Fire!! Never cover LiFePO4 with wood!!!

fhorst

making mistakes so you don't have to...
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New adventure..

I went inside the battery room.
As the exhaust fans where working, and they are temp based,
IMG_20210307_095703_239_copy_180x320.jpg

I felt OK to close the door.

I used wood (MDF) to cover the cells and sit on top, and to prevent accident if something falls
2 left over pieces, 10mm, but strong enough to sit on, as the threaded bolts aren't soft.

Working to install AMMeter above the inverter I can't hang to the front, over the battery pack, that long.

This morning opened the door and felt more heat then I expect.

The fans are sucking out air, right?

And I smell some burning.
First though it was from the AMMeters I fried yesterday.
(Apparently incompetible with my 450v solar, while rated 600v)

Then I started feeling for the temp...
The inverters not hot, battery was!!

Looking more closely..
The MDF slowly glowing....

I took off the sheet and brought it outside:
IMG_20210307_093212_copy_750x1000.jpg

The cells look like this:
IMG_20210307_093021_copy_1000x750.jpg

And glowing coal falling off the sheet when I removed:

IMG_20210307_093028_copy_750x1000.jpg

For all I can tell the fire started between those 2 threaded rods.
They are a little longer then the rest and would have made some imprint in the MDF.

IMG_20210307_095302.jpg

Lesson learned:
Wood is conductive!!!
With 1000Ah, there is a lot of power.
Even enough to make contact between 2 threaded rods with MDF sheet, and heating it up far enough to catch fire.
 

jwelter99

Solar Addict
Joined
Dec 6, 2020
Messages
552
New adventure..

I went inside the battery room.
As the exhaust fans where working, and they are temp based,
View attachment 39905

I felt OK to close the door.

I used wood (MDF) to cover the cells and sit on top, and to prevent accident if something falls
2 left over pieces, 10mm, but strong enough to sit on, as the threaded bolts aren't soft.

Working to install AMMeter above the inverter I can't hang to the front, over the battery pack, that long.

This morning opened the door and felt more heat then I expect.

The fans are sucking out air, right?

And I smell some burning.
First though it was from the AMMeters I fried yesterday.
(Apparently incompetible with my 450v solar, while rated 600v)

Then I started feeling for the temp...
The inverters not hot, battery was!!

Looking more closely..
The MDF slowly glowing....

I took off the sheet and brought it outside:
View attachment 39900

The cells look like this:
View attachment 39901

And glowing coal falling off the sheet when I removed:

View attachment 39902

For all I can tell the fire started between those 2 threaded rods.
They are a little longer then the rest and would have made some imprint in the MDF.

View attachment 39903

Lesson learned:
Wood is conductive!!!
With 1000Ah, there is a lot of power.
Even enough to make contact between 2 threaded rods with MDF sheet, and heating it up far enough to catch fire.

MDF is non-conductive, or at least rated as such. MDF also will typically not burst into flame but if kept above combustion temps will smolder which seems to be what you had happen. Is it possible something else shorted under the MDF and generated high enough temperatures?
 

fhorst

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@jwelter99 , I absolutely looked for this, but was unable to find.

Sure there where wires and molten.
1.5mm2 for BMS with external coating, so the cable and the cables coating had cover. Normal AC wire.

They could not have made Falce contact.

One other wire that was laying there was thin insulated, temperature probe for 12v fan controllerIMG_20210307_103336_copy_1200x1600.jpg

I find it hard to believe that this could have started the fire, especially as it looks like just to be unlucky victem.

The BMS wires look like this:
IMG_20210307_103555_copy_1200x1600.jpg

Anything is possible, but unlikely that this will make the short.

We did have a lot of rain the last few days here in Thailand, that made humidity rise a lot.
That could have made the MDF more conducive.
 
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cinergi

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It looks to me like the terminal & bus bar connection got hot probably due to a bad connection. The MDF, even under humidity, wouldn't have shorted anything out. Something went wrong with the battery. Without high rez pictures it's hard to tell (you'd need to upload elsewhere and link them here).
 

fhorst

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Well....
The contact between the cell terminals and bus-bar is absolutely tight as possible with aluminium threads, that where reinforced with Loctite, and firmly connect.
Internal resistance meter showed practically no increase, making that the contact as strong as possible.

It wasn't under high load.
500-750 watt on +1000Ah
And at 09.00 the sun wasn't providing a lot of energy.

The battery was is "resting phase" not actively charger or discharged.

So I don't know.
I do know that it wasn't a problem for weeks and weeks.

I do know that the one day I did cover it with MDF sheet, that sheet catched fire.

As that was the only thing changed in that area, it's a solid assumption that this was the cause of the fire.

All other suggestions are more speculation.

Even high resolution pictures won't give you the answer you look for.
As it's after the fire, where you can see the terminals where hot enough to melt the plastic around them.

I'm quite sure they have no longer optimal contact now, after the fire.
 

fhorst

making mistakes so you don't have to...
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It's obvious the 12 cells can't be trusted anymore to perform any close to what it was supposed to do.

Good thing about 48* 152 cells, it's easy enough to make it 32*152Ah.

No longer part of the +1000Ah family... But working setup 👍
 

Gazoo

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We did have a lot of rain the last few days here in Thailand, that made humidity rise a lot.
That could have made the MDF more conducive.
I am no expert but the high humidity could have made the MDF conductive and it may have been conductive when you received it. Some woods have moisture content and that makes them conductive. I just did a quick look on Google and that's where I got the info from.

I am glad you are OK and nothing worse happened. I would still check the connections for resistance. Thanks for posting and sharing your experience. I would have never thought wood could be conductive but now I know it can be thanks to you.. :)
 

Hedges

I See Electromagnetic Fields!
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Messages
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It looks to me like the terminal & bus bar connection got hot probably due to a bad connection. The MDF, even under humidity, wouldn't have shorted anything out. Something went wrong with the battery. Without high rez pictures it's hard to tell (you'd need to upload elsewhere and link them here).

That is how it appears to me. Hot terminal cooked MDF, not the other way around.

Well....
The contact between the cell terminals and bus-bar is absolutely tight as possible with aluminium threads, that where reinforced with Loctite, and firmly connect.
Internal resistance meter showed practically no increase, making that the contact as strong as possible.

Maybe the electrical fault was internal to the cell?

The battery was is "resting phase" not actively charger or discharged.

Which is not consistent with my idea of a poor contact inside carrying current.


I do know that the one day I did cover it with MDF sheet, that sheet catched fire.

As that was the only thing changed in that area, it's a solid assumption that this was the cause of the fire.

Mechanical force or disturbance?
 

fhorst

making mistakes so you don't have to...
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Last one could be.

From time to time there was a few kg (not my total weight of 80kg, but quite some) resting on 24 /36 threaded rods, and 2 are a little higher...

And no....
I didn't reconnect the smoke detector yet (what is powered by the BMS setup)
Cry...

So stupid, as I have battery operated alarms in the bedroom, and if the door would be open..
They sure would have been triggered.

Other lesson learned....

Anyways...
Time to rebuild and take out 16 cells.
They go to grandfather back up power, outside his house.
I probably make brick housing for them.

As long as they work, it's better then the alternative, nothing.

But I don't thrust them inside the wooden shed he calls his house.
And he is with right proud of his build.
In the west we call it a shed, at best, that's not intended negative here.

Some parts straw roof, metal sheets and loads of dry, termite eaten wood...

That will catch fire to quickly.
32* 152 and 32x 280 is still a nice large LiFePO4 battery
 

ArthurEld

Photon Sorcerer
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I suspect a short. You were talking about electro magnetic field before.
I think these batteries have certain spots that are just dying to short.
 

fhorst

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2021-3-7 12-42-53.jpg2021-3-7 12-42-40.jpg
@Hedges it seems you are right.

One terminal is really bad.
Probably that one had too much to suffer from the bodyweight that was resting on the sheet, who was being held up 36 threaded rods..

Too much force...

Expensive lesson..

So people: to not place too much weight on top of the threaded rods!!

You see the results.
 

MattiFin

Solar Addict
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Messages
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There is less than damage on terminals and bus bars than I would expect to see if something heated up there and ignited the MDF.

Then on the other hand MDF conducting enough current to ignite doesn't make any sense either unless someone spilled battery acid on the MDF previously or soaked it in sea water.

Amazing Thailand :ROFLMAO:
 

fhorst

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That doesn't look like what I was expecting to see under there.
I expected the terminal to be gone.

I don't understand what you are saying caused the fire.
During the installation of the AMmeters I placed a piece of MDF over the cells, and placed my knee on there to keep balance.
It wasn't my full weight, but apparently too much.

The threaded rod of the affected cell was slightly higher then the rest (5mm)
Here I'm happy to even find threaded rods with "allen wrench" (hex) , I can't be choosy.

Pressure on the thread/terminal apparently pressed out of place, and created a short inside the cell.

That got too hot and set the MDF sheet on fire, smoldering as MDF doesn't really burn well.

My walls and ceiling are covered with concrete fiber sheet, to contain accidents, but I doubt they can hold back fire long...

I guess I can say I got lucky, that it didn't burn our house down.

That would be a real shame.
 

stobbie

Solar Enthusiast
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Messages
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That's the second fire here on the forum? I have never found the cause of my fire, but it has cost me $ 40.000 dollars unfortunately :-(
Now put a small pack of four cells again in my new campervan, still a bit scared...
 
Last edited:

fhorst

making mistakes so you don't have to...
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How to make a poll on the forum??

I have atleast 4 cells so bad that I don't want to use them, at all.

The one with the really bad terminal, and 3 more as it will be sets of 4 to go to grandfather.

What to do with them?
Cut them open with a grinder or saw?
Use cutting torch
Fire?
Drill?
Drop?
Or build a temple for them, casualties from the learning process :)
 
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