new boat owner, how do I use the batter selector/shore power/generator?

Jaxn

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May 17, 2021
33
O'Day 272 Percy Priest
I recently purchased an O'Day 272 and I don't know what process I am supposed to follow for the electrical system. I am hoping it is relatively standard and that some of you might be able to help me get oriented.

Here are the components in play:
  1. Shore power. Seems like a standard cable. The box on the dock has 2 30A switches. I think one is for the GFCI on the dock and the other is for the cable to the boat.
  2. Diesel inboard. Westerbeke 10-two. I assume this has a generator capability in addition to being a motor. It has the Admiral instrument panel with gauges, two buttons and an on/off key. The panel has a sticker saying "charger disconnected?"
  3. Two batteries. I assume these are just like the batteries in cars/trucks.
  4. Perko battery selector. Has positions for Off, 1, All, 2. It has a warning to stop the engine before turning to Off, so I have been turning it to off after stopping the engine.
  5. Blue Sea Systems BatteryLink.. I think this is their "add a battery" kit. It appears to be hard-wired to both batteries and then plugs in via a 110 outlet in the cabin.
  6. Blue Sea Systems AC panel. It has a volt meter, dual switch for 30A Main and Reverse Polarity, and switches for battery charger, outlets, and spare.
  7. 12V panel with switches for cabin lights, running lights, 10A spare, radio, instruments, and a 3 position switch for anchor/off/running.
I am sure there are ways that I can screw all of this up fairly easily. Especially considering the instructions on the battery selector and engine panel.

My main questions are:
  1. What should be the configuration when I leave the boat. I assume I can leave shore power plugged in to charge/maintain the batteries? What should the Perko be set to? How should the AC panel switches read? Everything on the 12V should be off?
  2. When getting ready to depart, I unplug the shore power, and... what should the Perko be set to. What about the AC panel. Am I good to turn on the 12v instruments now?
  3. Once the engine is running and I am motoring out of the marina, should I change anything? What about after turning the engine off while sailing or at anchor?
  4. Do I ever touch the BatteryLink panel? Or does it just do it's thing automatically?
I guess my secondary questions are, what's the purpose of each of these things and where is my risk of messing it up?
 
Nov 26, 2012
1,653
Hunter 34 Berkeley
Not all boats are wired the same so it depends on what you have. A typical setup will have the battery charger that runs off of the A/C power wired directly to the batteries so it does not matter where you put the 1/2/both /off battery switch.
- The alternator on the engine will charge whichever battery the switch is set on or both.
- The batteries are not like in your car or, at least they are not supposed to be. They should be deep cycle batteries. Your car battery is not a deep cycle battery.
- When using the batteries it is typical to just use one (set the battery switch to 1 or 2, whichever battery you want to use) and save the other to start the engine if you are out on the hook or sailing.
- I recommend replacing the batteries if you do not know what condition they are.

There is no real danger of damaging anything but you could get stranded if you run the batteries down and cannot start the engine.
 
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Jan 1, 2006
7,040
Slickcraft 26 Sailfish
Since a lot of boat fires are caused by electrical problems I think it is good practice to turn the 12v system off while away from the boat. But there's always an exception. The bilge pump should remain on, many times wired directly to the battery with the wire protected with fuses and controlled by a float switch. That's why the pumps usually have 2 wires for positive, one for a switch on the panel for manual operation and one for the float switch.
As for the AC system the safest is disconnected from Shore Power. However, if you have refrigeration, or wish to keep A/C on (For combating moisture), or want to keep a charger on your batteries you may elect to keep shore power on.
 
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Jan 19, 2010
1,169
Catalina 34 Casco Bay
When you say generator do you mean alternator? Hard to have a generator in a small boat like the 272. On my 272, the bilge pump was not segregated on the battery switch.
 
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May 17, 2004
5,032
Beneteau Oceanis 37 Havre de Grace
Congratulations on your recent purchase! You’ve got a bit of reading to do. The Musings With Maine Sail sub forum here has a lot of resources, as well as his site Marine How To - DIY for Boaters - Marine How To. Some ideas to get you started -
The panel has a sticker saying "charger disconnected?"
Some people worry about having the battery charger active at the same time as the engine alternator. It’s not necessarily instant doom but might not be a best practice. The sticker was probably there as a reminder to the PO to turn off the AC charger before starting the engine.

Two batteries. I assume these are just like the batteries in cars/trucks
Like Mark said they shouldn’t be quite the same. The chemistry is likely the same, but car batteries are designed for providing lots of power quickly to start an engine. Boat batteries are designed to not be damaged when providing power slowly over a long period of time. If you ever need to buy replacement batteries try to buy matched sets of “deep cycle” batteries.

so I have been turning it to off after stopping the engine.
You don’t need to turn the switch off when you’re at the boat. Depending on how things are wired you may or may not ever need to turn them off. The important thing about the label is to never switch to Off while the engine is actually running. Doing that will damage the diodes in the alternator.

What should be the configuration when I leave the boat. I assume I can leave shore power plugged in to charge/maintain the batteries? What should the Perko be set to? How should the AC panel switches read? Everything on the 12V should be off?
Like Mark said that will depend on how things are wired. If you have an automatic bilge pump check whether it’s wired straight to the batteries or through the 1-2-B switch. If it’s through the switch I’d leave that to one battery or the other. If there’s no pump or it’s straight to the batteries you could leave the switch off. How to leave the AC switches depends on your battery charger. If it’s a reasonably smart charger and you’ll be away from the boat for any length of time, or if you’ve used the batteries and not already fully recharged them, then I’d leave the charger on. Otherwise you can leave it off. I’d leave all the other AC switches off when away from the boat.

Once the engine is running and I am motoring out of the marina, should I change anything? What about after turning the engine off while sailing or at anchor?
If you only have the two batteries I’d put the 1-2-b switch on either 1 or 2 when sailing and at anchor so you are guaranteed a charged battery to start the engine.
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Some people worry about having the battery charger active at the same time as the engine alternator. It’s not necessarily instant doom but might not be a best practice. The sticker was probably there as a reminder to the PO to turn off the AC charger before starting the engine.



That warning is there to protect the alternator from a load-dump (disconnecting the "load" (batteries) from the alt when running) and the resulting transient spike that can blow the diodes and damage sensitive marine electronics..
 
May 17, 2004
5,032
Beneteau Oceanis 37 Havre de Grace
That warning is there to protect the alternator from a load-dump (disconnecting the "load" (batteries) from the alt when running) and the resulting transient spike that can blow the diodes and damage sensitive marine electronics..
Could running the charger cause that kind of a load dump, or does it take physically (or via a switch) disconnecting the batteries?
 
Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
I think you should also determine how the batteries are connected to the selector switch with cables. Since you only have 2 batteries, it would be a logical assumption that one battery is wired to Post A and the other is wired to Post B. But that isn't necessarily the case. Verify that the batteries are independent. If they are wired in parallel, you would have a red cable linking the 2 positive posts on the batteries and a black cable linking the negative posts. If that is the case then the 2 batteries are functioning as a single battery with twice the capacity - that's "parallel (not twice the voltage - that would be wired in "series"). Just check that out to be sure.

I've made this recommendation before ... if you have 2 batteries that are essentially the same (size, make and age), I would wire them in parallel and connected to Post A (that would be the input post for Selector Switch position 1). I would buy a small battery for auxiliary, say a group 24 (and it would not have to be a deep cycle either). I would wire that to Post B (that would be the input post for Selector Switch position 2. I would have that battery fully charged and used to start the engine only when necessary if your House Battery Bank is depleted. It should be auxiliary - only used by necessity when the House Bank is dead.

Understand your selector switch ... it has 3 posts. Post A is the input or source from Battery Bank 1. Post B is the source from Auxiliary Battery 2. Post C is a common load post or output. When activated by switching to 1, 2 or ALL, Post C powers both your engine starter and your DC House Panel. Your engine has an alternator, probably with a built-in regulator. Like a car, it is charging your batteries while the engine is running. Which batteries are being charged is determined by the position of your selector switch. That is why the selector switch should NOT be turned to OFF when the engine is running. The electrical current would essentially run into a brick wall with no place to charge if you were to switch OFF. That is how the diodes get destroyed and you certainly don't want to do that.

Your Blue Sea BatteryLink appears to be a shore power battery charger. It converts AC current from your shore power to DC battery charging. Since there appears to be an integrated ACR (automatic charging relay) built into the charger, it would be connected to both batteries and will charge both batteries appropriately (it doesn't matter how the selector switch is positioned - it shouldn't be wired thru the switch). You will have to leave your shore power on and also the battery charger switch on when leaving the boat if you want to charge the batteries. It shouldn't hurt to do this. You can turn DC power off at the panel and at the selector switch. (The selector switch is only wired for DC power). When you leave the boat, you don't need to leave DC power on unless there is something connected thru the house panel that needs to be on. As talked about before, there may be some items wired directly to the battery (like a bilge pump auto switch) so that the DC power is available even when the selector switch is OFF and/or the DC house panel is OFF.

Usually you would disconnect shore power before starting your engine. I don't think it is critical, but it is good practice. Some of us have left the dock with the shore power plug still in at the dock ... DON'T be THAT GUY! :biggrin:

Good luck with your new boat! Don't stress over the mess-ups ... we've all been there! Read the sources mentioned ... Maine Sail's articles are the best and they will stimulate your interest in all things electrical and battery related!
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
Congratulations on your new boat. You have a lot to learn and have asked good questions. In addition to MarineHowTo, I offer this link that has a ton of material for you to read at your leisure.

Electrical Systems 101 Electrical Systems 101

Some of the links actually go to Maine Sail's site.

But before you start any of that, I suggest you invest in a good electrical boat system book. All of us were beginners at one time. None of us was born an electrician.

Charlie Wing's book is highly recommended. Look it up on Amazon.

For your own safety, before you start operating your boat, do some research and homework first.

Good luck, and luck should have nothing to do with it.
 
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Jaxn

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May 17, 2021
33
O'Day 272 Percy Priest
Wow. That is an impressive amount of help! I have a much better handle on what is going on now.

I have a lot of experience wiring low voltage, making cables, and a little electrical, but just didn't see how these pieces fit together. The wiring on this boat is not good, (multiple unterminated wires where things used to be, cable run along arbitrary paths, 12v panel only half screwed in to the wall,, etc.)

I'm going to dig in to these answers/links, buy some new batteries, and rewire the whole damn thing.

Thank you all!

In the meantime, had a great sail this afternoon with my dad. loving the boat and excited to make her better.