Batteries in plant room and 120 minute fire rated walls

[-rick-]

4 minutes ago, jimseng said:

The interesting thing about much of the discussions about fires and Lithium batteries is that they never seem to refer to LiFePo4 batteries.

 

Completely anecdotal but I've seen more reports of fires from loose connections on 48V wiring to batteries than I have of LifePo4 batteries burning.

[jimseng]

2 minutes ago, saveasteading said:

Or that fire extinguisher as above, but somehow automatically. Someone could sell these.

The Fogstar batteries I have just bought have this built in. 

[SteamyTea]

1 minute ago, saveasteading said:

So a water spray at an early stage could reduce the temperature enough

That is what I was questioning.  I don't know the answer.

[jimseng]

1 minute ago, -rick- said:

Completely anecdotal but I've seen more reports of fires from loose connections on 48V wiring to batteries than I have of LifePo4 batteries burning.

The key words there are "anecdotal" and "loose connections". Putting 32kw of energy in a small box carries a risk that if you allow it to escape quickly and uncontrolled it is probably going to say "boom". That is the same for Lead acid batteries, which also give off very nasty gas when they go wrong. 

[SteamyTea]

A bit about exothermic and endothermic reactions here.

https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Chemical_Bonding/Fundamentals_of_Chemical_Bonding/Bond_Energies

[Russdl]

Looks like the F-500 EA is the one to go for. Whatever that is. 

[saveasteading]

Heath Robinson could do this.

Fire burns through string supporting extinguisher, which topples forward onto its lever which opens it and the fire goes out., 

It would be better if every supplier included a self-extinguishing system, and insurance cover for house and contents.

[ProDave]

2 hours ago, Russdl said:

No, they make their own. Short of submerging them they can’t be extinguished and if you remove them from the water before they’ve cooled down sufficiently they’ll be off again. 

I have seen a video of a submerged EV still burning underwater.  So that won't extinguish the blaze buy might keep it cool enough to limit the spread until it has burned all it's fuel.

[jimseng]

At the risk of repeating myself, that video is of non LiFePo4 batteries! It looks scary but that sort of thermal runaway is specifically what LiFePo4 batteries were designed to avoid. I guess that's why they are starting to put them in EVs now. 

There are many but this is quite a fun video: 

 

[Dillsue]

11 minutes ago, jimseng said:

At the risk of repeating myself, that video is of non LiFePo4 batteries! It looks scary but that sort of thermal runaway is specifically what LiFePo4 batteries were designed to avoid. I guess that's why they are starting to put them in EVs now. 

There are many but this is quite a fun video: 

 

Reminds me of peeing around with fireworks as a kid and getting chased by ripraps, helicopters and aeroplanes!

[kandgmitchell]

The opening post was about being told by a BCO that 120 minutes fire resistance was needed for battery storage. Since the purpose of the regulations is to secure the health, safety and welfare of persons using the building (extended somewhat by mission creep to Parts L, S, R etc.) then being required by using statutory powers to go beyond the usual 30 minutes FR for two storey dwellings would seem excessive without the authority to do so. The occupants should have evacuated and fire fighters would not have to be inside.

 

However, that is not to say that the OP shouldn't consider upgrading the fire resistance for their own property protection but that is entirely up to them, not the whim of the BCO who may personally think it's a good idea (and I'm not necessarily arguing that it isn't).

[saveasteading]

The bco can't be an expert on everything, especially with changing technology. The regulations require safety, so I think it is fair that he asks for a formal proposal with references and risk assessment.

[mjc55]

Sigenergy batteries (which we are considering) do have inbuilt fire suppression.

 

I do not know how common this is.

[Nickfromwales]

120 mins is barking mad tbf. 
 

If this is inside a domestic residence and the battery(ies) go up in flames, after 15-30 mins anyone near it would be gasping their last ever gulps of air.

 

Early detection and a robust plan to GTFO is all you’ll have for a choice. Attempting to tackle it would require halon or CO2, but in an enclosed plant room that’ll kill you too.

 

If these go up in flames, grab the cat and get out quick. 
 

The automatic fire suppression demos are all lovely, but unless it’s a bloody huge reservoir then these just won’t have the legs to keep a terminally ill battery from showing you exactly what it’s capable of.

[saveasteading]

7 minutes ago, Nickfromwales said:

after 15-30 mins anyone near it would be gasping their last 

And that's all that really bothers the fire service. But for an extra layer of plasterboard and some rockwool, isn't it worth stopping or slowing the spread?

[JohnMo]

6 minutes ago, saveasteading said:

And that's all that really bothers the fire service. But for an extra layer of plasterboard and some rockwool, isn't it worth stopping or slowing the spread?

Is it going to make any meaningful difference? Battery inside or outside attached to house is a part of full rebuild of house, especially if you get a couple of fire tenders emptying their water 

[-rick-]

13 minutes ago, JohnMo said:

or outside attached to house is a part of full rebuild of house

 

This surprises me, at least on a masonry build with a decent cavity. I can imagine localised damage that needs work but totaling the house?

[JohnMo]

7 minutes ago, -rick- said:

 

This surprises me, at least on a masonry build with a decent cavity. I can imagine localised damage that needs work but totaling the house?

 

Auto correct - should have read.

23 minutes ago, JohnMo said:

part or full rebuild of house

 

[Russdl]

On 10/03/2026 at 16:46, jimseng said:

thermal runaway is specifically what LiFePo4 batteries were designed to avoid.

Quite reassuring as my battery sits quietly doing its thing in the roof space (not really a loft more a habitable space that we don’t inhabit).
 

I’d read all the manufacturers blurb regarding the safety of LiFePo4 before choosing the location but that video you posted brings more confidence that it won’t burn the house down any quicker than a loose wire somewhere. 
 

Thanks. 

[SteamyTea]

53 minutes ago, Nickfromwales said:

120 mins is barking mad tbf. 
 

If this is inside a domestic residence and the battery(ies) go up in flames, after 15-30 mins anyone near it would be gasping their last ever gulps of air

I think it is quite reasonable.

A lot of these batteries will be charged up over night.

Teenagers don't get woken up by a fire alarm (a gentle female voice is best apparently).

 

As @saveasteading says, 2 hours is a cheap fix, may also limit damage to the rest of the building. Look what had happened in Glasgow. Dodgy vape batteries and a major railway station is closed.

[JohnMo]

4 minutes ago, SteamyTea said:

major railway station is closed

And a massive building trashed. All from a AA sized battery or two. They were still spraying water in the place the next day.

[JohnMo]

[-rick-]

30 minutes ago, JohnMo said:

And a massive building trashed. All from a AA sized battery or two

 

thousand

 

Will be interesting exactly what was in there but expect it to be a lot. Those disposable vapes are such a travesty and if they sold disposables I'd bet they sold rechargable ones too along with spare 18650s. Wouldn't be shocked if the basement/back room was full to the gills of batteries/battery containing supplies.

 

Plus they are the high energy, very flammable LiPo. Not LifePo4