Charging 4 banks from 1 alternator?

[skipmac]

Originally Posted by ramblinrod

An ACR with manual house/start combine switch is a better solution than an echo charger and 1/2/B/Off switch combo.

Not quite sure I understand. Blue Seas makes several versions of their ACR. Are you referring to the version that automatically connects the start battery for charging but also allows paralleling the start and house banks for cranking?

If so, I still prefer using any of the voltage controlled relay combiners like the EchoCharge or in my case the Yandina Combiner and a manual 1-2-BOTH switch for emergency starting. The ACR method will always combine the house and start banks, but with a 1-2-B switch I can bypass the start battery and use just the house bank for cranking.
Reasons: If the start battery is totally dead it will divert current from the house bank leaving less cranking power. If the start battery is shorted then same thing.

Originally Posted by ramblinrod

That a 6 volt battery system may split unevenly, is actually another argument for sticking with 12 Vdc batteries.

There's an awful lot of cruisers using paired 6V batteries like the Trojan T105, generic golf cart batteries and I don't hear too many (any?) complaints about this. There are very few true deep cycle 12V batteries and the ones I can think of off the top of my head are large, like 4D size. I've muscled around 4D batteries and really don't care to do it again.

Originally Posted by ramblinrod

However, in an emergency situation, whether the house bank is split evenly is of little importance; the most important issue is to isolate the bad battery from those being relied on to supply the house loads until repairs can be made.

Never thought that was an issue. My only point in mentioning this was, in the very common situation of three pairs of 6V batteries for the house bank, to add a switch to separate the house banks for maintenance or in case of a bad battery the wiring would be somewhat complicated for three equal banks vs two unequal banks.

Originally Posted by ramblinrod

Some means to isolate is vastly superior to none.

On this I will completely agree.

[ramblinrod]

[QUOTE=skipmac;2222653]Are you referring to best practice by isolating the start and house batteries?


No!

I am referring to what the poster wrote in the quote I referenced.

Please read again.

[skipmac]

[QUOTE=ramblinrod;2223049]

Originally Posted by skipmac

Are you referring to best practice by isolating the start and house batteries?


No!

I am referring to what the poster wrote in the quote I referenced.

Please read again.

I did read Dockhead's post, several times, which is why I asked the question.

He said "Best practice is not to connect start battery and charging system, and domestic system, in any way." then followed up with suggestions for methods to do this but also more suggestions relating to the rest of the battery and charging system.

It seems pretty clear to me that he used "best practice" specifically to refer to isolating the start and house battery systems and not the rest of the wiring layout. However, I cannot pretend to always understand what someone meant so will defer to his comments if he's still following this thread.

[Dockhead]

[QUOTE=skipmac;2223057]

Originally Posted by ramblinrod

I did read Dockhead's post, several times, which is why I asked the question.

He said "Best practice is not to connect start battery and charging system, and domestic system, in any way." then followed up with suggestions for methods to do this but also more suggestions relating to the rest of the battery and charging system.

It seems pretty clear to me that he used "best practice" specifically to refer to isolating the start and house battery systems and not the rest of the wiring layout. However, I cannot pretend to always understand what someone meant so will defer to his comments if he's still following this thread.

Yes, you understood me correctly.

Best practice is to NOT use any part of the main engine starting battery and associated charging system for any other purpose but starting the main engine and running the main engine's wiring harness.

This requires a second alternator for the domestic power system.

Since car-type alternators, like what your main engine came standard with, are not designed for bulk power production, a great benefit of this approach is that you get to choose an alternator which is actually made for this purpose, that is, a heavy duty, hot-rated, school bus type alternator.

Interconnecting these systems even with a manual "1,2,Combine" switch is undesirable due to risk of operator error. Better to keep jumper cables, which you will never need anyway, unless you have a duff start battery, since there is nothing connected to your engine start battery which could run it down.

This is an extremely desirable configuration from several different points of view, and this is the way all expensive cruising boats (in Europe at least) are set up.


Unfortunately, it is not always possible to mount a second alternator, so best practice is not always achievable, in which case an echo charger is the next best thing.

Automatic battery combiners are not really good, because a dead bank or deeply discharged bank will drag down a good bank (I think SkipMac or someone mentioned that earlier in the thread), and also because one bank, if the cables to it are longer or thinner, may never get an adequate charging voltage. You cannot really properly regulate charging of two banks at the same time through an automatic combiner, because the alternator regulator (or battery charger) will respond to the voltage it senses -- either through a remote voltage sense wire, which will only be on one bank, or at the charger. It will not be able to be in the right regime for both banks simultaneously, so one bank will be chronically overcharged and one chronically undercharged, unless the two banks are exactly matched to each other in capacity, state of charge, and size and length of cabling, which will never happen. This is why echo chargers are so much better -- they create a separate charging regime for the secondary bank, merely powered by the primary bank, not getting the same voltage (or even worse, a different voltage determined by the cabling).


But two separate alternators and completely separate charging systems is a configuration which is so vastly superior to any other way to do it, that everyone should at least try to do it that way. It's not necessarily all that much more expensive, by the time you add up all the junk you will be buying and installing in order to manage multiple banks with a single charging source. If you calculate the batteries you will not ruin by charging them separately, you will actually probably come out ahead, cost wise.

[ramblinrod]

Originally Posted by skipmac

I can really think of no negatives at all for having an isolated starting battery for anyone.

Here's one that may apply to virtually every small cruising or liveaboard boat...

"The boater does not have sufficient space for the size of house bank that is needed and used 100% of the time when disconnected from shore power, so chooses to forego a start battery that is typically used less than 0.1% of the time."

Please don't respond that this has inherent risk of discharging the batteries so the engine can't be started. We all know this.

As I have stated many times before in this thread, it is acknowledged that this is not the most "failsafe" system configuration.

We also know that it is not good for the house bank (in any boat) to be discharged below 50%. SO DON'T, and you should have more than enough battery available in the house bank to start the engine.

Boaters identify, acknowledge, accept, and mitigate numerous risks every day they roll out of their berth.

Why do you feel this one relatively minor risk is so unacceptable?

Are you really having that much trouble comprehending this concept, or are you just being antagonistic?

Just out of curiosity, where are your batteries located?

[ramblinrod]

[QUOTE=Dockhead;2223078]

Originally Posted by skipmac

Yes, you understood me correctly.

Best practice is to NOT use any part of the main engine starting battery and associated charging system for any other purpose but starting the main engine and running the main engine's wiring harness.

This requires a second alternator for the domestic power system.

Since car-type alternators, like what your main engine came standard with, are not designed for bulk power production, a great benefit of this approach is that you get to choose an alternator which is actually made for this purpose, that is, a heavy duty, hot-rated, school bus type alternator.

Interconnecting these systems even with a manual "1,2,Combine" switch is undesirable due to risk of operator error. Better to keep jumper cables, which you will never need anyway, unless you have a duff start battery, since there is nothing connected to your engine start battery which could run it down.

This is an extremely desirable configuration from several different points of view, and this is the way all expensive cruising boats (in Europe at least) are set up.


Unfortunately, it is not always possible to mount a second alternator, so best practice is not always achievable, in which case an echo charger is the next best thing.

Automatic battery combiners are not really good, because a dead bank or deeply discharged bank will drag down a good bank (I think SkipMac or someone mentioned that earlier in the thread), and also because one bank, if the cables to it are longer or thinner, may never get an adequate charging voltage. You cannot really properly regulate charging of two banks at the same time through an automatic combiner, because the alternator regulator (or battery charger) will respond to the voltage it senses -- either through a remote voltage sense wire, which will only be on one bank, or at the charger. It will not be able to be in the right regime for both banks simultaneously, so one bank will be chronically overcharged and one chronically undercharged, unless the two banks are exactly matched to each other in capacity, state of charge, and size and length of cabling, which will never happen. This is why echo chargers are so much better -- they create a separate charging regime for the secondary bank, merely powered by the primary bank, not getting the same voltage (or even worse, a different voltage determined by the cabling).


But two separate alternators and completely separate charging systems is a configuration which is so vastly superior to any other way to do it, that everyone should at least try to do it that way. It's not necessarily all that much more expensive, by the time you add up all the junk you will be buying and installing in order to manage multiple banks with a single charging source. If you calculate the batteries you will not ruin by charging them separately, you will actually probably come out ahead, cost wise.

Based on your original post, and this follow up, my interpretation, is that you believe that "the start and house circuits should not be connected in any way", because "combiners are prone to failure", and therefore best practice is to use, "two alternators" instead of some form of combiner.

I disagree that this is considered "best practice" by the majority of experts, for the reasons already stated.

[skipmac]

Originally Posted by ramblinrod

Are you really having that much trouble comprehending this concept, or are you just being antagonistic?

I understand the concept very clearly, just don't agree. Regarding antagonistic, I have tried to reply politely and with logical answers to all of your posts and did not even feel the need to respond in a red font.

Originally Posted by ramblinrod

Here's one that may apply to virtually every small cruising or liveaboard boat...

"The boater does not have sufficient space for the size of house bank that is needed and used 100% of the time when disconnected from shore power, so chooses to forego a start battery that is typically used less than 0.1% of the time."

One that may apply to virtually every small cruising or liveaboard boat???? Not my experience. I even have room in my 18' ski boat for two separate batteries, one to start the engine and one to run lights, stereo, cooler. True my house loads are minimal and short lived but if I added more stuff I could find another place for another battery if needed.

I would think boats that don't have room for a house bank and a separate start battery to be such a small percentage of the cruisers as to be negligible. That at least is my experience. The few boats that small that I know personally are outboard powered anyway so can hand start if needed.

The fact that a start battery is used only 0.1% or whatever % of the time is irrelevant. The pertinent issue is the importance of being able to start that engine the 0.1% of the time.

Originally Posted by ramblinrod

Please don't respond that this has inherent risk of discharging the batteries so the engine can't be started. We all know this.

As I have stated many times before in this thread, it is acknowledged that this is not the most "failsafe" system configuration.

We all know this but my point is you continue to minimize it and argue against the importance of keeping fully charged, isolated start battery.

Originally Posted by ramblinrod

We also know that it is not good for the house bank (in any boat) to be discharged below 50%. SO DON'T, and you should have more than enough battery available in the house bank to start the engine.

Easy to say, and most of the time you "should" be able to do so, but not always as easy to do as to say it. It is extremely easy to run the house banks down more than intended by accident. Running an AP and the seas pick up, dramatically increasing the power draw, someone forgets to turn off a light (less of a deal now with LEDs if you have converted), batteries are getting a bit older, you didn't charge as much as you thought when the engine was running, I can think of dozens of things that can run down the house batteries and at the end of the day, I would rather lost a year or two or three off the life of my house batteries if that allows me to be sure I can always start the engine.

It may be rare but not that rare that the ability to crank the engine NOW can be a lifesaver or boat saver or at least a fender-bender preventer. Saving the cost of repairs from one smashup will pay for a lot of new batteries.

Originally Posted by ramblinrod

Boaters identify, acknowledge, accept, and mitigate numerous risks every day they roll out of their berth.

Why do you feel this one relatively minor risk is so unacceptable?

Because as I have commented several times, this minor risk has a possibility to have major repercussions. It's the standard in any situation to do a risk analysis. Weigh the potential for the risk plus the potential for catastrophic consequences to decide how to manage the risk. Even if the risk of an occurrence is very low, if the potential consequences are extremely bad then it is worth addressing a way to further reduce or mitigate the results of the concurrence.

It's easy to list some of the possible catastrophic consequences that can and do happen with cruisers. A couple of easy examples.

1. You're sailing in light air with minimal headway and see a powerboat coming that is not altering course. The only way to get out of the way is to immediately crank the engine and power away.

2. You're anchored, a thunderstorm blows in and you're dragging towards a lee shore with little room to hoist sail and gather headway. Crank engine to reduce strain on the rode or drop the rode and motor away.

I can think of dozens more but why? I think it's clear that anyone doing anything more than an afternoon daysail close to home in calm weather would want to always have engine immediately available, just in case.

Originally Posted by ramblinrod

Just out of curiosity, where are your batteries located?

Six X 6 V GC2 batteries in a battery box under the companionway steps forward of the engine. Since I just launched and had to leave the boat to visit the new granddaughter have not yet installed the start battery but it will be installed on a shelf over the house batteries.

Before this I had a 34' cruiser with separate start and house batteries and was never left dead. I learned to sail on a Morgan OI36 that had two dual function house/start batteries and a 1-2-B switch. This was before solar, before wind and before I had enough money to buy a portable generator so my only source for charging was the alternator or shore power. Got left without an engine in remote areas three times over the course of a few years cruising. It was always operator (me) error, usually forgetting to turn the switch away from BOTH but that is the point of setting up a foolproof system. It tries to keep the fools (even if that fool is yourself) from screwing things up.

[skipmac]

[QUOTE=ramblinrod;2223087]

Originally Posted by Dockhead

Based on your original post, and this follow up, my interpretation, is that you believe that "the start and house circuits should not be connected in any way", because "combiners are prone to failure", and therefore best practice is to use, "two alternators" instead of some form of combiner.

I disagree that this is considered "best practice" by the majority of experts, for the reasons already stated.

It seemed clear to me that Dockhead indicated dual alternators are best but at the same time, not possible in all boats and engine configurations.

Did not see anything saying combiners are prone to failure, just a few comments on some of the things that make them not as desirable as dual alternators.

Again as he confirmed, best practice is to isolate the start and house batteries. Off the top of my head I can think of two forum members that are on the ABYC, Nigel Calder who almost anyone recognizes as one of the top experts in the field and a few others that recommend separate start and house batteries with charging direct to the house batteries and some type of auto combiner for charging.

Is this perfect? Of course not. 99.99% of the stuff on a boat is a compromise, but this setup is the best for all but a very few boats; larger boats that can install dual alternators or the very few, very small boats that can only fit one battery.

I would also suggest that most of the small boats that can only fit a small house bank will generally have simple systems and a small energy requirement.

[skipmac]

RR, if I may ask one question, politely and sincerely.

What do you consider the more serious concern, running down and possibly damaging a house battery bank or not being able to start the engine in an emergency because the system was set to maximize use and charging of the house bank?

[Davidhoy]

I got to spend a few hours on my boat yesterday with the electrician who did all the lightning repairs - great guy, very knowledgeable! We discussed various charging scenarios, and he agreed that a good solution would be to lead all the charging sources to the house bank, and the connect the start bank and the windlass/thruster bank via charging relays, such as the Blue Sea System ML-ACR. He also agreed to let the generator take care of its own start battery.

Interestingly, right now, the alternator is connected to a dual output battery isolator, and there are TWO cables connected to each of the output studs. This would effectively combine the batteries on that stud - probably not what should be happening.

I also found that the Raritan ElectroScan MSD is connected to the windlass/thruster battery rather than the house bank. Any thoughts on this, good or bad? I imagine that the device could draw a fair amount of current, so having it off of the house bank may not be a bad thing, as long as the battery to which it is connected is properly maintained.

Another odd thing we found was that the Balmar ARS-4 regulator is programmed with a rather high output voltage of over 15 volts, which is probably not good for the batteries and will lead to their premature death. Any advice on how best to set up the ARS-4 for optimal charging and battery life?

Regards,
David

[Dockhead]

[QUOTE=ramblinrod;2223087]

Originally Posted by Dockhead

Based on your original post, and this follow up, my interpretation, is that you believe that "the start and house circuits should not be connected in any way", because "combiners are prone to failure", and therefore best practice is to use, "two alternators" instead of some form of combiner.

I disagree that this is considered "best practice" by the majority of experts, for the reasons already stated.

Not because "combiners are prone to failure". There are a dozen reasons for avoiding combiners, which I wrote about, and separate domestic and start banks with separate charging systems are definitely best practice, as evidenced by the fact that not a single expensive cruising boat (half a million dollars or more) will have anything else but separate systems.


Now that does not mean that using the start battery and charging system for domestic power needs is totally unacceptable in every case. Using a single charging system and combiner saves space and equipment, and on very small boats it may be hard to avoid. So you see this on small or cheap boats with small battery banks and no external regulation of the alternator. But it is extremely desirable to avoid this, for a whole list of reason besides possibility of failure of the combiner, which would be a very minor reason (main reason is neither bank will get a correct charge), and the larger the domestic power needs and larger the domestic bank, the more severe the disadvantages of battery combiners compared to other methods of charging.




Since the need for power on larger systems anyway quickly outgrows what a car-type alternator can produce, it's very natural to add the second, school bus alternator, anyway, as long as there is space for it.



P.S. -- A small deep cycle domestic battery bank discharged to 50% might very well NOT be able to start a diesel engine. Deep cycle batteries have thick plates and small maximum starting current. To start a diesel engine, you need a fully charged STARTING battery, which with its thinner plates is not suitable for deep cycle use. These two different types of batteries have different purposes, and need to be charged and discharged differently -- each according to its own purpose. This is yet another reason to keep them separated from each other. Deep cycle and starting batteries should really never be combined in any way from this point of view alone, without even getting to the other issues.

[Dockhead]

Originally Posted by Davidhoy

I got to spend a few hours on my boat yesterday with the electrician who did all the lightning repairs - great guy, very knowledgeable! We discussed various charging scenarios, and he agreed that a good solution would be to lead all the charging sources to the house bank, and the connect the start bank and the windlass/thruster bank via charging relays . . .

That will work, but an echo charger will work better. Because an echo charger creates a separate charging profile for the secondary banks, and also because combining different types of battery banks (and over possibly long cable runs!) can distort the system voltage the alternator regulator and battery charger feel, and screw up the charging profile for the domestic bank.


Glad you like your electrician, but remember that an electrician and an electrical engineer are two completely different things! Many very good electricians, have very strange and wrong ideas about electricity!

[ramblinrod]

Originally Posted by skipmac

One that may apply to virtually every small cruising or liveaboard boat???? Not my experience. I even have room in my 18' ski boat for two separate batteries, one to start the engine and one to run lights, stereo, cooler.

I don't consider an 18' ski boat a cruiser or live-aboard boat.

I would think boats that don't have room for a house bank and a separate start battery to be such a small percentage of the cruisers as to be negligible. That at least is my experience. The few boats that small that I know personally are outboard powered anyway so can hand start if needed.

Our experiences differ. In my experience, most 25 to 35 foot sailboats with auxiliary engines come from the factory with far too small a house bank to adequately support extended cruising or liveaboard, forcing the owner to use other space to mount additional batteries, just as you are in the process of doing on your vessel.

The fact that a start battery is used only 0.1% or whatever % of the time is irrelevant.

We disagree. In my opinion, for some individuals, myself included, a dedicated start battery consumes more space and contributes more weight than warranted, if one monitors their batteries closely.

It is extremely easy to run the house banks down more than intended by accident.

Of course it is, all one has to do is disregard their battery monitor.

However, it is also extremely easy to start the engine and recharge the house bank, if it reaches 50% SOC, mitigating the risk to acceptable levels (for some people).

Because as I have commented several times, this minor risk has a possibility to have major repercussions.

If one has a very low risk tolerance they shouldn't be sailing, let alone omitting the start battery.

Six X 6 V GC2 batteries in a battery box under the companionway steps forward of the engine. Since I just launched and had to leave the boat to visit the new granddaughter have not yet installed the start battery but it will be installed on a shelf over the house batteries.

You are arguing about the benefits of a system imperative to one's safety, that heretofor you have not had, in all your years of cruising experience, and yet you're alive to post about it?

PS, there is a risk that your batteries will explode if a spark is generated. Pretty catastrophic. Consider removing all SEVEN batteries. Geesh.

PSS, make sure you leave enough room under the shelf to easily remove, replace, and service the batteries below, and don't make it so high as to reduce the stability of the craft. The CoG of most sailing vessels is less than 1 foot off the bottom of the lowest point of the bilge. Good luck.

Again (and again, and again) I don't recommend the house bank only solution for everyone, and certainly not for you, but for those who need more house bank, understand the risks, and accept them, it is a valid solution.

[ramblinrod]

Originally Posted by Dockhead

That will work, but an echo charger will work better. Because an echo charger creates a separate charging profile for the secondary banks, and also because combining different types of battery banks (and over possibly long cable runs!) can distort the system voltage the alternator regulator and battery charger feel, and screw up the charging profile for the domestic bank.

I believe the Xantrax echo charger follows the alternator voltage.

When an echo charger or ACR is used, all batteries should be identical.

If a discrete charge profile is required, the best solution is a charging source, capable of supplying more than one charge profile.

[ramblinrod]

Originally Posted by skipmac

RR, if I may ask one question, politely and sincerely.

What do you consider the more serious concern, running down and possibly damaging a house battery bank or not being able to start the engine in an emergency because the system was set to maximize use and charging of the house bank?

Most serious concern:

a) With respect to worst possible scenario, not being able to start the engine.

b) With respect to most probable scenario, in some circumstances having insufficient house bank.

If one only considers the worst possible scenario, one should not have any electrical system at all. Electrical systems can catch fire and kill people. No batteries, no AC shore power, none.

Again, every individual has different risk vs reward tolerance.

I have not once said that omitting the start battery is a good solution for you. Clearly it is not.

But for an individual with limited battery space, who needs to maximize the house bank, omitting the start battery and carefully monitoring the house bank, is a valid consideration in most cases.

I have never encountered a sailboat auxiliary diesel under 50 HP, that can't be easily started with a 4 x Grp 27 DC house bank at 50% SOC or more, under normal conditions. Even if that house bank suffered some issue and half were isolated, it would still start the engine, no problem.

Any vessel can be left incapable of starting due to operator error.