Ben Stein, over at Panbo, has just published a good review of the new Victron NG LiFePO4 batteries and related BMSs, well worth the time to read for most any cruiser who is even faintly interested in lithium batteries.
I won’t try to duplicate the excellent job Ben has done describing what makes this new system from Victron exciting, but rather I’m going to highlight a few things that jumped out at me as probably1 making this a good option for offshore cruising boats, particularly when paired with one or more Lynx Smart BMS NG(s):
Assuming this system proves to work as described by Victron, and we build a system with two paralleled NG BMSes with a NG bank split between them, is the seamanlike system requirement for a lead acid bank in series to power critical loads eliminated?
There can still be good reasons to include at least some lead acid battery capacity in a system with paralleled Victron’s BMSs. One example is including a charging source (such as a Watt & Sea hydro generator) that is not capable of DVCC into an otherwise DVCC-enabled system. One way to accomplish that is to have the non-DVCC charger connected to a separate battery that is in turn connected to the main lithium bank with a DVCC-capable DC-DC charger.
Hi Mark,
Good point and I like your solution better than compromising DVCC at recommended here: https://support.wattandsea.com/hc/en-us/articles/115004346689-Can-I-use-Lithium-batteries-with-the-Watt-Sea-converter
Hi Jonathan,
Great minds think alike! I have been wondering about exactly that myself. For a big boat with a deep pockets owner, maybe so, but for smaller boats the serial backup lead acid is a lot less expensive option.
I consider DVCC to be one of the key competitive advantages of going with a Victron lithium battery system, but something that Stein fails to mention is the very limited selection of DVCC-capable components that are also fully ABYC compliant. This is particularly true for chargers, inverters and inverter/chargers. Unless Victron’s certification efforts are ahead of their documentation, the only options for these that satisfy the ABYC’s requirements (e.g. UL 458 for inverters and inverter/chargers) are a small selection of MultiPlus and MultiPlus-II inverter/chargers that include only models with 120VAC output, no more than 3000VA rating, and only 12V or 24V.
Of course, bigger systems can be built using the options to combine multiple inverter/chargers, and 230/240V can be achieved in a couple of different ways, but an insurable, ABYC-compliant, DVCC-capable system that includes an inverter running on 48V batteries does not appear to be possible at this time.
I still really like Victron gear and the parallel redundancy capability of the BMSs in particular, but potential users who want an ABYC-compliant system should be aware that their options are very limited and designing such a system requires careful reading of the ABYC standards and Victron’s documentation and certification statements.
Hi Mark,
Are you saying that UL 456 is a requirement for ABYC? If so, I guess you are right, but I did a quick google search and could not find that link.
That said, even if UL456 was required, I guess I would not be overly worried about that given that Victron is a European company and I would guess compliant with all CE and ISO requirements. Assuming that’s true, I can’t imagine an insurance company having a problem, particularly since ABYC is, at least as far as I understand it, not a real government standard but rather a set of industry guidelines, whereas CE is, I think, a European Union standard.
Yes, A-31 Battery Chargers and Inverters requires UL 458:
31.5.4.2 All marine power inverters shall meet the applicable requirements of UL 458, Power Converters/Inverters and Power Converter/Inverter Systems for Land Vehicles and Marine Crafts, and Supplement SA, Marine Power Converters/Inverters and Power Converter/Inverter Systems.
31.5.5.1 Devices that serve as both battery chargers and inverters shall meet the requirements o fboth battery chargers and inverters (see A-31.5.3 and A-31.5.4).
Full ABYC compliance is something that may be negotiable with an insurer, but if they want your boat to be ABYC compliant, then you can’t use many Victron products.
Hi Mark,
Good point, thanks for the research. You saved me doing just that. Anyway, seems like Victron are on this, although it’s worth checking before buying.
Hi Mark,
Seems like Victron are on this anyway: https://intelligentcontrols.io/blogs/technical-articles/victron-inverter-charger-ul-certification-cheat-sheet
That document isn’t entirely accurate, and there has been no change in it or Victron’s documentation for the items listed as “under progress” or “pending certification” for many months. Further, there is no indication that the higher power and voltage products will ever receive UL 458 certification. Rather, they are being certified to UL 1741, which is relevant to shore-based, grid-connected operation, not to ABYC compliance and marine use.
Wow, I really should have scoured the Victron docs before commenting based on the last time I did so. As of the end of February, there is now one 5000VA option that is UL 458 compliant: https://www.victronenergy.com/upload/documents/Certificate-UL-458-Quattro-12V-5kVA-120V-VE.Bus.pdf
A correction: There is one way to build a 48V system with an inverter/charger that is DVCC-capable and ABYC-compliant. The MultiPlus-II 48/3000/35-50 120V meets that spec.
https://www.victronenergy.com/upload/documents/Certificate-Safety-UL-458-MultiPlus-II-12-24-48V-3000VA-120V-080525.pdf
“Meets all ABYC requirements for fully automated BMS controlled disconnection.”
One detail on this: ABYC does require battery disconnect switch(es) between the batteries and the BMS that the Lynx Smart BMS NG cannot satisfy on its own, even though such ABYC-compliant battery switches do not appear in most Victron system diagrams.
Hi Mark,
Sure, that’s true, but adding a battery switch is no big deal.
Yup, not a big deal — just a detail to be aware of that is not obvious from Victron’s documentation.
Hi Mark,
Just checked and the latest example diagram from Vicron includes battery switches: https://www.victronenergy.com/upload/documents/Genless-monohull-with-Victron-MultiPlus-Lynx-Smart-BMS-NG-600Ah-NG-Li-HP-Alternator-Wakespeed-WS500-Pro-regulator.pdf
No, John, those switches do not meet the requirements of ABYC E-13. One serves to disconnect only the inverter/charger. Another only disconnects two branch circuits. And the third is the starter battery disconnect. E-13 requires that the switches disconnect the lithium batteries entirely, and that they be as close as practical to the batteries themselves — i.e. right next to the battery fuse(s), before the BMS. That diagram and almost all of the rest in Victron’s documentation relies upon the contactor in the Lynx BMS to disconnect the batteries from the rest of the system. ABYC specifically requires a lithium battery disconnect independent of the BMS.
And fwiw, using the Victron Lynx Class-T Power In in an ABYC-compliant manner (the 7” rule for battery fuses) is going to be challenging.
Hi Mark,
True but that can solved by sheathing the cables which make a longer run compliant (if memory serves) or using a single T fuse holder, which is generally my preferred solution:https://www.morganscloud.com/2024/03/21/lithium-battery-buyers-guide-part-4-fusing/
Hi Mark,
Perhaps you are right, I have not sussed it out. However, I do think you might be wrong, since I can’t see how it would be good practice to insert a switch between the BMS and the battery it’s protecting. How would that work with an internal BMS, as many batteries have? My thinking is that the BMS is part of the battery and therefore putting the disconnect switch after it makes sense. As to distance, that’s a diagram, there no reason that the switches can’t be close.
All that said, I think we are getting a bit far in the weeds here. Victron are an international company selling product all over the world and are, in my view, doing a good job of showing some example installations. Will they be totally compliant in all countries? Probably not. Should we expect that or devalue them because they are not? No, I don’t think so. It’s up to each of us to make sure we comply with the requirements of our own country and insurance company.
I also think that according any sort of sanctity to ABYC is a mistake. Let’s not forget that ABYC is made up of North American industry insiders, rather than being an impartial organization like CE. For example, at least in my view, requiring a North American standard (UL) of a company that has already passed CE smacks of protectionism not protecting the public, although I could be wrong, given that I’m not a standards expert even in my wildest dreams!
Yes, there is no way to put the battery disconnect between the battery and the BMS for batteries with an internal BMS, but ABYC still requires that those batteries can be disconnected independently from the BMS and with a switch “in a readily accessible location as close as practicable to the battery.”
You might be able to argue that disconnect switches after an external BMS like the Victron Lynx satisfy that requirement, but the system in that Victron diagram is still insufficient since the switches do not disconnect the batteries from the solar and alternator charging busses, and there are also multiple available, unused connection points in the Lynx Distributors that do not go through the switches. The arguable options for ABYC-compliant battery disconnect switches in a Lynx BMS system would then seem to be many switches covering every circuit on the distribution side of the BMS, or a small number of switches (or one) on the battery side of the BMS that disconnect the batteries before they attach to the Lynx busbars.
I realize that Victron sells all over the world and that their documentation shouldn’t be expected to be tailored to ABYC compliance. I’m simply calling attention to the fact that if ABYC compliance is a requirement, then a professional or DIY installer cannot indiscriminately purchase Victron equipment and blindly follow their documentation and example systems. Using that approach, there will be some significant points of conflict with the ABYC standards.
Hi Mark,
Not sure I agree. If you look closely at the diagram you can see that the solar has a breaker with switch, and again the is no reason that can’t be close to the batteries and I have a vague memory about an exception for the alternator feed because of the danger of turning it off at the wrong time, although I could be wrong about that—so many standards, so little time. Also note that the Alternator is fused and at the right end too, which is refreshing since I have seen far too many fused at the alternator which is wrong, but done by many ABYC certified techs. (#3) https://www.morganscloud.com/2022/03/19/8-checks-to-stop-our-dc-electrical-system-from-burning-our-boat/
That said, I think we are splitting the hair in four here. I’m sure Victron would not advise installing a system exactly as the diagram shows without being qualified, thinking about what we are doing, and consulting standards that apply in our country, and at least the owner who is not qualified and still installs a system will be at least somewhat protected from their hubris by a very smart BMS that can disconnect the whole thing using a massive contactor if it senses a problem. I for one would celebrate that ahead of anything we have discussed and never dream of inserting a battery switch, or anything else, between that BMS and the batteries, on the basis that the engineers at Victron are way smarter than I am and know way more about their kit than those setting ABYC standards.
ABYC does not require just over current protection, but a literal battery disconnect switch independent of the BMS.
Hi Mark,
The solar panel breaker has a switch. In my view that qualifies.
And I think my aging memory might be vindicated about the alternator. RC is not often wrong and you will note that in his last option at the bottom of the post he shows the alternator connected direct to the battery with a fuse: https://marinehowto.com/1-2-both-battery-switch-considerations/
That said, he does advocate for an alternator service disconnect, but if memory serves (yet again) that’s RC-smarts at work not ABYC.
A suggestion for you: A little less certainty is always a good idea. Starting a comment with “No, John…” is not a great way to keep things collegial.
The disconnect switch has to conform to ABYC C-7 Battery Switches. 285-Series circuit breakers typically do not, or at least are not listed by manufacturers as being ABYC C-7 compliant.
My reading of E-13 is that ABYC wants the battery disconnect switch in a lithium battery system to be a kind of manual backup to the “output disconnect device” controlled by the BMS. An output disconnect device is “a switch controlled by the BMS which disconnects a battery or battery bank from charge and discharge sources, and other batteries or battery banks.” That is a more stringent requirement than those for non-lithium batteries where E-11.6.1.2.1 allows battery charging equipment like alternators or solar controllers to be connected on the battery side of the switch.
FYI, the updated ABYC E-13 standard (July 2025 edition) clarifies the issue of battery switches and BMS contractors.
E-13 now states:
13.6.7.1.1 An output disconnect device shall be permitted to serve as the battery switch, provided
it meets the following conditions:
13.6.7.1.1.1 It shall be a normally open monostable contactor (not solid state),
13.6.7.1.1.2 It shall be energized to close, and
13.6.7.1.1.3 the energizing power shall be directly interrupted by a remote switch meeting the location requirements of E-13.6.7.2.
13.6.7.2 A battery switch shall be mounted in a
readily accessible location and as close as practicable to the battery.
By my read of this, the Victron Lynx BMS would appear to satisfy this requirement.
Yes, that’s a significant change that can allow a Lynx BMS in some configurations to serve as a battery disconnect. To be sure of being compliant, in addition to using the switched-high configuration of the remote BMS switch, I’d use discrete switches instead of just relying upon the remote switching capability of, e.g., a Victron GX monitoring/control device. That separate switch and the GX can be wired so that you can still use the convenient switching capability of the GX as long as the separate, discrete switch is closed, but for safety reasons alone I’d want the separate switches — one for each paralleled Lynx BMS, as well as a master switch that will force all of the BMSs to disconnect. That way I’d know that no matter what any of the fancy electronics and touchscreens are doing, as long as those separate switches were all off, then the batteries will be disconnected unless there is an extreme failure in the BMS causing the contactor to remain closed.
ugh… It looks like there may still be an issue. 13.6.7.1.1.3 requires that the “energizing power” that closes the contactor be “directly interrupted by a remote switch”. I’m pretty sure that the remote on/off capability of a Lynx BMS does not strictly do that. Rather, the remote switch will produce a control voltage that the BMS will interpret as a signal that it should open the contactor by de-energizing it. In other words, the remote switch sends an indirect control signal and doesn’t itself directly interrupt the flow of the energizing power.
Maybe the remote switch is directly enough affecting something like the gate voltage of MOSFETs inside the BMS that are regulating the flow of the energizing power, and that is good enough to comply. Maybe it’s not.
It’s still not 100% clear (to me, at least) that separate battery disconnect switches are not needed when using a Lynx BMS in an ABYC-compliant system.
Hi Mark,
Yes, I think I would probably feel the same way, although it would take a lot of manual reading and sketching out of scenarios for me to be sure. It will be interesting to see if Victron drop the manual switches from their sample layouts.
Hi Tyler,
Thanks for coming up on that, good to hear. I need to break some time loose to read the new version.
Wow, this is seriously advanced stuff—pretty intense! Even as an electrical engineer, I find it almost impossible to follow. I’m not currently working on converting to lithium batteries or keeping up with all the latest components, so I’m a bit out of the loop on the newest tech. Unless you’ve spent hours buried in Victron and ABYC manuals, your comments really sound like a whole different language!
By the way, do you still find time to get out sailing?
Hi Philippe,
Very good point! That said Victron is moving to address that with complete suggested configurations for different usage cases and seem to be taking into account the, what I would call, “peculiarities” of ABYC like requiring a product that is fully CE certified to also get UL certifications.
And yes, sailing quite a bit at the moment, rowing too (just back), In fact that’s why you are seeing more short Tips at the moment, rather than the real deep dives I tend to do in the winter.
Sorry for pulling the discussion into the deep end of Victron vs. ABYC, but I do think that the details are relevant and worth being aware of. I really do like the design and features of Victron’s Lynx NG BMS, and I’ll try to shut up about the ABYC compliance issues now.
This is funny, I am just returning home from this install tonight. I purchased 2 300Ah NG LiFePo4 batteries + LynxSmart NG BMS tying it into my existing CerboGX with Skylla charger. I also am installing the WS500Pro with a new Balmar XT-250 alternator. It went very smoothly and everything worked as advertised. Once I had all the cables made for the connection to my boat, including the Victron smart Shunt (now redundant with all the data from the Lynx.) it’s all great and is charging up now, I can see and control everything via the VRM. I Love this stuff!
My experience with technology, 25 year IT vet, there is no such thing as ‘plug & play” but this did exactly that.
I am also an ABYC electrical tech, but still, surprised at how well this went together.
Hi. Timothy,
That’s so great to hear about how well this went for you. It would be great if you could update us from time to time as you use the system