LTO battery fire

[Skypower]

The funny thing about this forum. You will get critique, some of which is good for your ego and that’s not, most of which is well deserved. This is a learning location, learn to suck it up, get a thicker skin and use the advice you deem appropriate. Or don’t expose yourself by posting.

LTO is the safest of the commonly used lithium chemistries. That being said, we are now using DC battery voltage that can easily have an arc fire. A bad terminal connection (resistance) can start out with heat damage (cell&buss) cascading all the way to something similar to hyper powerful DC arc welder, spraying molten debris. My guess is the cell didn’t fail per se, but it got drilled out buy arc. The overcharge failure tests I’ve seen involved one cell and the result was underwhelmingly boring, that could be quite different if it’s part of a group with higher voltage coursing through it. So an out of balance cell could also be the cause.
The critique whether or not you like it. Periodically check the torque of the cell nuts. Loose the slotted buss bars in favor of a full hole type. Drill and tap the busses for a balance lead and use large hole terminals for the end cell balance leads. Use a flame resistant (or fire retardant treated wood) support surface to evenly support the cells off the storage shelf wire mesh.
Take it or leave it.

 

[Lt.Dan]

What is dividing the cells on the bottom shelf? I can't imagine that is metal, and risk the very easy possibility of shorting a 22S bank capable of a continuous 8-10C??? If it's wood, then that's another can of worms...

 

[Tulex]

LTO is the safest of the commonly used lithium chemistries.

That's not what I am reading online.

2. Which battery type is safer?​

Both LTO and LiFePO4 batteries are considered safe options compared to other lithium-ion chemistries. However, LiFePO4 batteries have a reputation for superior safety due to their high resistance to thermal runaway and overheating. They are less prone to accidents or fires, providing peace of mind when using them.

 

[JJJJ]

There have been multiple times where I have enthusiastically presented something. Sometimes I get a thumbs up. Other times I decided to swallow my pride because the critique while difficult to swallow was spot on.

There is nothing wrong with trying new things. That is why we are here.

We are fortunate to have members who have extensive practical experience not only in solar. We are gifted with some very interesting and intelligent members who love to teach.

There is a lot to learn.

 

[Checkthisout]

OP, don't get your feelings hurt.

Would have had less critique and more LULz if you posted this in the "Up In Smoke!" Forum.

That's an impressive amount of power there.

Those kinds of cells look like you just chopped up a bunch of Optima batteries into individual cells.?

 

[Partimewages]

- accused of "disrespect"

I did not accuse you, I stated a fact!

 

[42OhmsPA]

Periodically check the torque of the cell nuts. Loose the slotted buss bars in favor of a full hole type. Drill and tap the busses for a balance lead and use large hole terminals for the end cell balance leads. Use a flame resistant (or fire retardant treated wood) support surface to evenly support the cells off the storage shelf wire mesh.

This part hit home for me and has me thinking....

I went from drilled and tapped DIY bus bars that were made with 1/4" aluminum stock to slotted flexible bars when I moved everything to the new shelf. The entire time I was tightening the flex down I was cursing myself for not drilling and tapping the balance lead wires again....
I'll more than likely drill and tap when I add my 4th pack and build a bigger and better shelf, my C rates will be even lower with the 4th pack too.

 

[Skypower]

That's not what I am reading online.

2. Which battery type is safer?​

Both LTO and LiFePO4 batteries are considered safe options compared to other lithium-ion chemistries. However, LiFePO4 batteries have a reputation for superior safety due to their high resistance to thermal runaway and overheating. They are less prone to accidents or fires, providing peace of mind when using them.

They are about the same in regards of safety when in service. The LTO is impressive by itself. All bets are off regardless of chemistry in regards of an external short or arc of a loose terminal. If there’s any I wish to convey to all is to check the terminal torque. Different alloys creep differently with time. Torque and check a few days later than a month, half year. After a while you’ll get a feel for how often you should check a YOUR system if ever again.

 

[Skypower]

This part hit home for me and has me thinking....

I went from drilled and tapped DIY bus bars that were made with 1/4" aluminum stock to slotted flexible bars when I moved everything to the new shelf. The entire time I was tightening the flex down I was cursing myself for not drilling and tapping the balance lead wires again....
I'll more than likely drill and tap when I add my 4th pack and build a bigger and better shelf, my C rates will be even lower with the 4th pack too.

The busses on the OP’s are open ended not a closed slot like your flexible buss bar. I’d be hesitant to drill&tap a hole in those because it hard to tell where the resistance welded area of the laminated copper ends. It’s been done before with success but I don’t think the risk to reward is worth it. If anything I’d try to use a crimp terminal for the balance lead that has the widest surface area eyelet for a 6mm-1/4”
hole. There are those that don’t want anything between the TOP of the buss and balance terminal but I’ve used a washer there without any issues.(Not between the terminal and buss!) The biggest problem that I’ve seen with balance leads is a poor crimp. For some reason those little things can be pitha to crush.
Those slots on those flexible buss are my pet peeve, however I have not heard of any failures( if so let me know). Just check the torque and don’t worry about it. That looks like a tube of Ox-Gard. While this and Noalox are great for power panel junctions. I’ve found etched, discolored surfaces on tinned lugs and nickel plated buss after being in use a while then disassembled. This leads me to thinking that something’s happening that shouldn’t.(no resistance or voltage difference measured) I’ve switched No-ox-Id A special and have not seen any issues.

 

[curiouscarbon]

sad to see the destruction
happy to see the sharing of info

thanks for braving the fire

hoping for success in rebuilding and continued working system.

surely this information will help protect some from same.

---

electrical connection resistance leading to temperature increase seems to be implied by the image.

 

[Nobodybusiness]

My home build LTO battery had a fire last night.
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.

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

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

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.

LTO chemistry is amazing.
This could have been much worse.
Our small arch fire was easily put out with a CO2 fire extinguisher.

The battery cart was on wheels and easily wheeled outside, away from the house, while we dealt with the fire.

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

Make sure your batteries are on wheels, you have a fire extinguisher, and a fire plan to get flaming batteries away from your home.

Be safe.

Yikes!

Hope everyone is fine.
I had a Heltec balancer pop a cap and ruin a cell.
No fire but still drained the cell.

Also had a JK stand alone balancer that “ went bad?” And almost killed a battery.

If I can’t control it then I don’t use stand alone balancers anymore.
Just my opinion.

At least the integrated balancers have BMS to stop anything unless it goes bad too.
Luckily haven’t had that happen yet.

 

[Skypower]

Yikes!

Hope everyone is fine.
I had a Heltec balancer pop a cap and ruin a cell.
No fire but still drained the cell.

Also had a JK stand alone balancer that “ went bad?” And almost killed a battery.

If I can’t control it then I don’t use stand alone balancers anymore.
Just my opinion.

At least the integrated balancers have BMS to stop anything unless it goes bad too.
Luckily haven’t had that happen yet.

You’ve had your fair share of bad luck in balancers ?
The only problem I ever had with a balancer is one Heltec 4s had a capacitor installed backwards! No, I didn’t use it.

 

[sunshine_eggo]

That's not what I am reading online.

2. Which battery type is safer?​

Both LTO and LiFePO4 batteries are considered safe options compared to other lithium-ion chemistries. However, LiFePO4 batteries have a reputation for superior safety due to their high resistance to thermal runaway and overheating. They are less prone to accidents or fires, providing peace of mind when using them.

The difference is the pervasive nature of LFP vs. LTO. LTO cells are comparatively rare, thus LFP gets the reputation since very very few have LTO. I'm semi-active on this board, and my perception is that the ratio of LFP to LTO cells is at least 1000:1.

 

[sunshine_eggo]

THIS.

Also, what are you powering that requires a 22S pack???

LTO nominal voltage is 2.4V, so 22 * 2.4 = 52.8V - pretty reasonable for a 48V pack.

 

[Skypower]

I'm semi-active on this board

?

 

[sunshine_eggo]

@Systems Planet

Thank you for showing your ass. Glad it's not singed.

Everybody else:

Anyone leveling criticisms should be specific. It's one thing to say "your system is shit and it's unsafe." It's far more valuable to point out the specifics so others can learn.

This an excellent example:

LTO battery fire

The funny thing about this forum. You will get critique, some of which is good for your ego and that’s not, most of which is well deserved. This is a learning location, learn to suck it up, get a thicker skin and use the advice you deem appropriate. Or don’t expose yourself by posting. LTO is...

diysolarforum.com

 

[sunshine_eggo]

Yikes!

Hope everyone is fine.
I had a Heltec balancer pop a cap and ruin a cell.
No fire but still drained the cell.

Also had a JK stand alone balancer that “ went bad?” And almost killed a battery.

If I can’t control it then I don’t use stand alone balancers anymore.
Just my opinion.

At least the integrated balancers have BMS to stop anything unless it goes bad too.
Luckily haven’t had that happen yet.

I've discovered that my active balancers make my battery worse than when it's left on its own with an occasional passive balance via Batrium.

They are individual units, and I'm pretty sure their voltage measurement error forces a 0.04V drift in my cell voltages. They'll seek that dV after about a week following a Batrium 0mV balance. When I leave them off, it takes about a month before my Batrium needs to be fired up for a few Ah of burning. Batrium cell voltages are within ±.005V of my Fluke. I have no idea what the balancers are measuring.

 

[rodrick]

Our small arch fire was easily put out with a CO2 fire extinguisher.

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

 

[Checkthisout]

Yikes!

Hope everyone is fine.
I had a Heltec balancer pop a cap and ruin a cell.
No fire but still drained the cell.

Also had a JK stand alone balancer that “ went bad?” And almost killed a battery.

If I can’t control it then I don’t use stand alone balancers anymore.
Just my opinion.

At least the integrated balancers have BMS to stop anything unless it goes bad too.
Luckily haven’t had that happen yet.

I put a heltec on my pack. Failed in 2 weeks.

Junk

 

[Skypower]

I put a heltec on my pack. Failed in 2 weeks.

Junk

I really can’t complain about my experience with Heltec’s and Neey active balancers they were in use till the BMS failed. The Heltec for a 16S and the Neey for a 2P 16S kept the batteries happy and supper balanced. They only came on around the upper “knee”. I still have them to augment a sick old battery if needed in the future. Now the JK bms’s handles everything

Edit; Yeah, I know, the wire were a mess, but at least I didn’t waste time since it wasn’t the final product