LiFePO4 batteries explosion risk mitigation

bluedog225 · May 6, 2026

Interesting video of the failure of a LiFePO4 battery bank. Quality batteries associated with a solar power system. They were contained in a separate, well-constructed building (2x6 and 3/4 ply). Well insulated to keep the cells cool. This chemistry does best at human comfortable temperatures.

There was a failure causing a cell or cells to vent hydrogen (and other) gas. This is unusual but can occur. The damage was impressive.

The obvious answer is to vent the battery compartment. Lead acid venting is pretty straightforward. Open at the top and bottom. This obviously works against cooling the batteries.

Taking it a step further, enclosing the batteries in a relatively airtight compartment, vented top and bottom, would limit the spread of vented gas. And I’d speculate it would limit the damage from ignition. Then how to keep the batteries cool?

I wonder if a liquid cooling line as is used for higher power computers would be the best approach? Or a small window unit or mini split dedicated to the sealed box. Or something like a kegerator or small fridge.

My batteries are in a conex. I will have to move them or come up with a solution that works inside the container.

Any ideas welcome.

Stock photo.

zimman · May 6, 2026

I have a small LifePo4 battery with a battery management system inside. This one ***** canal water and I wish I could get my money back. I'm not a fan..................................yet.
Zim

mike93lx · May 6, 2026

How well sealed is your conex?

How about putting them in a fire cabinet that has air intake in the conex but vents to outside? Trigger the fan based on temp so it isn't just constantly dumping conditioned air.

bluedog225 · May 6, 2026

mike93lx said:
How well sealed is your conex?

How about putting them in a fire cabinet that has air intake in the conex but vents to outside? Trigger the fan based on temp so it isn't just constantly dumping conditioned air.

Conex is well sealed and insulated.

Something like the fire cabinet. But it has to be independently powered. And it’s off grid.

I’m thinking there batteries have to be moved out of the conex. With a separate air con.

I can’t predict the overall temp rise from one cell venting.

It’s going to be an energy hog.

mike93lx · May 6, 2026

A used refrigerator in a shaded spot would be a lot cheaper...

bluedog225 · May 6, 2026

mike93lx said:
A used refrigerator in a shaded spot would be a lot cheaper...

Yep. But these things go for over a grand each. Need a cage or box.

But a fridge is a good idea. 100 lbs each (?) may be an issue.

twagler · May 6, 2026

Interesting - especially since I've been investigating LiFePO4 batteries to upgrade the lead-acid batteries in my own off-grid solar installation.

The video seems to indicate that LiFePO4 batteries don't off-gas as a normal part of the charge/discharge cycle, but in this case one battery had a runaway thermal event because of a failed on-board BMS or an internal manufacturing defect. The video also stated that utility-scale installations build explosion panels into the structure. Here is my DIY suggestion for a completely sealed and insulated building/enclosure: (1) Install a smoke detector, opacity sensor, or thermal scan camera - something that will detect that a battery is fuming or is having a thermal runaway event, (2) Connect the detector to an actuator (e.g. garage door opener) that opens up a door or panel on your enclosure to safely vent the gases and avoid explosion risk.

The trick is to find a good detector. Specialized detectors are commercially available (see picture below), but I'm not sure where to find at the readily available consumer level (like Amazon).

Good luck with your system.

duneslider · May 6, 2026

twagler said:
Interesting - especially since I've been investigating LiFePO4 batteries to upgrade the lead-acid batteries in my own off-grid solar installation.

The video seems to indicate that LiFePO4 batteries don't off-gas as a normal part of the charge/discharge cycle, but in this case one battery had a runaway thermal event because of a failed on-board BMS or an internal manufacturing defect. The video also stated that utility-scale installations build explosion panels into the structure. Here is my DIY suggestion for a completely sealed and insulated building/enclosure: (1) Install a smoke detector, opacity sensor, or thermal scan camera - something that will detect that a battery is fuming or is having a thermal runaway event, (2) Connect the detector to an actuator (e.g. garage door opener) that opens up a door or panel on your enclosure to safely vent the gases and avoid explosion risk.

The trick is to find a good detector. Specialized detectors are commercially available (see picture below), but I'm not sure where to find at the readily available consumer level (like Amazon).

Good luck with your system.

This is the right answer if you have large qty of lithium batteries there are detectors to watch for thermal runaway or failed bms. It is NOT common for Lifepo4 to have this sort of issue and having an enclosure that is vented would reduce a lot of the risk.

theoldwizard1 · May 6, 2026

bluedog225 said:
Interesting video of the failure of a LiFePO4 battery bank.

I question the ACCURACY of this video !

From what I have read, Lithium Iron Phosphate (LiFePO4) batteries will not explode even if over charger OR over discharged. They may cause a fire if short circuited, but NOT explode.

Lithium Ion batteries WILL EXPLODE it over charged or over discharged, ! Lithium Ion is used in cell phones, laptops and power tools and some electric vehicles.

bluedog225 said:
There was a failure causing a cell or cells to vent hydrogen (and other) gas. This is unusual but can occur. The damage was impressive.

I have NEVER heard of any Lithium battery "venting" ! Some lithium ion batteries are made in a polymer pouch (Lipo). The pouch does expand when being charged or discharged. Care need to be taken that there is adequate room inside the device for this expansion.

There are probably MILLIONS of installations of LiFePO4 batteries installed inside building with NO SPECIAL VENTING ! Probably 10s of thousands installed in residences.

Segue : The server room I was responsible for had a giant (think 5 or 6 side by side refrigerators) UPS in the corner. I used lead-acid batteries. There was no special venting ! I don't recall any odor coming from it when we had a power outage that lasted for hours.

wyliesdiesels · May 6, 2026

wow!!!

bluedog225 · May 6, 2026

theoldwizard1 said:
I question the ACCURACY of this video !

From what I have read, Lithium Iron Phosphate (LiFePO4) batteries will not explode even if over charger OR over discharged. They may cause a fire if short circuited, but NOT explode.

Lithium Ion batteries WILL EXPLODE it over charged or over discharged, ! Lithium Ion is used in cell phones, laptops and power tools and some electric vehicles.

I have NEVER heard of any Lithium battery "venting" ! Some lithium ion batteries are made in a polymer pouch (Lipo). The pouch does expand when being charged or discharged. Care need to be taken that there is adequate room inside the device for this expansion.

There are probably MILLIONS of installations of LiFePO4 batteries installed inside building with NO SPECIAL VENTING ! Probably 10s of thousands installed in residences.

Segue : The server room I was responsible for had a giant (think 5 or 6 side by side refrigerators) UPS in the corner. I used lead-acid batteries. There was no special venting ! I don't recall any odor coming from it when we had a power outage that lasted for hours.

This may help. From: https://www.sciencedirect.com/science/article/abs/pii/S0306261922002185

rlitman · May 6, 2026

twagler said:
...Install a smoke detector, opacity sensor, or thermal scan camera - something that will detect that a battery is fuming or is having a thermal runaway event, (2) Connect the detector to an actuator (e.g. garage door opener) that opens up a door or panel on your enclosure to safely vent the gases and avoid explosion risk...

Not a thermal camera. That only sees the surface. A smoke detector might pick up a venting battery early enough to be useful. A CO detector is more likely to catch it. A flammable gas detector would be the best external air sensor. But all of these have high levels of both false positives and false negatives. But the best way to prevent thermal runaway is to have temperature sensors on every cell, and turn off charging BEFORE you have an issue. Once it starts, you've got a big problem on your hands, and opening a door doesn't vent every closed space that's now permeated with flammable gases.

theoldwizard1 said:
I question the ACCURACY of this video !

From what I have read, Lithium Iron Phosphate (LiFePO4) batteries will not explode even if over charger OR over discharged. They may cause a fire if short circuited, but NOT explode...

Segue : The server room I was responsible for had a giant (think 5 or 6 side by side refrigerators) UPS in the corner. I used lead-acid batteries. There was no special venting ! I don't recall any odor coming from it when we had a power outage that lasted for hours.

Look up StacheD Training on youtube. There are lots of examples of LFP explosions. The usual issue is that thermal runaway vents huge amounts of incomplete combustion byproducts (think CO), which can exceed the LEL, and when that happens, it goes boom.

SEALED lead acid batteries require no venting or special precautions other than adequate cooling. That's what I use in every UPS at work (we do have a thermal runaway protection system I manage, but the risks with SLA are nothing compared to lithium). On a related note, miniaturization has caught up to the UPS world. I just replaced a PowerWare 9315 with a Mitsibishi 9900B, and the guts inside the new one (with higher nameplate specs) are around half the size (and weight) of the old one.

Anyway, in the telecom world, lots of UPS still rely on wet cell batteries. These require hydrogen sensors when charged in enclosed spaces. The hydrogen they vent is odorless!

gtae07 · May 6, 2026

I'm a satisfied customer of these batteries. Yes, they are that light.

wyliesdiesels · May 6, 2026

gtae07 said:
I'm a satisfied customer of these batteries. Yes, they are that light.

wow great marketing video

theoldwizard1 · May 6, 2026

bluedog225 said:
This may help. From: https://www.sciencedirect.com/science/article/abs/pii/S0306261922002185

I still do not believe your "source" !

Google AI says :
• Normal Operations: No venting of off-gassing is required.
• Fail-Safe Design: Many LiFePO4 cells include a pressure release valve that opens only if the cell fails and builds up internal pressure.
• Safety Precaution: While rarely needed, it is recommended to have some airflow, especially if the batteries are in a sealed, high-heat, or cramped environment.
• BMS Protection: A Battery Management System (BMS) usually prevents the scenarios that cause venting.

Their source is DIY Solar Power Forum

As I said before

theoldwizard1 said:
There are probably MILLIONS of installations of LiFePO4 batteries installed inside building with NO SPECIAL VENTING ! Probably 10s of thousands installed in residences.

bluedog225 · May 6, 2026

Easy there tiger.

rlitman · May 6, 2026

theoldwizard1 said:
I still do not believe your "source" !

Google AI says :...

ROFLMAO. Talk to ANY insurance company.

dcg9381 · May 7, 2026

bluedog225 said:
Taking it a step further, enclosing the batteries in a relatively airtight compartment, vented top and bottom, would limit the spread of vented gas. And I’d speculate it would limit the damage from ignition. Then how to keep the batteries cool?

I own 15 LifePo4 batteries @ 5kWh each. 12 of them are contained in "metal boxes" - Which are basically like closed server racks with venting. Like this:

You could enclose them air-tight, but they build heat during normal operation. In a "catastrophic" event, you've got hydrogen in an enclosed space and you're probably got a thermal problem that goes way beyond liquid cooling. If you're "assuming" that the batteries are going to go "catastrophically bad" my go to would be constant air-flow and venting to de-concentrate the hydrogen.

The type of "really bad thing" that might cause a LifePo4 to off-gas to explosive levels is not going to be cooled off by a mini-spit.

Understand that you can build multiple levels of safety into these systems and you'd need a cascaded failure:

1) They have internal BMS to handle cell health, over charge, over capacity discharge (amps), and low voltage. Often they have internal temperature sensors.

2) If the upstream charge system has a controller, often these talk to the batteries by "coms". I know that my LiTime batteries will tell Victron that they are "full" (or over-charged) and Victron will stop charging. Discharge (amp) limits are set and I use 52V fuses that are rated under the wire capacity. Batteries will tell Victron that it's "too cold" to charge (haven't tested this) but it's part of the design, as are the blankets that the batteries sit on to heat them.

3) You can put temperature sensors in the case and halt on over-temperature. One or more.

I have 2 of these sitting basically "under the bed" in the cargo/camper... And OEM RV providers are using these batteries as well in modern "solar/off-grid packages" with no special explosion-proof casing.

Normal lead-acid batteries can and do off gas. Normal operation. No BMS. And were often installed with "dumb" charge controllers that'd hard charge to 14.7v so the batteries would boil out, at least in my experience with RVs.

Don't let the original drama of Li-ion and Li-poly scare you too much. When this tech was new, lots of people hard charged them without any type of BMS cell regulation.... We've got 80 kWh of lithium-ion in an EV, although liquid cooled, the battery chemistry is there and somehow we manage to park it in the garage and charge it....

bluedog225 · May 7, 2026

dcg9381 said:
I own 15 LifePo4 batteries @ 5kWh each. 12 of them are contained in "metal boxes" - Which are basically like closed server racks with venting. Like this:

You could enclose them air-tight, but they build heat during normal operation. In a "catastrophic" event, you've got hydrogen in an enclosed space and you're probably got a thermal problem that goes way beyond liquid cooling. If you're "assuming" that the batteries are going to go "catastrophically bad" my go to would be constant air-flow and venting to de-concentrate the hydrogen.

The type of "really bad thing" that might cause a LifePo4 to off-gas to explosive levels is not going to be cooled off by a mini-spit.

Understand that you can build multiple levels of safety into these systems and you'd need a cascaded failure:

1) They have internal BMS to handle cell health, over charge, over capacity discharge (amps), and low voltage. Often they have internal temperature sensors.

2) If the upstream charge system has a controller, often these talk to the batteries by "coms". I know that my LiTime batteries will tell Victron that they are "full" (or over-charged) and Victron will stop charging. Discharge (amp) limits are set and I use 52V fuses that are rated under the wire capacity.

3) You can put temperature sensors in the case and halt on over-temperature.

I have 2 of these sitting basically "under the bed" in the cargo/camper... And OEM RV providers are using these batteries as well in modern "solar/off-grid packages" with no special explosion-proof casing.

Normal lead-acid batteries can and do off gas. Normal operation. No BMS. And were often installed with "dumb" charge controllers that'd hard charge to 14.7v so the batteries would boil out, at least in my experience with RVs.

Don't let the original drama of Li-ion and Li-poly scare you too much. When this tech was new, lots of people hard charged them without any type of BMS cell regulation.... We've got 80 kWh of lithium-ion in an EV, although liquid cooled, the battery chemistry is there and somehow we manage to park it in the garage and charge it....

Keeping them cool in daily operation and venting explosive gases are two separate processes. And an active fan needs to be independently powered. At the end of the day, the container probably needs to be outside with a lightly constructed lid.

rlitman · May 7, 2026

bluedog225 said:
...At the end of the day, the container probably needs to be outside with a lightly constructed lid.

Daily temperature swings aren't good for batteries. Neither is baking in the sun, or condensation (which is likely in an unconditioned space). An isolated shed with a blowout wall facing a river may be ideal for preparing fireworks, and it will go far to mitigate the risks WHEN you have a thermal runaway, but I don't think it does much to prevent that runaway, and may in fact bring it on sooner.

Having dealt a bit with the storage of flammable and explosive materials in laboratories, the usual method is with a double walled fire-resistant container kept in a conditioned space, but with ventilation to the outside through flashback screens (to keep the interior below the LEL), and has blowout panels (to limit pressure buildup). But that's assuming the material being stored isn't it's own ignition source, and here, it is.

dcg9381 said:
...Understand that you can build multiple levels of safety into these systems and you'd need a cascaded failure...

Normal lead-acid batteries can and do off gas. Normal operation. No BMS. And were often installed with "dumb" charge controllers that'd hard charge to 14.7v so the batteries would boil out, at least in my experience with RVs.

Don't let the original drama of Li-ion and Li-poly scare you too much. When this tech was new, lots of people hard charged them without any type of BMS cell regulation.... We've got 80 kWh of lithium-ion in an EV, although liquid cooled, the battery chemistry is there and somehow we manage to park it in the garage and charge it....

SEALED (VRLA) lead-acid batteries should not off gas. If they do, that's outside of normal operation. For deep cycle storage, you're normally using wet cells, and yes, they do off gas, and yes, you should have hydrogen sensors, but outside of the telecom world, most people get away with taking the risks and living dangerously. Lead acid is pretty forgiving, but I've still seen plenty of examples of it going into thermal runaway, even WITH active thermal runaway protection circuitry.

I also think you're misrepresenting the real risks of cascaded failures. Plenty of "good" lithium based energy storage products have been "well engineered" and still ended up being recalled. Just search CPSC. When a failure mode is able to bypass every built-in safety measure in a single step, it's hard for me to say that's a cascaded failure, and that happens way too often.

dcg9381 · May 7, 2026

rlitman said:
Daily temperature swings aren't good for batteries. Neither is baking in the sun, or condensation (which is likely in an unconditioned space). An isolated shed with a blowout wall facing a river may be ideal for preparing fireworks, and it will go far to mitigate the risks WHEN you have a thermal runaway, but I don't think it does much to prevent that runaway, and may in fact bring it on sooner.

I hear you, but LifePo4 is going into interior and exterior of homes and in my particular case, may be transported in 2 EV Vans or my converted cargo trailer which may be in Texas or Michigan. The "issue" I design for is freezing as they can't discharge. Condensation ***** for electronics, but ask yourself when there is condensation - it's cooling with high humidity.

Is this any worse than under the hood of a 1970s muscle car with a lead acid battery that constantly vents hydrogen. Or the literal "bomb" that is boiling out hydrogen in every ill-programmed converter in many RVs with lead-acid?

rlitman said:
Having dealt a bit with the storage of flammable and explosive materials in laboratories, the usual method is with a double walled fire-resistant container kept in a conditioned space, but with ventilation to the outside through flashback screens (to keep the interior below the LEL), and has blowout panels (to limit pressure buildup). But that's assuming the material being stored isn't it's own ignition source, and here, it is.

I don't disagree and won't argue. These perhaps (subject to my limited knowledge) are the right designs.
But what's more realistic? A LifePo4 or with a cascade of failures, or a propane / C02 leak / failed smoke detector in my home? Or in the home of the average consumer?

I'm 100% for safety, but air bags without seat-belts don't make sense.

rlitman said:
Plenty of "good" lithium based energy storage products have been "well engineered" and still ended up being recalled. Just search CPSC.

I'll admit, that happens. Even without looking up CPSC, I know of massive bus recalls, charger failures, all that. Yes, poor engineering is out there, including aviation where they've recalled commercial jets using this tech. I'm not saying it "can't" fail. I'm simply saying that if you "roll your own" that you can't mitigate this without going full bomb shelter. I'm also saying that the tech has improved and I'll sleep at night in my "off grid" camper directly above these batteries. I'd worry more about my propane skills than I worry about the batteries and wiring. And I worry more about the RIVA "techs" that are propane **** into every day RVs.

There are 4 million model Y's on the road (and in garages). Some % of them, let's call it 20% are performance variants with Li-ion batteries. They are cancelling home insurance over hail, wind water, and trees, not battery tech.

bluedog225 · May 7, 2026

I believe they can discharge fine in freezing temps. But cannot charge.

theoldwizard1 · May 7, 2026

dcg9381 said:
I own 15 LifePo4 batteries @ 5kWh each. 12 of them are contained in "metal boxes" - Which are basically like closed server racks with venting.

Are hey vented to the outdoors ? If they release toxic fumes, what good did you metal box do ? Is it fire rated ?

theoldwizard1 · May 7, 2026

dcg9381 said:
I'm also saying that the tech has improved and I'll sleep at night in my "off grid" camper directly above these batteries. I'd worry more about my propane skills than I worry about the batteries and wiring. And I worry more about the RIVA "techs" that are propane **** into every day RVs.

There are 4 million model Y's on the road (and in garages). Some % of them, let's call it 20% are performance variants with Li-ion batteries. They are cancelling home insurance over hail, wind water, and trees, not battery tech.

This is the point I was trying to make !

dcg9381 · May 7, 2026

theoldwizard1 said:
Are hey vented to the outdoors ? If they release toxic fumes, what good did you metal box do ? Is it fire rated ?

No. None of the above. Unlike lead-acid, they do not "normally" discharge hydrogen. The "metal box" is designed to hold the weight of individual a batteries at 100lb each, provide a bus-bar, and secure the batteries, provide a shell of protection. Not fire rated. Not explosion rated. Putting them in a sealed metal box makes no sense to me, all the energy is going to go somewhere and concentrating the hydrogen in a case just sounds like building ammo to me...

Unlike lead acid, they do not normally produce hydrogen. Hydrogen production would be the by-product of an internal ****-show (catastrophic failure) - perhaps a puncture or other unregulated failure.

Absolutely you can have an "unregulated" failure. But the same thing can be said of your gas tank which is just as combustable in the event of a physical puncture. With triple redundant "checks" on batteries, I'm good with this being in my space. Tell me that your RV is better designed and more resilient to a propane puncture? I can see adding a "hydrogen" alarm if you really wanted to GTFO. I'm pragmatic about safety. Put a HALON system in your muscle car makes it safer, but it doesn't change the fact that you've got lap-belts and no airbags.

I'm not saying that these batteries can't do something bad. They can. I'm just saying that there are bigger problems to worry about.

Here are some photos of the risks I'm taking in vehicle spaces:

JCrabtree4 · May 7, 2026

I am a electric vehicle expert working for a vehicle OEM. I've spent quite a bit of time diagnosing, repairing, and driving engineering improvements for automotive Lithium Iron Phosphate (LFP aka LifePo4) batteries and BMS control logic.

LFP cells shouldn't be venting during normal operation. An LFP cell that is emitting gasses is indicative of a thermal issue. Cells are designed with vents that will fail open if pressure inside the cell exceeds a threshold, this is to prevent explosions. Once you package those cells into a larger air-tight pack, you should also include a vent for the same reason (to prevent pressure buildup leading to explosions).

If a thermal runaway occurs, the cell vent will typically emit gasses and debris. Below is an image (source: https://www.sciencedirect.com/science/article/pii/S2352152X25019334) of a single-cell thermal runaway, you can see the cell vent working as intended in these images.

In the image above, the researchers provided an external ignition source above the cell vent. This ignition source caused the flammable gasses to ignite. In LFP cell thermal runaway, the decomposition temperatures are typically below the autoignition temperature of the vented gasses. Additional the cathode structure of LFP cells do not release free oxygen to sustain combustion. External ignition sources are possible but uncommon during LFP thermal runaway, example sources can be frictional sparks from safety valve ruptures or electrical arcs caused by electrolyte release creating short circuits.

Regarding temperature's impact on the batteries, storing the batteries in high ambient temperatures exponentially increases the rate of undesirable chemical reactions such as SEI layer growth and electrolyte decomposition. SOC is also a factor to consider during storage. Storing the cells at high SOC (> 80% or so) significant increases the rate of lithium inventory loss (causing capacity fade). Storing the packs at low SOC can risk them self-discharging below 0% charge and causing permanent damage. It's generally best to store LFP cells between 40-60% SOC in temperatures around 20-25°C.

JCrabtree4 · May 7, 2026

dcg9381 said:
There are 4 million model Y's on the road (and in garages). Some % of them, let's call it 20% are performance variants with Li-ion batteries. They are cancelling home insurance over hail, wind water, and trees, not battery tech.

All Model Y vehicles use lithium-ion batteries. Nickel Manganese Cobalt (NMC) and Lithium Iron Phosphate (LFP) are both lithium-ion battery chemistries.

Tesla’s longer-range and performance models generally use NMC batteries because they are more energy dense, while some standard-range/rear-wheel-drive models use LFP cells.

JCrabtree4 · May 7, 2026

rlitman said:
But that's assuming the material being stored isn't it's own ignition source, and here, it is.

LFP cells in thermal runaway are generally not their own ignition source. Typically LFP cells in thermal runaway emit gas, debris, and plastic from the vent. LFP battery fires are typically caused by multiple factors - not just thermal runaway.

wandrur · May 7, 2026

I highly, highly recommend checking out https://diysolarforum.com/ for everything off-grid solar, LFP, etc.

One of the common factors in these OMG terrible experiences is either poor quality batteries or poor/ignorant/irresponsible/insufficient installation practices. Quality LFP batteries are as reliable as the sunrise, but many people insist on grabbing a good deal or haphazardly wiring systems that result in failure.

WildBill · May 7, 2026

Everybody Hates China’s Hilariously Bad Battery Ejector Idea

Launching an EV battery at missile speed as a safety measure seems a little suspect.

www.thedrive.com

rlitman · May 8, 2026

JCrabtree4 said:
External ignition sources are possible but uncommon during

You had me up until that insanity. If that argument fails for propane or natural gas, then it fails for emissions of ANY flammable gas. And a venting cell releases just as much gas as the A2L refrigerants on the market that require flammable gas sensors that are such a big debate today.

rlitman · May 8, 2026

wandrur said:
...One of the common factors in these OMG terrible experiences is either poor quality batteries or poor/ignorant/irresponsible/insufficient installation practices. Quality LFP batteries are as reliable as the sunrise, but many people insist on grabbing a good deal or haphazardly wiring systems that result in failure.

Un huh. It's reliable as the sunrise, until it fails, and then blame the manufacturer or installer. But hey, every one that hasn't failed is reliable, right? Every tail light warranty sounds like that too.

theoldwizard1 · May 8, 2026

JCrabtree4 said:
I am a electric vehicle expert working for a vehicle OEM. I've spent quite a bit of time diagnosing, repairing, and driving engineering improvements for automotive Lithium Iron Phosphate (LFP aka LifePo4) batteries and BMS control logic.

LFP cells shouldn't be venting during normal operation. An LFP cell that is emitting gasses is indicative of a thermal issue. Cells are designed with vents that will fail open if pressure inside the cell exceeds a threshold, this is to prevent explosions.

This is point I have been trying to make !

If a LiFePO4 cell vents, it is because the BMS failed. If it has vented, it is trash.

rlitman · May 9, 2026

JCrabtree4 said:
...LFP battery fires are typically caused by multiple factors - not just thermal runaway.

I think here we also need to differentiate between CELL thermal runaway and PACK thermal runaway. Everyone who says that thermal runaway isn't risky has only experienced the first. Anyone who's experienced the second knows your best option is to run away.

theoldwizard1 · May 9, 2026

rlitman said:
I think here we also need to differentiate between CELL thermal runaway and PACK thermal runaway.

Some EV battery packs are WATER COOLED !

rlitman · May 10, 2026

theoldwizard1 said:
Some EV battery packs are WATER COOLED !

I thought all plug-in EV packs were liquid cooled nowadays.

gte718p · May 11, 2026

rlitman said:
I think here we also need to differentiate between CELL thermal runaway and PACK thermal runaway. Everyone who says that thermal runaway isn't risky has only experienced the first. Anyone who's experienced the second knows your best option is to run away.

I have been in the EV world for approaching 20 years now. Packs don't run away, cells do. Everything that happens in a battery happens at the cell level. With certain chemistries a cell running away can create an incident that is spectacular. That being said LiFePO4 are considered inherently safe. As JCrabtree pointed out the run away doesn't reach auto ignition temps.

They are extremely tolerant of abuse. You can run them to zero and then over charge them and while you will damage the capacity, they will not catch on fire. Do that with a Lion and all bets are off. It takes work to light LiFePO4 on fire in the real world. To get LiFePO4 to burn, you need to overcharge with a significant current source and then have an external spark. I have tried. It is surprisingly difficult.

As for the explosion, even if the vents fail, the plastic cases crack and pressure dissipates before they explode.

It is kind of like why gas powered autos don't blow up in accidents the way they do in movies. While theoretically possible, in reality it doesn't work that way.

If you do manage to light off a Lithium chemistry, any lithium chemistry, I concur with rlitsman and run the f away. They are very toxic and very hard to put out.

dcg9381 · May 11, 2026

rlitman said:
Un huh. It's reliable as the sunrise, until it fails, and then blame the manufacturer or installer. But hey, every one that hasn't failed is reliable, right? Every tail light warranty sounds like that too.

I mean the LS car is currently stinking up the garage, found an OEM problem typical to the make and model at the filler neck. Basically it's puking a small amount of fuel and a bunch of fumes. I had to move it out until I fix it. How you'd justify putting lead-acid in (which inherently off-gasses hydrogen) but refuse LPF - I don't quite understand.

Assess your own risk for you, no one is telling you any tech is perfect, but the "lipo" scare came from (IMHO) the RC industry - almost no case to the batteries, batteries that fit in your hand rated for 100A. And people were "dumb" with them (with dumb chargers) and treated them like prior battery chemistry. Because these batteries might have 1 cell or 12, super easy to get a setting wrong on a dumb charger and burn your garage down.

How many modern Makita/DeWalt/Milwaukee fires do you read about? I'm sure they happen.

YMMV. I'd GTFO if I had any sort of modern lithium battery fire too, but this stuff reliable enough that insurance companies let you park it in your garage and aren't (to my knowledge) dropping home insurance policies over implementation of battery backup systems.

rlitman · May 11, 2026

dcg9381 said:
... How you'd justify putting lead-acid in (which inherently off-gasses hydrogen) but refuse LPF - I don't quite understand...

Well, try reading what I actually wrote, rather than what you're looking to hear.

dcg9381 said:
...How many modern Makita/DeWalt/Milwaukee fires do you read about? I'm sure they happen...

I know they do. My neighbor lived in a trailer for a year because of a Milwaukee battery. I still use several lithium chemistry tool battery brands. I had a Milwaukee charger start to melt on me once.

gte718p · May 12, 2026

dcg9381 said:
I mean the LS car is currently stinking up the garage, found an OEM problem typical to the make and model at the filler neck. Basically it's puking a small amount of fuel and a bunch of fumes. I had to move it out until I fix it. How you'd justify putting lead-acid in (which inherently off-gasses hydrogen) but refuse LPF - I don't quite understand.

Assess your own risk for you, no one is telling you any tech is perfect, but the "lipo" scare came from (IMHO) the RC industry - almost no case to the batteries, batteries that fit in your hand rated for 100A. And people were "dumb" with them (with dumb chargers) and treated them like prior battery chemistry. Because these batteries might have 1 cell or 12, super easy to get a setting wrong on a dumb charger and burn your garage down.

How many modern Makita/DeWalt/Milwaukee fires do you read about? I'm sure they happen.

YMMV. I'd GTFO if I had any sort of modern lithium battery fire too, but this stuff reliable enough that insurance companies let you park it in your garage and aren't (to my knowledge) dropping home insurance policies over implementation of battery backup systems.

To be fair lithium polymer (normally LiCoO2 or LiNiMnCoO₂) is a much different chemistry then LiFePO4. Lipo are very energy dense and can push sustained currents of 5,6,10 times their capacity rating. LiFePO4 generally can’t exceed 4c for any sustained amount of time. That is why LiPo are/where popular in the RC world. You also find them in laptops and cell phones. They are not intrinsically safe. Their run away temps are well above the auto ignition temp. They also have some really fun characteristics. For example, they do not respond well to deep discharge. Their internal resistance does up and a "normal" recharge even on a smart charger can set them on fire. Because of how the anode and cathode are assembled, they are extremely susceptible to mechanical damage, especially when made as pouch cells. Bend or puncture one and you guessed it fire. Overcharge a perfectly healthy cell, fire.

You still see them in a lot of cell phones, computer, and power tool batteries because they are so energy dense. However, you see a lot of safeties on both the charge and discharge cycles. They are not inherently bad. How many Mac Books or Dells have you seen spontaniously combust?

The real fun come with the 18650 form factor. They come in all kinds of chemistries from safe to crazy insane. If you are not buying from a reputable source you never know what you are getting.

LiFePO4 batteries explosion risk mitigation

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