2/1/2023: Initial Post
2/2/2023: Post-publish formatting cleanup and minor edits
2/19/2023: Add comparative Spider Diagram
Much of what has been written about Lithium Ion Batteries on boats in the preceding 18 months suggests that they are “absolutely life changing.” To this observer, much of that commentary seems optimistic, written by technical people and generally to the exclusion of the needs of technical laymen. This article summarizes, but does not focus on, the technical merits of Lithium technology. I have written other articles   that focus on the technical considerations in much greater detail, and that material hasn’t changed since its preparation. This article considers a financial analysis of the factors and costs surrounding a retrofit of boats built upon traditional lead-acid technology to lithium chemistry technology. Conclusions: there are significant potential benefits and consequential risks that appear when retrofitting lithium chemistry batteries to pre-existing lead-acid applications. The costs of retrofitting an older boat probably cannot be justified on any financial basis; that possibility is not zero, but it is “minimal.” Lifetime retrofit-to-lithium costs are less only if the resulting system is owned for many years after the initial retrofit project is completed. Justifying a Lithium retrofit project in 2023 is only possible based on “personal, purely subjective value,” and not on any economic or financial basis
Just as there are several lead-acid battery technologies:
1. flooded wet cell,
4. Carbon Foam, and
there are also several lithium chemistry battery technologies found in widespread use today. Lithium chemistries include:
1. Lithium Cobalt Oxide (LiCoO2) – LCO
2. Lithium Manganese Oxide (LiMn2O4) – LMO
3. Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) – NMC
4. Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2) – NCA
5. Lithium Titanate (Li2TiO3) – LTO
6. Lithium Iron Phosphate (LiFePO4) – LFP
The current American Boat and Yacht Council Lithium Ion Battery safety standard, E-13, is silent on requiring any one specific lithium chemistry for use on boats. The E-13 standard uses the non-specific terms “Lithium Ion Battery,” or “Lithium Ion Battery System” throughout. However, the boating industry worldwide has chosen to utilize the least energy dense, safest of the lithium chemistries, the Lithium Iron Phosphate (LiFePO4) chemistry. At year-end 2022, LFP batteries have the least risk of any of the lithium chemistries for fire or explosion on boats or in RVs, and are as safe as lead-acid batteries in equivalent use. While these batteries do not spontaneously burst into flame or explode, if they are caught up in a fire of remotely-located origin, they are reported to be more difficult to extinguish than any of the lead-acid technologies.
Several of the lithium battery chemistries are routinely found in residential household electrical and electronics applications, such as the batteries used in handheld consumer electronics, UPS (Uninterrupted Power Supply) equipment, computers, hobbyist drones, home fire alarm and security systems, wireless telephones, eBikes, skate boards, portable power tools, Electric Vehicles (EVs), and of course, marine navigation equipment. Each chemistry has different electrical and mechanical characteristics. In the laboratory and in industry, different chemistries are compared to one another and selected for use in different applications based on six axises of their fundamental physical and electrical properties, as shown in graphic form as a “spider diagram” as shown in Figure 1
Figure 2 shows three spider diagrams overlaid on one another comparing three different, popular Lithium chemistries. This allows direct comparisons of the six battery selection criteria. LiFePO4 (LFP) is the chemistry most preferred for use on boats. The three most popular lithium chemistry batteries for e-Bikes and e-Scooters are Nickel Manganese Cobalt (NMC), Lithium Cobalt Oxide (LCO), and Lithium Iron Phosphate (LFP). Any e-Bike battery bought at or after late 2022 and onward should be certified to conform to the safety requirements of UL2849. Two things to note on this chart:
- LFP has best Specific Power, Life Span and Safety (which is consistent with marine industry descriptions of this chemistry);
- NMC and LCO both have better Specific Energy ratings than LFP;
- Cost and Performance numbers are similar for all three.
The configuration choices for lithium batteries range significantly, and each choice carries differing proportions of risk. One of the easiest and safest ways to upgrade to lithium today [early 2023] is with commercially manufactured “drop-in replacement” batteries from respected manufacturing companies like Battle Born, Lithionics, Mastervolt, ReLion, Renology, Victron and Xantrex. Many of these “drop-in” form factor batteries come with built-in BMS controllers, but not all. The specific disconnect device in drop-ins are not always mechanical solenoids. Many are solid state switches sensitive to all typical solid state component failure modes; in particular, surges induced from nearby external sources. In 2023, few of these BMSs comply with ABYC requirements for pre-disconnect warning alarms and integration of cross-BMS communications controls required by the current Lithium Battery Standard, ABYC E-13.
Individual LiFePO4, 3.2V cells can be bought from any number of online sources, and in recent years DIYers have been buying these 3.2V cells and “assembling” them into complete 12V, 24V and 48V LFP batteries. This project requires the inclusion of a suitable aftermarket external BMS controller and disconnect solenoid, which should be selected to comply with now-current ABYC E-13 requirements. It is well known in the professional boating industry and amongst insurers that this DIY approach has been “abused” by many DIY builders, either through lack-of-knowledge or willful disregard of safety requirements, so availability of some components have become limited. For example, to limit corporate liability, some manufacturers of BMS equipment have stopped selling their stand-alone external BMS units to DIYers.
As of January, 2023, some marine insurers are refusing to insure vessels with “Lithium Ion” battery platforms. We aboard Sanctuary were formerly insured by Markel America, a good option for us because Markel offers Personal Liability Insurance through a “liveaboard” endorsement to their base policy. In 2021, Markel started turning away boats with Lithium Ion battery systems. Entering 2023, Markel and Hanover are two underwriters that have adopted very strict underwriting regarding lithium Ion batteries.
Hanover Insurance will not bind, or remain with an insured at renewal, for a boat that has, or adds, lithium ion batteries to the vessel.
Markel – guidelines for lithium (LiFePO4) batteries are:
1. maximum hull value $150,000,
2. maximum liability limit $500,000,
3. batteries must be sourced from a known and proven USA manufacturer, and have a BMS also “made” by a US company; note: “assembled in the USA” does not mean “made in the USA,” and
4. batteries must be professionally installed.
Markel is using these very strict criteria on all new risks.
If a current Markel policyholder installs LiFePO4 batteries, the company would not know unless/until their presence was exposed at a survey or became apparent in a claim scenario. If a claim were to occur, the underwriter could interpret that as a contract violation, so read the insurance contract exclusions very carefully.
If a new construction vessel is built with a LiFePO4 system designed and installed by the OEM manufacturer, the above conditions “may be” waived as of the time of this writing.
LiFePO4 batteries provide more energy density per unit space and weight than lead-acid, so watt-hour for watt-hour (amp hour for amp hour), LiFePO4 batteries take up less space and are less weight than their lead-acid cousins. In the equivalent floor footprint of a lead-acid installation, a lithium installation can provide much larger usable energy storage capacity. Re-charging LiFePO4 batteries can take less time, reducing generator runtime. Sailboats, because of their relatively short periods of engine runtime, can benefit from Lithium batteries to a larger degree than power boats. Blue Water power boats on ocean transits may benefit from lithium batteries to a greater degree than intracoastal and near-coastal cruisers. For all boats, auxiliary additions like solar panels are more functional, utilitarian and affordable for most small and mid-sized cruisers.
If the desire to retrofit LiFePO4 batteries is to extend the practical limits of “off-grid living” – that is, long-term anchoring with comforts like air conditioning and space heating – LiFePO4 can provide that technology potential, albeit with significant additional electrical system engineering needed within the operating platform, and certainly, enormously more charging system capacity. Twelve volt systems aren’t practical for these larger power demand requirements, so electrical system upgrades to 24VDC and 48VDC platforms, and resulting segmentation of the boats’s electrical system, may become a retrofit expense, and greatly add to the “total cost of retrofit.”
The ABYC Lithium Ion Battery standard, E-13, released in July, 2022, is neither stable nor comprehensive at this time. For example, the v1.0 document states (blue text are quotes from the E-13 Standard text):
13.5 General Requirements
13.5.2 Lithium Ion Battery Systems shall be installed, commissioned and maintained in accordance with the manufacturer’s recommendations.
But, not all battery manufacturer’s have provided specific instructions in the past, nor do they all do so today. The standard is out ahead of the market. Perhaps by July, 2023…
13.4.3 SOE Parameters shall be adhered to for determining the system design, installation, storage and operation of a lithium ion battery.
But, not all battery manufacturer’s provide detailed Safe Operating Envelop (SOE) specifications today, so buyers must be familiar with the ABYC standard’s content in order to be sure the batteries they buy are actually compliant.
13.5.4 Batteries or cells shall meet the testing requirements of at least one of the following standards:
18.104.22.168 IEC 62133
22.214.171.124 IEC 62619
126.96.36.199 IEC 62620
188.8.131.52 SAE J2929
184.108.40.206 UL 1642
220.127.116.11 UL 1973
18.104.22.168 UL 2054
But the above is just a list of Euro and North American test standards. Their content coverage either doesn’t overlap or only partially overlaps. The value of certification to any one of them is questionable – “feels good” – but anyone who reads that list has to conclude it’s likely to change.
I expect there will be an early review cycle for E-13 rather than the normal three year or five year standards review cycle. So Lithium buyers today are exposed to a moving target upon which insurance underwriters will roost until some form of relative stability is achieved. There are no US-made batteries on the market today that have pursued UL or ISO certification requirements in the past. One safety standard that is widely promoted is UL 1973; not itself a performance standard, but a physical abuse standard that applies generically to all battery chenistries. The good news is, UL 1973 testing does confirm that LiFePO4 batteries do not burst into flame or explode when abused. The bad news is, certification to UL 1973 is very expensive for the manufacturer and is not yet widely done. Because batteries are competitive, some less expensive than others, buyers can easily overlook a testing standard while trying to contain out-of-pocket costs of a lithium retrofit solution. I consider “standards” to be a critically important step forward, but not yet a stable environment.
Some [mostly high end] boat manufacturers are installing LiFePO4 systems as optional equipment on new construction. Boat manufacturers who are offering LiFePO4 in new construction have performed system design integration engineering (in the context of what’s known today about these systems) beyond the capabilities or self-discipline of most DIYers. These systems include the best available supplementary/ancillary controls, in order to deliver an entire system design solution that minimizes ownership risks and performance disappointments to their retail buyers. The buyer of such a vessel receives the benefit of the more detailed engineering required by the system to operate reliably. And, those new-construction systems – of which the lithium battery cells are only one component part – are itemized as “optional equipment,” carrying delta price tags of up to $100K per boat build above the prices of their base lead-acid platforms.
DIY Owner Responsibility:
One must know one’s personal skills and skillset limitations. Lithium technology brings new skills and new technology issues to the workplace. To illustrate this point, one might ask themselves if they can DIY install an inverter/charger, from scratch, so it works as intended and doesn’t trip ground fault breakers ashore. To make an even easier test case, suppose I limit the task to swapping out an old, failed inverter/charger with a compatible new unit of greater power capacity? Extending that same skills self-analysis to lithium powered electrical system design is instructive. A lithium system retrofit is a far more complex and technical undertaking than simply installing or replacing an inverter/charger, especially if the retrofit involves moving from 12V to 24V or 48VDC power.
Batteries are a commodity purchase and Return-On-Investment (ROI) is a financial measurement. The only way to get LiFePO4 batteries to offer ROI is by owning the retrofit system for 10 – 12 years at a minimum. Many buyers approach major purchase decisions based on ROI. Very few buyers will achieve any financial return from retrofitting a boat built on a lead-acid battery platform. In consideration of the often “hidden” costs of retrofitting these batteries into a boat designed and built for lead-acid platforms, the actual return period is likely to be much longer than stated above, but will not be less. For those anticipating a boat sale within 12 – 24 – 36 months, a retrofit of this magnitude would be financially unwise.
A “value proposition” includes financial considerations but IS NOT purely a financial measurement. Value propositions are filled with “personal preference” choices. A succinct “value statement” I support was recently suggested as follows: “Value is not always monetary. It can be in creature comforts, safety or just the satisfaction of ownership.” My own previous “value statement” has been: “if you want it, and you can afford it, then you should have it.” These statements describe buyers who can spend $5K or more on the batteries, and on unknown additional retrofit costs ranging from an additional $5K to $20K to $50K, without caring about any kind of actual financial return for that outlay. I view that as equivalent to paying $25K to go to the Super Bowl; “if you want to and you can afford to, then you should go.” But lots of us choose to watch the game on TV. For those who cannot or do not care to treat battery replacement as a “disposable cost,” then the calculus for “value” ranges back towards typical economic measures.
There are many personal values and attitudes involved here, and it’s unfortunate that lower total-cost-of-ownership (TCO) and actual ROI is often a primary advertising and sales strategy, suggesting to buyers that retrofitting an older technology boat can justify the cost. A full and fair discussion of “financial return” would be balanced and truthful. And for those who “want it and can afford it,” also realize that two years post retrofit, not much, if any, of the upfront retrofit “investment” cost will be recoverable/recovered at boat resale time. Especially so when strict insurance limitations are factored in.
“How is ROI calculated?”
Following is my attempt to answer the question…
Some relevant, necessary background:
Reviewing technical detail and language behind the “cost analysis” discussion. In the lead-acid world, there are “start service” (engine starting) batteries and “deep cycle” (house) batteries. “Start service” batteries cannot generally be used in “deep cycle” applications, but “deep cycle” batteries can be used very successfully in “start service” applications. “Deep cycle” batteries make up “house,” “inverter” and “thruster” banks on boats. The US “industry standard” is that “start service” batteries are rated by their manufacturers in terms of Cranking Amps (CA, CCA, MCA) and Reserve Capacity (RC). “Deep cycle” batteries are rated by their manufacturers in “Amp Hours.” Amp Hour ratings in North America are based on an assumed standard rate-of-discharge of 20 hours. Lead-acid batteries discharged faster than the 20-hour rate cannot return their rated amp hour capacity. If a battery with a 20-hour rating of 100 amp hours is discharged in 10 hours, that battery will only return ~80 amp hours. This is electrophysics science; a function of Peukert’s Law, and all lead-acid batteries display this behavior.
The term “charge-discharge cycle” describes the average discharge withdrawn from a battery or battery bank as a percentage of the total capacity of the bank, per discharge, before subsequent recharge. The lifetime number of “charge-discharge cycles” a given battery or battery bank can return varies with several factors, an important one being the average depth-of-discharge per charge-discharge cycle. Depth-of-discharge is dependent on the capacity of the battery/battery bank, the electrical loads placed on the battery during use, and the time duration that loads are present. Laboratory studies show that 50% depth-of-discharge is the approximate point where lead-acid batteries return their greatest lifetime total Amp Hours of stored energy. Lesser average depth-of-discharge will provide more charge-discharge cycles, but not more lifetime Amp Hours returned. This leads to a reasonable design goal for boats with lead-acid batteries: battery bank capacity should result in an average Depth-Of-Discharge, in average use, of between 40% State-Of-Discharge (60% State-of-Charge) and 50% State-Of-Discharge (50% State-of-Charge).
Careful electrical system design is necessary to maximize battery service life. Amp hours returned over the total period of ownership is the basis of financial ROI. Aboard Sanctuary, we had times when we exceeded the 20-hour discharge rate (microwave use, main engine starter motor), which I deemed acceptable in bursts of less than 3 – 4 minutes. The way we used our boat, Depth-Of-Discharge averaged ~45% of total bank capacity (55% State-Of-Charge) by the time we recharged, measured from our Magnum coulomb-counting technology (vs conductance technology) battery monitor. “Charge-discharge cycle count” is a key advertising claim used by manufacturers to “project” usable service life. There is significant boat-to-boat variability in what different individual users and specific boats might experience in actual depth-of-discharge per charge-discharge cycle, but each specific case is unique to the specific boat and the way the particular owner uses the boat. Each specific use case is definable, predictable and repeatable.
Individual Ship’s Preferences/Needs:
Peg and I didn’t routinely anchor in one place for multiple days, but we do prefer anchoring to using marinas for our overnights. Anchoring in one place for multiple days does require periodic generator runtime. Our overnight anchoring goal was to never have to run the generator for our onboard energy needs, save in cooler weather for space heating or in warmer, humid weather for air conditioning. We never ran the genset overnight while both of us slept. The way we used our boat;
1. Battery stored energy was used for:
• house infrastructure (bilge pump(s), house water pump, toilet macerator(s), propane gas safety solenoid, inverter/charger “keep alive,” electric panel indicator lights, “always on” (parasitic) loads like boat monitor, AM/FM radio memory, etc),
• refrigeration (the single largest energy energy consumer on our boat),
• microwave, for heating drinks and meal prep (mostly supper),
• crockpot meals,
• space lighting as needed,
• TV/DVR/DVD (3 – 4 hours per evening),
• “always on” computer/network router/wi-fi
• iGadget overnight battery charging,
• anchor light,
• occasional overnight instrument use (VHF, GPS, AIS, depth sounder), and
• “Mr. Coffee” for coffee while doing email, forum, weather and route planning “stuff” in the morning, prior to engine start.
2. Management variables:
• more TV and less reading, more battery energy used;
• less TV and more reading, less battery energy used;
• oil lantern used for space lighting, less battery energy used;
• electric lights used for space lighting, more battery energy used;
• LEDs for space and nav lighting purposes reduces battery energy needs;
• more propane stove use, less microwave needed, less battery energy used.
Battery Capacity Design:
To accomplish our goal of “no generator use on overnights,” in the summer months (9 hours of darkness), we generally needed ~220 Amp Hours of battery capacity per overnight. In the winter months (14 hours of darkness), our overnight energy consumption needs went up to ~300 Amp Hours. To set up our boat for our “maximum use case,” we needed at least 300 Amp Hours of usable stored energy to be available. To get that needed energy while also honoring the 50% lead-acid technology “capacity penalty,” we needed ≥600 Amp Hours of total battery capacity to maximize service life ROI on my battery investment. So the above provides context to approach the question, what “amp hour” energy storage capacity do you need, as an individual boater on your specific boat (yes, this is a personal question) in order for you to use your boat the way you want to use your boat? EVERY BOAT AND EVERY BOATER IS DIFFERENT.
Sanctuary was fit with a 12V DC electrical system. My options for getting 300 Amp Hours of usable energy in the lead-acid world included:
- 12V Group 24, Group 27 and Group 31 form factor (“size”),
- 12V 4D and 8D form factor (“size”), and 6V
- Golf Cart form factor Batteries.
Available size(s), space for batteries to occupy on the boat, and unit weight that I could safely handle unassisted determined our best choice. Spec sheets of all of the various US Battery manufacturers show Amp Hour capacity by battery form factor, so it’s easy to look up and compare manufacturer to manufacturer.
The final choice is one of the three practical, usual and prevailing lead-acid technologies:
1. flooded wet cells,
2. AGM and
All of these lead-acid technologies come in all standard battery form factors, so that’s not planning limitation. Across manufacturers, all of the same form factors offer about the same amp hour capacities, so that’s not a planning limitation. The only practical difference is that wet cells need periodic watering, and AGMs and Gels do not. Flooded wet cells are 1/3 the cost of AGM and Gel batteries. They also all have about the same kind of service life if used in the same average profile of charge-discharge cycles. I had space and convenient access to my batteries, so that brought me to meet my 300 Amp Hour minimum usable capacity with six, 6V flooded wet cells. The batteries I chose were “Duracell labels” from Sam’s Club, and are manufactured in the United States by East Penn. East Penn is a major US national battery manufacturer, maker of “house label” batteries for West Marine, NAPA and other large retailers. Each of those EGC2 Golf Cart batteries was rated at 230 Amp Hours. Conclusion: a bank of three paralleled sets of two 6V EGC2s in series gave me 690 total amp hours, 345 usable amp hours, for a total cost in May of 2022 of $650, DIY installed, after core deposit.
The service life of ALL BATTERIES is measured in usable charge-discharge cycle capacity. Most lead-acid manufacturers claim ~300 charge-discharge cycles for flooded wet cells and ~400 charge-discharge cycles for AGMs and Gel. These claims are based on laboratory conditions, and I have never actually reached those numbers in the real world. I have had multiple sets of AGMs and I have never gotten anywhere near the claimed 400 charge-discharge cycles while discharging to 45% – 50% SOC. And, AGMs fail dramatically; they go from “perfectly fine” to “unserviceable” in a day or two.
Six 6V GC2s became our baseline choice, at a discount club price of $650. For AGMs of that same total capacity (~700 Amp Hours), $1800, and about the same cost for Gels. Flooded wet cells are available anywhere in the developed world and all third world countries, in ANY small town or any big city anywhere, and every minimally trained mechanic everywhere can install them. Six 6V GC2s fit in the same space footprint as two 8Ds, so more energy density can be achieved in that form factor footprint. Recycling wet cells is easy. Utility is very high. And for my $650 investment, I get 5 years of useful service life from my humble 6V flooded wet cell Golf Cart batteries the way I use my boat. Never a hiccup; it just works.
Let’s consider the Lithium option. I’ve shown that I needed 300 amp hours of usable capacity, which is a function of the boat loads and our usage of stored energy, not of the batteries themselves. To get 300 amp hour capacity with lithium, there is no 50% capacity “penalty.” I only need a little more than the real 300 amp hours. A myth about lithium is that they can be routinely 100% discharged; but that is NOT true. Doing that will shorten their service life. But the “capacity cushion” penalty is much less than lead-acid, at about a 15% – 20%. So in preparing this analysis, I used Mr. Google as my cost researcher (I “looked ’em up” online).
December 13, 2022, online ad sampler:
1. Battle Born, 400 amp hour package of 4 drop-ins, $3796.00
2. Lithionics, single 320 amp hour battery, $4499.00
3. Xantrex, 240 amp hour, $2800.00 at West Marine
Clearly, a lot more raw dollars for 300 Amp Hours of LiFePO4. And these numbers do not include any cost contingency for additional retrofit costs to protect against things like accidental BMS shutdown, bigger alternators or voltage regulators, system voltage increase or system segmentation, battery monitoring equipment if not already in place, pre-disconnect alarm signaling or drop-in coordination (or an interface to CANBUS communications and other monitoring systems). Purchasers of lead-acid batteries could safely assume that the batteries from commercial sources met the ABYC E-10 Battery Safety Standard for lead-acid batteries. In order to assume an apples-to-apples comparison here, this analysis assumes that these Lithium batteries meet the current – and still emerging – ABYC Standard E-13 for LiFePO4 batteries. Probably not a universally true assumption in 1Q2023.
So three pages later, we finally get to the question, “where is the ‘payback?’”
It is very reasonable to expect LiFePO4 batteries to last longer, in charge-discharge cycles, than lead-acid batteries. My experience was that we got 5 full years from my six 6V batteries. If the batteries are supposed to deliver 300 charge-discharge cycles, 5 years is 60 nights at anchor per year. LiFePO4 batteries claim to deliver 2000 – 4000 charge-discharge cycles. So at 60 nights per year, that means LiFePO4 batteries will last between 33 and 67 years. Well, that’s the math, anyway…
IF I JUST ACCEPT THAT MATH AS TRUE, looking at $4000.00 initial cost of lithium batteries, and coming from AGMs at $1800, the AGMs would be replaced $4000/$1800=2.22 times in order to “break even” on the cost of the batteries. The payback there comes from the lifetime difference in projected charge-discharge cycles: 2000-(2.22*400)=1112, so the LiFePO4 gives at least 1112 more charge-discharge cycles, a very nice potential lifetime return on amp hours per dollar spent. Maybe. And with my 6V flooded wet cell batteries, that projected payback would be $4000/$650=6.15 times to get to “break even” on the cost of the battery. But this time, 2000-(6.15*300)=155, so LiFePO4 gives more, but not nearly as much more, benefit in charge-discharge cycles returned.
Since the lithium batteries keep on giving “far into the future,” the $4000 initial battery cost is amortized over a longer time period, and that makes the annualized cost-of-ownership less than lead-acid. In the longer term, therefore, lifetime dollars-per-amp-hour returned is more favorable for lithium than it is for lead-acid, but getting to that point on a retrofit of an existing boat is still a lengthy proposition, measured in tens of years. Assuming the above are “typical numbers” that “most boaters” are experiencing/will experience, the straight “break even” financial return with AGMs happens after year 11 or 12, and the financial return with simple flooded wet cells happens at 6.15 *5 years=30.77 years from date of installation. Yes, owners that keep the boat long enough will certainly see ROI with a Lithium battery retrofit.
In either case, though, it may be true that you may “never need to replace batteries again.”
The “Value” Argument Revisited:
“Personal Value is not always monetary. It can be realized as creature comforts, safety or just the satisfaction of ownership.” I completely support that statement. If one buys into the, “I JUST PLAIN WANTS IT NOW” argument, my question becomes, “WHY?” What do you think this is going to do for you that warrants the enormous sunk cost? What else could those same discretionary dollars go into that would ALSO return “creature comforts, safety or just the satisfaction of ownership?” Nice stabilized binoculars, refurbished salon with “his” and “hers” reclining lounge chairs, bigger/brighter video displays at dual stations for viewing the chart plotter? Something that might provide even greater personal value and utility?
The battery costs in this analysis are all proportional to amp hour energy requirements, and scale up in proportion to amp hours needed in pretty much linear fashion. As capacity-of-installation goes up (in Amp Hour needs) the ratio behind my ROI calculations stays pretty constant. Which is why I say, wait one more replacement cycle (3 – 5 years). Then at least, when making the upgrade, there will be a STABLE, PLUG ‘N PLAY system that will be much less likely to disappoint.
Now one further consideration. for those who are “a little older,” as we found ourselves to be in 2022, and facing the realities of mobility limitations and health issues, the very real question of how much longer you’ll be aboard the boat becomes real. I replaced our batteries in May, 2022. As a forced accommodation to advancing age, mobility and health issues, we sold our beloved Sanctuary in August, 2022. So I ask readers: in your opinion, which made more sense for us in May of 2022: $650 or $4K, and the need at minimum to segment my electrical system? Part of this analysis has to be, how much longer will you really own the boat? If that answer is, “greater than 10 – 12 years,” then depending on your personal values, your spending calculus could be different than if the answer is, “less than two to three more years.”
SUMMARY: there is no doubt that LiFePO4 systems have specific applications today, and I don’t doubt they are going to become the mainstream design platform in the near-term future. As of today [late 2022/early 2023], for the owner operator without electrical training, and for the less-skilled DIYer, on small and intermediate sized intracoastal and near-coastal cruising boats, these systems are very much an “emerging [beta test] technology.” To achieve “success” with them, owners must know a great deal about them. Users must be able to install, maintain, troubleshoot, and repair them WITHOUT outside technical assistance or support. Systems must include the capacity to re-charge them. Owning them is definitely not yet “install, forget and enjoy;” not “Plug ‘n Play.” The demands these systems place on owners far exceed the demands of equivalent lead-acid systems fit with a battery monitor. And note that the voices who most loudly extol the benefits of these Lithium chemistry batteries are people who, themselves, personally possess more advanced electrical skills.
My advice for the period of early 2023 through 2025: to those considering a lithium upgrade today, a thoroughly self-critical personal skills assessment is appropriate:
1. Understand that you are out ahead of the most current ABYC Standard, E-13, and thus exposed to unforeseen non-compliance issues as the standards mature and evolve.
2. Understand that UL Testing and Safety Standards, and EC/US/CAN safety standards, are also ahead of manufacturers current engineering and manufacturing ability to demonstrate compliance.
3. Be able to evaluate and select control and monitoring equipment, including the batteries and the internal BMS solutions that provide user safety, from a marketplace of generally inadequate and non-standards-compliant present equipment availability.
4. Understand what the existing standards require, and be able to do your own system design work, or be prepared to hire a qualified professional consultant to create a custom design deliverable, including a full-blown financial budget and an “Errors and Omissions” warranty.
5. Personally have the skills to install, operate, maintain and troubleshoot the installation yourself, on your own, without help.
6. Understand that paid, professional diagnostic skills are in very short supply worldwide, so if a performance or safety problem arises, be able to personally diagnose and correct a failing underlying design of a failing component(s), or both together, and implement your own updates to correct the issue(s) yourself, in exotic places and under less than convenient circumstances.
For those WITHOUT advanced electrical technical skills, then my advice is, wait another 3 – 5 years while this stuff works itself out via new and updated standards, new standards-compliant equipment and new system designs. Why? Because the current environment does have the ability to disappoint.
 First edition, published July, 2022, effective for boat builders and boat equipment manufacturers July, 2023.
 References found online in many places; i.e., here: https://batteryuniversity.com/article/bu-205-types-of-lithium-ion
 SomEV website, here: https://www.som-ev.com/blog/everything-about-e-bike-batteries-from-a-battery-engineer
 Source: Jack Martin Insurance, Annapolis, MD; 14 December, 2022.
 Lithium Ion batteries are often rated in “Watt Hours,” a close cousin of “amp hours,” and the two quantities are easily converted back at forth.