Lithium Batteries

[marcham]

First off, it should be noted that with LFP (LiFePo4) batteriers, they are safer than flooded lead acid batteries. FLA batteries can and do explode due to the release of hydrogen gas. [Remeber the Hindenburg?] Maine Sail has offered a cash reward to anyone who can provide evidence of a fire or expolson of an LFP battery and to the best of my knowelge, he has not yet needed to shell out any cash. They can provide enough current that other components will over heat and they then cause a fire but that is true of any large battery bank.

How about the NTSB report ? https://www.boatinternational.com/yachts/news/visionf-82-yacht-fire-miami-flagship-battery-explosion

An abandoned ship full of EVs is burning in the Pacific

The crew of the Morning Midas had to abandon ship in lifeboats off the coast of Alaska.

www.popsci.com

https://www.capecodtimes.com/story/news/fire/2025/04/09/lithium-ion-battery-thruster-boat-fire-in-osterville-comm-fire-department/83005774007/

Deadly Yacht Fire Believed To Be Caused by Lithium-Ion Batteries

A deadly yacht fire aboard a 70-foot Viking is believed to be caused by lithium-ion batteries.

www.the-triton.com

Flooded lead acid batteries can explode (I've seen the aftermath), but they don't burn internally. The vented hydrogen though, can ignite if ignition protected equipment is not used and the batteries are not properly vented. Yes, there will be acid everywhere... The question is not whether Lithium (lifepo4) is safe, not safe or safer than Flooded/AGM, just that they have different installation considerations, which are reflected in published marine electrical standards and in manufacturer's installation instructions.

Under the right conditions, scientific research shows that LifePo4 can produce combustible gases. https://www.sciencedirect.com/science/article/abs/pii/S0957582024013995
"In this study, thermal runaway behaviors of two real-world LFP battery packs with different venting areas and void volumes were compared. Fire and explosion occurred in battery pack I, which had a small venting area and void volume. But such dangers did not appear in battery pack II, which came with a large venting area and void volume. To explain these phenomena, a new experimental method on a single LFP battery cell was proposed to analyze the venting behavior from the perspectives of venting."

Basically, properly built with good cells and a proper design, they are sufficiently safe. Nothing is 100% safe. How can you protect yourself? Buy reputable manufacturer packs!

The flammability of vented gases does not necessarily make them unsafe, given the right safeguards. Do we carry anything else very flammable on boats? Wood and fiberglass/resin burns well. We carry LPG, gasoline, diesel onboard safely everyday, so long as those systems are properly installed and maintained (who changes their LPG hoses every 20 years ???)

How long before admins lock down this thread ? ?? LOL

 

[Hayden Watson]

How about the NTSB report ? https://www.boatinternational.com/yachts/news/visionf-82-yacht-fire-miami-flagship-battery-explosion

An abandoned ship full of EVs is burning in the Pacific

The crew of the Morning Midas had to abandon ship in lifeboats off the coast of Alaska.

www.popsci.com

https://www.capecodtimes.com/story/news/fire/2025/04/09/lithium-ion-battery-thruster-boat-fire-in-osterville-comm-fire-department/83005774007/

Deadly Yacht Fire Believed To Be Caused by Lithium-Ion Batteries

A deadly yacht fire aboard a 70-foot Viking is believed to be caused by lithium-ion batteries.

www.the-triton.com

Flooded batteries can explode (I've seen the aftermath), but they don't burn. Yes, there will be acid everywhere... The question is not weather Lithium is safe, not safe or safer than Flooded/AGM, just that they have different installation considerations, which are reflected in published marine electrical standards.

Do I win the cash award ? ... I suspect I'll never see a dime... LOL

You will need to ask @Maine Sail that question.

A quick read of the first case found this statement. "The agency found that Flagship's inoperable battery management systems led to a practice of manually charging the batteries with a portable charger, which compromised their safe monitoring. "
With no BMS, there is no control, and manual charging is never prudent. Stupid is, as stupid does. When you bypass all of the safety gear and end up with an unsafe condition, that really is no big surprise. FLA will have the same problem if you have unregulated current going to a fully charged battery.

The container ship fires are not from LFP batteries. Most cars use other chemistries which is very susceptible to fire in order to have greater energy density.

The last article I cannot read without subscribing to the Cap Cod Times so cannot speak to that one.

 

[Davidasailor26]

How about the NTSB report ? https://www.boatinternational.com/yachts/news/visionf-82-yacht-fire-miami-flagship-battery-explosion

I guess it’s fair to say that was caused by the batteries, but in case anyone just sees the link and doesn’t read the article, this is a pretty key caveat - “The agency found that Flagship's inoperable battery management systems led to a practice of manually charging the batteries with a portable charger, which compromised their safe monitoring.”

 

[Davidasailor26]

Deadly Yacht Fire Believed To Be Caused by Lithium-Ion Batteries

A deadly yacht fire aboard a 70-foot Viking is believed to be caused by lithium-ion batteries.

www.the-triton.com

This one was caused by “the battery of an e-bike… The e-bike and its battery fell into the water earlier in the day of the fire... After retrieval of the bike it was parked on the dock, but the battery was removed and placed on a wooden cabinet inside the vessel. The cabinet also contained USCG-required safety flares, which were ignited after the wooden cabinet caught on fire due to the battery.”

I don’t think it’s fair to say that has anything to do with LiFePO4 installations.

The Cape Cod article was pretty light on details, only saying it was caused by a Lithium Ion battery (exact chemistry undeclared) used for a thruster.

 

[pgandw]

Unfortunately, the HumsiENK app will not display the individual cell voltage. They told me they are working on it (apparently in conjunction with WattCycle), but not available yet.

Greg

Greg, I also bought a no-name (Techcella, which is no longer available on Amazon) LiFePO battery. Knowing the app would get little technical support, I put the Overkill Solar app on my phone. Overkill Solar works with almost all Bluetooth capable BMSs, is free, and is well maintained by a dedicated user group. Will let you change anything in the BMS that the BMS allows to be changed. Highly recommended.

Fred W

 

[dlochner]

Under the right conditions, scientific research shows that LifePo4 can produce combustible gases. https://www.sciencedirect.com/science/article/abs/pii/S0957582024013995

This is an interesting article and on the surface, suggests LFP batteries are subject to thermal runaways. Upon careful reading, this is not the case. The study indicates that when a LFP battery is subjected to high heat, it can produce explosive gases, primarily Hydrogen and methane along with carbon dioxide and carbon monoxide. While specified, the source of these gases is probably from the electrolyte, which is flammable. This is very different from a thermal runaway which can occur with other lithium ion chemistries.

In a thermal runaway the components of the battery react to provide electricity and generate heat. In a thermal runaway, the heat generated accelerates the reaction which generates more heat which further accelerates the reaction. Here's how Wikipedia describes a thermal runaway:

Thermal runaway describes a process that is accelerated by increased temperature, in turn releasing energy that further increases temperature. Thermal runaway occurs in situations where an increase in temperature changes the conditions in a way that causes a further increase in temperature, often leading to a destructive result. It is a kind of uncontrolled positive feedback.

The fire hazard from a thermal runaway is due to the heat generated igniting something near the battery. This is why in commercial vessels the USCG requires lithium ion batteries to be contained in a vented fire proof location. The only way to stop a thermal runaway is to remove the heat generated faster than it is produced, in other words rapidly cooling the battery, usually by flooding it with water. The other option is to just let the reaction continue until the reacting chemicals are done.

It is easy to create a thermal runaway reaction in your own backyard. Mix up a batch of epoxy on a warm day and put it in a cup that does not allow the heat to dissipate quickly. After a few minutes the epoxy will begin to get hot and that heat will accelerate the curing process. The epoxy will begin to bubble and foam. This is an example of an exothermic reaction that has gone into a thermal runaway. In a paper cup there may be enough heat to ignite the cup.

So far, there is no evidence that LFP batteries can go into a thermal runaway and cause a fire. That is not to say, that a poor installation or poor charging practices can cause an LFP to fail and emit flammable gases, but that is a very different situation from a thermal runaway. Proper installation and management along with providing good ventilation will mitigate any fire hazard.

 

[Hayden Watson]

Greg, I also bought a no-name (Techcella, which is no longer available on Amazon) LiFePO battery. Knowing the app would get little technical support, I put the Overkill Solar app on my phone. Overkill Solar works with almost all Bluetooth capable BMSs, is free, and is well maintained by a dedicated user group. Will let you change anything in the BMS that the BMS allows to be changed. Highly recommended.

Fred W

I did the same with my Basen Green batteries. I have also loaded the Liontron app which is also in the JBS family of apps. This app allows you to monitor up to seven individual battereis in a parallel bank as a single large battery of the total capacity. I use it to combine my two 460ah batteries into one 920ah battery. Very nice for monitoring the total SOC and remaining Ah.

 

[Dave]

How long before admins lock down this thread ? ?? LOL

Now why would I want to do that?

However, if the discussion should go south and the comments begin to echo those on Sailing Anarchy, then we might find a few posts deleted and the SBO membership a bit smaller.

Cheers!

 

[Hayden Watson]

Now why would I want to do that?

However, if the discussion should go south and the comments begin to echo those on Sailing Anarchy, then we might find a few posts deleted and the SBO membership a bit smaller.

Cheers!

Dave, I agree. This has been a very civil and informative discussion.

 

[Tally Ho]

I'm wondering if the long run from the charger's negative terminal to the battery is contributing to the problem. Is there a negative bus bar? If so, putting the charger negative on that instead of the engine would shorten the run and reduce the resistance from the wire. Where are you measuring charging voltage, at the battery or the charger?

I am measuring voltage at the battery (BMS), the charger report (also Bluetooth) and a Renogy shunt/monitor.

Greg, I also bought a no-name (Techcella, which is no longer available on Amazon) LiFePO battery. Knowing the app would get little technical support, I put the Overkill Solar app on my phone. Overkill Solar works with almost all Bluetooth capable BMSs, is free, and is well maintained by a dedicated user group. Will let you change anything in the BMS that the BMS allows to be changed. Highly recommended.

Fred W

Thanks Fred.

I tried the Overkill app, and no bueno. Won’t connect.

Greg

 

[Foswick]

Note that in all of the articles listed in post #41, the chemistry of the battery was not mentioned. In fact, we can be almost certain that at least two of those (the EVs and the bike) were LCO or NMC.

It's like digging up an article about mushroom poisoning and saying, "See, mushrooms are dangerous."

In fact, here is a challenge to the community: See if you can find one ... just one ... reliable report of an LFP battery catching fire on a boat. I will tell you, you can find a few, but mostly involving portable batteries brought aboard (like for a power tool). But, they are exceedingly rare.

As @dlochner points out, thermal runaway is not an LFP problem. It is technically possible to invoke it if you physically damage a cell, but not typically easy to do. And, importantly, no one has successfully caused one cell to put neighboring cells into thermal runaway. (If someone knows of a reliable study that succeeded in doing this, I would be like to see it, but I know of none.)

The IIMS addressed this in: Lithium-ion battery safety: A series of fires on recreational vessels have been linked to lithium-ion battery powered devices - The International Institute of Marine Surveying (IIMS)

The key takeaway supporting my point is, "All the critical evidence we have links these boat fires to accessories, tools and toys that are either stored or charged onboard."

 

[Hayden Watson]

Note that in all of the articles listed in post #41, the chemistry of the battery was not mentioned. In fact, we can be almost certain that at least two of those (the EVs and the bike) were LCO or NMC.

It's like digging up an article about mushroom poisoning and saying, "See, mushrooms are dangerous."

In fact, here is a challenge to the community: See if you can find one ... just one ... reliable report of an LFP battery catching fire on a boat. I will tell you, you can find a few, but mostly involving portable batteries brought aboard (like for a power tool). But, they are exceedingly rare.

As @dlochner points out, thermal runaway is not an LFP problem. It is technically possible to invoke it if you physically damage a cell, but not typically easy to do. And, importantly, no one has successfully caused one cell to put neighboring cells into thermal runaway. (If someone knows of a reliable study that succeeded in doing this, I would be like to see it, but I know of none.)

The IIMS addressed this in: Lithium-ion battery safety: A series of fires on recreational vessels have been linked to lithium-ion battery powered devices - The International Institute of Marine Surveying (IIMS)

The key takeaway supporting my point is, "All the critical evidence we have links these boat fires to accessories, tools and toys that are either stored or charged onboard."

Correct, your boat is much more at risk from a fire cause by your chordless tool or cell phone batterery than it is from the LFP house bank.

 

[dlochner]

Correct, your boat is much more at risk from a fire cause by your chordless tool or cell phone batterery than it is from the LFP house bank.

Case in point, the Dive Boat fire a few years ago in SoCal. All the phones and devices were being charged in the same location and placed close together (if not in just a big pile). The heat generated by the charging built up and sent one or devices into thermal runaway. There were other issues too that made the fire worse.

A similar fire occurred on a freighter in the bridge the handheld VHFs were being charged and they went in to thermal runaway.

 

[Screen Saver]

Ok, but then…

So for clarity;

• Charging Systems If people are still using basic old fashion non multi stage chargers my point was this should have been looked at long before considering LifePo4, and if there charging system was working correctly before considering LifePo4, it will continue to work, and without damage..
• Alternator, Problems that might occur ??? a bit vague to say the least. But again my point LifePo4 is NOT going to create an alternator problem that wasn’t already there, these should have been addressed as part of normal maintenance if they existed.
• Other substantial changes “We regularly sustain over 150A” There would be less than 1% of NON lifepo4 boats doing that, simply because they cant, so if they are substantially changing there use or consumption or rate of consumption in any upgrade then yes many other things, things must be considered. But there is no suggestion of that in this post.
• “Diodes blowing from Significant current flow drop” how many amps is significant I wonder, the charger design whether it has reverse voltage protection etc…. Bottom line here is not the blowing of the diodes, which as I suggest is unlikely but not impossible, but more importantly is the disconnection which could be at a crucial time and how long it takes you to get the batteries back on line. ie do I really care the fire brigade smashed my $500 front door down (diodes), no I care that the piddly Lithium battery (non Lifepo4) in my ebike caused my house to burn down and be lost (boat) (hypothetically) and the insurance company wriggled out of it, even though I told them I had an ebike.

The original question was How are Batteries paralleled: The answer is not different for Lifepo4 and they should be in a star format with equal lead lengths, which if I read the post correctly they not. He is seeing a problem because probably he never checked whether the old None LifePo4 batteries were equal before ( an most of us did the same), or he has been advised that they must be balance the two batteries to within 0.xxx V and is doing his best to achieve that. Bottom line is that will never happen (especially in the light loads being referred to) , and never did or will, Two separate batteries will never totally agree, or consume at the same rate, hence one reason why there are all sorts of Balancers around.

The other question how is the Charger connected ? I suspect is not really the question, but taking it as presented the answer is as per any of the accepted best practice /manufactures procedures, LifePo4 is no different it should be the shortest and most even cable length possible to the star connection point. The imbalance in discharging ( ie low amps) given individually they are said to behave ok, and assuming there were star connections are all good is unlikely to be resolved. The same will likely be seen in charging which can be aided by active balances, but unless it's a substantial difference not essential.

Advice is always best deduced from hearing both sides

 

[Maine Sail]

Will stated that that by all info he has seen, this issue is only relating to the 300Ah mini. None of the other Watts cycle batteries are affected. It is a glitch in the BMS installed in that case and will likely be resovled very quickly.

All WC batts have Overcharge protection even non BT models. Folks who assumed BT was not useful just never see the problem.. OCP will probably be in every LFP batts within a year..It's good that Epoch and Wattcycle are out ahead of the curve because LI Time/REDODO/POWERQUEEN have not fixed this yet.

 

[Johann]

So for clarity;

• Charging Systems If people are still using basic old fashion non multi stage chargers my point was this should have been looked at long before considering LifePo4, and if there charging system was working correctly before considering LifePo4, it will continue to work, and without damage..
• Alternator, Problems that might occur ??? a bit vague to say the least. But again my point LifePo4 is NOT going to create an alternator problem that wasn’t already there, these should have been addressed as part of normal maintenance if they existed.

I know of one boat on a circumnavigation that damaged his very expensive Lithionics bank by charging with the stock internally regulated alternator. It was fine with AGMs, but during extended motoring he began to get HVC events which left him without power… in the dark. This was due to the high voltage set point of the alternator. He ended up having to replace the bank due to the loss of capacity and install external regulation mid circumnavigation.

When I bought my Lithionics they wouldn’t sell them to me if I was going to charge directly from an internally regulated alternator. And no, they weren’t trying to sell me a solution.

The original question was How are Batteries paralleled: The answer is not different for Lifepo4 and they should be in a star format with equal lead lengths, which if I read the post correctly they not. He is seeing a problem because probably he never checked whether the old None LifePo4 batteries were equal before ( an most of us did the same), or he has been advised that they must be balance the two batteries to within 0.xxx V and is doing his best to achieve that. Bottom line is that will never happen (especially in the light loads being referred to) , and never did or will, Two separate batteries will never totally agree, or consume at the same rate, hence one reason why there are all sorts of Balancers around.

First, with two batteries you cannot improve on the diagonal wiring method from a circuit resistance point of view.

Second, you have missed what is actually occurring here. These batteries have BMS “Full charge” protection that disables both charge and discharge FETs. My 48V Epoch has full charge protection but only disables the charge FETs. Still a pain to deal with, but it would not cause these issues. For some reason when his BMSs go into full charge protection and the charge stops, only one of the paralleled batteries will enable the discharge FETs. The other battery, while paralleled, will not enable the discharge FETs and so with only one battery powering the loads a significant imbalance (between batteries) develops. As Maine Sail has pointed out, Epoch had fixed this (unfortunately not for my battery) and WattCycle is working on a fix. In the meantime the OP should look for a workaround. I have suggested a lower absorption voltage (this is my solution for my Epoch) to test the limits of the full charge protection.

 

[sailme88]

I monitor several catamaran-focused forums where many (if not most) of the boats have lithium banks. I haven’t heard of any insurance denials over this question. Please reference

Underrated comment

GOOGLE: Insurance companies and marine lithium batteries...

 

[Jim Legere]

GOOGLE: Insurance companies and marine lithium batteries...

Most of us have an agreed value marine insurance policy that is based on a current survey (<5 years). A reputable surveyor - the kind that marine insurance underwriters require - will verify that any battery installation complies with ABYC E11 & E13. LiFePO4 battery installations are covered under these standards. The kind of horror stories that Google will dredge up using the search terms you suggest are mostly about fires caused by Lithium Ion batteries. A battery from an ebike, a cordless drill, or even a cellphone is more likely to cause a fire than a properly executed LiFePO marine installation. Marine insurance underwriters know this. If your boat is insured under a rider on your household policy YMMV.

 

[marcham]

Most of us have an agreed value marine insurance policy that is based on a current survey (<5 years). A reputable surveyor - the kind that marine insurance underwriters require - will verify that any battery installation complies with ABYC E11 & E13. LiFePO4 battery installations are covered under these standards. The kind of horror stories that Google will dredge up using the search terms you suggest are mostly about fires caused by Lithium Ion batteries. A battery from an ebike, a cordless drill, or even a cellphone is more likely to cause a fire than a properly executed LiFePO marine installation. Marine insurance underwriters know this. If your boat is insured under a rider on your household policy YMMV.

as ABYC / European standards change, you are not expected or required to update the boat to the new standard. Same as your house. Building, electrical, plumbing codes must be adhered to for additions or renovations, but you don't have to rebuild your house each time a code changes UNLESS something is deemed unfit. Good examples of things that were code compliant at the time but would be picked up during a home inspections today are PolyB water lines, Knob and Tube wiring, etc...

For a boat survey, the surveyor would not comment on an installation that was done when a code didn't exist or was less specific unless: your current equipment/installation is deemed as unsafe, or if there's evidence that the work was recently performed not according to standards. It really depends what the surveyor picks up and how they write down their findings. Remember that wiring, plumbing, etc... all have date codes on them, so it's very easy to know when something was installed/modified. So if someone installed lithium 5 years ago when E-13 didn't exist, but the installation appears safe and fit for function, I can't see how a reputable/knowledgeable surveyor would pick that up as an "essential" recommendation for remediation.

 

[Jim Legere]

as ABYC / European standards change, you are not expected or required to update the boat to the new standard. [...] For a boat survey, the surveyor would not comment on an installation that was done when a code didn't exist or was less specific unless: your current equipment/installation is deemed as unsafe, or if there's evidence that the work was recently performed not according to standards. [...]

Agreed. But the OP is contemplating a new LiFePo4 installation. Indeed, most of the posters in this thread are discussing current or planned conversions. ABYC E-13 applies. This thread is not about installations done prior to 2023, when E-13 was first released. Good surveyors will often suggest complying with new standards that increase the safety and suitability of the vessel. Mine always have. And, if such suggestions are in the survey, you can be sure your insurance will ask you to comply. I can't imagine that any boat owner with a Lithum battery system that complies with ABYC recommended practice would have trouble obtaining insurance.