Charging 4 banks from 1 alternator?

[Dockhead]

Originally Posted by ramblinrod

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.

You are right, and I have learned something -- thanks.

I was thinking of the Sterling Battery-To-Battery Charger (Battery to Battery Chargers (50A 12V/24V) ( 2 years warranty) | Sterling Power Products) which works differently.

A device which the OP might consider, because it solves this problem -- of providing the right charging profile, to the right battery bank.

[skipmac]

Originally Posted by ramblinrod

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.

You accuse me of being argumentative yet you insist on posting red text, reading things into my (and Dockhead's) posts that were clearly not said and ignoring numerous, thoughtful and logical (and polite) responses to your arguments.

So one last response.

1. I never said nor implied in any way that an 18' skiboat is a cruiser. Wouldn't that be extremely silly? I responded to your argument that many boats are too small to have enough house battery capacity to have a separate start battery. My point was ONLY to say if I can have separate battery systems on an 18' ski boat it would take a very unique cruiser to not have room to do the same.

2. How a boat comes from the factory in most cases is based on marketing and cost. Very, very few boats come from the factory equipped for cruising (boats that are actually cruised are a very small percentage of the market anyway, Oysters, Moody's and the like excepted) and it is SOP to have to upgrade to make it suitable. That includes not just batteries but usually alternators, bilge pumps (how many boats come from the factory with good emergency bilge pumps?), safety gear and a host of other boat systems. So the argument that it requires work to change the factory battery system to make it better for cruising really doesn't make sense.

3. Low risk tolerance??? Remove all the batteries to avoid sparks??? These statements are just plain silly and pointless. Sailing, done properly is a pretty low risk endeavor. I'm talking about managing the risks that do exist. Having a reliable starting system is like having a good fire extinguisher. Just because I carry a fire extinguisher doesn't mean I'm afraid or have a low risk tolerance, just means that I have the good sense to take a very easy precaution to deal with a low probability occurrence that could have a very serious outcome IF it occurred.

4. I don't care what system you want or how carefully you can monitor your system. Your boat, your decision. But to argue that it isn't feasible to have a separate start battery in any typical cruiser, even 25-30' is not correct.

5. No I didn't spend my cruising career on boats with the system I recommend but I also spent years cruising with nothing but a sextant, VHF and depthsounder. Technology improves, techniques evolve, my knowledge and experience has increased and I have learned about better ways to do things than I did 30-40 years ago. Sure I lived through it but almost lost a boat because I couldn't crank an engine and did end up on the beach. Almost got stranded in a remote island in the south Bahamas because a crew changed the battery switch and I didn't catch it. TIP, if you have two almost dead 12 V banks that won't quite crank an engine you can connect them in series to 24V and they will probably do it. I did have to make most of a trip from the USVI to FL with no engine and no lights from running down the 1-2-B batteries so couldn't crank the engine to recharge. I admit, all operator error and I would probably manage better today than I did then but at the end of the day, we're all fallible and the more foolproof one can make a boat the better.

- Can you live without a separate start battery? Of course
- Can you never run down both banks and always have cranking power? Probably or maybe if you're perfect in always checking the switches, never forget, never make a mistake, never have one of the batteries go bad and drain the others, and never have a crew mess with the switch.
- Is it more reliable and foolproof to have a separate, isolated start battery? YES
- Is it expensive or complicated, does it take an inordinate amount of space to add a separate start battery? NO.
- Any overwhelming reason not to add a separate start battery? Have not yet seen any compelling argument or reason not to.

OK. I'm done. You're welcome to the last word.

[skipmac]

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, 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

Hi David,

My guess is the dual battery isolator is a diode based devise that drops 0.7V in the device. That may be why the Balmar regulator is set so high, to compensate for the voltage drop in the isolator.

Where do the two cables lead that are connected to each terminal of that isolator? What happens will depend on what they're connected to.

I second Dockhead's comment that being a good electrician doesn't always confirm a good knowledge of the subject. I knew a guy that was a great mechanic. Could take apart and reassemble an engine with his eyes closed but once I asked him something about the four stroke cycle; intake, compression, combustion, exhaust, he had no clue about what it was, how it worked or what it meant. He could still fix anything on the engine but had no understanding about how it worked.

[Davidhoy]

Originally Posted by skipmac

Hi David,

My guess is the dual battery isolator is a diode based devise that drops 0.7V in the device. That may be why the Balmar regulator is set so high, to compensate for the voltage drop in the isolator.

Where do the two cables lead that are connected to each terminal of that isolator? What happens will depend on what they're connected to.

I second Dockhead's comment that being a good electrician doesn't always confirm a good knowledge of the subject. I knew a guy that was a great mechanic. Could take apart and reassemble an engine with his eyes closed but once I asked him something about the four stroke cycle; intake, compression, combustion, exhaust, he had no clue about what it was, how it worked or what it meant. He could still fix anything on the engine but had no understanding about how it worked.

Good point about the regulator voltage being set a little high to offset the voltage drop across the isolator. There definitely is a drop, I just don't recall the actual value except that it was more that 0.5 volts. I should measure the voltage at the output of the isolator, that will tell me what voltage is actually going to the batteries.

I was reading the manual for the ARS-4 alternator voltage regulator - is there any more confusing document on the planet? I think even Donald Trump's tax return is simpler than that ;-)

Regards,
David

[skipmac]

Originally Posted by Davidhoy

Good point about the regulator voltage being set a little high to offset the voltage drop across the isolator. There definitely is a drop, I just don't recall the actual value except that it was more that 0.5 volts. I should measure the voltage at the output of the isolator, that will tell me what voltage is actually going to the batteries.

I was reading the manual for the ARS-4 alternator voltage regulator - is there any more confusing document on the planet? I think even Donald Trump's tax return is simpler than that ;-)

Regards,
David

If it is a diode and a standard silicon diode then the voltage drop will be 0.7V almost exactly. Germanium or Schottky diodes (less common and more expensive) around 0.2-0.3V.

I have a Balmar 614 regulator and found the manual just slightly clearer than mud. Also found a mistake in the wiring diagram in the manual that labeled several of the connections incorrectly. Fortunately I caught the mistake but what the heck?

[ramblinrod]

Ok I'll take you on your word that you will not post again so I will not post any new argument that should require rebuttal.

Originally Posted by skipmac

You accuse me of being argumentative yet you insist on posting red text,

I have been writing in coloured text to differentiate Author.

reading things into my (and Dockhead's) posts that were clearly not said

[COLOR="red"] I'm not aware of any misinterpretation on my part.[/COLOUR]

and ignoring numerous, thoughtful and logical (and polite) responses to your arguments.

I have not ignored your posts. I have attempted to respond to many of them, equally politely.

So one last response.

1. I never said nor implied in any way that an 18' skiboat is a cruiser.

[COLOR="red"]When I referred to a problem on live a aboard and cruising boats, you responded with a reference to an 18 ft ski boat as if it were relevant to that discussion.[/COLOUR]
I responded to your argument that many boats are too small to have enough house battery capacity to have a separate start battery. My point was ONLY to say if I can have separate battery systems on an 18' ski boat it would take a very unique...

i disagree. Insufficient space for house bank batteries is a common problem on small cruising and live aboard boats and has nothing to do with 18 ft ski boats.

2. How a boat comes from the factory in most cases is based on marketing and cost. Very, very few boats come from the factory equipped for cruising (boats that are actually cruised are a very small percentage of the market anyway, Oysters, Moody's and the like excepted) and it is SOP to have to upgrade to make it suitable. That includes not just batteries but usually alternators, bilge pumps (how many boats come from the factory with good emergency bilge pumps?), safety gear and a host of other boat systems. So the argument that it requires work to change the factory battery system to make it better for cruising really doesn't make sense.

not my argument.

3. Low risk tolerance??? Remove all the batteries to avoid sparks??? These statements are just plain silly and pointless.

I disagree. As stated before, The safest electrical system is none Electrical system at all. Anything beyond that is a risk vs reward consideration.

Sailing, done properly is a pretty low risk endeavor. I'm talking about managing the risks that do exist. Having a reliable starting system is like having a good fire extinguisher.

No argument. As stated before, a properly charged house bank can be a reliable starting system. Mine, for example, has been starting reliably for 4 years.

Just because I carry a fire extinguisher...

i never said it did.

4. I don't care what system you want or how carefully you can monitor your system. Your boat, your decision.

Correct. Thank you.

But to argue that it isn't feasible to have a separate start battery in any typical cruiser, even 25-30' is not correct.

I never argued this once. I have stated all along that a dedicated start battery is a more fail safe system, but that omitting a start battery is a viable consideration in some cases.

5. No I didn't spend my cruising career on boats with the system I recommend

Now let's be accurate, you have cruised for over 30 years, with zero time with the system you have purported is essential to safety.

Technology improves, techniques evolve, my knowledge and experience has increased and I have lear Sure I lived through it but almost lost a boat because I couldn't crank an engine and did end up on the beach.

Almost got stranded in a remote island in the south Bahamas because a crew changed the battery switch and I didn't catch it.

Now let's be clear, none of this is because your vessel did not have a dedicated start battery.


TIP, if you have two almost dead 12 V banks that won't quite crank an engine you can connect them in series to 24V and they...

Because I vowed not to introduce new arguments, I will not comment on how unsafe this is, and that there are vSlty superior solitions.

- Can you live without a separate start battery? Of course

Thank you, first time acknowledged.

- Is it more reliable and foolproof to have a separate, isolated start battery? YES

No argument, ever.

- Is it expensive or complicated, does it take an inordinate amount of space to add a separate start battery? NO.

It may take more space than one is willing to give up.

- Any overwhelming reason not to add a separate start battery? Have not yet seen any compelling argument or reason not to.

As above, whether one considers it compelling is a personal matter.



OK. I'm done. You're welcome to the last word.

Ill take you for your word on this.

[Davidhoy]

Come on, guys, please play nice.


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[boatbod]

Originally Posted by RaymondR

Been through all the manual switching and automatic switching relay setups and sooner or later one comes to grief with them. The only really reliable way to do it is entirely separate the house and cranking systems and put two alternators on the engine, one for each. Probably the lowest cost in the long run.

While having two alternators has some merit due to increased redundancy in charging sources, it will be an order of magnitude more expensive by the time you've purchased the alternator, an external regulator, had a custom alternator bracket fabricated and added a an extra pulley to the crankshaft to drive the new belt.

The simplest answer to the OP's question is to connect his one alternator to the biggest bank (presumably the house) and then install several voltage-sensitive combiner relays (e.g. ACR Link) to provide charging support to each of the other banks. The combiners must necessarily be sized (and fused) to accommodate the full rated amperage of the alternator, even though in common usage you'll only see a fraction of that current flowing through them.

[skipmac]

Originally Posted by boatbod

While having two alternators has some merit due to increased redundancy in charging sources, it will be an order of magnitude more expensive by the time you've purchased the alternator, an external regulator, had a custom alternator bracket fabricated and added a an extra pulley to the crankshaft to drive the new belt.

35 years ago I upgraded from a stock 60 amp alternator to a 120 amp, an upgrade only, not a second but did have to build a custom bracket and change pulleys. Including the alternator it cost me almost $1000 then. Would certainly be more now and doing it as a second alternator probably even more.

Adding a Yandina combiner to keep the start battery charged cost me about $100. As a backup to my high output alternator with external smart regulator I bought a single wire, 100 amp, internally regulated, dumb alternator for $100. So for $200 I have a system that I feel gives sufficient redundancy for me. Add the solar panels and Honda generator and I'm covered.

[Dockhead]

Originally Posted by boatbod

While having two alternators has some merit due to increased redundancy in charging sources, it will be an order of magnitude more expensive by the time you've purchased the alternator, an external regulator, had a custom alternator bracket fabricated and added a an extra pulley to the crankshaft to drive the new belt.. . .

Dual alternators will allow the OP to charge his house bank not only with its own alternator, but also with an alternator designed for charging deep discharge batteries, and regulated to do it properly. The standard main engine alternator is not designed for this and won't do a really good job, even with external regulation. Large case, hot rated, school bus alternators can produce their full rated power continuously.


There is far less which can go wrong with the main engine starting system if nothing is connected to it -- nothing which can discharge it, and nothing which can interfere with its charging.


. . .

By the way, if you have a separate bow thruster battery bank, and charge it with a combiner relay, it's a good idea to use a latching relay which you can latch from the hlem. That's because the automatic relays will open when the voltage drops, and the voltage of the thruster bank will not be supported by either the house bank or the alternator. This can seriously reduce the thruster's performance.

MaineSail writes about this somewhere.

I do not use separate bow thruster batteries on my boat, although I have a large (10 horsepower) bow thruster. I have heavy cabling to my house bank of 420 amp/hours x 24v. System voltage during thruster operation is supported by the second alternator, which puts out about 2.5kW at fairly low RPM. This works well despite the long cable runs, but is obviously easier with 24v than it would be with 12v.

[Dockhead]

By the way, there is one other problem with using combiner relays with a bow thruster. If the relays are closed because the engine is running (as it always will be if you're using the thruster), and if the house bank is discharged, there can be a large current flow from the well-charged starting battery which can blow up the relay or overheat the cables. If this draws the voltage down enough, then an automatic relay might open again and cause back EMF, which can blow up the relay.

There is discussion of this on the Sterling site:

Voltage Sensitive Relay Pro Connect VSR | Sterling Power Products



Sterling recommend connecting the alternator to the start battery, not the house bank, if you're using a B2B charger. This has a significant advantage that you don't then need a smart external regulator on the alternator. That's because the B2B charger creates its own charging regime for the house bank -- it's basically a DC powered smart charger.

I wouldn't do it, however, with a typical 80 amp car type alternator, because the B2B charger will be trying to pull maximum output out of it all the time, which will cause it to run hot and reduce output. You have a much better chance of getting a reasonable amount of power out of a crappy car type alternator, if it's externally regulated with temperature control. You won't get 80 amps, because these alternators are not capable of producing their rated output continuously, but you'll get a lot more than if the alternator is left to its own devices.

There is a lot of information about this problem, and also about the other serious drawbacks of car-type alternators on boats, on MaineSail's website:

Automotive Alternators vs. Deep Cycle Batteries Photo Gallery by Compass Marine How To at pbase.com

[boatbod]

Originally Posted by Dockhead

Dual alternators will allow the OP to charge his house bank not only with its own alternator, but also with an alternator designed for charging deep discharge batteries, and regulated to do it properly. The standard main engine alternator is not designed for this and won't do a really good job, even with external regulation. Large case, hot rated, school bus alternators can produce their full rated power continuously.

That's all true, but the OP said he wanted to charge 4 banks not 2. While suggesting the addition of a second alternator does boost the vessel's charging capabilities, it does not meet the original requirement. Obviously if he only has one alternator it needs to be pretty capable (externally regulated, continuous duty etc etc), but you still have to get the charging current into the batteries that need it.

[Dockhead]

Originally Posted by boatbod

That's all true, but the OP said he wanted to charge 4 banks not 2. While suggesting the addition of a second alternator does boost the vessel's charging capabilities, it does not meet the original requirement. Obviously if he only has one alternator it needs to be pretty capable (externally regulated, continuous duty etc etc), but you still have to get the charging current into the batteries that need it.

No one ever suggested that adding a second alternator would solve this problem all by itself.

You can be nearly 100% sure that if he only has one alternator, it is the standard car-type alternator which was originally delivered with the main engine, so is NOT capable of continuous duty, even if it is externally regulated.

Therefore, installing a second alternator, a large frame school bus alternator, would be an excellent first step towards improving the OP's charging system, if it's possible on his boat.

Then, assuming the generator has its own alternator (and I've never seen one without), he only has to deal with one bank without its own charging source -- the thruster bank. This can be dealt with with a latching relay.

[boatbod]

Originally Posted by Dockhead

No one ever suggested that adding a second alternator would solve this problem all by itself.

You can be nearly 100% sure that if he only has one alternator, it is the standard car-type alternator which was originally delivered with the main engine, so is NOT capable of continuous duty, even if it is externally regulated.

Therefore, installing a second alternator, a large frame school bus alternator, would be an excellent first step towards improving the OP's charging system, if it's possible on his boat.

Then, assuming the generator has its own alternator (and I've never seen one without), he only has to deal with one bank without its own charging source -- the thruster bank. This can be dealt with with a latching relay.

I've worked on lots of vessels with single alternators that have already been upgraded to high output/externally regulated. While there are certainly many weekend sailors out there running standard 60A Hitachi's, the numbers are certainly not anywhere close to "nearly 100%".

[Davidhoy]

A little detail may clear up some of the discussion. I have a Westerbeke 82B engine with a Balmar 120 amp externally regulated alternator. The alternator output goes into a dual output battery isolator, currently programmed at 15.1 volts to compensate for the voltage drop across the isolator diodes. Strangely there are two battery cables connected to each of the output studs on the isolator. There is other strange wiring, and lots of 1/2/both switches (at least 3 that I've counted). I want to find a simple and reliable way to charge all the batteries with a minimum of fuss, and reduce the chance of accidentally leaving a switch in the wrong position that drains the wrong batteries. I also want to plan for future addition of solar panels and an appropriate charge controller

So what I've come up with, subject to change of course, is as follows. Get rid of all the 1/2/both switches and the isolator. Run the output from the alternator (and any other future charging sources) directly to the house bank. Reprogram the external ARS-4 regulator to a lower voltage more suitable for charging the house bank. House bank is 4 brand new group 31 12v 105Ah FLA batteries connected in parallel. Next, connect charging bank (2 12v FLA batteries connected in parallel) to the house bank via either a Blue Sea Systems ML-ACR or a Xantrex Echo Charge. Include a switch to connect the house bank to the engine start circuit in case start bank is depleted, just an plain selector switch rather than a 1/2/both to avoid a large current surge from a full house bank to an empty start bank. Next, connect the windlass/thruster bank (currently a single 12v FLA battery, but thinking of adding a second in parallel for extra capacity) via an ML-ACR or Echo Charge. This bank is not so critical, so no switch to manually merge the banks. As others have suggested, I'm going to let the generator take care of its own start battery, perhaps with a manual switch to connect the engine start bank if something bad happens.

So, how could I improve upon this general plan? ML-ACR or Echo Charge? Both have pros and cons...

-David


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