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Old 30-03-2021, 20:37   #1
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Another 1-2-Both-Off question

I have a pretty conventional setup, I believe, 1-2-Both-Off wired so alternator is disconnected on off, but bilge pump still connects to 1 (I believe, it may be 2).

Iím thinking of adding solar. Since Iím a weekender, and I want it to charge when Iím away, the solar MPPT will go directly to 1, bypassing the switch. Once I do that, I figure I might as well move the alternator as well, so as to avoid the fried diode risk. (Iíll add an ACR to charge 2).

Once I have that equipment (alternator, solar, bilge pump) all bypassing the switch, do I need an emergency override switch to disconnect everything? Maybe I missed it on all the threads in this topic, but even if it wouldnít be used in normal operations, it seems like good safety practice to have the ability to cut everything off in an emergency. Iím thinking of something like an electrical fire, or just if everything goes haywire for unexplained reasons.

Thanks.
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Old 30-03-2021, 20:40   #2
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Re: Another 1-2-Both-Off question

all 3 should be fused near the battery. you could use breakers instead to turn them off.
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Old 30-03-2021, 21:19   #3
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Re: Another 1-2-Both-Off question

I've been working on this diagram and I think it is similar to what you are after. I have it shown with a 1/2/Both and On/Off. The use modes are on the right. Most of this came from marinehowto.com I just edited the diagram.
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Old 03-05-2021, 17:21   #4
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Re: Another 1-2-Both-Off question

So what SHEAzbird posted was not what I was thinking, but my thinking has evolved. I’d like to do basically that diagram with two difference:
1. The 1-2-Both-Off switch will control the starter, not the house loads. The design is “symmetric” so I don’t think this will make a difference, I just find it more intuitive.
2. The alternator will be attached to the starter battery, and solar attached to the house battery, with a Victron Cyrix combiner.

My logic:
* I like an independent start circuit, so I don’t get transients effecting my electronics when I start.
* The start battery can be high CCA, not deep cycle, and the alternator will recharge it immediately.
* The house battery will be low CCA, deep cycle, recharged by solar.
* The risk that both batteries will die because one is not “reserve” is no worse than the risk in a conventional setup that (a) the reserve battery will die without my noticing until much later, or, (b) human error of killing the battery while on “Both”.
* I think this will help with the problem of a combiner leading to over/under charging, because each bank will have a primary charger most suited to it’s usage pattern.

Comments?

In particular, is wiring a different charge source to each bank with a combiner a relatively standard practice? I haven’t seen it recommended.
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Old 03-05-2021, 17:25   #5
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Re: Another 1-2-Both-Off question

Quote:
Originally Posted by smac999 View Post
all 3 should be fused near the battery. you could use breakers instead to turn them off.
Good point, although I canít figure out where to mount a breaker in my install. Given space considerations, and that I am attaching directly to the battery, I was thinking of using a fuse block on the battery:

https://www.bluesea.com/products/519...k_-_30_to_300A
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Old 03-05-2021, 17:44   #6
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Re: Another 1-2-Both-Off question

Quote:
Originally Posted by DanielI View Post
So what SHEAzbird posted was not what I was thinking, but my thinking has evolved. Iíd like to do basically that diagram with two difference:
1. The 1-2-Both-Off switch will control the starter, not the house loads. The design is ďsymmetricĒ so I donít think this will make a difference, I just find it more intuitive.
2. The alternator will be attached to the starter battery, and solar attached to the house battery, with a Citrix combiner.

My logic:
* I like an independent start circuit, so I donít get transients effecting my electronics when I start.
* The start battery can be high CCA, not deep cycle, and the alternator will recharge it immediately.
* The house battery will be low CCA, deep cycle, recharged by solar.
* The risk that both batteries will die because one is not ďreserveĒ is no worse than the risk in a conventional setup that (a) the reserve battery will die without my noticing until much later, or, (b) human error of killing the battery while on ďBothĒ.
* I think this will help with the problem of a combiner leading to over/under charging, because each bank will have a primary charger most suited to itís usage pattern.

Comments?

In particular, is wiring a different charge source to each bank with a combiner a relatively standard practice? I havenít seen it recommended.
Hi, on mine there are two 1-2-both switches, the common on one goes to the starter, on the other the common goes to the pos bus for all house loads. Both switches are connected to both battery banks enabling either function to be performed by either or both banks. Alternator is connected to the start bank and both banks are connected via a vsr when the engine is running. Solar is connected to both banks via a dumb PWM duo charge controller.
Has worked well for as long as I have owned the boat, however I can see an MPPT controller in my future to maximise the power harvest.
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Old 03-05-2021, 18:08   #7
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Re: Another 1-2-Both-Off question

Quote:
Originally Posted by Uncle Bob View Post
Solar is connected to both banks via a dumb PWM duo charge controller.
Just curious, which bank is the solar directly connected to? I assume it isnít directly connected to both, because then it would be bypassing the VSR.
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Old 03-05-2021, 18:30   #8
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Re: Another 1-2-Both-Off question

Oh, golly, you may consider avoiding reinventing the wheel:


OEM 1-2-B Switch Wiring History http://c34.org/bbs/index.php/topic,4....html#msg30101

1-2-B Considerations (New 2020 - Rodd finally got around to diagramming what I had done in the above link in 2009 )
https://marinehowto.com/1-2-both-bat...onsiderations/

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowner...d.php?t=137615

This is a newer primer for boat system wiring design with a thorough diagram: Building a Good Foundation (October 2016)
http://forums.sailboatowners.com/ind.../#post-1332240
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Old 03-05-2021, 20:23   #9
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Re: Another 1-2-Both-Off question

Quote:
Originally Posted by DanielI View Post
Just curious, which bank is the solar directly connected to? I assume it isnít directly connected to both, because then it would be bypassing the VSR.
Connected to both banks, the VSR is wired so it only works when engine is running.
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Old 03-05-2021, 22:07   #10
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Re: Another 1-2-Both-Off question

Stu,

Let me start by saying I have read most of those posts in the past, and I greatly appreciate the work you and others have put into educating people (including me) on these points. Perhaps I should have stated that context to begin with. That said, a few points.

1. When I first read those posts, particularly the one from Maine Sail, as a newbie, my takeaway was: donít have HOUSE & START banks, have PRIMARY & RESERVE. That was where I was when I posted originally. After watching my electronics flicker while starting, thinking about different types of batteries for different applications, and re-reading the relevant sections in Nigel Calderís book, I started coming around to HOUSE & DEDICATED START. It was only after going back to the references you post a second (or fourth) time, that I realized that none of them opposed that approach (provided proper isolation and battery selection are still supported).

Iím still not clear why this latter approach is not more widely emphasized. The technical requirements of adding one additional switch donít seem to be difficult enough to outweigh the advantages. When I wrote, ďMy logic,Ē it wasnít intended to suggest that bigger experts hadnít already realized the same things, but these were points that swayed my thinking that, again, I hadnít seen emphasized elsewhere. I posted them so if I am wrong in weighing those considerations, someone more knowledgeable can correct me.

2. It seems that most of the designs in these threads put all the charging sources on one bank. With a HOUSE & DEDICATED START, it seemed to make more sense to me to put the alternator on the START and the other sources on the HOUSE. Since, after reading your links and several others, this didnít seem to be the norm, I really wanted feedback as to whether this was not a good idea, and if so, why.

3. Possibly a trivial point, but it feels more intuitive to me to have a ďUSEĒ selector for the starter, and then a paralleling switch if the HOUSE needs to operate off the DEDICATED START (which would be a ďrealĒ emergency). Itís the mirror image wiring, just using the switches on the opposite banks. Iím not trying to convince anyone else to do it this way, just wondering if there is any reason not to do that, if it is more intuitive for me.

3. Calder makes the point that there is no ďtypicalĒ sailboat. Simply directing people to these links is not likely to answer every question, especially for someone non-expert enough to need them in the first place. Now perhaps I should have started by saying what reading I had done, and making clear that these were the questions I still had. However, if people are going to learn, they are going to need to post questions about how these principles apply to their specific installation. Even following those links, there are multiple options discussed, and asking for feedback on why one might choose one over the other is helpful to the poster and other readers.

Thanks.
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Old 03-05-2021, 22:09   #11
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Re: Another 1-2-Both-Off question

Quote:
Originally Posted by Uncle Bob View Post
Connected to both banks, the VSR is wired so it only works when engine is running.
I must be missing something. If there is a wire from the PWM controller to bank 1, and then another wire from the controller to bank 2, that would be a current path from bank 1 to bank 2. So, whether the VSR is activated or not, the batteries would be combined. So I assume that is not what you are doing.
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Old 03-05-2021, 22:38   #12
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Re: Another 1-2-Both-Off question

Quote:
Originally Posted by DanielI View Post
I must be missing something. If there is a wire from the PWM controller to bank 1, and then another wire from the controller to bank 2, that would be a current path from bank 1 to bank 2. So, whether the VSR is activated or not, the batteries would be combined. So I assume that is not what you are doing.
The controller is designed to charge two banks independently, with the ability to assign the amount of charge to whichever bank, the vsr is wired with the neg wire run through a relay that has the coil pos taken from the ignition so that the VSR only operates when the ignition is on. All automatic not requiring intervention unless required.
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Old 03-05-2021, 23:11   #13
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Re: Another 1-2-Both-Off question

Quote:
Originally Posted by Uncle Bob View Post
The controller is designed to charge two banks independently, with the ability to assign the amount of charge to whichever bank, the vsr is wired with the neg wire run through a relay that has the coil pos taken from the ignition so that the VSR only operates when the ignition is on. All automatic not requiring intervention unless required.
Got it, thanks. Iíve seen several dual PWNs, and very few dual MPPTs. Victron doesnít seem to have one, and I liked their specs otherwise, and also had this idea that NMEA 2K compatible would be a ďgood thingĒ (TM), although it seems Iíd need a rather expensive bridge that Iím not buying to actually get the data into my MFD.
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Old 06-05-2021, 15:29   #14
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Re: Another 1-2-Both-Off question

Daniel,


You're quite welcome, and glad they helped in your planning.

Two major things:

1. Those diagrams DO include options to address your starting voltage sag.

2. For years we've been trying to explain to skippers, new and old, the folly of bothering to prioritize their start banks for recharging. It makes little sense because Maine Sail shown and proved that our diesel engines, even with glow plugs, only use a few amp hours to start, which is always almost immediately replenished when the engine starts, via a relay or a switch, when the alternator kicks in. A house bank should always get priority. This is anathema to UK sailors, but is something we recommend for everyone.


Your boat, your choice.


But we DID explain it all before...







Quote:
Originally Posted by DanielI View Post
Stu,

Let me start by saying I have read most of those posts in the past, and I greatly appreciate the work you and others have put into educating people (including me) on these points. Perhaps I should have stated that context to begin with. That said, a few points.

1. When I first read those posts, particularly the one from Maine Sail, as a newbie, my takeaway was: don’t have HOUSE & START banks, have PRIMARY & RESERVE. That was where I was when I posted originally. After watching my electronics flicker while starting, thinking about different types of batteries for different applications, and re-reading the relevant sections in Nigel Calder’s book, I started coming around to HOUSE & DEDICATED START. It was only after going back to the references you post a second (or fourth) time, that I realized that none of them opposed that approach (provided proper isolation and battery selection are still supported).

I’m still not clear why this latter approach is not more widely emphasized. The technical requirements of adding one additional switch don’t seem to be difficult enough to outweigh the advantages. When I wrote, “My logic,” it wasn’t intended to suggest that bigger experts hadn’t already realized the same things, but these were points that swayed my thinking that, again, I hadn’t seen emphasized elsewhere. I posted them so if I am wrong in weighing those considerations, someone more knowledgeable can correct me.

2. It seems that most of the designs in these threads put all the charging sources on one bank. With a HOUSE & DEDICATED START, it seemed to make more sense to me to put the alternator on the START and the other sources on the HOUSE. Since, after reading your links and several others, this didn’t seem to be the norm, I really wanted feedback as to whether this was not a good idea, and if so, why.

3. Possibly a trivial point, but it feels more intuitive to me to have a “USE” selector for the starter, and then a paralleling switch if the HOUSE needs to operate off the DEDICATED START (which would be a “real” emergency). It’s the mirror image wiring, just using the switches on the opposite banks. I’m not trying to convince anyone else to do it this way, just wondering if there is any reason not to do that, if it is more intuitive for me.

3. Calder makes the point that there is no “typical” sailboat. Simply directing people to these links is not likely to answer every question, especially for someone non-expert enough to need them in the first place. Now perhaps I should have started by saying what reading I had done, and making clear that these were the questions I still had. However, if people are going to learn, they are going to need to post questions about how these principles apply to their specific installation. Even following those links, there are multiple options discussed, and asking for feedback on why one might choose one over the other is helpful to the poster and other readers.

Thanks.
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