What this covers
In this episode of Sound Bites, Jeff and Nigel discuss lithium battery technology for use in boats. They discuss some new technologies on the market, charging rates and the idea of "plug-and-play" lithium.
If you are interested in learning more about troubleshooting technical problems on your boat, check out Nigel's "Boat How To" Course online at https://boathowto.com/#aff=pysystems
Read our Boating Tech Talk Article, "Lithium vs. Firefly Carbon Foam Batteries?", https://www.pysystems.ca/resources/boating-tech-talk/lithium-vs-firefly-carbon-foam-batteries/
Check out the PYS website for more information on batteries, https://www.pysystems.ca/shop/power/battery/
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Nigel Calder argues that lithium-ion batteries for marine applications require UL 1973 certification, external BMS communication, proper understanding of actual charge rates (0.3-0.5C, not theoretical 3C), and realistic cycle-life economics; most boat owners cannot exploit lithium's cost advantage due to low annual usage, and marketing claims about drop-in replacements misrepresent the safety and technical requirements.
- UL 1973 testing provides necessary safety assurance against thermal runaway in critical locations (under beds, behind heads)
- Actual marine lithium batteries accept 0.3-0.5C charge rates, far below 3C marketing claims, making high-charge-rate specifications unusable without matching chargers
- Most boat owners cycle batteries 300 times/year, not the 2000 cycles needed to achieve lithium's cost-per-cycle advantage over lead-acid
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Lithium-ion batteries without external BMS communication capability and UL 1973 certification are unsafe for marine use, particularly when installed under bunks or behind heads, as thermal runaway can cause fires that destroy the vessel.
“the other thing that i want in my boat with lithium ion which i don't have at the moment i do have lithium-ion batteries i won't discuss which brand they are um but the other thing i want with my lithium-ion batteries is a sticker on the battery that says it's tested to ul 1973. that's the most aggressive abuse testing standard in the marketplace”
A lithium-ion battery with external BMS communication is fundamentally different from a passive battery—it becomes an 'energy storage system' capable of sending shutdown signals to charging devices when overfull, warning messages when depleted, and coordinating with all boat charging systems to manage state-of-charge actively.
“it's not really a battery it's an energy storage system because now we've got the capability to integrate this battery uh with all the charging devices on the boat for example so that if the battery sees a condition in which it's it's likely to get over charged it can send out a message to shut down the charging devices if it sees a condition in which it's getting close to shutting down because of a lack of charge you can send out a warning message”
Testing systems intentionally to destruction is a valid engineering approach: it identifies failure modes that normal operation would never reveal, and communicating these failure modes back to manufacturers drives design improvements that protect all users, creating 'bulletproof' systems.
“that's that that's a i mean breaking things to learn things is a good way i mean we we don't intentionally break things uh our client base do that for us right you know the thousands of voters that we can help out and we learn from we learn from our own mistakes other people's mistakes yeah you know as long as you're learning from the mistakes then tomorrow is a better day”
UL 1973 testing for lithium-ion batteries includes extreme abuse scenarios: heating until thermal runaway occurs, deliberately creating cell imbalance by fully discharging one cell while fully charging all others at maximum charge rate, introducing BMS faults while requiring redundant fault-handling capability, and ensuring case strength sufficient to prevent projectile ejection.
“they do crazy stuff like they put a battery in a with a metal screen around it and they put it in an oven and they heat it up until it explodes when you know which you can get pretty much any lithium-ion battery to explode and it has to have a battery case that's strong enough to make sure there's no projectiles that will come through the screen outside”
Most marine lithium-ion batteries available accept 0.3C to 0.5C charge rates, with a small handful accepting 1C; this is substantially lower than the theoretical 3C maximum often marketed and far lower than typical AGM batteries, which accept up to 0.5C charge rate at 50% state of charge.
“most of the boat batteries lithium-ion batteries we have uh looking at 0.3 c not 3c one-tenths of that charge rate many of some of them will go to 0.5 c and a handful of them will go to one seat”
People are resistant to being told what to do, but when given reasoned explanations for why something should or shouldn't be done, they typically arrive at the correct conclusions themselves and become fully committed to the action, rather than remaining skeptical about a directive.
“people have a hard time being told what to do in general that all of us certainly myself but if you tell me why i should do something tell me the reasons you give me an explanation and i'll come to that conclusion then yeah i'm all in you know and i think that's what it comes down to it's not just telling them voters what they should or shouldn't do but educating them that's the reasons why we should do something or the reason we shouldn't and then let most people will come to the same conclusions”
Most boats above 30 feet with standard electrical loads require a minimum 400 Ah battery bank at 12 volts (equivalent to 4 golf cart batteries), which is a baseline for typical marine electrical systems.
“you know 400 amp hours is a tiny battery bank for any boat above 30 feet i mean it's it's it's vanilla like there's nothing to it it's like it's just a sedan four doors that's it it's basic”
High-efficiency alternators (APS and Ocean Planet Energy brands) have three key performance advantages: high maximum output (typically rated when cold but drops as internal temperature exceeds 100°C requiring efficiency focus), high efficiency ratings around 70% (vs typical automotive alternators at ~50%), and critically, the ability to ramp up output at low RPMs rather than requiring 2000-3000 RPM to reach full output.
“well there's two things one is the the maximum output actually the three things the maximum output which is typically speaking for these alternators are radio when they're cold well when you run them hard within five minutes they're uh up to the case is probably up to well over 100 degrees centigrade um so then they they uh the output goes down so then efficiency becomes really important and there's fps alternators are some of the more efficient ones on the market you know the typical automotive alternator is maybe 50 efficient much of the time uh these aps alternators around 70”
Most marine lithium-ion batteries do not carry UL 1973 certification because the testing is prohibitively expensive, creating a market where the safest batteries are also the most expensive and least commonly purchased.
“there's not many batteries have it because the testing is very expensive”
Nigel created a list of design specifications for the integral alternator system without having technical capability to implement them himself, but drew from 40+ years of experience using marine electrical equipment to define what he wanted, then found engineers capable of translating those specifications into implemented technology.
“i drew up a list of design characteristics that i wanted to see anything i have no technical capability whatsoever to to make it happen but i know what we want because i've been doing this for long enough and dealing with the bitter kit that we have and the failings that they have so i know what i want uh it's a matter of finding the people that can then take that and translate it into a piece of kit that will do that”
Nigel deliberately has no air conditioning or major electrical appliances on his boat as a design choice that enables his power generation system to supply all electrical needs without external charging, representing a philosophy of autonomy and system matching.
“on our boat because we don't have air conditioning uh but we don't have you know fridge and freezer and microwave and all kinds of bits and pieces uh but in uh on half an hour of engine run time when we're pulling up the anchor to get out of an anchorage or we're leaving the dock in the time it takes us to do that we can put enough energy in that battery bank with that integral alternator to run the boat for 24 hours”
Calder and his team learned from direct field testing by their customer base (thousands of boat owners), their own mistakes, and other people's mistakes, and that learning from these mistakes makes tomorrow better than today.
“we don't intentionally break things uh our client base do that for us right you know the thousands of voters that we can help out and we learn from we learn from our own mistakes other people's mistakes yeah you know as long as you're learning from the mistakes then tomorrow is a better day”
Boat owners are willing to spend $300,000–$1,000,000 on a 40-50 foot catamaran but then seek to minimize battery costs, creating a misalignment between vessel investment and electrical system investment, despite the battery being in a high-risk location (under beds or behind heads) where failure means loss of the entire boat.
“i see but voters that are buying you know catamarans for you know half a million you know 300 400 750 a million dollars which sounds like an obscene amount number but i mean that's some books are costing that and that's not on the top end that's you know that's a 40 foot 45 foot 50 foot camera right and and yet they've they've spent x on the boat and then they're looking and i have to have some orders and it's it's almost like a misalignment in values”
Developing a high-output low-RPM alternator system with integrated electrical controls required $3 million in corporate R&D funding plus additional private investment, and involved extensive testing to failure (destroying belts, blowing diodes, testing open-circuit scenarios) to identify and solve design problems.
“we spent three million dollars of of uh some big corporation in the u.s funded that project three million dollars developing now wow yeah yeah that was then and then we had other money that we put in so it was a pretty intense uh development program”
The analogy of buying a cheap, flammable couch despite expensive boat purchase illustrates that rational cost-benefit thinking breaks down when facing price pressure, suggesting that cost-minimization becomes a psychological priority that overrides risk evaluation.
“i tell them i'm like why would you why would you be a smoker and have a flammable couch right you know it's less money to put flammable material on the couch but why would you want that”
During integral alternator testing, Calder discovered a harmonic vibration phenomenon that could break automotive timing belts (used in the system for durability) in just 4 minutes, a failure mode unique to his specific boat at certain engine speeds and with particular resonant features.
“there was one point with that testing where i'm where i discovered a means to create something called a harmonic vibration and i could break a belt in four minutes you know these are these are timing belts rip timing belts off a car that we were using because they're very rugged and i could make this belt go totally crazy and break a belt in four minutes so so then the uh the manufacturer had to spend a ton of money fingering it figuring out how this was happening nobody else could do it it was it was unique to our boat and certain speeds and and resonant features”
With a high-output alternator (8 kW) and lithium battery system, a 48-foot boat can generate enough electrical charge in 30 minutes of engine run time (during anchor-pulling or dock departure) to power the entire vessel for 24 hours, eliminating the need for extended engine runtime or fuel consumption for battery charging.
“on our boat because we don't have air conditioning uh but we don't have you know fridge and freezer and microwave and all kinds of bits and pieces uh but in uh on half an hour of engine run time when we're pulling up the anchor to get out of an anchorage or we're leaving the dock in the time it takes us to do that we can put enough energy in that battery bank with that integral alternator to run the boat for 24 hours”
Calder spent 40 years stressed about the state of charge of his batteries before developing the integral alternator system, constantly checking charge status and deciding when to run the engine for battery charging, which is a fundamental quality-of-life limitation of traditional battery systems.
“you know we've spent 40 years stressing over the state of charge of our batteries like everybody else you know constantly checking the state of a charge thinking maybe i better do a bit of battery charging and anchor these last few years”
When testing the integral alternator at 8 kilowatts and suddenly open-circuiting the battery bank to simulate a sudden load disconnect, the controller reacted fast enough and had sufficient dump load capability to shut the system down without any damage to the alternator or diodes.
“one of the tests i i did was to run the thing up to eight kilowatts and open circuit the batteries to see what happened you know with another one did you immediately smoke the alternator you blow all the diodes yeah that's what i heard our controller reacted so fast and it had such a decent dump capability that shut the system down without any damage”
Calder's boat has an 8 kW inverter installed to test what components fail under extreme load, deliberately maxing out electrical usage (boiling water with electric kettle, microwave, and hot water heater running simultaneously) to load the system at full capacity.
“what size inverters do you have on board right now yeah eight kilowatt inverter yeah how much eight kilowatts oh yeah everything maxed out i wanted to see what would break first”
The host visited UL (Underwriters Laboratories) testing facilities to observe how they conduct UL 1973 certification testing on lithium batteries, gaining first-hand knowledge of the testing methodology.
“i actually went to ul to see how they do that oh yeah oh yeah they do crazy stuff”
The boat is called a 'Model 46' but is actually 48 feet long, illustrating the disconnect between nominal marketing designations and actual vessel length in the marine industry.
“well it's they call it a model 46 but it's actually 48 feet”