LiFePO4 fire safety

[Jordi]

In a few occasions I have seen in the forum comments about materials to be put under or around a battery to prevent fire hazards.
My understanding was that people asking these questions were looking for a material where the heat of the cells would not start a fire on its supporting material or other surrounding materials.

Also, I have seen videos of batteries going wild with fire and fireworks due to a failure and was wondering If there really is a way to protect the battery surroundings with a material layer. The fire should easily reach the 800*C in the flame body and that fall in the range of metals, ceramics or composites (mix of materials).

Anybody has experience with this?
I have been doing some research and believe an aramide layer could help preventing fire spread.

Correction 16-06-22: Now I refer to batteries in general.

 

[robby]

LiFeP04 batteries almost never catch on fire, they typically just out gas smoke which I assume is somewhat toxic. Using Hardy board seems to be fairly safe. You also have to consider the possibility that the inverter can burst into flames, so properly mount that also.

 

[jberger]

LFP doesn't go "wild with fire" so I think you might be confusing the chemistry types.
Check out this video on the different chems and how they react.

Most of the fire risk is due to short circuits and burning cabling that then ignites surrounding materials. So keeping the fire from starting is critical, once it's burning, the only thing you can do is remove heat to slow it down and stop it.

 

[Maitake]

LiFeP04 batteries almost never catch on fire, they typically just out gas smoke which I assume is somewhat toxic. Using Hardy board seems to be fairly safe. You also have to consider the possibility that the inverter can burst into flames, so properly mount that also.

Almost

 

[timselectric]

I would sleep fine, with LiFePo4 batteries under my bed.
I wouldn't be comfortable, with Lithium-ion batteries in a shed outside of my house.

 

[Browneye]

Here's another one...

I have zero fear of my DIY battery pack catching fire. ZERO.

 

[RCinFLA]

The most practical beneficial thing you can do is to place a moderate thermal barrier between cells. This prevents one shorted cell from transferring heat to adjacent cells setting off a chain reaction of cell destruction.

A quarter inch thick shower wall dry board is a good candidate.

Electrolyte solvent can catch fire, but it has high vapor temp and high flash point temp, like fuel oil. LFP cathode material creates little oxygen when it breakdowns compared to other lithium battery chemistries. Bloating gases is mostly carbon dioxide, so when a LFP cell burst and spits out electrolyte it is surrounded by carbon dioxide gas restricting oxygen from mixing with electrolyte.

Most battery pack fires are created by poor electrical connections. Anytime you have a lot of stored energy in one place it is potentially dangerous.

 

[robby]

Almost

Yes and a TV almost never catches fire. The chances of your LFP batteries burning down your house are about the same a Plasma TV catching on fire and burning down the house. If you keep your TV outside in fear of it catching fire then you probably should do the same for your LFP batteries. The only place I would not mount them is a location where the Gas fumes could get to me in my sleep. So no i would not put them in my bedroom.

 

[anschluss]

I would consider using fireproof materials around the battery cells an excellent method to keep a fire from spreading.

• Any power storage system has the potential to release its energy in an undesirable, fast and dangerous fashion. No system is 100% fireproof, which is why I think it is important to design it to mitigate the effects if a fire occurs despite all preventative measures.
• A LiFePo4 battery can be considered less dangerous than a LiMnCo battery only with respect to self-ignition
• There is always the possibility of manufacturing defects. The DIY market is not the primary target of the cell manufacturers, and it is difficult to assess the reputation of sellers in this segment
• Looking at reports in this forum, it seems that fires are predominantly caused by faults in the external electric circuit, which may lead to enough heat being produced to ignite material unrelated to the internal battery chemistry (the links are just for illustration, I have no way of knowing if this was indeed the source of the problem):
  • Loose or suboptimal connections (fuses, vibration, incorrect torque, wire size, crimps, pressure on terminals)
  • Isolation problems (aluminum cell casing is not potential-free)
  • Accidental short circuits (foreign objects, structural damage)
  • Charging faults (unsuitable charging device, incorrect voltage, lack of overvoltage protection, low temperatures)
  • Cell level protection fault (defective or absent BMS)

Summing up, I think it is best to consider the hazardous aspects of a complete system rather than those of the battery itself.

 

[timselectric]

My batteries are in the closet, with the gas furnace.
I sleep in the room, just outside of this closet.
So I'm either not concerned, or living on the edge. lol

 

[Offgridummy]

There is a material called Refractory Wool used to line furnaces that are built to heat up metal to red hot tempuratures for forging. Typically used by DIY bladesmiths for home forging knife blades. Its not extremely expensive, is fairly lightweight and flexible. It could be used as some type of battery box liner. HOWEVER in my opinion the wool should be sealed in plastic or some type of encasing because the fibers can be hazardous if inhaled... Similar to abestos.

 

[joanna_lannie]

Correct. LiFePO4 battery safety is great, does not explode, and is very difficult to catch fire. More often the wire or device connected to the battery catches fire...so some insulation would be very welcome.

 

[robby]

I would consider using fireproof materials around the battery cells an excellent method to keep a fire from spreading.

• Any power storage system has the potential to release its energy in an undesirable, fast and dangerous fashion. No system is 100% fireproof, which is why I think it is important to design it to mitigate the effects if a fire occurs despite all preventative measures.
• A LiFePo4 battery can be considered less dangerous than a LiMnCo battery only with respect to self-ignition
• There is always the possibility of manufacturing defects. The DIY market is not the primary target of the cell manufacturers, and it is difficult to assess the reputation of sellers in this segment
• Looking at reports in this forum, it seems that fires are predominantly caused by faults in the external electric circuit, which may lead to enough heat being produced to ignite material unrelated to the internal battery chemistry (the links are just for illustration, I have no way of knowing if this was indeed the source of the problem):
  • Loose or suboptimal connections (fuses, vibration, incorrect torque, wire size, crimps, pressure on terminals)
  • Isolation problems (aluminum cell casing is not potential-free)
  • Accidental short circuits (foreign objects, structural damage)
  • Charging faults (unsuitable charging device, incorrect voltage, lack of overvoltage protection, low temperatures)
  • Cell level protection fault (defective or absent BMS)

Summing up, I think it is best to consider the hazardous aspects of a complete system rather than those of the battery itself.

Agree.
I am more afraid of an electrical fire than the LFP batteries catching fire, but my main concern is that the batteries might out gas. They put those pressure relief valves on there for a reason and I have never seen any data on how toxic the fumes are.

 

[crossy]

LiFePO4 is indeed pretty safe.
That said our packs are in a steel and cement board "shed" well away from the house.
There's a LOT of energy tied up in there, you can never be too safe.

EDIT Our (not really that big) 10kWh pack is the equivalent or roughly a litre of petrol (gasoline). All our fuel is in a similarly constructed outhouse, if it went "whoosh" the only injuries would be the chooks that live next door.

 

[Shimmy]

LiFeP04 batteries almost never catch on fire, they typically just out gas smoke which I assume is somewhat toxic. Using Hardy board seems to be fairly safe. You also have to consider the possibility that the inverter can burst into flames, so properly mount that also.

Hardieboard/cement board isn't really any safer than Type-X drywall, which is why it is funny that it is so often presented as a universal solution here. Neither gypsum nor cement burn... the risk is the paper on the drywall face. Two layers of 5/8" Type-X taped with staggered joints is likely better than hardieboard. In all the electrical fires I have seen the aftermath of, scorched drywall has never burned through. (That includes one incident where a 480V, 4,000A switchboard was vaporized; molten metal was embedded in everything. The fire sprinklers eventually cooled off the room.)

I would generally say the best material to use is aerated concrete block (ACB), the lightweight autoclave-cured stuff. It won't add fuel or toxic fumes, and it will provide good thermal isolation between itself and surrounding materials. LIkewise, the best mounting procedure is to mount equipment off of strut so it isn't making direct contact with the wall. (Never, ever mount a panelboard or similar electrical equipment with drywall anchors! If you don't have the blocking, you anchor the strut to the studs and mount the panels wherever you want them to be.)

 

[robby]

Hardieboard/cement board isn't really any safer than Type-X drywall, which is why it is funny that it is so often presented as a universal solution here. Neither gypsum nor cement burn... the risk is the paper on the drywall face. Two layers of 5/8" Type-X taped with staggered joints is likely better than hardieboard. In all the electrical fires I have seen the aftermath of, scorched drywall has never burned through. (That includes one incident where a 480V, 4,000A switchboard was vaporized; molten metal was embedded in everything. The fire sprinklers eventually cooled off the room.)

I would generally say the best material to use is aerated concrete block (ACB), the lightweight autoclave-cured stuff. It won't add fuel or toxic fumes, and it will provide good thermal isolation between itself and surrounding materials. LIkewise, the best mounting procedure is to mount equipment off of strut so it isn't making direct contact with the wall. (Never, ever mount a panelboard or similar electrical equipment with drywall anchors! If you don't have the blocking, you anchor the strut to the studs and mount the panels wherever you want them to be.)

That is why all of my equipment is in a Concrete room with a slab roof. If anything catches on fire everything will be contained and away from my house.

 

[timselectric]

My system is in my bedroom. That way I am the first to know if something goes wrong. And I have a front row seat for the show. lol

 

[SparkyJJO]

Concrete floor. Concrete block wall. Cells sitting on a metal shelf. Some plywood in use to fixture the cells, but if something did go whoosh, it would just set off smoke detectors and scare the crap out of the kids like when I burned something in the kitchen, only this time the lights may go out too ?‍

 

[timselectric]

I sleep fine at night. These batteries are not a safety Hazzard. Bad wiring to them, is a different story.

 

[OzSolar]

I don't think many of us adequately understand what is right under our nose that will kill you in an instant should the right circumstances line up.

How much spray paint do you have stored in your garage? How close is the ammonia based cleaner to your bleach? What other chemicals are lurking under your kitchen sink?

How much gasoline are your storing? There's at least 10 gallons in one car in your garage. I have 35 gallons of diesel in my F250. My wife's Prius has 10 gallons and a NIMH battery pack.

Do you have any fire extinguishers? If you do have you looked at them one time in the last 3 years? I bet not.

I'm not saying I'm different, just saying one might ought to take a look at the big picture of what's going on at your house.