30 Seconds. That's What a Lithium Fire Gives You.

[dlandersson]

30 Seconds. That's What a Lithium Fire Gives You.

[Strange]

Just because you CAN put something on a boat doesn’t mean you should.

[pitchpolehobie]

It seems to be a very rare but catestrophic event. I have thought about switching but my use case of mostly inland day sailing and weekly excursions with mostly marina overnights means I dont need the energy density and weight improvement of Li batteries. Id be open to the tech in the future if there are further improvements. Currently I use 2 deep cycle lead acid batteries from 2020 that I top off twice a year and run maintainers in the offseason. Each has a dedicsted voltmeter too. Iwas thinking of replacing this year and considering AGM.

[rsvpasap]

It's important to remember that the term "lithium battery" has a variety of meanings. And just for clarity I'm going to point out that the video link above concerns a YouTuber's speculation about a cruising sailboat that installed an electric car battery (such as a Tesla) to power their large inboard electric motor, also referred to as a saildrive.

Meanwhile, lifepo4 batteries, which are the type of lithium batteries widely adopted in the marine industry and now common on boats, are actually safer and less likely to experience thermal runaway or other fire producing events than are any other type of battery, including traditional lead acid batteries.

https://www.google.com/search?q=what+is ... a+sailboat

[pitchpolehobie]

Very good to know. Currently I have 2x lead acid hooked up to a perko battery selector and charge straight thru to terminals without a battery management system. Thst is how the boat came to me and seems to have worked great with 2 batteries of the same age and health. I have pretty sparse electrical needs with basically my garmin sonar as the main power draw. I have all LED lights inside and rarely use my exterior lights. If i switched to a lifepo4 system - would it be a drop in replacement for each of my lead acid batteries? Do i need batteried with built in BMS and a new charge selector?

[Be Free]

It seems to be a very rare but catastrophic event. I have thought about switching but my use case of mostly inland day sailing and weekly excursions with mostly marina overnights means I don't need the energy density and weight improvement of Li batteries. I'd be open to the tech in the future if there are further improvements. Currently I use 2 deep cycle lead acid batteries from 2020 that I top off twice a year and run maintainers in the off-season. Each has a dedicated voltmeter too. I was thinking of replacing this year and considering AGM.

Yes, thermal runaway is very rare in lithium (LiFePO4) batteries. Early forms of other lithium chemistries had serious problems. While I would not consider them appropriate for use as a house bank on a boat, they are much safer and better understood now.

Car batteries are usually Lithium Nickel Manganese Cobalt Oxide (NMC). In my opinion, they have no place on a boat. They are more likely to experience thermal runaway and while they weigh less than an equivalent LiFePO4 battery, I don't feel the weight savings are worth the decrease in thermal stability. I would never put a used battery in my boat and that goes double for a used automotive lithium battery.

If what you are have now is working for you and you don't foresee any significant change in your sailing habits then I don't see any reason to change your battery chemistry. If you are not staying off-grid for days at a time anything built around healthy lead acid batteries will likely work just fine.

Based on your use case, I wouldn't even switch to AGM. Eliminating the regular maintenance would not be worth the extra cost to me. They have a slightly better energy density, don't require regular maintenance, and can be charged a little bit faster but there are no actual deep cycle AGM batteries regardless of what the label says. If the battery is rated to start an engine (it will have a CCA or MCA rating) it is unlikely to be a true deep cycle battery.

[Be Free]

It's important to remember that the term "lithium battery" has a variety of meanings. And just for clarity I'm going to point out that the video link above concerns a YouTuber's speculation about a cruising sailboat that installed an electric car battery (such as a Tesla) to power their large inboard electric motor, also referred to as a saildrive.

Meanwhile, lifepo4 batteries, which are the type of lithium batteries widely adopted in the marine industry and now common on boats, are actually safer and less likely to experience thermal runaway or other fire producing events than are any other type of battery, including traditional lead acid batteries.

https://www.google.com/search?q=what+is ... a+sailboat

Exactly!

While he suspected that the fire started from the inappropriate battery (a very high probability) his main points were related to changing our "ditch" procedures and relatively inexpensive tools that can help rescuers find us easier. I know from experience that my VHS and my AIS can communicate with the Coast Guard anywhere I've ever chosen to sail but he's almost got me convinced to add a PLB to my ditch bag. I know the boat is unlikely to sink (I still have all of my flotation) but it could burn. Even in my prime (and I'm way past my "best by" date) 20 miles would be a long swim to shore.

[Be Free]

Very good to know. Currently I have 2x lead acid hooked up to a perko battery selector and charge straight thru to terminals without a battery management system. Thst is how the boat came to me and seems to have worked great with 2 batteries of the same age and health. I have pretty sparse electrical needs with basically my garmin sonar as the main power draw. I have all LED lights inside and rarely use my exterior lights. If i switched to a lifepo4 system - would it be a drop in replacement for each of my lead acid batteries? Do i need batteried with built in BMS and a new charge selector?

Lots to unpack here...

Lead acid batteries don't have or need a battery management system. Their internal chemistry and internal resistance work with the alternator/voltage regulator/battery charger to keep the battery from charging too quickly.

You are correct when you mention having batteries of the same age and health if you are going to connect them together with your Perko switch (both position). To simplify a whole lot of stuff, when you connect them together they will only work as well as the worst of the two. A bad battery will degrade (possibly damage) a good battery when you hook them together. Keep them as "matched" as you can.

On the supply side, your Garmin and lights won't notice if you switch to a Li battery. The charging side is much more complicated and has been covered in other threads. I don't want to add drift to this one by going down that path here. Given your electrical needs, you don't need Li unless you want to be off-grid for a week or more without recharging. Switching to Li is more complicated than just swapping out the batteries.

A lead acid bank is fine for the use case you've mentioned. If you do change to Li your existing Perko switch will work fine.

"Drop in" is about as varied as "lithium" in this context. It really only means that the battery case meets the size requirements (eg: group 24 or group 27). The important part is what is actually inside the case and how it is constructed. I'd recommend checking out Will Prowse's YouTube channel where he deconstructs a lot of lithium batteries. Some batteries are surprisingly good and some are scarily bad. A lot of the cases are surprisingly empty.

I don't know of any "drop in" batteries that have no BMS but there are differences. A good system will monitor battery temperature and voltage (both high and low), individual cell voltages, charge cycles, and will initiate balancing between the cells if they vary too much. In a lithium battery, individual cells need to be kept balanced for the same reason your lead acid batteries need to be as similar as possible.

[dlandersson]

Nice observation.

It seems to be a very rare but catestrophic event

[dlandersson]

Ditto

but he's almost got me convinced to add a PLB to my ditch bag.

[pitchpolehobie]

Nice observation.

It seems to be a very rare but catestrophic event

[Strange]

Clearly a personal opinion, but …

I get the increased power capacity. But in a SMALL boat with only 2 exits, that rare, catastrophic event will result in serious injuries if not death. And the total loss of the boat is a given.

It is a chemical fire that cannot be fought. ANYTHING you do to try to extinguish it will only spread it.

And I get that marine rated systems have almost everything in place to prevent such failures. But, the best laid plans always have a weak point.

Do you keep gas (a fire you CAN fight), propane or other explosive chemicals in your cabin? (An obvious exception here is BOOZE!). I doubt that you do.

For me, a portable gas powered generator (and a couple extra gas cans lashed to the deck) keeps me powered (and the A/C running all night). Many would be bothered by the noise. I find it comforting for 2 reasons. First, if I can hear it, the A/C will be working. That is really important ‘round here! Second, if I can hear it, no one has stolen it from where I sat it up on shore!

[OverEasy]

Boy that’s a lot to unpack…. AND sobering….

While some lithium batteries have more stable chemistries than others and some are more damage tolerant than others they ALL store a lot of chemical and electrical energy and deserve a lot of respect and caution.

In the same thought lead acid batteries, while having a relatively stable history and construction, are also to be treated with caution and respect. They also have a relatively high chemical and electrical density. One can DC arc weld with just a couple wires and a regular lead acid car or marine battery regardless of whether it is a start battery or a deep cycle battery or any construction. (Been there done that and have the tee shirts…I also took the appropriate precautions.)

Lead acid batteries also generate explosive gasses when charging … hydrogen… while also generating the optimal amount of an oxidizer … oxygen! So free, open, unobstructed and adequate ventilation is of paramount concern when determining a suitable location for lead acid batteries. Lead acid batteries can also overheat and potentially self detonate when they are low on electrolyte and charging. The internal plates can warp and potentially contact short making a spare or sufficient resistive heat to become an ignition source for the hydrogen and oxygen contained within the battery void space (that should have been filled with electrolyte). While in basic batteries with the old standard pop off plugs (yes that why they were designed that way… to ‘pop’ off) there are now ‘maintenance free’ batteries that have restricted vents which can result in potential case fracturing. This is important to understand in that in the event of an internal overheat or detonation the lead acid battery will almost inevitably discharge concentrated sulphuric acid with is highly corrosive to lots of things like organic tissue (you!) via skin contact and/or vapor inhalation. So that is why it is recommended practice to NEVER place a lead acid battery in a sealed compartment. It is also why it is recommended practice to have a lead acid battery inside an acid resistant vented container or dedicated battery box. These dedicated battery boxes are basically an acid resistant bucket to safely contain any leaking or spraying acid from a compromised battery. They are readily available from a variety of sources like Walmart.

On Over Easy we utilize two standard manufactured battery boxes (one for each battery) and have them located in the aft seat next to the OEM galley of our Mac26X which has a chemically resistant plastic lid. This compartment is freely vented through our modified galley to preclude the potential build up of hydrogen gases. Hydrogen gas is lighter than air and float upward and out of the cabin to safely dissipate into the atmosphere outside. If it were the in the original OEM configuration I would definitely add dedicated non obstructive ventilation to that location or any other potentially enclosed location. We have our batteries rigidly secured with in place in all directions to avoid any potential tipping or bouncing. We also have an active stand alone smoke and carbon monoxide alarm directly above our battery compartment in the cabin.

Moving on to Lithium type batteries… I’m duly impressed by the power density that lithium batteries are capable of and duly respectful of the potential threat they can pose. (I recently found a pair of olde cell phones that had split their cases due to swelling lithium ion batteries and I honestly scared the bejeezez out of me! I removed the batteries, placed them in a container of water and quickly disposed of them properly at our town trash transfer station which had basically and armored dumpster just for them).

If/when we ever actually consider going to a lithium iron phosphate house battery system for our boat I would definitely incorporate some sort of appropriate fire resistant enclosure that is directly and adequately vented over board. Most likely a double Stainless Steel walled box with ceramic tile insulation between them as well as similar vent (flue) to the exterior of the boat. While some might consider that to be a bit overkill I’d rather have the peace of mind that it might give an opportunity of time when time is of the essence. I’d also incorporate a separate redundant thermal alarm trigger sensor within the box to provide notification of an untoward event occurring… maybe a low melting point thermal link type alarm.

At one time we looked at some of the RV type lithium all-in-one power boxes with an inverter for AC power like those made by Jacoby (sp?) and others but they were primarily based upon lithium ion type batteries which seem to pose the higher risk levels. I am hoping that there are newer all-in-ones that are lithium iron phosphate based.

I’m also impressed by t(one that have built their own lithium battery systems and have put in the effort to understand the needs of what they are accomplishing. The more I look into what is involved the more respect I gain for the potential benefits as well as the inherent need for proper design and mitigations.

Having personally to have dealt with how fast, intense and devastating fire can permanently, painfully and destructively change lives in moments it has my utmost respect and caution. It’s why we went to an AC electric induction cooktop and electric heat on our boat (we removed the OEM alcohol stove and don’t use/carry propane onboard).
(Yes that means shore power hook up currently or a small portable Honda generator (which I am also very cautious about how and where it is used).)

We have a long standing primary standing order on Over Easy…”If there is ever a fire everyone is to abandon ship immediately.”
There is no point in even attempting to fight a fire onboard a fiberglass boat with upto 24 gallons of gasoline onboard. Just leave it!
It’s just stuff that can be replaced. We can always deal with whatever it is … from a safe distance.

Again, these are just my perspectives as it relates to my experience and needs.

Best Regards,
Over Easy