Lithium Battery Fire Mitigation for Boats

[Lovey80]

I know how safe the LifePo4 chemistry is and the likelihood of a thermal runaway event is very remote with this chemistry. @250 degrees LifePo4 has significant advantage in this department over other lithium chemistries. Particularly the ones that use Cobalt. The LIfePo4 cells, from what I have read, don’t release their own oxygen when they break down (like the other lithium chemistries) to assist in maintaining that thermal runaway event. I’ve seen them burn after being pierced as the electrolyte is flammable. But this in my mind is no more dangerous than the gases of a lead acid battery being combustible. So an event that could maintain 250c temps to get one to do a proper thermal runaway would be super remote.

One major concern in such an event such as this type would the he highly toxic nature of the fumes on a boat as you can’t exactly remove yourself easily from the fumes. They could kill you faster than the fire would.

With all of that said, if you were designing a boat layout from scratch that was already going to be fully custom. Would you consider building a specific battery compartment that was plumbed to salt water to fill the compartment in the event of a lithium battery fire if it was not too difficult and/or you already had water plumbed going past that batter compartment?

Let’s not get into the old myth about salt water and lithium please.

[bluefin59]

I found this recently and found it interesting https://www.nautilusinsurance.com.au...attery-safety/

[Volvo]

Vely Intelesting , Stll thinking of staying away from Lithium onboard Boats..

[ranmar850]

Vely Intelesting , Stll thinking of staying away from Lithium onboard Boats..

What , after reading about how LFP batteries are probably the safest battery of ANY kind to fit to a boat, as long as they are correctly installed and protected? After reading how the losses of boats to "lithium battery fires" are down to the other chemistries used in power tools, and toys stored on board, not the house LFP banks? Seriously?

[Dignity]

What , after reading about how LFP batteries are probably the safest battery of ANY kind to fit to a boat, as long as they are correctly installed and protected? After reading how the losses of boats to "lithium battery fires" are down to the other chemistries used in power tools, and toys stored on board, not the house LFP banks? Seriously?

Agreed, I've seen a lead acid battery explode, fortunately from a distance. The clean up was awful including all the damage to the surrounding surfaces.

[disorderly]

Also remember that just because the law requires you to carry a single fire extinguisher on board doesnt mean a couple of extras wont go astray...they are really cheap anyway..

and as ranmar mentions, think about all the other batteries you carry on board as well..Go pro batteries, drones, mobile phones etc all burn hot and nasty..

Personally i think if my LFP's exploded and were on fire..I would be grabbing my safety gear,Epirb, phone, garmin inreach and jumping overboard...that smoke would be bloody horrible and I think the chances of actually extinguishing it would not be great...my 12 v and 36 v LFP's are made up of 4 indiividual plastic cased cells per 12v in a home made larger case then inside a compartment...good luck putting that out..

[marto78]

It would be handy to have a quick disconnect feature to be able to send them over board, but batteries tend to be installed in hard to reach places which isn't ideal.

My old man has set up a thermal cut out on his lithium battery in his campervan. I haven't looked at the set up yet but it cuts all power into the battery once it reaches a certain temperature.

[Dignity]

Also remember that just because the law requires you to carry a single fire extinguisher on board doesnt mean a couple of extras wont go astray...they are really cheap anyway..

and as ranmar mentions, think about all the other batteries you carry on board as well..Go pro batteries, drones, mobile phones etc all burn hot and nasty..

Personally i think if my LFP's exploded and were on fire..I would be grabbing my safety gear,Epirb, phone, garmin inreach and jumping overboard...that smoke would be bloody horrible and I think the chances of actually extinguishing it would not be great...my 12 v and 36 v LFP's are made up of 4 indiividual plastic cased cells per 12v in a home made larger case then inside a compartment...good luck putting that out..

It seems the issue is with charging, not actual use of any battery, so that limits any solution to the charge process. I do like the idea Marto's dad has for charging at home and if needed on the water.

[ranmar850]

Agreed, I've seen a lead acid battery explode, fortunately from a distance. The clean up was awful including all the damage to the surrounding surfaces.

I've had one explode at close quarters, have no wish to repeat the experience. Showered me with acid and bits of case, luckily I had my back to it. That was ignition of the hydrogen on a charging battery. But there is another form of explosion risk with the so-called " sealed" lead-acid batteries. Hydrogen is given off in large quantities on charge AND discharge. But more on discharge . So when a large battery bank is suddenly hit with a demand for a thousand amps to crank a heavy diesel, the gassing can be of a level to cause the battery to explode from sheer pressure, if the tiny vent that these "sealed" batteries all have is even partly blocked. I have a mining background, and standing close to a battery bank while heavy machinery is cranking is a no-no.

So everything has its risks. Pick your own poison.

[Lovey80]

I was thinking of something along the lines of a semi-sealed box where the doors to the battery box could have foam or rubber seals on the surfaces that meet when it is closed. Then simply plumb in a salt water pipe from my deck wash that could flood the compartment with salt water to reduce the heat. The water would not only cool the battery sufficiently to stop a thermal runaway event but the salt water would act as an electrolyte and discharge the energy from the cells. This solution would only be even contemplated if it was even possible for a thermal runaway event happening with the battery.

I am still yet to get evidence of a single LifePo4 chemistry going into thermal runaway in any real world application. Even in the videos where they pierce them and a flame starts these aren't a thermal runaway event and it could be easily put out with a fire extinguisher-dry powder. I can only assume that the 250-260degree thermal runaway figure was done in a lab by adding a shit load of external heat. In a boating scenario, if it requires 250degrees of external heat to get them to runaway, you already have a massive fire on board and your lithiums cooking off are a secondary issue and you are probably already in the water with the eprib set off and lifejackets on.

@Ranmar850 can you imagine a scenario where this chemistry could get to 250degrees outside of there already being a massive fire on board that impacts the battery? Even with something as dramatic as a sustained dead short across the terminals with something thick like a spanner, could this cause such an event?

[ranmar850]

A sustained dead short on an encased LFP battery is simply impossible, if the BMS works as it should. If you had naked cells, it would be possible, but a cased battery with the BMS built in should be a complete non-event in the case of someone dropping a spanner across the terminals. Every BMS has two ratings--one for continous current, and the other for a short-term peak, usually measured in single units of seconds. Exceed that, the BMS cuts supply to the terminals. So a sustained short circuit current, even directly across the terminals, is simply not possible.Unlike lead/acid, etc, where it will keep supplying current until the batteries dies, or the shorting medium melts away. I had a deckhand drop an engine dipstick across one of the start batteries ( 12v cell, half of a 24v system) on my first command, and it blew it in half.

When I size protection for the output of an LFP battery, I use one size up from the max continuous rating, but below the max peak . Or, if cable size is the limiting factor, the max current rating of that cable. Whichever is less.

Somebody on here dug up the report on LFP batteries in pleasure boats commissioned by the peak boat building body in the US, after these concerns were raised, and it speaks for itself. Basically, the only way they could get one to catch fire was to douse it in accelerant, then it burnt at whatever the case material burnt at. So I don't think it is even a consideration, to be honest.

To anyone who is still uncomfortable about it, well, stick with what you know and are happy with. Things have changed very rapidly in the last few years--for example , when I fitted out the Reefrunner back in early 2018, two lead-acid batteries and a changeover switch was considered to be the standard. Adding a VSR was almost hi-tech. Everything starting changing just after that, it was all a bit wild west, people making all sorts of claims, interesting times. And now, it is all just accepted as pretty established, manufacturers put out new boats with LFP house batteries as standard.

[Dignity]

I guess I'm a bit confused about Lovely's comment of 250° outside temperature influence. But still at the initial query if there is a thermal runaway it will be around 2,000°C (from memory)and the small amount of salt-water you introduce into that small space is going to do stuff all. As Ranmar suggest, set the system up properly, don't buy cheap batteries as their BMS would be suspect and all will be well.

[Lovey80]

Basically for Lifepo4 to sustain a thermal runaway (continue to break down by itself) and turn into an event that essentially won’t be stopped, the cells need to get to 250 degrees. Once burning they are pumping out serious numbers though. Other lithium chemistries, such as the ones with cobalt actually create oxygen when they burn so are extremely hard to put out.

Think I will ditch the idea and put it in the waste of time basket.

[Alchemy]

Somebody on here dug up the report on LFP batteries in pleasure boats commissioned by the peak boat building body in the US, after these concerns were raised, and it speaks for itself. Basically, the only way they could get one to catch fire was to douse it in accelerant, then it burnt at whatever the case material burnt at. So I don't think it is even a consideration, to be honest.

.

https://www.ausfish.com.au/vforum/sh...hium-batteries

[Flex]

I see alot of ignorance around Lithium batteries. This often stems from the mixup between Lithium Ion v phosphate and especially the charge requirements.

The issue generally isnt the batteries. Its the chargers being used and their application causes the issues.
The same way static used to cause havoc in old motor cars before we learned to mitigate it.

There is the slight increased runaway risk with Lithium. (certain lead acid can runaway aswell just not spoken about as much)

However, Lead acid has a increase shorting risk that no one talks about due to no BMS.

I think its extremely uncommon for average fishing boat Lifepo4 battery to cause any issues. Theres literally thousands of these batteries in boats and 4x4,caravans with zero problems.

We float around the ocean with hundreds of litres of exploding liquid onboard and no one blinks and eye.

I think there's alot of fear mongering when it comes to lithium. you can buy Lithium-ion fire extinguishers now. dunno how good they are though.

To mitigate the risk. I would run my lithium in a battery box with anderson-plug in easy to access spot.
Soon as that puppy starts to smoke, unplug it and chuck it overboard. but youd have to be quick as they burn at 2000deg.