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Batteries and Switch Selectors

AlanO

Member II
The User's Manual on our recently purchased 1988 Ericson 38 consisted of a laminated 3x5 card (engine start-up procedure). Needless to say there is a lot to figure out and hopefully some of the old salts on the forum can help.

I'm trying to figure out the appropriate way to set the battery switch selectors under different circumstances. The User's manual says set the battery Switch to 1, then start the engine. Great! That works. Now what? While I have some experience with DC electronics (Ham radio operator), I'm not an expert by any means.

A little background. The boat is set up with two 8D house batteries, one in the V-berth and one in the starboard cockpit locker. The starter battery is in the settee adjacent to the Nav station. There are two switches adjacent to the starter battery: one (Switch 2) for the house batteries with On/Off and a second switch (Switch 1) with Off/1/All/2 selectors. In the photo below the left is Switch 2 and the right is Switch 1. The positive (red) cable going to Switch 1 with a label is identified as being from the alternator. There are no labels on any other wires in the photo. I have a crude wiring diagram, but I haven't got it cleaned up yet. Hopefully folks may have some insights without the diagram. I'm hoping there is nothing unusual with how this was wired.

I'm guessing that the terminal that the alternator cable goes to is the "source" terminal, while the other two are the switched terminals. In addition to the alternator cable, the other positive cable on that terminal is from the Starter battery. The positive cable attached to middle terminal on Switch 1, as well as one of the black cable to the ground bus, head through the floor boards, so I believe these go to the starter. As you can tell from the photo one of the positive cables on the right terminal goes to the house battery switch, while the other one goes to the charge regulator for the starter battery.

The User Guide says select Battery 1 (Starter battery) for starting the engine. As indicated above, yes that starts the engine, but there is nothing about what to select under any other circumstances or when the engine is turned off. So here are my questions:

1) Presumably selecting Battery 1 on Switch 1 makes sure the starter is just using the starter battery. I'm I correct that I should never select All or Battery 2 unless there is a failure in the starter battery, in which case I could use Battery 2 (the House bank) for a start?
2) When the engine is running, I should never Select Off for Switch 1 because the juice from the alternator would have nowhere to go?
3) When the engine is running, can I select either Battery 1, Battery 2, or All depending on what batteries I want to charge off the alternator? If so, I'm thinking All should be the typical choice.
4) When the engine is off while cruising, should I select Battery 2 (House batteries) on Switch 1, so that there is no risk of drawing power off the starter battery?
5) When the boat's on shore power should I select All on Switch 1 to make sure both the House batteries and Starter battery are being charged? This is what I have been doing so far.
6) Is there any reason to Select Off for Switch 2 (House batteries), except perhaps for doing some testing/rewiring in the DC power panel (cabin lights, etc.) or elsewhere on the boat (i.e., de-energize the DC system)?
7) Any cautionary advice (e.g., don't do this or you might fry that)?

I know this just scratches the surface on understanding the electrical system on our boat, but it seems like a good place to start.

Thanks.

Alan

Battery and Switches.jpg
 

goldenstate

Sustaining Member
Blogs Author
Without following the wires on your individual boat it is difficult to offer reliable advice on your situation. Most of your conclusions seem to make sense. It also looks like you have a battery isolator in your compartment shown. CompassMarine/Maine Sail has a good discussion of the 1-2-both switch and Pacific Yacht Systems on YouTube addresses a lot of these issues.

If you want to grow in confidence try to make a wiring diagram showing how all the components fit together. That will be of value to you and future owners.

$.02,

Tom
 

bigd14

Contributing Partner
Blogs Author
That looks like a Blue Seas ACR (Automatic Charging Relay) which would in theory charge a second battery if the first is being charged by the alternator and battery charger. The question is which battery comes first. You definitely need to map it out to determine appropriate switch settings. It looks neatly done which should give some confidence that the entire system has been well designed. Good luck sorting it all out.
 

AlanO

Member II
Without following the wires on your individual boat it is difficult to offer reliable advice on your situation. Most of your conclusions seem to make sense. It also looks like you have a battery isolator in your compartment shown. CompassMarine/Maine Sail has a good discussion of the 1-2-both switch and Pacific Yacht Systems on YouTube addresses a lot of these issues.

If you want to grow in confidence try to make a wiring diagram showing how all the components fit together. That will be of value to you and future owners.

$.02,

Tom
Thanks Tom. I agree with preparation of a wiring diagram (here and for the whole boat). As mentioned in the post, I have started a diagram of what is in the photo, but I need to clean it up to make sense to anyone else. I think the equipment you are referring to is the Blue Sea SI-ACR, which I just looked up. It is an Automatic Charging Relay and isolator, so you are correct. I'll have to investigate more about what it does. Thanks for the tips on the You Tube videos. I will check them out.
 

Kenneth K

1985 32-3, Puget Sound
Blogs Author
1) Presumably selecting Battery 1 on Switch 1 makes sure the starter is just using the starter battery. I'm I correct that I should never select All or Battery 2 unless there is a failure in the starter battery, in which case I could use Battery 2 (the House bank) for a start?
2) When the engine is running, I should never Select Off for Switch 1 because the juice from the alternator would have nowhere to go?
3) When the engine is running, can I select either Battery 1, Battery 2, or All depending on what batteries I want to charge off the alternator? If so, I'm thinking All should be the typical choice.
4) When the engine is off while cruising, should I select Battery 2 (House batteries) on Switch 1, so that there is no risk of drawing power off the starter battery?
5) When the boat's on shore power should I select All on Switch 1 to make sure both the House batteries and Starter battery are being charged? This is what I have been doing so far.
6) Is there any reason to Select Off for Switch 2 (House batteries), except perhaps for doing some testing/rewiring in the DC power panel (cabin lights, etc.) or elsewhere on the boat (i.e., de-energize the DC system)?
7) Any cautionary advice (e.g., don't do this or you might fry that)?

As goldenstate said, "without following the wires on your individual boat it is difficult to offer reliable advice on your situation."

The biggest cautionary advice is what you asked in question (2), Never set your switches so the alternator current has nowhere to go--this will fry your alternator. It sounds like keeping Switch 1 out of OFF accomplishes this, but this is something you should verify. With no sources of charging on your boat*, and all battery switches off, put a voltmeter between the output lug of the alternator and any ground on the engine block. If you read battery voltage at the alternator output lug with all battery switches OFF, then your alternator is hotwired to a battery bank (this is not very common, but it is sometimes done when users install an ACR). If you don't read voltage, start flipping your battery switches until you do. Any switch position that gives you a voltage reading at the alternator lug means you have a created a circuit between the alternator and a battery and thus, this configuration won't fry a running alternator.

*with any charging source on the boat (solar, shore charger, alternator, etc) the ACR will close and both banks will be paralleled through the ACR which can give you different results.​
Since someone installed an ACR, and your instructions guide you no further then selecting Batt 1 for start, one simple possibility is that
(1) this selection routes alternator current to Batt 1, charges Batt 1, and doesn't fry the alternator,
(2) sensing the charge on Batt 1, the ACR automatically parallels Batt 1 to the House bank (to charge it, too), so,
(3) it doesn't matter what you do with the house bank switch during charging.

In this case, the ACR handles the house bank for you during charging, and you really only need to use the Batt 2 switch when choosing to draw power from it. Again, all this can be verified with a voltmeter on each battery/bank under various configuration of charging and switch positions.

1) Presumably selecting Battery 1 on Switch 1 makes sure the starter is just using the starter battery. I'm I correct that I should never select All or Battery 2 unless there is a failure in the starter battery, in which case I could use Battery 2 (the House bank) for a start?

Once you have your system figured out, use whatever bank you want to start your engine. It doesn't matter whether the batteries types are automotive (a typical start battery) or marine deep cycle (typical house batteries), either will start the engine just fine. However, if you're running sensitive marine electronics during the engine start, you should not start off of the same bank that is powering the electronics. The voltage drop/surge can hurt the electronics. There is really no reason to start in ALL. If one bank is more charged than the other, the stronger bank will just be providing current to both the weaker bank and the starter motor simultaneously.

3) When the engine is running, can I select either Battery 1, Battery 2, or All depending on what batteries I want to charge off the alternator? If so, I'm thinking All should be the typical choice.

That is the way I do it, but I don't have an ACR. The purpose of an ACR is to parallel the banks (same as selecting ALL) any time a charge is present. If this is how your ACR is hooked up, it doesn't matter what you select for Batt 2, the alternator will be charging both banks through the ACR.

4) When the engine is off while cruising, should I select Battery 2 (House batteries) on Switch 1, so that there is no risk of drawing power off the starter battery?

That is what most people do--consume house power and keep the start battery isolated so you can still start the engine even if you deplete the house bank. Just check the positions of your multiple battery switches to verify they are doing what you think they are doing. Check the battery voltages during switch changes until you've verified how it's all connected. Remember, in a discharge situation, the ACR is just sitting there doing nothing--it gives full control of your battery switches back to you.

5) When the boat's on shore power should I select All on Switch 1 to make sure both the House batteries and Starter battery are being charged? This is what I have been doing so far.

Most shore chargers are multi-bank, and are thus, wired individually and directly to each battery bank. This usually means that NO battery switch is required to be ON for shore charging. Or, your shore charger may be wired to only one bank, in which case the ACR would combine it to the second bank once charging is detected. How your shore charger is wired to the banks and whether this requires various positions of the battery switches is something you'll have to verify.

6) Is there any reason to Select Off for Switch 2 (House batteries), except perhaps for doing some testing/rewiring in the DC power panel (cabin lights, etc.) or elsewhere on the boat (i.e., de-energize the DC system)?

Yes. Most of us refer to the original collection of wires behind the main electrical panel as a Rat's Nest. Unless your panel has been rewired, or had all the connections checked, the panel itself can be considered at least a mild-to-moderate hazard. My entire ground bus bar was only glued to the panel and nearly came loose while I was working in there. Since I haven't re-done my main panel yet, I take the mirror-image view, and choose to keep the panel depowered unless I specifically need it for something. I wouldn't be comfortable leaving my boat with the main panel powered. Others who have rewired their panels report leaving it on 24/7 to run refrigeration, gadgets, etc. Also, if you have automatic bilge pumps, verify what they are wired to so you can manage your system to ensure they are always powered.

20200430_184545.jpg Rat's Nest

One final thing to check: You said you had a house battery in the v-berth. This would sound unlikely (because of the long wire runs) unless you have a windlass. If you do have a windlass, it sounds like it's wired to the House bank, but again, you'll have to verify what switch selections are required to power it.
 
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AlanO

Member II
Ken, thanks for the detailed responses to my questions and tips for tests I can do to sort things out. The boat may have had a powered windlass once upon a time, but the current windlass is manual. There are some filled holes in the deck that leads me to believe the current windlass is not the first. The 8D battery in the V-berth is definitely one of house batteries and yes it's a long cable run. The survey when the boat was purchased did not identify that as a potential problem.

I started watching the 12 part videos from pacific yacht systems that Tom mentioned. They are very informative. One thing I learned from the first couple of videos was the utility of having both switched and unswitched ( e.g., bildge pump) sides to the DC system and on my visit to the boat yesterday I discovered everything appears to be switched. I also discovered the 12V service breaker on the panel does nothing. All of the individual device breakers work regardless of whether the service breaker is on or off. Clearly, I've got some work ahead of me. Among other things, there are quite a few legacy wires on the boat from previous repairs or upgrades that I need to remove or make sure they are properly terminated. I'm won't be surprised at a rats nest of wires behind the panel.

Alan
 

Kenneth K

1985 32-3, Puget Sound
Blogs Author
Glad to help. One thing that may simplify understanding of the "stock" Ericson setup is this: The output post ("C" terminal) of the OFF/ALL/1/2 switch only directly powers 2 things: 1) the power lug on the starter, and 2) the DC circuit breaker panel. This is why it is sometimes funny when people argue excessively over a "start" vs "house" battery. With the "stock" setup, you can only ever power both the starter lug and the House DC panel simultaneously, regardless of which bank you have selected on your BATT switch.

The power lug on the starter also typically powers the engine panel and accepts charging from the alternator. I.E., the alternator always sends power to the starter lug--which bank this is gets distributed to depends on the setting of the OFF/ALL/1/2 switch. And, if you still have an ammeter in your engine panel, you have on "old" original charging circuit most people choose to replace.

The rest of the boat is powered from the DC breaker panel.

That's the stock Ericson setup. Always hard to say once people start changing things. You have a second BATT switch, an ACR and, likely, had an electric windlass at one time. You'll have to do that sleuthing yourself to figure out what changes previous owners made along the way.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Whether our boat's 1988 wiring was "stock Ericson" or might've reflected the wishes of the original buyer, our panel did indeed control all of the DC distribution. Our panel had and still has a "bilge pump" breaker that powers two separate Jabsco pumps, each with own pickup and float switch. One 'standard' bilge panel mounted on the main surface adjacent to the main breaker panel, and the other bilge pump control panel mounted in the head to reassure someone showering there that the shower drain water was being pumped overboard. Actually that water just flowed into an aft bilge section with the associated pickup and float switch.
It was/is great having two functioning auto-switched bilge pumps, albeit each with a 3/4" discharge hose. As Christian points out, these are still really only going to remove incidental water. But, allied with the large cockpit manual pump, should give the second crew person (if there is one...) a fighting chance to stem the unexpected leak.

I do like the safety of having all (except a couple of small sensing circuits) of our DC power capable of being shut off instantly in case of a wiring short or other sort of fire on board.
 
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Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
I did all the usual owner work and thought through the many complications of the DC/AC and charging systems.

But the best thing I did, when finished, was to have a boat electrician come around and explain to me what I did, and why, and confirm everything, and reverse a few mistakes.

Everything depends on how the boat is wired and fused, and I am not particularly good, on my own, at seeing both the forest and the trees.
 

Bolo

Contributing Partner
AlanO, My E32-3 has two battery switches that control the distribution of a starter battery (with it’s own charger located under the Nav station seat) and two larger “house” batteries below the salon seat just forward of the Nav station. These two batteries also have their own charger. Depending on how the switches are set I can start the engine using any one of the three batteries or all three. Sound familiar? Well, a previous owner set this all up and fortunately left a chart showing how the batteries are connectEd and how to set the switches dependent on what you want to do.

Not saying that my boat is setup the same as yours but it might give you more of an idea as to how it’s wired. Unfortunately I’m no where near my boat as of the writing but planning on being their this Saturday when I can photograph the diagram and post it here. In the meantime, I’d suggest what Christian did, maybe find a good boat tech who knows his (or her) way around boat wiring to look over your setup to not only explain what’s happening but to check what’s been done.

The one advantage to the two switch system on my boat is that when I anchor I turn off the starter battery so that I’m only drawing power from the house batteries. If those batteries are weak and near the end of their life then your boat’s electrical system will draw from the starter battery too (if it’s turned on) and weaken it to the point where you can’t start the engine. I learned that the hard way and had to call Boat US for a battery jump! BTW, It was not covered on my insurance policy although towing is so I should of just had the boat towed back to my marina, which wasn’t that far away, and simply plugged it back in. Unfortunately the Boat US guy told me about the $50 charge (which I assumed was covered) AFTER he did his work. I wasn’t happy.
 

bsangs

E35-3 - New Jersey
The information in this thread is very illuminating. Thanks for the post Alan. Would love to rewire our entire boat, but my electrician advised against it, unless we're certain this is our "forever" boat - which at this point, we're not. At the very least I've replaced some wires, terminals, and am planning to clean up the rat's nest a little bit.
 

AlanO

Member II
Christian, thanks for the how tos. I figure the best way to understand the electrical system is to do as much as I can myself and the recommendation to have an electrician check my work is a good idea. When the weather turns here in the PNW, these inside jobs will keep me busy.
 
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