Fire!! Never cover LiFePO4 with wood!!!

fhorst

making mistakes so you don't have to...
Diamonds, sounds great!
Like the laser welding system, a tiny bit beyond budget :)

Perhaps Kapton, the yellow non conductive heat resistant tape?
Thin layer that does conduct most heat, but is strong. It doesn't break easy (or get penetrated)

That would work?
 

Hedges

I See Electromagnetic Fields!
I was thinking of the expandable mesh that comes on mechanical parts like shafts to prevent nicks. Much of surface area would be exposed. It probably softens at too low a temperature and may not be think enough for complete protection against accidental contact.

Expandable braid sleeve. Intended as mechanical not electrical protection.

When 3-D printing, could print a structural pattern with vent holes. A layer of ribs running in "X" direction then a layer running in the "Y" direction, letting air pass between.

I don't think these busbars are heatsinks for your battery, rather the other way around. Unless cross section is greater than ampacity charts call for, these busbars (if insulated) would be running hotter than 90 degree C without batteries taking the heat and dissipating through their greater surface area.
 

fhorst

making mistakes so you don't have to...
I don't think these busbars are heatsinks for your battery, rather the other way around.
You are probably right.

Bad contact will heat up the terminal and bus-bar under load.

Good contact should heat up the cell inside doing its chemical thing.

I can't speak for others, my setup have the cells compressed, and it's almost like massive block of 60*70, +20cm high, 200kg LiFePO4
(2 layers, 400kg)

The little bit blue that's "exposed" to air and the black top plastic aren't giving off much heat.

When I need to take it apart, I'm surprised about how warm the cells are, compared to the Bus-bars.

It takes a lot of hours before that mass is cooled, and I just dive-in when I stop the connection.

Bars then are cold, cells still warm.
Warm like 35-40, nothing special.

+175A charge does give some temperature increase. :)

I thought about how to improve this, get better cooling.
Without liquid.... Not easy.
Submerged in 2 phase cooling will work fantastic.

Again, a tiny bit beyond budget.
35-40C is just fine for a room temperature of about 27-30C

I'm also always looking for improving, many ideas don't even make it to the drawing board.
 

Just John

Photon Sorcerer
I was planning to cut it to the size of my battery so that helps some.
But you are correct, 5/8" thick drywall isn't light.

I'm always thinking of possible improvements. Most of them never happen. :oops:
I'm just going to place a smoke detector above the batteries and hook it into my home monitoring Ring system via z-wave. Add a big CO2 extinguisher at the door where I'm putting the batteries, and call it a day. May not be the best or most effective, but when you buy them in 3 packs at Costco, the smoke detectors are about $35/each, and I already pay the $100/year for burglar and fire monitoring. Battery operated, and you can even read the battery level via the phone app. So far I've been very pleased with the system. I bought and installed one for my daughter, and was impressed enough to buy one for myself after I installed hers.
 

fhorst

making mistakes so you don't have to...
Add a big CO2 extinguisher at the door where I'm putting the batteries, and call it a day.
I read about CO2 and their danger for in-house use, one or 2 breaths of "pure" CO2 and you are a dead man.

For me as I'm sometimes away for several weeks, I can't bet in a CO2 cylinder to do the trick, it has to be automated.

With the small room, CO2 would have been 40% cheaper.
Opening the door after it went off might be a huge problem.
Perhaps the children around, who knows what will happen if I'm not there and the tank puts out a fire.

Probably my wife wants to open the door, with daughter right behind.

I don't know for sure if CO2 is that deadly.
I didn't want to take a chance.

Halotron seems to be the safest bet.

My Chinese smoke detectors signal eachother if there is a fire, all 20 or so will go off :)
The other smoke detector will trigger the BMS to cut contact, solar, AC, battery, Wind.

Just saying..
Better prepare that it will happen and not only focus on prevention/ flame retardant products.
 

Hedges

I See Electromagnetic Fields!
CO2, N2, and natural gas are asphyxiants, as are the Halon and similar extinguishing agents. If they displace air until there is insufficient O2, the atmosphere won't support life.
Natural gas is also flammable, so a substance with odor is added to let you detect it.
Halon suppresses fire at a lower concentration, so atmosphere in a closed space can still support life. Smaller extinguisher Halon will accomplish that, vs. a larger CO2 cylinder would have been required.

I think a couple of breaths of pure CO2 followed by breaths of fresh air, and you'll be OK. Remaining in a room with O2 too low is a problem.

Some gasses like CO stay attached to hemoglobin, unlike CO2 aren't rapidly released from the bloodstream to allow O2 to be taken in. Low levels in the air over a period of time will build up in the blood, causing asphyxiation. Treatment includes moving to fresh air and giving O2, but takes time to raise O2 levels of blood back up.

Water may not be a bad thing for a 48V battery room (with no electronics). A volume of water will produce more cooling than your small Halon. How about sprinkler heads with a higher temperature than your Halon system? Only if fire gets out of hand will that be operated.
 

fhorst

making mistakes so you don't have to...
There is 1 inch pvc pipe on the floor, originally the electro room wasn't supposed to be there.
Water tap pressure, before the lines are empty, it's a big mess...
(On the floor)
Water pressure (enough to ensure enough cooling) is build by the AC pump, who would have been out of power after the detection of smoke.

Halotron intended for 25-30m3 in 6 to 8m3 absolutely should be enough.
If it isn't, I can't create enough pressure and water volume to make a difference.

We have a large pond and gasoline operated 3 inch pump, what goes to 2inch flat hose.

That should be able to put out the rest of fire if things go really bad.
Electricity danger is then almost 0 as it's fully disconnect.

I hope to never use.
(Except for irrigation)
 

Hedges

I See Electromagnetic Fields!
I was thinking fully automatic water sprinkler. Minutes matter when it comes to fire spreading.
12V pump, battery powered.. One car battery kept at float voltage should do it.. Thermostat to enable.
Except, an active when closed circuit could fail in a fire. Instead, NC relay held open by wire to NC contact of thermostat. Either thermostat actuating or wire burning open turns on pump and hoses down fire.
If temperature drops, thermostat turns off. Unlike fire sprinkler heads.
 

Freep

Solar Addict
I would say fairly easy to learn. I have been around engineering all of my career but have never done mechanical design. There is a lot of help on the internet. I have a $200 printer and a free design program. I just start trying to make something and keep after it until it works. A set of calipers is most helpful.
Also many cities have maker spaces with 3D printers you can use.
 

ArthurEld

Photon Sorcerer
I read about CO2 and their danger for in-house use, one or 2 breaths of "pure" CO2 and you are a dead man.

For me as I'm sometimes away for several weeks, I can't bet in a CO2 cylinder to do the trick, it has to be automated.
I'm going away for a couple months. I took all of my busbars off. :p
 

fhorst

making mistakes so you don't have to...
I'm going away for a couple months. I took all of my busbars off. :p
Lol.
That won't make the missus happy!
No power is not easy off grid.
The pond should provide water for a while, buckets.
Drinking water=boiled pond water.
Laundry by hand
List goes on.
I probably spoiled her too much :)

And yeah, while water is really good in stopping fire, it should only start if the Halotron fails.

I simply don't have the funds to rebuild.
While it's good the house doesn't burn down all the way, it would be enormous loss.

The Inverters, Mining equipment, batteries....
With halotron most of it will be salvaged, cleaned and used again.
With water....
It's all lost beyond repair.

If the fire starts in that room, and the Halotron isn't able to put it out, there is enough time to get the pump going.

It should fill that room in about 15 minutes, I doubt the walls will hold pressure of 3000L

Seriously, if halotron isn't stopping it, we need to rebuild a lot of the house.

Straw bale walls (really good environmental friendly and cheap insulation) don't like water.

Straw bales smolder, they don't really burn.

Halotron will do the trick, if not, it will have damage that takes us years to recover.

Wild fires are more realistic a problem.
It's burning season, and not all farmers care about their lands and control the fire.
(Rice and sugar cane fields are burned instead of plowed)
If the plot of your neighbors catch fire... Bad luck.

It's impossible to get them to pay for damages.
Most don't have the funds.

That's the reason we have the pond and pump, and have some free space around the house.

If the fire is too crazy bad, nothing will help.

Water in the electronics room..
Only if all is lost.
 

johntaves

Solar Enthusiast
Once again: S16 LiFePO4. (That is nominal voltage 51.2v)
S16P2 280Ah and
S16P3 152Ah
What does this mean? Are you saying that the whole battery consists of 2 strings of 16 where one string has 2P and another 3P? I assume no, but ...

I did not find a satisfactory explanation for this heat. For me, the 2 different hot spots, one at the negative terminal and one at one of the cells, seems to not support the notion that a damaged cell cause the heat and that heat was carried by the bus bars. The main hot spot seems at the positive terminal minus one cell, so the negative terminal is 15 cells away. The other bus bars don't seem to support the notion that they carried the heat to the negative. Maybe the heat damage at the negative terminal is caused by the heat escaping from the MDF cover? Maybe that MDF board sort of funneled the heat/smoke towards the negative? Maybe the negative terminal damage is mostly soot?

Just to be clear, the physically damaged terminal/battery theory is that the damaged battery now is draining the two other batteries that are in parallel with it, causing the heat, right?
 
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Hedges

I See Electromagnetic Fields!
fhorst -

Have you read this one?
(and the linked UL report.)


"Many of the gases and vapors emitted from lithium-ion cells during thermal runaway are
flammable, and they can create an explosion hazard if they are allowed to accumulate in a confined
volume without burning [20]. Therefore, the Novec 1230 likely created an environment in which
flammable gases and vapors emitted during cascading thermal runaway accumulated in the ESS in
the absence of a fire."
 

ArthurEld

Photon Sorcerer
The type X would be a heavy lid :)
And a lid stops heat from escaping.
Holes would give ventilation, also location for fire to spread...

For me, the room has concrete fiber sheet against the MDF and plywood walls. It doesn't have to hold the fire back for a long time, just long enough to let the heat reach 68 degrees..

It might even be an idea to have "fire food" available that smokes like crazy, to trigger the smoke alarms more quickly.

Fire doesn't have to be a (really) bad thing. Not good, obviously.
That idea seems bad to me. There is a fine line between smoke and fire.
A slight error could be disastrous.

I'm not sure if you are talking about creating smoke or heat. I don't like either.
As long as it's contained long enough and there is (automatic) equipment available to put it out..
I am thinking that if you keep the problem contained well enough and long enough that the problem could run it's course without starting a fire.
This is a complicated subject. I assume there needs to be ventilation. But with ventilation comes oxygen.

Another issue you need to consider is that your extinguisher might not stop a short. And the short might take longer to burn itself out than your fire extinguisher lasts. I assume this can be a problem.
We all know about prevention, and do it to the best of our abilities.
If there is a mishap, something goes terribly wrong.
Think about that.
And that you aren't there to put it out.
Will your setup still be there if you leave to the town for groceries?
-> and there is an accident like I had..

Prevention is good.
After the normal standard ways, it's (I think) better to prepare that there is a fire, and spend the money on that, instead of possible crazy expensive flame retardant alternatives. Most of us aren't building an airplane.

We have room for error, our house doesn't fall out it the sky.
There isn't a thermal meltdown (right term?) of LiFePO4 cells, but we do have many thousands of watts potential energy stored.

Am I wrong?
Accepting that prevention isn't all.
But prepare for the possibility that fire will occur and that I won't be there (on time) to put it out?

TV's used to be number one for creating fires for decades, I never thought about placing a halotron tank above it :)
 

technerd1988

New Member
Something tells me loctite is a no no on battery threads. You don't need it. I've had many of these cells in service in my rv for years now. It looks like nothing shorted rather, but you made a horrible connection. NEVER cover batteries with wood, especially the vent side. clamp your cells together and torque to 5ft lbs and your good to go, even in a mobile situation like me. On these batteries the machine screw stud is part of the amp carrying capacity. Don't EVER use loctite again
 

SherylinRM

GO GO JUICE BOOMER ZOOMER MAKER
Just a thought. An old bar fridge. Dismantle it carefully. Put the coils on the batteries and if you can get a temp probe to work only at 40 to 50 farenheit, and maybe a bit higher. It could work. And the motor would be small enough to not cost a lot in electricity. Yes it would lower the batteries output, but might be worth it to keep them cool.
Hope this helps. :)
 

Gazoo

Dumb Dumb
Something tells me loctite is a no no on battery threads. You don't need it. I've had many of these cells in service in my rv for years now. It looks like nothing shorted rather, but you made a horrible connection. NEVER cover batteries with wood, especially the vent side. clamp your cells together and torque to 5ft lbs and your good to go, even in a mobile situation like me. On these batteries the machine screw stud is part of the amp carrying capacity. Don't EVER use loctite again
Actually use of Loctite or any thread locker is a good idea. I don't know what cells you are using but the threads in these cells are very weak. The EVE cells have 5 or 6 threads to work with and the cell terminal threads are soft aluminum. Generally tapped by the suppliers.

4nm or 35 in lbs is what we have found to be a safe torque. EVE's specs state to limit torque to 8nm to prevent damage to the cells terminal. I think Lishen is in the same ball park. However recently cells are being sold with laser welded studs. This might present it's own problems because we are not sure how many amps the connection can support.

The bulk if not all of the current is carried by the busbars, not the machine screws or studs. If a busbar is loose then of course it could heat up and cause problems. I am not so sure that's what happened here. There has been a lot of speculation and it's all interesting. No one knows for sure what caused the fire and we will most likely never know.
I've had many of these cells in service in my rv for years now.
Who is the manufacturer of the cells you have had in service for many years? Are they aluminum cased cells? And what type of metal are your cells terminals constructed of?
 
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