The Offshore Voyaging Reference Site

Tips, Tricks & Thoughts:


  • An Interesting Sailboat Electrical System Upgrade Case Study

    Scuttlebutt have an interesting two-part story about upgrading the electrical system in a J/105. Worth a read, even though this is a racing boat.

    To me the takeaways are:

    • How terrible the electrical systems are in production boats, to the point of useless, at least for offshore use. They were running the engine 8 hours a day to keep up with demand!
    • Replacing the stock alternator driven by a single belt is job #1 in any electrical system rebuild.
    • Replacing the standard internal regulator that ramps down charge current way before the batteries (lead or lithium) are even close to charged is part of job #1.
    • Details like properly crimping battery cables are vital.
    • In most cases the best bet with a production boat electrical system is to tear the whole battery and charging system out and start again.
    • Read the manuals, several times.
    • Most of what you see out there on YouTube about lithium is bogus.
    • A dedicated and isolated start battery is the only way to go. Off/one/two/both switches are just silly.
    • Seems like Electromaax has some good kit. I spent a little time on their web site and was impressed.

    All useful, but the biggest takeaways are:

    • Just getting the alternator and regulator right reduced charging from eight hours a day to one.
    • They would have got the same benefit with an appropriately sized lead-acid bank, but it would have been bigger and heavier, so in this case lithium was a clear winner, but only for that reason.
    • Without the alternator and regulator upgrades, upgrading to lithium would have been a total waste of time and money—getting charging right is the key to success.

    Much more on electrical system upgrades:

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  • How To Blow Up Your Alternator

    Anytime I write about batteries and charging someone is bound to bring up one of the clever gadgets that fool a stock alternator into charging at a higher current for longer without resorting to external regulation.

    Some of these gadgets, particularly the VRC-200 from Nordkyn Electronics, are undoubtedly very clever—here’s another one I wrote about.

    And I can certainly see using one of these as a quick and relatively inexpensive way to make the stock alternator charging a small battery bank on a boat used for weekends, and perhaps the occasional week cruise, charge more quickly and efficiently.

    But for an offshore voyaging live-aboard boat, these things are not a good idea.

    Most alternators that come with our engines will not last long if pushed hard day in day out, particularly if trying to charge a large bank (lithium or lead-acid)—stock alternators are simply not designed for that kind of duty cycle.

    That said, the Nordkyn will extend alternator life by monitoring its temperature, but that’s going to mean that most of the time the alternator will not be putting out much because stock OEM alternators heat very quickly as soon as they come under load.

    Of course you could use the Nordkyn with a heavy duty alternator, which would be a good combo.

    But my thinking always has been, and remains, if we are going to the trouble of installing a high-capacity bank, we might as well do the charging right with a rugged alternator designed for the job, installed right, and with an external regulator that won’t be subjected to the heat inside the alternator.

    And then if we are going to do the alternator right, we might as well go the whole hog and do the regulator right too.

    Fun Demo

    By the way, Victron have a fun demo showing how fast they can burn out an alternator when charging lithium batteries. There’s a lot of good stuff to learn here, particularly the counterintuitive fact that low engine RPM will do more damage.

    That said, we offshore boat owners should understand that even a big lead-acid bank can fry alternators too—our 800 Ah at 12 volts (9 kWh) AGM lead-acid battery bank on the McCurdy and Rhodes would happily lap up 250 amps for an hour, at least, if we had had an alternator that big, and regularly sucked 150 amps for two hours out of the alternator we did have.

    Anyway, have a watch, it’s interesting:

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  • Beware Lithium Battery Sales

    In the last few weeks I have been getting a series of emails from Battle Borne aggressively promoting sale pricing on their lithium batteries, see the above.

    As far as I can see, these are batteries that don’t have any way to communicate with external charging sources or even a way to inform you that they are about to load-dump and turn your lights out.

    In our opinion, this type of battery is:

    And further, our advice is that only batteries that can communicate through CANbuss (wires), not Wi-Fi or Bluetooth, with charging sources and monitoring systems should be used on boats, particularly offshore boats.

    Much more here:

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  • Wind Generators Can Be Dangerous

    A few weeks ago I wrote an article on renewables in which I opined that the days of wind generators are, for most cruising usage profiles, over. Too much windage, too much noise, in return for less generated electricity, particularly when it matters, than many people believe.

    The interesting thing is I got surprising little pushback.

    Anyway, here’s another reason to think seriously before installing a wind generator: the things can be seriously dangerous, as this cruiser found out the hard way.

    So if you do decide to install a wind generator:

    • Make sure it’s high enough that no crew member, even standing on the side deck or lazarette, can extend their arm into the spinning blade.
    • And, further, if the thing runs amok in high winds, it’s better to let it destroy itself, rather than risk limbs trying to physically stop it.

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  • Kilowatts and Horsepower

    I’m as concerned about climate change as anyone, and maybe more than most, but obfuscation and pretengineering does not help us get to a sustainable future.

    A good example is the way that electric-drive vendors use horsepower when talking about the diesel engine they want to replace and kilowatts when talking about their offerings.

    You see, horsepower and watts measure the same thing: power.


    It’s that simple,

    I was triggered to write this by an electric-drive company claiming that installing their serial-hybrid drive—diesel generator driving an electric motor—in a long thin efficient motorboat would save 30% in fuel burn over the standard diesel engine that comes with the boat.

    But here’s the smoking gun, they promised 8.5 knots top speed with the generator driving the electric motor, but with the standard diesel that boat can do 18 knots and cruises efficiently at 10.

    Yup, all they have done is decrease the power, probably by more than half. Of course that will save fuel.

    But here’s the thing, in most usage profiles for cruising boats, simply putting in a right-sized diesel engine and settling for say 9 knots cruise and about 11 knots wide open—still faster than the electric—instead of 18, would almost certainly save more fuel as well as costing way less (think less than half), and weighing less, than an electric motor, generator, and a huge lithium battery bank.

    The latter to run silent for an hour or so…and then have to be charged with…the diesel generator, in most cases.

    Wait, it gets worse, weight is a killer on a boat like this, making the hybrid setup an even sillier idea since it will weigh way more than the right-sized diesel and so make her even less fuel efficient and take up more space.

    What fevered mind came up with the idea that burning diesel to create rotation (generator engine), and then turning that into electricity (generator alternator), and then turning that back into rotation (electric motor), is more efficient than burning diesel to make rotation (diesel engine) in the first place—conversion losses are a bitch (they compound)—one conversion always beats three.

    Sure, electric is great, as long as we stay close to a source of renewable produced power, but staying close to the dock is not what people will use this boat for—and no, a practical amount of solar panels are not going to help much.

    Which brings us a full circle.

    It’s always a danger signal when a sales person talks HP one moment and kW the next. They are probably trying to hide something, and now you know what that is.

    And no, there is nothing magical about a horsepower or a watt just because it was produced by an electric motor. The whole torque thing is most-all BS too when applied to cruising boats—great though if you want to get a heavy train moving from a standing start.

    More about all this here, including a very cool calculator, which will let you see if your usage profile will benefit from an electric drive. It’s a bit out of date but the basic physics does not change…conversion losses are a bitch…wait, I already said that.

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  • An Even Better Alternator Regulator?

    There has been a lot of excitement recently about the release of a new alternator regulator that takes direct aim at the WakeSpeed WS500‘s position as the only truly smart regulator, primarily because it measures the current (amperage) that goes into the battery and then acts on that information, rather than making a bunch of guesses about the state of the battery that are usually more wrong than right, like, for example, the regulators from Balmar—I explain all this in more detail here and here.

    The new regulator is the Zeus from ARCO, and both Panbo and Rod Collins, who advised during the development, are pretty excited—I recommend that you read Rod’s article for an insider’s view on how this new regulator came to be.

    I’m super excited too since the new regulator fixes a problem that I have been beating on Al Thomason, inventor of the WakeSpeed, about since the WS500 came out: no easy way to program it and see what it’s doing over Bluetooth—Al and I seem to chat every six months or so about one thing and another and I’m sure he is getting sick of hearing it!

    And the Zeus seems to be easier to install and program in a bunch of other ways; for example, the harness it comes with will work with both N- and P-type alternators.

    But here’s the thing.

    I know from our chats that since the WS500 was released, much, possibly most, of Al’s energies and smarts, which are prodigious, have gone into making his regulator work seamlessly, mostly over CAN bus, with the ever more sophisticated lithium battery management systems from companies like Lithionics and Victron, as well as many others.

    Here’s an example of how tightly Al has integrated the WS500 with Victron’s products, including their system monitors.

    We are talking close cooperation here. For example, in a multi-BMS multi-battery Lithionics setup, if one of the BMSs goes offline, the WS500 will know that and automatically adjust its charging profile accordingly.

    The point I’m making is that it’s all very well for ARCO to claim that they have all this cracked on day one, and much more besides, but is that real when one of the smartest engineers in the business has a five-year lead on them?

    And process control programming and communication, which is what this is, is an iterative process of try, debug, try again, debug…

    And further, keep in mind that with this stuff one bad bug could take out thousands, or even tens of thousands, of dollars worth of equipment in the blink of an eye, or render your system down until sorted out.

    And one of the things that I know Al has focused on, because he’s a deeply experienced process control engineer, is failsafe, so if his regulator ever gets confused about what’s going on it defaults to shutting things down, or at least switching to less potentially damaging charge parameters.

    This is actually one of the reasons it can be a bit frustrating to get the WS500 working the way we want it to. The default configurations are very conservative.

    So sure, if you have a nice simple and robust lead-acid battery-based electrical system, give the Zeus a try, if you wish.

    But if you have, or are contemplating, installing a sophisticated lithium battery-based system, I suggest sticking with the WakeSpeed WS500 for a while while ARCO make the almost inevitable early-days mistakes on someone else’s boat. And also until the manufacturer of your battery and BMS tell you they are 100% happy seeing their batteries charged by the Zeus.

    And one final thought. The Zeus page claims to make it super easy to change parameters with your phone. Sure that’s cool, but with ease of change comes the temptation to play around indiscriminately and changes can lead to big problems, so be careful.

    All that said, don’t get me wrong, I’m still super-happy to see a competitor to the WakeSpeed WS500—bet we see that Bluetooth capability I have been bitching about for four years real soon.


    I like Al Thomason and he has been good to me by tirelessly sharing his smarts in phone calls and emails.

    On the other hand, I’m on record as more than a little sceptical about Firefly/Battle Born, the company that bought WakeSpeed, so I think those two kinda cancel out.

    You should also be aware that Al has arranged for AAC to get two WS500 regulators for free, one of the early ones (now working on our J/109), and a month ago, one of the newer ones with a NEMA 2000 output that I will install this winter and play with next summer.

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  • No, Lithium Batteries Don’t Burn Boats

    Every so often, someone sends me a link to this article, originally published in Professional Boat Builder and repeated at Sailing Anarchy, that starts with the line:

    Lithium-ion batteries start fires.

    First off, the author does not differentiate between lithium cobalt oxide (the battery type in your phone) and lithium iron phosphate (LiFePO), the chemistry generally used for service batteries on boats, which is much safer and less volatile.

    In fact, recently, ABYC tried to set one of the latter types on fire and had no luck.

    Second, he goes on to say that a large number of boat fires are caused by batteries.

    I don’t think that’s true.

    What I would agree to is that a large percentage of fires on boats are caused by poorly designed and installed electrical systems, and that includes those installed by the “professionals”:

    The electrical system on our new-to-us J/109, as installed by the builder in 2004, was a fire looking for a place to happen, mainly because of inadequate fusing.

    And then in the years after she was built and before we bought the boat and rebuilt the electrical system, “professionals” had made the fire risk far worse with stupid changes and additions.

    This is a distressingly common situation, and don’t make the mistake of thinking that just because your boat has passed survey that the electrical system is safe. Ours did and wasn’t.

    And don’t get me started on the dangers of electrical systems designed and installed by boat owners who watch a few YouTube videos, source lithium cells from some vendor on eBay, and have at it.

    So to me, the correct statement is:

    Lithium batteries don’t burn boats, poor battery and electrical installations burn boats, regardless of battery chemistry.


    I have written a lot more about this in this Online Book, including how to decide if lithium batteries are right for your boat:

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  • Sneaky Power Users

    We were on the boat for a couple of days last weekend and one evening I decided to check email and the weather on my iPad.

    But when I picked it up, it turned out I had forgotten to charge it—it was as dead as John Cleese’s parrot.

    Not a problem, we have a USB charging port on the boat and a USB C (it’s a newish iPad) cable.

    I plugged in the iPad and, since this had reminded me, my iPhone 13, then at about 50% charge, into a different port.

    The photo at the top of the Tip shows the total current draw before plugging in these devices:

    • Five LED lights on below,
    • AIS with drag alarm,
    • propane sniffer,
    • boat monitoring system,
    • and two anchor lights
      • will be another Tip and is why the radar is on (in standby).

    The photo below shows current with both devices charging, and no other changes.

    Yikes, these two handheld devices are drawing 3.5 amps at 12 volts, or 160% of what it takes to power a small boat at anchor at night.

    Yes, I know, in a couple of hours or so both devices will be fully charged and only require a trickle of amps to keep them there.

    Still, suppose Phyllis charged her iPad and iPhone, too, and then maybe we have guests with devices, and then there’s the iPad we use for navigation. And many boats have one or two laptops…

    It’s stuff like this, albeit not by itself, but added to other sneaky users of amps, that push cruisers into expensive electrical system upgrades including: excessive arrays of solar panels and/or the clutter, noise, and weight of wind turbines; or a generator.

    Worth thinking about.

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  • Good LED Steaming/Deck Light

    We fitted a MarineBeam LED Steaming/Deck Light on the mast on our J/109 a year ago, and so far I’m impressed.

    Small, light, relatively inexpensive, and amazingly bright, with incredibly low current draw.

    Of course we don’t know how reliable it will be over time, but so far so good.

    By the way, I have never used deck lights at sea. Too dazzling and disorienting, and, worst of all, our own bodies throw shadows just where we want to see. Much prefer, and recommend, head lamps.

    The primary reason we have a deck light is to reduce the risk of someone running into us because they did not look up and see our masthead anchor light. Yes, it happens.

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  • Tidy Up The Wiring

    One of the most satisfying jobs we can do in a refit is to simply tidy up the wiring.

    I took the above picture a few days ago. Certainly not perfect, and not as nice as I could do if I tore the whole works out and started again, but a heck of a lot better and easier to troubleshoot than it was when we got the boat two years ago.

    Everything is now properly fused and labeled, and I also must have taken 50 pounds of unused or over-length wire out of the boat.

    Cleaning up gave me space to move the AIS that some lazy tech had installed in the head to where it belongs, and to install a boat monitoring gadget (far left)—more on that coming in an article.

    And best of all the high-voltage wiring is now safely covered. Here’s how.

    And here’s a pic of the dog’s breakfast I started off with when we got the boat.

    Much more on electrical systems.

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  • Battle Born Batteries Get The Memo

    Great to see that one of the largest vendors of lithium batteries has finally got wise to the fact that when used on boats, lithium batteries with an internal BMS must be able to communicate with external devices and the user to be safe and compliant.

    That said, Battle Born are making a lot of noise about the phone app (user communications) but are ominously quiet about CAN bus communication, which is the best way to manage a safe and functional marine installation.

    However, given that Dragonfly, the parent company of Battle Born (not to be confused with Firefly Batteries), bought Wakespeed last year, hopefully Al Thomason, designer of the best alternator regulator out there, the WS5000, will pull levers behind the scenes to make sure they actually do this right, rather than just produce a pretty phone app to bamboozle the non-technical.

    One other point, Battle Born are making a big deal out of now being ABYC compliant with this announcement, but kind of glossing over the fact that, as I read the standard, all of the tens of thousands (guess) of batteries they have sold to yachties over the years without these features are not compliant.

    I wonder how long it will be before insurance companies start requiring ABYC E-13 compliance before renewal? Could be a lot of secondhand Battle Born batteries looking for a home, and some very pissed off boat owners.

    Seems to me that the very least Battle Born should do is offer a very nice discount on the new batteries to anyone who bought the old batteries, say in the last two years. Some sort of trade-in would be even better. Heck, maybe they could even upgrade the old batteries with the new communications technology.

    Anyway, moral of the story: Don’t buy batteries with an internal BMS that can’t communicate with charging sources or warn you before things go wrong.

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  • Recommended Deck Wiring Glands

    I have a pathological hatred for drilling holes in the deck of our boat, but sometimes it’s unavoidable, and when it is I’m guided by a healthy dose of deck-leak paranoia—it only takes one passage with a leak over your bunk to instill said condition for life.

    The cables in the shot will be under the instrument pod, but even so I wanted them properly waterproof, since green water hitting the pod would definitely find a way in—see…paranoid.

    These glands from Scanstrut are the best I have used. Multiple sizes and styles and each comes with several seals with different-sized holes and even a blank in case we need a custom size as I did on the one on the right.

    Highly recommended.

    And if you are wondering how I built the little shelf for them, here’s the hack.

    Now all I have to do is get over my case of the sulks at Tillotson Pearson for building a boat with a nice instrument pod and then not providing a sensible way to get wires to it. I ask you.

    This is the kind of stupid, but far too common shit we want to fix with the Adventure 40.

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  • Wire Routing Hack

    I have been running a bunch of new cables up to the instrument pod on our new-to-us J/109 while installing a better on-deck navigation system, including radar.

    The cables run through the head under some trim in a very tight space with no room for wire ties, and they needed to stay put while I got the trim back on.

    The answer was a hot glue gun. Worked a treat as you can see in the above photos and only took a few minutes.

    I bought a low-temperature gun (100c) to avoid any risk of melting the insulation on the cables (105c).

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  • While Converting To Lithium

    Member Rob sent us the above photo of the very cool (in more ways than one) equipment and battery bay he and his installer built in the aft cabin of his 2002 Beneteau Oceanis 473 while they were changing the boat over to a lithium house (service) bank.

    Prior to that change, as is so often the case with productions boats, the batteries were in much less functional positions, too low in the bilge and subject to engine heat.

    This brings to mind two thoughts:

    • Lithium battery systems are way more fragile and complicated than lead-acid, so when making the change we want to make sure everything is well away from the engine, well ventilated, and easy to access, as well as laid out in an organized way to make troubleshooting easier.
    • Lithium batteries are about four times lighter and three times smaller than lead acid for a given usable capacity, so improving location and installation is way easier than it would be with lead acid.

    Does this make changing to lithium a no-brainer for everyone? No. Here’s how to decide if lithium is right for you.

    For those of you who want to nerd-out, Rob was kind enough to provide the following details on the photo:

    Equipment from forward to aft in this locker under the starboard quarter berth (forward = bottom of picture):

    • Two Damp Rid containers in process of being changed and secured with cable ties
    • 3 x LiFePO4 batteries secured with truck-style ratchet tie-downs
    • 3 x Blue Sea safety relays
    • 3 x high-capacity fuses
    • At right slightly out of picture on longitudinal bulkhead, MasterBus interfaces
    • Hidden behind bunk crossbeam is the mains 240V residual current device (RCD)
    • Top right is the MV shore-power charger and inverter Mass Combi Pro
    • Top left are the two MV solar controllers
    • Out of picture and the other side of the boat is the MV AlphaPro regulator connected to MV 130A alternator

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  • Answer to Electrical Quiz

    The Answer

    A bit over a week ago I posted an electrical quiz question.

    A couple of members came close in the comments, but no one got it exactly right.


    I had the volt meter connected between a reference anode, immersed in the water next to the boat, and the boat’s bond system, and was looking to see if the meter kicked when I disconnected and reconnected loads and charging sources from the main positive busbar.

    If the boat had been metal I would have been connected to the reference anode and the hull.

    The clues to the right answer were that I was measuring volts, not amps or continuity, and that neither of the meter probes are present in the picture.

    I’m pleased to say there was no kick, but if there had been, that would have indicated stray currents flowing from the battery positive, through the connected piece of gear, through the water, and back to the bond system, and eventually the battery negative—we must always think about circuits.

    This is a good test to perform regularly on any boat and that goes triple for metal boast and those with saildrives.

    Further Reading

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  • Instrument Loads

    Seems like a lot of cruisers are leaving their instrumentation on, even when at anchor, these days.

    Do what you want, but this practice could push you into a major electrical system makeover that might not be necessary if we just turned that stuff off.

    The above photo shows the load (battery monitor to the right) from the instrument package and NMEA 2000 network on our J/109, added to a 9″ plotter.

    Nearly two amps at 12 volts. Leave that on for 24 hours and that’s nearly 50 amp hours out of the battery!

    And our system is comparatively small and miserly. Add in a big plotter, AIS, and worst off all, a laptop computer running navigation software, and we can easily burn through 100 amp hours or more.

    To put that in perspective that’s over a third of the power Phyllis and I used in the run of a day for everything on our 56 foot live-aboard boat!

    When left on all the time, small loads add up to big usage.

    Here’s how to estimate usage and choose the right battery bank size, the easy way—no long boring spreadsheet to fill out…we provide a short, and not boring, spreadsheet.

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  • A very bad place to put a solar panel

    Seriously? One wave strike, or even a gale, and this will end very badly. More on why we should not do stuff like this, at least if we plan to go offshore.

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  • Electrical Quiz

    Quiz is closed, here’s the answer.

    Why am I methodically disconnecting each load from the battery, and then reconnecting it while looking at a volt meter? And what’s the meter connected to?

    Answer in the comments:

    First right answer wins an Adventure 40 T-shirt.

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  • Gel Batteries a Winner?

    While researching for an upcoming article I noticed something interesting:

    Victron rate their Long Life Gel batteries at 2500 50% cycles, as against their AGM Super Cycle Battery at 1000 cycles, and not a lot less than their much more expensive lithium batteries at 3000 cycles.

    Could it be that the pivot away from gel cells toward AGM that occurred in the sailing community some 20 years ago was a giant mistake?

    I do know that both members Dick and Ginger Stevenson, and Phyllis and I, had very good service from Prevailer Gel batteries back in the day.

    Now before we get too excited it’s important to note that gels have one Achilles’ heel: they can’t be conditioned to get rid of sulphation from being left in a partial state of charge, as is common on cruising boats.

    Hit ’em with any more than 14.2 volts and they are toast in very short order.

    Whereas AGMs from both Victron (14.9V) and LifeLine (15.5V) can be charged at higher voltages to blow off that nasty battery wrecking stuff.

    Still, these days, with cost effective and efficient solar, fully charging a lead-acid battery regularly without shore power is a lot less of a problem than it once was.

    Should those who want to avoid the expense and complications of lithium be thinking of poor old neglected gels?

    Don’t know, but it’s worth thinking about.

    Anyone out there using gels?

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  • Wire Tie Best Practice

    Our new-to-us J/109 was filled with wire ties like the one on the left. Horrible things because when changes and additions are made people tend to just add more wire ties over the existing bundle.

    So, as I clean up the wiring, I’m replacing the ones on the left with those on the right (first photo). Way better, because when I make changes at a later date I just snip the old tie and replace it with new, like so:

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  • Q&A—New Lead Acid Batteries From Victron


    Member Kimbal asked:

    I’m looking at an ad on Yachtworld for a boat that has “New Victron Super Cycle AGM batteries – 3 x 125ah (2022) – Note: These batteries are a new type of AGM which approach lithium in some respects, and matches the Carbon Foam Firefly batteries performance – capable of up to 100% depth of discharge occasionally, and 60-80% frequently without damage.” Have you heard of this, and does it sound legit?


    Yes, in fact that’s what we have installed on our new-to-us J/109, and testing at Ocean Planet seems to indicate that they do very well on deep discharges.

    So far we have not used them enough to say anything really useful, although they are looking good after one season.

    That said, it’s important to understand that Victron have two offerings with different strengths:

    • Super Cycle, which we selected because we have a very small bank and occasionally will need to take it a long way down, say when aboard for a weekend, but will be able to bring up to fully charged at our wharf when we get home.
    • Carbon Foam, which might be better for a long-distance cruising boat since they are more resistant to being left in a partial state of charge.

    Do note though that all discharge cycles of all batteries (lithium included) reduce life to some extent (batteries are expendables) so claims like “and 60-80% frequently without damage” are simply not true. Like with Firefly, it’s important to read the fine print.

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  • Portable Solar Panels For Cruisers

    The good folks over at Ocean Planet Energy are selling these foldable and portable solar panels.

    A couple of these will provide a cruising boat with around 100 amp hours at 12 volts over the course of a reasonably sunny day at anchor.

    To me this is a way better idea, at least to supplement a reasonable number of fixed panels, a good cruiser’s alternator, and possibly a hydro-generator for offshore use, than festooning a boat with a huge unseamanlike fixed solar array.

    Might even get one of these for our J/109, and I also think this, or something like it, could be a great solution for many Adventure 40 owners.

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  • Great Risk Quote

    You should obsess over risks that do permanent damage and care little about risks that do temporary harm, but the opposite is more common.

    Morgan Housel

    Morgan is one of the best thinkers about financial risk around. Often his thoughts apply to offshore voyaging too.

    This one applies best to the majority of cruisers who worry about lithium battery load dumps blowing the diodes in their alternators, a comparatively easy problem to fix, and completely miss the much greater risks from load dumps.

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  • Batteries And Generators Are Different Things

    It drives me crazy when sales people suggest that installing their lithium batteries automatically means we don’t need a generator.

    Batteries are a storage device, generators are…wait for it…a generation device. They are different things.

    Sure, installing a larger capacity battery bank (of any chemistry) might mean that we can anchor for longer, or sail for longer, without starting a charging source, but eventually, and in some way, those batteries will need charging…duh.

    And if we have enough solar to never need a generator, then we might not even need lithium batteries.

    Point being that confusing this basic difference between batteries and generators, sets us up to make bad system design decisions…and often spend our money unnecessarily.

    Navico should know better.

    More on the generator decision here (needs updating).

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  • ABYC Bans Twin Busses For Lithium

    Turns out that the new ABYC E13 standard for lithium battery installations on boats in effect bans separate busses for loads and charging sources. (Thanks to member Rick for pointing this out.) BMS shall respond to any conditions outside the SOE by activating the output disconnect device.

    My guess, and hope, is that this is probably the result of poor drafting, rather than intended. The problem, of course, is the word output.

    In my view, compelling the BMS to dump the loads just because of an overcharge does not increase safety, it decreases it, since load dumps are dangerous in and of themselves and overcharge is the most likely scenario to cause a disconnect.

    Hopefully ABYC will fix what I believe to be a mistake soon. Banning something that most industry experts I have talked to consider much better design (separate charge and load busses) does their credibility no good at all.

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