LTO battery fire

[OffGridForGood]

From the picture and description - this could have ended very bad.

My home build LTO battery had a fire last night.

Interesting to see LTO - from what I have seen these cells are expensive compared to LFP - why use them for stationary set up? just learning experience or was there some specific reason to use these cells? IIRC the LTO voltage curve is basically 1.5 to 2.6v so a 22s will run 33v to 57v.
I don't know what inverter can operate in this wide range, makes me wonder what the current would be doing as the voltage drops below 48v.

We heard a large pop and came out to find a small arc fire in one of the cells. One of the cells had popped completly apart. The wiring was arcing and causing a small flame.

If you had not hear the pop, we may not have seen this posting...
Imagine if the pop happened while you were asleep, or just out of the house for a few hours.

We were running five 10 amp active balancers on five 22S banks.

10 amp active balancers: Did the cells require 10-Amp active balancers to stay in balance?
is this a normal requirement for LTO?

Either:
- the balancer died
- a cell went bad, or
- the wiring became corroded and high current.

Any insight since the event to indicate the cause of the fire? is there data available from your monitoring system to indicate if a cell went into over-voltage without the BMS cutting it off? What BMS(s) are you using for the 22s?

I post this to remind people that we need a mechanism to detect these events and shut everything off and alert you to the problem.

Good - glad you did. Now follow through:
Safety starts with following best practices in the original set up. If you think your set up is being judged harshly - you are not seeing the hazards we see, and you should re-evaluate.
I like to play with test set-ups on my workbench and try out new ideas. Sometimes I cobble together some parts and run a test under direct supervision. Then I disconnect it when I leave the work area. Non-permanent test set ups should not be left unattended, after all we are testing, we need to be present. Permanent systems need to be built to operate without supervision.
Clearly the original set up is not a model of safe battery practices, and wheather pointed out by members here or not does not alter the facts. We would be remiss to Not point out the hazards, 10's of thousands of others will see a posting on the forum, many of those viewers will not realize the hazards without this being pointed out.

I think this post should be moved to "up-in-smoke, learn from my mistake".

 

[Skypower]

Thanks for the detailed reply. Good eye on the GB OG, I haven't seen any issues after ~ 1 year when I disassembled but I'd rather be extra safe long term.

NO-OX-ID Two 2-Ounce Tubs A-Special Electrical Contact Grease - Improves Conductivity and Fights Corrosion in Automotive Marine Industrial Maintenance Antenna and Railroad Applications https://a.co/d/dfBzPBT
I'll order that, the brushes will be nice and it should last me the next decade.

A couple things; the NO-OX-ID A doesn’t spread well when cold so keep it in a warmer place till use. Use paper towel to lightly pull the brush stands to remove any potentially loose strands or contaminants. They actually supply a high quality acid bush and haven’t seen any loose strands. Keep the exposure to open tub, brush and parts treated to a minimum. Cap them and finish the assembly asap to minimize any contamination. A spec of contaminants or a brush strand defeats the purpose. I store the brush in a ziplock.
If you haven’t seen an issue in a year then I wouldn’t be too worried and unless you’re redoing something I’d just leave it alone. Any time you mess with something there’s always a risk to gain.

 

[rhino]

Crocodile clip - Wikipedia

en.wikipedia.org

A crocodile clip or alligator clip[1] is a plier-like spring-tensioned metal clip with elongated, serrated jaws that is used for creating a temporary electrical connection.

 

[Sanwizard]

FYI your fire was not put out with a co2 fire extinguisher what you used was a dry chemical charged with nitrogen gas which leaves a very corrosive substance which will destroy your electrical and electronics components that fine yellowish white powder will react with moisture in the air

anything in the area that was exposed to the dust can become damaged due to corrosion

I would recommend buying a co2 extinguisher because no residue and it also cools the fire and removes oxygen
there is no way I would set a dry chem extinguisher off in my solar shed

@rodrick, can I ask which CO2 extinguisher you use? I am shopping around for black friday deals on CO2 extinguishers, but I am finding most are in the $400 to $500 dollar range.

 

[Nobodybusiness]

Lol, you’re not alone. Most of the time I’ve got Mr Murphy’s Law riding on my shoulder. One of my mantras; Just because someone else’s can get away with doing something that way, doesn’t mean I can, because Murphy’s Law will find me.

I hear ya. Sounds like we have similar problem.

 

[Skypower]

From the picture and description - this could have ended very bad.

Interesting to see LTO - from what I have seen these cells are expensive compared to LFP - why use them for stationary set up? just learning experience or was there some specific reason to use these cells? IIRC the LTO voltage curve is basically 1.5 to 2.6v so a 22s will run 33v to 57v.
I don't know what inverter can operate in this wide range, makes me wonder what the current would be doing as the voltage drops below 48v.

If you had not hear the pop, we may not have seen this posting...
Imagine if the pop happened while you were asleep, or just out of the house for a few hours.

10 amp active balancers: Did the cells require 10-Amp active balancers to stay in balance?
is this a normal requirement for LTO?

Any insight since the event to indicate the cause of the fire? is there data available from your monitoring system to indicate if a cell went into over-voltage without the BMS cutting it off? What BMS(s) are you using for the 22s?

Good - glad you did. Now follow through:
Safety starts with following best practices in the original set up. If you think your set up is being judged harshly - you are not seeing the hazards we see, and you should re-evaluate.
I like to play with test set-ups on my workbench and try out new ideas. Sometimes I cobble together some parts and run a test under direct supervision. Then I disconnect it when I leave the work area. Non-permanent test set ups should not be left unattended, after all we are testing, we need to be present. Permanent systems need to be built to operate without supervision.
Clearly the original set up is not a model of safe battery practices, and wheather pointed out by members here or not does not alter the facts. We would be remiss to Not point out the hazards, 10's of thousands of others will see a posting on the forum, many of those viewers will not realize the hazards without this being pointed out.

I think this post should be moved to "up-in-smoke, learn from my mistake".

The main place I see a lot of use for LTO is high performance automotive audio. They like the punch of the high discharge that these offers. I’ve seen some without any balancers employed and have no idea if that’s acceptable or wise for this chemistry. From what I’ve gathered LTO has an extremely high cycle life and stable chemistry. The round trip efficiency is what I’d like to know. I’ve noticed throughout the forum where an unbalanced battery is considered, a bad connection/loose terminal is a likely culprit and no amount of balance current can fix it. If the OP had need of a lot of balance current I’d be wondering.

I’m so glad his whole house didn’t go up. He could probably just make some corrections, replace the blown cell and the two adjacent cells then be back in business. I’d be watching it like a hawk for balance, heat and remove anything flammable in the vicinity.

 

[Skypower]

@rodrick, can I ask which CO2 extinguisher you use? I am shopping around for black friday deals on CO2 extinguishers, but I am finding most are in the $400 to $500 dollar range.

Yeah I was just looking too. I’ve got a new ABC on an opposite wall but I like the Co2 idea. Seen some five pounders on Amazon for $204.

 

[JJJJ]

Regardless of the chemistry used it is a good reminder to review the basics. Good for us all:

1. Ensure proper connections, recheck as needed.
2. Include adequate fuses and breakers
3. Make sure wire size and capacities are above the required or expected loads
4. Consider a technical review by other members prior to going live with the installation. It is amazing the number of "small" things others saw with my build that can really add up (in a bad way)

Periodically look over your system with a critical eye. Especially if in a mobile application.

If your design is experimental, perhaps considering a location outside the home? Each person needs to make their own choice on this. Just a thought.

I have driven a car for many many years. Even with this vast experience it still pays to follow certain safety procedures when getting behind the wheel. Even the most experienced person takes a chance if they skip basic safety considerations.

 

[OffGridForGood]

The main place I see a lot of use for LTO is high performance automotive audio. They like the punch of the high discharge that these offers.

I am an auto buff - by other addiction er hobby, and on the car forums I have seen quite a lot of chat about LTO - from Honda Plug-in hybrids IIRC. They have often talked about doing a manual balance a few times per year "if needed" or checking the balance every few months. This was why I asked the OP if they 'needed' 10-amp balance - since it didn't seem to add up with what I have read over the last few years in the automotive area.

I’ve seen some without any balancers employed and have no idea if that’s acceptable or wise for this chemistry. From what I’ve gathered LTO has an extremely high cycle life and stable chemistry. The round trip efficiency is what I’d like to know. I’ve noticed throughout the forum where an unbalanced battery is considered, a bad connection/loose terminal is a likely culprit and no amount of balance current can fix it. If the OP had need of a lot of balance current I’d be wondering.

agree.

I’m so glad his whole house didn’t go up. He could probably just make some corrections, replace the blown cell and the two adjacent cells then be back in business. I’d be watching it like a hawk for balance, heat and remove anything flammable in the vicinity.

Some proper connections, bus bars and cases would be a great start. He said five packs - so this was not some spur of the moment set up, just to test an idea for a few days, this was a build. Hope he comes back and learns something from the more experienced among the forum.

I have to wonder if the voltage range for those LTP allowed his current to climb as the voltage dropped down lower and lower, I can imagine from the comments about "pushing the system to the limit" could mean the voltage dropped to sub-48v and the amperage climbed to maintain the power output increasing heating at a poor connection leading to the arc and cell exploding. Too bad there wasn't a camera set up to record the whole event, we could have seen what happened. I should put a cheap aftermarket dash-cam in my solar room, to watch and record in a loop what is going on in there!
If as you say, if he replaces the blown cell, what are the other changes this set up needs to be safe(er):
Proper bus bars and cell holders,
proper sensor wires and ring terminals for the BMS leads,
metal cases for each pack,
Heat and smoke detectors in the vacinity - alarm in the house and link to his phone,
some relays to allow remote disconnect of the ESS ?

I would be interested to know what the rest of the system set up looks like, and what loads are being applied.

 

[TomC4306]

But telling a complete stranger "Time to revisit basics" is polite?

Based on what we can clearly SEE in YOUR photo?
Yes

 

[Skypower]

I am an auto buff - by other addiction er hobby, and on the car forums I have seen quite a lot of chat about LTO - from Honda Plug-in hybrids IIRC. They have often talked about doing a manual balance a few times per year "if needed" or checking the balance every few months. This was why I asked the OP if they 'needed' 10-amp balance - since it didn't seem to add up with what I have read over the last few years in the automotive area.


agree.

Some proper connections, bus bars and cases would be a great start. He said five packs - so this was not some spur of the moment set up, just to test an idea for a few days, this was a build. Hope he comes back and learns something from the more experienced among the forum.

I have to wonder if the voltage range for those LTP allowed his current to climb as the voltage dropped down lower and lower, I can imagine from the comments about "pushing the system to the limit" could mean the voltage dropped to sub-48v and the amperage climbed to maintain the power output increasing heating at a poor connection leading to the arc and cell exploding. Too bad there wasn't a camera set up to record the whole event, we could have seen what happened. I should put a cheap aftermarket dash-cam in my solar room, to watch and record in a loop what is going on in there!
If as you say, if he replaces the blown cell, what are the other changes this set up needs to be safe(er):
Proper bus bars and cell holders,
proper sensor wires and ring terminals for the BMS leads,
metal cases for each pack,
Heat and smoke detectors in the vacinity - alarm in the house and link to his phone,
some relays to allow remote disconnect of the ESS ?

I would be interested to know what the rest of the system set up looks like, and what loads are being applied.

Now I know what I’ll do with my spare Nest cameras. The motion detector will definitely see something change (flash, flame or smoke) and send an alert to my phone. if I set sensitivity to max. Already have house network smoke and heat detectors above(not internet). That would definitely wake the house and 99% of the time an adult is there.

List to do today, tidy up garage, order Co2 extinguisher, check cell torque, set out new glue traps and mount Nest cameras.

 

[Lt.Dan]

I don't know enough about fire extinguishers, but I would assume that any extinguisher would be acceptable because you are just trying to prevent the fire from spreading. Putting out a lithium fire is wasted effort. If this is the case, the $40 extinguisher I got online that is hanging on the wall next to my batteries should be perfectly acceptable

Can anyone tell me if this is wrong thinking?

 

[summit]

Dude. I've lived through Outback, Solark and EG4 inverters.
This is not my first rodeo.

This was a test rack that I built myself by hand and it behaved beautifully for four years. I've intentionally ran it balls out 100% charge to discharge daily.

I got every dollar out of what little I invested.

So go give your unsolicited advice to some other thread.
You are not needed here.

four years balls out test is a long test, glad every one is ok

 

[SamDeleted]

but I would assume that any extinguisher would be acceptable because you are just trying to prevent the fire from spreading.

Sadly not the case I'm afraid

Some fires need specific extinguishers

 

[JJJJ]

Just keep in mind that when using a CO2 unit to get to fresh air quickly to avoid suffocating.

 

[Ampster]

When you plan for a fire,
you're ready for a fire.

My plan was to change chemistry from NMC to LFP. My 42 kWh pack is to large and heavy for wheels.

 

[Ampster]

Just keep in mind that when using a CO2 unit to get to fresh air quickly to avoid suffocating

Also NMC when overheated produces its own oxygen so using any extinguisher which relies on smothering will be of no use. Only lots of water to cool the overheating will stop that fire

 

[Hedges]

@rodrick, can I ask which CO2 extinguisher you use? I am shopping around for black friday deals on CO2 extinguishers, but I am finding most are in the $400 to $500 dollar range.

I bought Ansul Clean Guard. Had considered Halotron, but effective concentration and LC50 (concentration lethal to 50% of rats tested) changed my mind.
Note that any of these extinguishing agents with fluorine can make nasty chemicals depending on the temperatures they experience, so exit and ventilate the room.

Ansul CleanGuard+ FK-5-1-12 Clean Agent Fire Extinguishers

Ansul CleanGuard® extinguishers are designed for the protection of commercial and industrial facilities traditionally protected by Halon 1211 such as computer centers, data/document storage areas, communications facilities, control rooms, electronics manufacturing, museums, art galleries...

www.safetyemporium.com

This is because I have expensive electronic test equipment as well.
If you've just got a low cost inverter (some priced less than these extinguishers!) other options make more sense.

I don't know enough about fire extinguishers, but I would assume that any extinguisher would be acceptable because you are just trying to prevent the fire from spreading. Putting out a lithium fire is wasted effort. If this is the case, the $40 extinguisher I got online that is hanging on the wall next to my batteries should be perfectly acceptable

Can anyone tell me if this is wrong thinking?

Depends on what else is in the vicinity.

I sat on a failure analysis team after a contractor grabbed a dry chemical extinguisher ran ran into a computer room to put out an electrical fire. $Millions of of equipment destroyed. Simply turning off power was all that was required to stop FR4 PC board from burning, due to about 1kW of red hot glowing metal (shield shorted across 5V 200A power supply.) The purpose of the analysis was to determine who's material was responsible for starting the fire. (combination of design flaw and defect.)

 

[Lt.Dan]

Sadly not the case I'm afraid

Some fires need specific extinguishers

View attachment 179572

Ok so based on your picture, all that is around mine is metal tables, a metal tool box, cement board, and drywall. Standard Foam Spray is good enough for me.

 

[Shimmy]

I don't know enough about fire extinguishers, but I would assume that any extinguisher would be acceptable because you are just trying to prevent the fire from spreading. Putting out a lithium fire is wasted effort.

I'd vote more for inherent safety rather than trying to put out fire in adjacent materials: keep combustibles away from an ignition/fuel/oxidizer boxed together. The fire extinguisher will put out a fire in wood... but it will likely re-ignite almost immediately if the source heat is not addressed.

 

[Bluedog225]

I would move the extinguisher away from the things most likely to burn.

 

[Bluedog225]

In addition to an abc extinguisher, I keep an H2O extinguisher and an old fashioned big bucket of sand.

 

[Ampster]

Yes, you want to be able to access it without burning yourself.

 

[JJJJ]

I found a company out of Niagra Falls that manufactures a paint that has been shown to dramatically reduce the ignition potential. Not cheap

 

[JJJJ]

The take home message for me is to double check your system connections. A dc arc fault near a combustible material is not a good idea. Also another example of benefits of properly sized fuses and breakers.