The Best Lithium Marine Batteries For Your Boat 2025
Looking for the best lithium marine batteries for your boat?
If you’re looking to power your boat, then investing in quality marine batteries is essential. From providing energy for lights and pumps to propulsion, marine batteries are a must-have for water activities.
It took us a long time to make the upgrade but now that we have we wouldn’t go back. As a bit of a nerd about things like this I’ve been lusting over lithium batteries for a while now, and they live up to all my expectations.
With a decent set of lithium marine batteries (and of course well set-up solar and a marine wind generator) we can now comfortably run two laptops all day long, run our water maker, nav lights, cooking equipment, and pretty much anything else we might want or need onboard.
Watching sailing movies outside in the cockpit with a beautiful sunset backdrop is a new favorite evening activity that simply wasn’t possible before.
LiFePO4 lithium marine batteries are becoming increasingly popular due to their ability to provide reliable energy with minimal maintenance, which makes them the perfect choice for any boater wanting peace of mind on the open sea.
In this article, we’ll cover some of the best lithium marine batteries on the market today and explain why they could be just what you need on your next nautical adventure!
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Table of Contents
- Should you choose lithium batteries for your sailboat?
- Why Switch from Lead-Acid to Lithium?
- Is LiFePO4 better than lithium-ion?
- What’s the best brand of LiFePO4 batteries?
- What’s the best brand of lithium-ion batteries?
- The cheapest lithium marine batteries
- What about cold weather?
Looking For A Quick Answer?
✅ We recommend BattleBorn LiFePO4 lithium batteries
This is the setup we’ve gone for in our catamaran refit and couldn’t be happier.
If you want a long explanation then read on!
Should You Choose Lithium Batteries For Your Sailboat?
For most sailboats, the answer is now a resounding yes. You probably should upgrade to lithium batteries for your boat.
Lithium batteries have a huge number of advantages over older chemistries like lead acid.
They’re more efficient both while charging and discharging, you get more energy out of the pack without damaging them (they have greater “depth of discharge”); they last for a decade or more, versus 2-4 years for lead acid, and they’re lighter and smaller than their lead counterparts.
In fact, about the only disadvantage is price up front – but because they last significantly longer, they actually do work out cheaper on longer timelines.
Lithium battery technology has come on in leaps and bounds in the past few years, as we’re about to explore, and the cost has fallen quite drastically too.
The advent of LiFePO4 has even made them safer than lead acid, despite the common myths about exploding batteries!
Let’s jump in and look at the major differences between LiFePO4 and lead acid.
Why Switch From Lead-Acid To Lithium?
LiFePO4 has at least five major advantages over traditional options like wet lead-acid or AGM.
- Greater depth of discharge
- Far longer service life, or number of cycles
- Faster charge/discharge rate
- Greater efficiency when charging and discharging
- Greater energy density
Let’s look at each of these in turn.
Depth of discharge
If you’ve currently got lead-acid or AGM batteries on your sailboat, you’ll probably be aware that you can’t actually use their whole capacity without damaging them.
Say your lead acid battery nominally holds 100Ah (amp-hours). In an average lead acid battery, you can only discharge around half of that (50Ah) before you damage the battery. This is your battery’s safe “depth of discharge” (DoD).
Why is that?
Because your lead acid battery contains plates of lead immersed in an electrolyte solution – sulfuric acid.
When you discharge the battery, the acid reacts with the lead; producing electricity and causing crystals of lead sulfate to grow in the process.
The further you discharge the battery, the more sulfate forms and the harder it becomes. Push it too far, and the crystals harden onto the plates, preventing them from touching the acid, and you permanently lose that part of the capacity.
“Hard sulfation” is permanent and irreversible; it reduces the battery capacity, reduces the amount of power (amps) it can provide; causes the battery to get hotter when charging and discharging, dramatically reduces its life, and eventually kills it entirely.
Most cruising sailboats carry at least 400Ah of batteries to meet the demands of life aboard, but because the maximum depth of discharge of lead acid is 50% or less, in reality, they can’t access more than 200Ah.
When it comes to lithium marine batteries (LiFePO4), you can safely use 80% of the capacity every day, and you can go all the way to 100% DoD occasionally without doing any damage – you just shouldn’t make a habit of it.
So in the example above, the boat with 400Ah could actually access at least 320Ah of it – and up to 400Ah in a pinch.
That means the lithium pack has 60% to 100% more usable energy than the lead acid pack.
You could either carry half as many batteries or have twice as much power at your fingertips for comfort and convenience aboard.
Far longer service life or number of cycles
Every battery can only be charged and discharged a certain number of times before it dies. A quality lead acid battery can be charged and discharged – cycled – somewhere in the region of 750 to 1,000 times. LiFePO4 lithium batteries can be discharged somewhere between 5,000 and 10,000 times.
Why the huge range of values?
Because it’s relative to depth of discharge, which we talked about above.
The 750 figure is for 50% discharge of a lead acid battery. If you regularly discharge a lead acid battery down to 80% you can only expect around 220 cycles.
The 5,000-cycle figure for LiFePO4 lithium marine batteries is for 80% depth of discharge. If you only need to use 60%, you’ll see a lifetime of 10,000 cycles. if you only use 30% you could easily get to 100,000 cycles.
How do battery cycles translate to days, or time in the real world?
Most sailboats fully charge the battery bank from solar or motoring during the day, and then discharge them overnight to keep loads like fridges and lights running. In other words, you typically cycle the batteries once a day while you live aboard.
That means the 750-cycle expected life represents two years for a full-time liveaboard, or up to four for the seasonal sailor.
The pessimistic 5,000 cycle life of a lithium pack is 13.7 years full-time, and the optimistic 10,000 cycle life is… about 27 years. Naturally, double those if you only sail in the summer.
There are a few huge perks to having a pack that lasts decades instead of just a couple of years.
Firstly, if you’ve ever tried to lift a battery and remove it from your boat… those things are heavy. It’s awkward and stressful and time-consuming to change your pack every two or three years.
Secondly, it’s less likely to let you down when you least expect it. We’ve had lead acid batteries fail at really inconvenient times, and we’ve had to cut trips short or end our whole season early to deal with it.
When you’re on a boat, you’re relying on your batteries to keep the navigation lights on, the bilge pumps functional, keep the autopilot alive, start the engine, and often to pick up the anchor… it can be a real safety issue if they cop out at the wrong time.
And thirdly – cost. Lithium batteries are expensive, but once you divide the cost by the service life they’re actually far better value than traditional alternatives like lead acid and AGM.
Lithium might cost three or four times as much as quality lead acid, but the service life is at least six times longer – if not ten, or more. As a result, they’re generally two-to-three times better value than lead acid over a lifetime.
Faster charge/discharge rate
All batteries have something called a “C rating”, which represents how fast the battery can charge or discharge without damage.
Somewhat confusingly, the C-rate also changes with factors like temperature and voltage, and reduces as the battery fills up – it’s “harder” to cram the last bit of energy in – but for the purposes of this article, we’ll keep it as simple as possible, at the cost of technical accuracy.
Lead acid initially accepts about 0.1C – meaning you can charge the battery at 10% of its rated capacity per hour – so, our 400Ah pack could take up to 40A.
Assuming we’ve been good battery owners and only discharged it to 50%, we have 200Ah to put back, and in theory, we could be full in 5 hours.
But because the C rate falls off as the battery fills, we actually get to about 80% in the first 5 hours, and the last 20% takes another 3-5; for 8-10 hours of charge time in total. You can see this as a graph in the link above if you’re a visual learner.
LiFePO4 lithium batteries, on the other hand, can happily accept 0.5C. That means you can charge 50% of the capacity of a lithium battery per hour, or fill the whole pack in 2 hours.
And you really can fill the pack in 2 hours, because they have a very flat charge curve – their C-curve barely falls off as they fill up. You can actually charge them at 1C – 100% in an hour – but it reduces the service life of the pack, so most high-quality lithium battery manufacturers recommend sticking to 0.5C.
So how does this affect a sailboat in the real world?
Say there’s no wind and you’re motoring. Your engine probably has an alternator that charges the batteries when your motor, and on many sailboats that alternator can put out 90 amps, or even 150A.
If you have 400Ah of lead acid, you can accept less than half of the 90A figure, or less than a third of the 150A.
If you have LiFePO4, you can accept… all of it.
Assume both packs are 50% discharged, and you motor for two hours. The LiFePO4 pack would be fully charged – 95% or 100%, depending on which alternator we choose.
The lead acid pack would only have reached 65%. This is starting to blend into our next topic, so let’s talk about:
Greater efficiency when charging and discharging
It’s not just about speed – lithium batteries are more efficient when charging and discharging, too. Your charging sources – solar, wind, alternators, and generators – effectively go further when paired with lithium.
Up until now, we’ve talked about charging and discharging as though they’re 100% efficient – we supply 40A to the battery, it charges at 40A.
But that’s actually not true. Only about 80% of the energy you supply to a lead acid battery actually goes into charging – the remaining 20% is wasted, mostly as heat.
And when you try to stuff that final 20% in, and it gets “harder” – your C-rate drops right off – so does the efficiency, to as low as 50%.
LiFePO4, on the other hand, has 90% “round-trip” efficiency across the whole charge curve. 90% of the energy you supply gets used to charge the battery.
Let’s illustrate this with another real-world example (physics purists beware, we’re going to over-simplify a little here for the sake of convenience).
Say you have 400 watts of solar – a fairly average amount for a family cruising sailboat. We’ll assume our batteries are 12 volts (the most common set-up).
Watts simply means “amps times volts”, so 400W divided by 12V gives us 33.3A – that’s how much charging current those panels can put out.
Let’s also say we’re in the Caribbean, so we get a solid 6 hours of “solar insolation” (charge time) per day. For this example, we’ll assume we’ve run our 400A packs down 50% overnight.
Lead acid first.
To avoid dealing with complex curves, we’ll simplify things in lead acid’s favour and say that for the first four hours it can accept the full 33A. At 80% efficiency, that’s 26.4A per hour; 105.6Ah.
We’re now at 75% charge, so it starts to get harder… our chart shows the battery can now only accept 0.05C, so that’s max 20amps for hours five and six.
Realistically, our efficiency is now well below 80% as well, but we’ll continue being generous and call it 16A after losses; 32Ah total. Added to our 105.6Ah from earlier, we’ve managed to charge 137.6Ah in total. We end the day with ~337 amp hours stored in the battery; 84% charged.
Now LiFePO4.
We can accept the whole 33.3A all day long, and we do at 90% efficiency. So our calculation is nice and simple: (33.3*0.9)*6. We charge 179.8 amp hours and end the day with ~380 amp hours stored in the pack; 95% charged.
Same panels. Same charger. Same boat. Same sun.
More power from the same equipment.
The same applies when discharging, too. Explaining this properly would require getting super nerdy, and it’s probably beyond the scope of this article.
But suffice it to say lead acid batteries suffer from something called the Peukert Effect, which means that the voltage of the battery falls quite drastically when you try to pull power from it.
Because power (watts) is voltage times amps, if the voltage falls, you need more amps to provide the same power.
The voltage of a nominally 12V lead acid battery falls from 13V fully charged to as low as 10V when discharging (a 14% voltage drop). 400W at 13V is ~31A. At 10V, it’s 40A – you’re using 30% more current, discharging 30% faster, to do the same work.
Lithium (you guessed it) has a super flat discharge curve, and the voltage barely falls at all under load. We start higher, at 14.4V fully charged, and end higher too – 12.9V even way down at 80% DoD. 400W at 14.4V is 27A – already 10% less current than lead acid to do the same job.
And even when the pack is nearly empty, we’re pushing 31A – equivalent to the best-case current draw for lead acid, and 30% less than the depleted lead acid pack.
Okay, we went there… we got pretty nerdy. Let’s zoom out a bit.
Greater energy density
Energy density refers to how much power can be stored in the pack relative to its size (volume) and how much it weighs. Sailboats tend to have limited space, and also be pretty weight-conscious, so that’s an important metric.
Lead acid can store about 50 to 70 watt-hours per gram. LiFePO4 can store 200 to 260 watt-hours per gram.
That means lithium batteries have about five times the energy density of lead acid.
You can either have five times more energy in the same weight of battery, or, if you want to increase your sailboat’s performance, you could go a different route and carry one-fifth the weight in batteries for the same energy capacity.
In terms of volume, lithium is about three times more energy-dense. So again, you can either have a pack that’s three times smaller than your old lead-acid batteries and reclaim some space, or you can get a lithium pack that’s the same size and have three times more power.
Is LiFePO4 Better Than Lithium-Ion?
In a word, yes.
Lithium-ion batteries can be cycled between 300 and 500 times, depending on how deeply you discharge them.
As we’ve seen above LiFePO4 can be cycled 5,000 times if you abuse them, or more than 10,000 times if you take care of them. As a result LiFePO4 batteries last at least 10x longer, if not 20x or more, than lithium-ion.
To compound that, it’s much easier to damage a lithium-ion battery by over-discharging. In a pinch, you can use the whole 100% in a LiFePO4 battery, but you risk damage if you drop below 20% capacity in a lithium-ion pack.
LiFePO4 is a safer technology than lithium-ion – it’s extremely difficult to light a LiFePO4 pack on fire (check out this video of fire service professionals overcharging, piercing, crushing, and eventually attacking the pack with a blowtorch).
At the time of writing, there have been zero reported LiFePO4 fires on boats anywhere in the world; the ABYC recently collaborated with the world’s leading fire investigation organisation and likewise concluded there have been zero incidents.
When people tell horror stories about lithium battery fires, they’re usually talking about a third technology called lithium polymer – but lithium ion packs can and do undergo “thermal runaway” and catch fire. On a boat, where safety is critical, LiFePO4 is by far the most sensible choice.
Lithium-ion packs have slightly higher “self-discharge”, meaning the amount the pack discharges while it’s sitting idle. Lithium-ion self-discharges at about 5% a month, where LiFePO4 is 3% or less.
Lithium-ion packs also contain cobalt, which is toxic, making them more difficult to dispose of and recycle than LiFePO4. As the icing on the cake, LiFePO4 is slightly cheaper than lithium-ion because it relies on less-exotic elements like iron and phosphorus over cobalt.
So why would anyone consider using lithium-ion over LiFePO4?
The only real advantage to lithium-ion over LiFePO4 is that it has higher energy density. If you need to store lots of energy in a tiny package – like a battery for a smartphone or smart watch – then maybe it makes sense to choose lithium-ion.
Lithium-ion has an energy density of 150-200 Wh/kg, where LiFePO4 is usually between 90 and 120Wh/kg. As a result of the higher energy density lithium-ion packs tend to be lighter, which is another reason we see them used in mobile devices (and some electric vehicles).
But again, on a boat, the small difference in weight and payload is never going to justify the significant utility penalty.
One final thing to note is that LiFePO4 means “lithium ferro-phosphate”, and the “ferro” part refers to the fact they contain iron. As a result, some people call LiFePO4 “lithium IRON”, which is incredibly easy to mix up with “lithium ION”. Not very helpful!
We’ve gone into a lot more depth on LiFePO4 vs lithium-ion batteries, so if you’re still unsure then you should give it a read.
What’s The Best Brand Of LiFePO4 Batteries?
As you can see from the table below, when comparing three of the top brands of LiFePO4 batteries there is very little between them.
We went for BattleBorn batteries and our decision came down to a combination of who we felt had the best reviews, customer support, and price.
We’ll do a full review of our BattleBorn setup and the process we went through with them in another article, but we are thrilled with them so far and recommend them to everyone.
🏆 Don’t take our word for it! 🏆
Get in contact with BattleBorn today and see what they can do for you.
12 Volt Lithium Marine Battery Comparison Chart
We’ve compared three of the most popular brands of lithium marine batteries.
As you’ll see, there isn’t much in it, so you’ll want to get in contact with the manufacturers to be sure you’re happy with their customer service and knowledge base before making a purchase. It’s also worth noting that they do come with different price tags!
| Discharge current | Charge current | Cycle life | Weight | Data sheet | |
| BattleBorn | 100 A/200 A(30s) | 50 A | 75-80% of capacity after 3000 cycles | 31 lbs | Check here |
| Relion | 100 A/200 A(7.5s) | 5 A – 50 A/100 A max | 80% of rated capacity after 2000 cycles | 26.4 lbs | Check here |
| Dakota | 100 A/200 A(10s pulse) | 50 A | 80% capacity for 2000 cycles | 31.9 lbs | Check here |
What’s The Best Brand Of Lithium-Ion Batteries?
For all the reasons we’ve explored above, we’d strongly recommend choosing LiFePO4 over lithium-ion.
If you’re absolutely set on choosing lithium-ion though, the best lithium-ion batteries tend to be made by companies you probably already know and trust for your regular consumer electronics – like LG, Panasonic, Samsung, and Toshiba.
Fun fact, most of these companies make more from battery manufacturing than the phones, tablets and TVs you probably associate them with.
Another reputable manufacturer of lithium-ion cells you’re less likely to have heard of is China-based BYD. Given the comparatively short-service life and potential safety risks of lithium-ion, you’d be unwise to choose batteries of that chemistry from anyone but a major trusted brand.
But again, you should have a really compelling reason for choosing the less-safe, less-practical chemistry of lithium-ion over LiFePO4. I’ve yet to meet a boat owner who had a good reason.
FAQ
Let’s look at some of the most frequently asked questions surrounding lithium marine batteries.
Are Lithium Marine Batteries Worth It On A Boat?
Absolutely – as we’ve explored above, lithium batteries have a huge number of advantages over older chemistries like lead acid.
The really compelling reasons to choose lithium over lead is its ability to output more power (current), for longer, and use far more of the available pack without damaging it (greater depth of discharge).
Perhaps the only drawback to lithium is price, but over a multi-year timeline lithium batteries actually work out cheaper (especially because of the heavy service life batteries on a boat tend to experience).
The Cheapest Lithium Marine Batteries
There are two ways to think about price – “cheapest up front”, and “cheapest over a certain period”.
We tend to think in terms of the latter because that gives you a clearer understanding of price/performance ratio. There are plenty of “cheap” lithium batteries listed on import portals like Alibaba, but an overwhelming number of them are poor quality and fail quickly.
They tend to have far less than the advertised capacity and often use cheap components that severely limit the amount of power they can push around.
As a result, they may be “cheap”, but they offer poor performance for their price.
We’d argue that it’s worth spending a little extra to get a solid pack. Take a manufacturer like Battleborn, for example – who provides a TEN year warranty on their batteries. They may be a little more expensive than the off-brand packs you find on Alibaba, but those packs typically have no warranty or 12 months at most.
There are plenty of reports of off-brand packs failing after only 2 or 3 years, meaning you might have to replace them three or more times to reach the 10-year mark. A “cheap” pack can actually work out very expensive!
Be aware as well that the “marine” part of “marine lithium batteries” is significant. Packs that are made for stationary storage, e.g. to store solar energy in a house, don’t need to be water-resistant or shock-proof.
Packs that are designed for use in vehicles will be protected against vibration and shock, they’ll use sturdier components and connectors, and often “pot” their circuit boards (seal them in resin) so they’re impervious to water and corrosion.
If you decide to buy a pack that hasn’t been designed for use in the harsh marine environment you’ll likely need to invest in extra protection for it, or it may well shake itself to bits in the first heavy sea you encounter.
What About Cold Weather?
Batteries of all chemistries – be they lead or lithium – don’t love cold temperatures.
A battery produces power through a chemical reaction, and when the mercury falls that reaction slows down. This affects both charging and discharging.
Most manufacturers will publish some data on how their packs are affected, e.g. a graph with curves to show how much power you get out of the pack at a range of different temperatures.
Lithium is marginally more sensitive than lead, in that you can still charge a lead acid battery in the cold – you just need a charger with “temperature compensation” built in, and a lot of patience.
Lithium, on the other hand, can actually be damaged if you try to charge it when the core temperature of the cells is below around -4C (24F).
Your pack should have a BMS – battery monitoring system – to regulate and protect the cells, and the BMS almost always has a function that monitors the temperature and shuts off charging if the core temperature drops below -4C (24f).
It’s very rare to see a BMS without this function – typically only the shoddiest of cheap imports skip on this.
Some manufacturers make cells that are specifically designed for cold climates and can accept a charge as low as -20C (-4F). Others make little heating pads for your batteries that kick in automatically to keep them above freezing.
Another easy mitigation is to site your battery pack somewhere well inside the boat, like in the saloon, where it can benefit from the insulation of the boat itself – and any heating you use to keep the space warm.
If you plan to sail in arctic climates, it’s something you’ve got to bear in mind. Most sailors favour sunnier climates though, where this is rarely an issue.
Conclusion: The Best Lithium Marine Batteries For Your Boat
It’s very rare for cruisers these days not to need a decent power bank to Marine batteries come in all shapes and sizes, making it important to do your research before you buy.
We’ve outlined the best lithium marine batteries on the market and what to look for when purchasing one for your boat.
Hopefully, this information will help you make an informed decision about which battery is right for you and your vessel. And hopefully, lithium batteries will help make sailing less dangerous for everyone.
Looking for more great sailboat-related content? Check out these top-performing posts.
