Lithium battery fire extinguisher???

ylop said:
Nigel Calder seems quite convinced there's a risk of destroying your alternator
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That isn’t a safety issue with the battery though.
ylop said:
Puncture consequences are dramatically different
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What consequences? LFP has been tested and shown safe many times in puncture tests. Obviously it’s not ideal, but you don’t get acid spray in your face like with lead.
 
Hermit said:
I was also planning to put a heat alarm in the battery compartment which will alert me in the event of heat over over about 180 which is below the thermal runaway start so I can then flood the battery compartment with the AVD extinguisher through a hole.
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Are your batteries in the engine compartment ? Since mine are situated away from the engine heat I'm planning on a thermal alarm set to around 50 or 60 Celsius, since that's higher than would occur under normal conditions and would give early warning of a fault having developed.
 
PaulRainbow said:
Do not do this. You should only have a single auto extinguisher in the engine space. With two small ones a fire could start and set one off, which isn't big enough to extinguish it, the fire then spreads and sets the other one off, which also isn't big enough to extinguish it. One bigger extinguisher will give it everything it's got.

EDit; oops, beaten to it by Momac
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Thank you , I hadn't thought that one through.
I will calculate a volume for the engine /systems room when I am up at the boat next week
 
lustyd said:
That isn’t a safety issue with the battery though.
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I never said it was - its a safety issue with the system. No point in obsessing about the chemistry in the battery if you are adrift at sea with an engine that won't start. LA's have been serving sailors and motorists well for many decades - they aren't 100% foolproof but I find the suggestion that you'd replace them with a different technology for safety reasons quite comical! Especially if that different technology relies on some fancy electronics to stop it doing bad stuff!
lustyd said:
What consequences? LFP has been tested and shown safe many times in puncture tests. Obviously it’s not ideal, but you don’t get acid spray in your face like with lead.
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Well I wouldn't want this happening on my boat:

And I definitely wouldn't call this safe:

The acid in a LA isn't under pressure it dribbles out if you puncture it!

And since the OP was asking about fire extinguishers before we derailed his thread, have you seen a LiFePO4 battery in a fire? There's a youtube video somewhere (but I can't find it now) of one, it stands up pretty well and then suddenly goes pop with a big flash of flame. I'd say similar to what I'd expect from a tin of varnish or similar. Its not an "explosion" nor an inferno like you get with a LiPo etc but if you had a fire in your battery compartment you'd certainly want to either get it out, or get out quickly. I suspect it probably doesn't need a Li specific extinguisher because its really a solvent fire, but sometimes its easier just to do what your insurer says rather than argue the toss.

I'll reiterate I've no gripe with LiFePO4 on boats, and don't rule it out when the time comes to replace my Lead Acids, but my reasons for switching would be capacity/weight/space not safety.
 
lustyd said:
They literally said it in the paper. Did you read it?
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So. I hear and see a significantly more cautious approach to LFPs outside of this forum, and I want to know whether people here are not cautious enough, or the other way round. I include in this commercial. So, you, if my memory is correct, were not convinced an LFP battery produced hydrogen as there is little electrolyte. So I did some legwork, and found that it does. Since I care about sources of information, I tried to find a paper that was authoritative on the subject (for some reason the results of saying 'I read it from some bloke on a forum somewhere' doesn't cut the mustard with some people for some reason), and that particular paper in the link seems to provide the information pretty well. It is somewhat surprising just how much hydrogen is expelled, as a percentage, and looking at Nigel's Youtube link (and others), a significant amount of gas gets expelled when a LFP gets too hot. I admit to not reading the whole of the other paper I linked to, but what I did read was a lot more from study than I had seen before, and I think provides some nuggets. I find it disingenuous that you were so dismissive about the paper on hydrogen expulsion, but not surprised as It sounded as though you had hoped for a different outcome.

I do not find your arguments for ignoring hydrogen stored in batteries compelling without more information.

I have not read the whole of the other paper I linked to in this thread, but what I did read was a lot more from study than I had seen before, and I think provides some very interesting information.

To attempt to unpick the differences in attitude to LFPs, I have taken the approach of trying to find out just what it takes to set one off, and what the consequences are if they do. I do not understand the reluctance here to want to know these things. With knowing exactly what sets an LFP off, it may be possible to decide if it is at all possible to replicate this on a boat (without another more serious uncontrollable fire, for example). The consequences of an LFP fire may well be a boat leaving event, or worse, I do not know, but it has certainly been mooted. From the number of LA explosion or fire photos that turn up, it sounds as though a LA event in itself may well not automatically lead to a loss of craft. Perhaps others have knowledge and experience as this seems to be a more common event. A further thought is that LA are used as well as LFP in the same boat, and may well be next to each other - can a LA failure lead to sufficient temperatures for an LFP failure? If so, separation would be wise. Perhaps there are other ways to unpick the differences in LFP safety attitude, and would certainly entertain them.

I would like to know why the canal boat exploded. I know you have dismissed this case, but am not aware that the full information has yet come out about this.

In terms of saying that LFP is safer than LA - I really didn't want to get into this - but I agree with others that there may be a bit of subjectivity here. An event, say, which is far less common may have the trade off of a much more serious outcome. Which is safer? Do you assess by probability alone, or probability of death/injury/damage, or something else?


lustyd said:
Please provide details. This has been discussed many times on the forum and no examples have ever been provided.
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Sadly commercially sensitive. Now I know that this will not be good enough for you, and you will reject my comments as a result, so I will save you the trouble of replying. But the information is still with me, and a significant reason why I have asked the 2 questions.

What I would say is that only a fraction of issues and problems end up in the public domain, so just because you don't hear of things does not automatically mean they do not happen.
 
Pye_End said:
. . . In terms of saying that LFP is safer than LA - I really didn't want to get into this - but I agree with others that there may be a bit of subjectivity here. An event, say, which is far less common may have the trade off of a much more serious outcome. Which is safer? Do you assess by probability alone, or probability of death/injury/damage, or something else? . . .
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In my opinion, it's not even relevant which is safer. Lead-acid is history; the only question is whether what we have now IS safe, in absolute and not relative terms, and can it be made safer with reasonable effort?

My old lead-acid system was not properly fused, had lots of safety weak points. That's not the standard for a new system!! The new system is a clean sheet of paper, and the result should be MUCH safer, if possible, thinking through all aspects of it from zero.

My boat was originally built with ventilated battery boxes with ducts leading out the transom -- a good start. I added in-line ignition protected blowers to those ducts activated in case of a fault condition. The off-gassing from LiFePo4 in fault condition is well documented to be something really bad, much worse than anything lead does. In my opinion it's worth taking serious measures to mitigate.
 
Pye_End said:
I do not find your arguments for ignoring hydrogen stored in batteries compelling without more information
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The scientists who wrote the paper literally said they had to drive the battery in ways that would never happen just to make it give hydrogen out. The quantity of hydrogen was a fraction of that given by lead acids under normal conditions when overcharged.
I was asking where the hydrogen came from, not saying it didn’t happen. The available quantity in a LFP is a fraction of that in the water in a lead acid and almost impossible to release in real world conditions.

It is utterly irrelevant to normal users.

Pye_End said:
Sadly commercially sensitive
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Amazing. If there were genuinely issues they would be documented. You’re just stirring the pot, although not as accomplished as shanemax. I don’t see the purpose in people trying to badmouth LFP, does it make you happy to put people off of these massive upgrades in performance and safety?
 
lustyd said:
Weird, I thought you were responding to my statement that LFP batteries were safer than lead acid. I just checked and you were doing exactly that so I’m unsure what conversion you think you’re in.
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Go back and read post 28 again then. My point is quite clear: the chemistry may well be quite safe when installed properly but insurers are not worried about that, they are worried about bodged upgrades. That’s why I didn’t refer to chemistry in post 28 and I talked about systems. But people here like to get angry about lithium so don’t bother to read what’s written because they have a fight they want to have.
 
So you were having your own conversation. That makes far more sense.
Any installation can be bodged and dangerous. Lithium isn’t special in that regard. Insurers have already started rolling back the wording.
 
ylop said:
Well I wouldn't want this happening on my boat:
And I definitely wouldn't call this safe:
The acid in a LA isn't under pressure it dribbles out if you puncture it!
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So don't take a drill with you when you're fiddling with the batteries. 😉

Yes, I know it happens, Someone will get careless with drill, but an electrical fire is far more likely to be from a loose or corroded terminal heating up. Is there a risk with LFP batteries? Probably but, unless I'm really careless with the installation, it's remote. I take my life in my hands every time I cross the road, and I reckon that crossing the road is probably the more dangerous activity.
 
This is a very good article from PBO.https://www.pbo.co.uk/gear/latest-lithiumion-battery-advice-that-every-boat-owner-needs-to-know-101328
Also I would recommend that you look at water mist fire extinguishers. They will douse most fires including electrical and are much more user friendly. Powder extinguishers are dreadful. The YM test boat has a very good video showing how bad they are.
 
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