switch positions on the face of the switch. http://c34.org/bbs/index.php/topic,6911.0.html

You can find out what they do by turning the switch to a position and removing either the wire behind the switch or from the battery to see whether or not things turn off - turn your interior lights on and do that.

West Marine Advisors have a very good section on electrical issues: http://www.westmarine.com/webapp/wc...51&catalogId=10001&page=West-Advisor-Articles One of them includes "Adding a Second Battery" - just scroll down to electrical.

I'd forget about the AFDs mentioned earlier, most boat switches do NOT have them and it is confusing the issue. For figuring out how to wire your boat and alternator output, try the reading the links in that article from our C34 Forum.

Good luck.