Not if I don't put my switch in the "combined" position. If I simply leave it "on" my start batt would get me home while the house bank would remain incapacitated until charged or replaced. You make a presumptuous statement.
Did I buy right battery size?
- Thread starter John_F
- Start date
My set up is a little different than what has been mentioned. It was designed by the PO so no credit or blame to me. I have 3 batteries. Two for house and one smaller starting. The two batteries are batt one and batt two on the selector switch. If the start battery should fail, I switch to ALL and the house bank will start the motor. They are all wired to be charged by either the alternator or my charger.
Switching a smaller start battery in parallel with a large dead house bank could kill the start battery before you can start the engine ! And it could cause much more serious problems as the large house bank could look like a short circuit to the start battery. In general it is probably not a good idea to connect a dead battery to a fully charged battery.
I have a 410 Ahr house bank, it does everything including starting the diesel. An echo charger off the house bank maintains a 100 Ahr emergency start battery. Once in a while I switch to the emergency battery to start the engine and confirm all is well with it.
If the engine could not start off my house bank I would switch to the emergency battery and start with that, not combine both battery banks. I think that is the safest way to go. I don't see much use for the both position in my battery selector switch. Maybe if both banks appeared to be dead both might start the engine.
If you have two large banks it will be difficult to keep them both topped up because of the time involved to top off a large house bank. I think that is the system recommended by most "experts", I'm just following along
Bob
I have a 410 Ahr house bank, it does everything including starting the diesel. An echo charger off the house bank maintains a 100 Ahr emergency start battery. Once in a while I switch to the emergency battery to start the engine and confirm all is well with it.
If the engine could not start off my house bank I would switch to the emergency battery and start with that, not combine both battery banks. I think that is the safest way to go. I don't see much use for the both position in my battery selector switch. Maybe if both banks appeared to be dead both might start the engine.
If you have two large banks it will be difficult to keep them both topped up because of the time involved to top off a large house bank. I think that is the system recommended by most "experts", I'm just following along
Bob
Bob, you may not know, and others may not know, that Scott has one of those Dual Circuit switches, not a 1-2-B. He, Maine Sail and I had a spirited conversation a few years ago about that switch, but Scott knows what he has and how to use it, and what the consequences of that switch are for HIM on HIS boat. He cannot, on HIS boat, use the start bank for limited house loads. Once the switch is turned, he ends up combining the two banks.
His boat, his choice.
AGM Battery Failure and a good discussion of the Blue Seas Dual Circuit design concept in a real life situation.
Thanks again to Maine Sail.
Darn AGMs
http://forums.catalina.sailboatowners.com/showthread.php?t=133773
His boat, his choice.
AGM Battery Failure and a good discussion of the Blue Seas Dual Circuit design concept in a real life situation.
Thanks again to Maine Sail.
Darn AGMs
http://forums.catalina.sailboatowners.com/showthread.php?t=133773
Thanks Stu, you are right, and thanks again to Maine Sail and to you as well for all the tips and guidance on these electrical systems, it has taught me a lot. I don't know anything about Scott's boat and I was not directing any remarks to him. I think Scott has a good handle on what he is doing.Bob, you may not know, and others may not know, that Scott has one of those Dual Circuit switches, not a 1-2-B. He, Maine Sail and I had a spirited conversation a few years ago about that switch, but Scott knows what he has and how to use it, and what the consequences of that switch are for HIM on HIS boat. He cannot, on HIS boat, use the start bank for limited house loads. Once the switch is turned, he ends up combining the two banks.
His boat, his choice.
AGM Battery Failure and a good discussion of the Blue Seas Dual Circuit design concept in a real life situation.
Thanks again to Maine Sail.
Darn AGMs
http://forums.catalina.sailboatowners.com/showthread.php?t=133773
Really just commenting on the issues that could develop when combining a dead battery and a fully charged one. It had not occurred to me when I started out and I thought it was a good lesson I could pass on to others reading this thread. I wanted to point out it was something I learned from the experts around here.
Regards, Bob
Stu, do you have just a smaller emergency battery on your 2nd battery bank or do you carry a full complement of batteries for your 2nd bank which essentially mirrors your primary house bank? I'm curious because I am genuinely surprised by the comments. I thought the purpose of having a redundant 2nd bank was to mirror the 1st bank. I did not expect to hear that on boats that are used for cruising, the 2nd bank is typically just a battery for emergency starts.
Just to be clear, Ron said that I WOULD use my start battery for house loads. He's wrong because I COULD by setting the switch to COMBINE but I WOULD NOT use my start battery for house loads if I had a problem with a dead house bank. I WOULD use the switch in the normal 'ON' position and start my engine. When the batteries are charged via the alternator thru the ACR, then I might be able to use the house bank again, but if the batteries are truly dead, then I would simply motor home without using the house bank. If that means no navigation lights, and it's dark, I suppose I would have to wait for daylight. If I can't use my hard wired VHF, I suppose I might have to rely on a battery operated hand held. All I know is there is always going to be a way to handle a "situation".
IF I thought that I might safely use my start battery for house loads (say navigation lights, navigation aids and communication) by combining it with a dead house bank, I COULD switch to the COMBINED position with the engine running (and charging the functioning battery) because the switch IS a Make, then Break, switch. But I WOULD probably heed Bob's advise in most circumstances, which is that combining a good battery with a bad bank can lead to trouble.
Conversely, if my house bank was strong, I would have much less trepidation in setting the switch to COMBINE so that I could start the engine (and charge batteries via ACR)even if the start battery is dead. In this case, I think that there is little danger. I will be corrected if I am wrong.
But seriously, how am I going to have a problem with battery banks if I religiously monitor the health of my batteries with a Linkpro battery monitor? Isn't that the point of monitoring your batteries? ... to PREVENT battery troubles? That's where I get a little crazy about discussions that revolve around needing an emergency back-up. I think it just makes a lot more sense to simply have the batteries you need or want, separate the purposes if you like, and make sure they are healthy. There is no need to carry dead weight.
Just to be clear, Ron said that I WOULD use my start battery for house loads. He's wrong because I COULD by setting the switch to COMBINE but I WOULD NOT use my start battery for house loads if I had a problem with a dead house bank. I WOULD use the switch in the normal 'ON' position and start my engine. When the batteries are charged via the alternator thru the ACR, then I might be able to use the house bank again, but if the batteries are truly dead, then I would simply motor home without using the house bank. If that means no navigation lights, and it's dark, I suppose I would have to wait for daylight. If I can't use my hard wired VHF, I suppose I might have to rely on a battery operated hand held. All I know is there is always going to be a way to handle a "situation".
IF I thought that I might safely use my start battery for house loads (say navigation lights, navigation aids and communication) by combining it with a dead house bank, I COULD switch to the COMBINED position with the engine running (and charging the functioning battery) because the switch IS a Make, then Break, switch. But I WOULD probably heed Bob's advise in most circumstances, which is that combining a good battery with a bad bank can lead to trouble.
Conversely, if my house bank was strong, I would have much less trepidation in setting the switch to COMBINE so that I could start the engine (and charge batteries via ACR)even if the start battery is dead. In this case, I think that there is little danger. I will be corrected if I am wrong.
But seriously, how am I going to have a problem with battery banks if I religiously monitor the health of my batteries with a Linkpro battery monitor? Isn't that the point of monitoring your batteries? ... to PREVENT battery troubles? That's where I get a little crazy about discussions that revolve around needing an emergency back-up. I think it just makes a lot more sense to simply have the batteries you need or want, separate the purposes if you like, and make sure they are healthy. There is no need to carry dead weight.
BobIf the engine could not start off my house bank I would switch to the emergency battery and start with that, not combine both battery banks. I think that is the safest way to go. I don't see much use for the both position in my battery selector switch. Maybe if both banks appeared to be dead both might start the engine.
If you have two large banks it will be difficult to keep them both topped up because of the time involved to top off a large house bank. I think that is the system recommended by most "experts", I'm just following along
Bob
If your Echo Charger was to fail - a rare event - the "both" position would allow you to charge both banks with the engine running.
I agree that a dead battery should never be combined with a good battery for the reasons posted above. If I had the Dual Circuit switch that Scott has, a switch I dislike when used for other than its intended purpose - all it takes is a wrench to move the positive from one battery to the other in the event of a dead and possibly internally shorted battery.
The Dual Circuit switch is intended for small powerboats with equal sized battery banks, not boats where the house bank is larger than the start battery.
Small powerboats don't even bother with a battery switch. All I have been on have ignition and lights, etc. wired directly to a single battery. I think MS has described the use of the Circuit Plus as adapted to sport fishing boats where the house bank and the starting bank (for a larger engine than the typical sailing vessel) are separate and NOT alike ... very much more like the use you have described as a house bank and a separate start or emergency battery. Pretty much the way I use it. It definitely works that way for me even though I recognize that a separate starting bank is not necessary for our small auxiliary engines. I just happen to like it that way because I like knowing the 2nd bank (battery) actually has a purpose (for starting the engine) rather than sitting there unused for an emergency that will more than likely never happen.
By small I mean the 16' to 24' sportfishing boats. And they do most often have battery switches, especially if they are concerned about safety. And using electric downriggers all day will leave them without the ability to start the main outboard if they only have one battery. I sell Blue Seas products and sell many Add A Battery systems (in both sizes) for these types of boats. They don't need a large battery to start a 150 or 200 hp outboard - most often a group 27 for start and another group 27 for house loads.
That's absurd ... the switch is designed specifically to separate the house bank from the start bank, so that both banks can be on at the same time .... which the 1-2 -Both switch CAN'T do unless the banks are combined in the BOTH setting - something that everybody seems to think is a bad thing. I agree with you that it is a safety feature on sport fishing boats so that the auxiliary uses don't leave the start battery dead. Every ski boat I've ever been on doesn't bother with a switch or multiple batteries. There is no reason to carry the extra weight.
In fact, in earlier posts, you and others said that they separate the start battery from the house bank. So how does that work for you with a 1-2- B switch when you have to put it on 1 to use the house bank and 2 to start the engine? Makes no sense, right? That's why most sailors just start their engine with the house bank and the second bank is dead weight.
How is our 27' sailboat used any differently than the "small" fishing boats you describe? They're not, are they. I think sailors just have this attitude that they have to be different than powerboaters. It's really silly. I know that is exactly how my boat is set up ... 2 nice deep cycle batteries for house loads, and a separate start battery ... exactly why the switch was designed. I turn it "ON" and both banks are functional. If I had your switch, I'd be turning it from 1 to 2 until I wore the switch out ... dumb.
Absolutely nothing to do with sailors being different from powerboaters. I wouldn't recommend a Dual Circuit switch for a powerboat with a large house bank and smaller start battery or bank either. It gives you less options and an issue with either bank means you end up combining a bad battery with a good battery - not a good idea.
The 1/2/both switch allows you to select each battery (or bank) individually and doesn't force a combining of the banks, but it remains an option. Since many people who upgrade their boats have the 1/2/both switch already it doesn't make sense to throw it away for a switch that doesn't allow you as many options and it works well, whether you start on one battery and switch to house bank after or start on house all the time, keeping the "start" battery as an "emergency" battery.
My actual preference is the 3 switch combination that Maine prefers as well. On/off for house, on/off for start/ and a 3rd on/off for using either bank for either purpose without combining.
The Dual Circuit switch is not a terrible choice for a boat with only one battery for each purpose but most cruising sailboats have a larger house bank than a start bank. It does limit your switching options though.
OK, Electrical 102. Scott, I have a 390 ah house bank (three 130 ah 12V) and a 60 ah RESERVE bank.
This whole reserve vs start bank has been beaten to death over the years and the links I continually provide explain it all. I don't have ANY fancy electronics, so I didn't go for separate switching for starting the engine.
I also do not believe in split 1/2&1/2 house banks.
I think your application of the Blue Sea Dual Circuit works for you (because of your battery arrangement and boat use), it wouldn't for me because of what Bob said, and what we've been saying for years.
I just LOVE my simple 1-2-B switch with the AO to the house bank.
Does that answer it?
Except that's just wrong. I keep saying: B is for backup, backup, backup in case your relay (ACR, combiner, echo charger) fails,
AND
should be used only for when you're charging.
Once again:
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.sailboatowners.com/showthread.php?t=137615
Scott,
I agree with your thinking & Ron's although some thoughts differ.
I like to keep it simple. Having two batteries, The best setup is to have equal size batteries with equal reserve capacity. It also makes more sense in charging parameters.
It is better to have a deep cycle for the house. Yea, you can have the second battery as just a starting battery but, the experts say equal batteries are the best. I would feel better knowing I have two deep cycles to cover all situations that may arise. If the first battery drains, I would feel more confident in knowing my second battery had a higher reserve capacity.
CR
I agree with your thinking & Ron's although some thoughts differ.
I like to keep it simple. Having two batteries, The best setup is to have equal size batteries with equal reserve capacity. It also makes more sense in charging parameters.
It is better to have a deep cycle for the house. Yea, you can have the second battery as just a starting battery but, the experts say equal batteries are the best. I would feel better knowing I have two deep cycles to cover all situations that may arise. If the first battery drains, I would feel more confident in knowing my second battery had a higher reserve capacity.
CR
The only thing "wrong" was what I quoted, 'cuz Scott seems to think having a separate "start" bank separating electronics via the switch is more important than separating banks when things go wrong with one bank. Yes, the 1-2-B can't do it by itself, and requires one more switch to do so, but the benefits far outweigh the downsides to me at least, but NOT to Scott. I understand. Let's get off this bus already.
In retrospect, I was wrong, he was right. About the switch and what it can do.
I agree, his boat, his choice. Did I already say that?
You may note I came to Scott's defense of his DCP switch "Yeegads!
)!!! Who woulda thought. :dance:Anyway, I agree, the same guys saying the same things over and over don't make it any more basic and simple.
And I like Ron's three switch idea. We should all have Beneteaus and teach the rest of the world how to switch!!!
Stu, I've never insisted that anybody should do what I do for my reasons. But you seem to insist that I'm argumentative when I'm not, except when the logic is just wrong. Mitiempo says that DCP is for small boats where each bank is small and equal. That's not the case. I use it exactly how it is intended. I have 200ah deep cycle using 2 batteries on main bank and a start batt on start bank. I never said that I think it better, I just like it because I don't carry dead weight.
So you reveal that you carry a small reserve with a large main bank. First, that surprised me because I was always under the impression that the reserve bank would be similar to the house bank. That's fine but I wonder why you carry dead weight when you monitor your batts and would seem to be on top of everything.
Also, some contributed that everybody must have an isolated start battery. I only contributed that I have one but that it isn't necessary, in fact most sailors don't. If you have only 2 batteries on your boat, why would you put them on separate banks and then use the 1-2-B switch. That's what doesn't make sense to me. I would simply combine the 2 equal batteries on 1 bank for better efficiency and batt life.
Stu, you never answer my question ... If you monitor your house bank so carefully, why do you carry a small reserve? Is it just for tradition or to make position 2 seem useful?
So you reveal that you carry a small reserve with a large main bank. First, that surprised me because I was always under the impression that the reserve bank would be similar to the house bank. That's fine but I wonder why you carry dead weight when you monitor your batts and would seem to be on top of everything.
Also, some contributed that everybody must have an isolated start battery. I only contributed that I have one but that it isn't necessary, in fact most sailors don't. If you have only 2 batteries on your boat, why would you put them on separate banks and then use the 1-2-B switch. That's what doesn't make sense to me. I would simply combine the 2 equal batteries on 1 bank for better efficiency and batt life.
Stu, you never answer my question ... If you monitor your house bank so carefully, why do you carry a small reserve? Is it just for tradition or to make position 2 seem useful?
Scott, I've explained my battery design in Post #32, didn't I? What makes you think I only have two small batteries? I have a good sized house bank and a small reserve, NOT start, bank. All this is explained in those links I keep posting.
The assumption that two banks should be the same is way outdated, back before I bought my boat in 1998. That concept, the old two equal house banks, has been shown to be wasteful, since a larger house bank works better than two smaller ones of equal capacity.
Reveal? What are you smokin'? I've been explaining this since 1998.
Dead weight? Hardly. It's a reserve bank. It weighs all of 30 pounds, like a few bottles of rum!
Look, Scott, I know you have a DCP switch and like it. Fine. I agree, it works for you.
It doesn't work for those of us who have larger house banks, don't marina hop, and don't ever want to have to un-wire anything if something fails, and don't want to kill a reserve bank by connecting, without any option, to a dead house bank.
Stu, you never answer my question ... If you monitor your house bank so carefully, why do you carry a small reserve? Is it just for tradition or to make position 2 seem useful?
Funny one. Or just: Malarkey. I answered it in all my posts and links. Large house bank, small reserve bank, just in case. No different than your two batteries redundancy, isn't it? I do NOT need a start bank because I don't have fancy electronics. I said that before, too, right? I understand you "use" all three of your batteries, I don't "use" one of mine on a regular basis.
They are just two of many electrical system designs.
That's all. Ron was right, play nice, let it go.
In ALL of our discussions about this, MS & I have been very clear on what we have: large house bank, small reserve bank. NOT two equal house banks. Have no idea where ya got that from.
The assumption that two banks should be the same is way outdated, back before I bought my boat in 1998. That concept, the old two equal house banks, has been shown to be wasteful, since a larger house bank works better than two smaller ones of equal capacity.
Reveal? What are you smokin'?
I've been explaining this since 1998. Dead weight? Hardly. It's a reserve bank. It weighs all of 30 pounds, like a few bottles of rum!
Look, Scott, I know you have a DCP switch and like it. Fine. I agree, it works for you.
It doesn't work for those of us who have larger house banks, don't marina hop, and don't ever want to have to un-wire anything if something fails, and don't want to kill a reserve bank by connecting, without any option, to a dead house bank.
Stu, you never answer my question ... If you monitor your house bank so carefully, why do you carry a small reserve? Is it just for tradition or to make position 2 seem useful?
Funny one. Or just: Malarkey. I answered it in all my posts and links. Large house bank, small reserve bank, just in case. No different than your two batteries redundancy, isn't it? I do NOT need a start bank because I don't have fancy electronics. I said that before, too, right? I understand you "use" all three of your batteries, I don't "use" one of mine on a regular basis.
They are just two of many electrical system designs.
That's all. Ron was right, play nice, let it go.
Did we manage to confuse John (OP). Best suggestion especially for a new owner is to read read and re-read. Educate yourself. Suggest buying Nigel Calder's Boatowners's Mechanical and Electrical Manual. It takes time to digest and understand this whole subject. The one common denominator here is everyone responding knows how to use what they have and it works for them. The energy budget Stu suggested is a good place to start. There are two things you can do. Reduce your energy needs (LED lighting) or increase your battery capacity. Most of us have done both. An energy budget is the best way to evaluate this. Who knows, you might find what you have will work for you. You'll answer your question with experience. Good luck.
Yeah,I'd rather switch than fight !...And I like Ron's three switch idea. We should all have Beneteaus and teach the rest of the world how to switch!!!