lifepo4 fire

[slowhand]

Got an urgent phone call from my neighbour this morning in a panic, claiming his battery pack was on fire. Raced over to see smoke wafting from the shed he had his batteries in and him in a panic not knowing what to do. He wouldn't go into the shed for fear they would explode, so I went in to find a jet of fire coming from the cell pack. Ripped of the BMS, got some bags and smothered the flames and opened the doors and window.

When the bags were lifted the fire was out and a jet of smoke was billowing out of what appeared to be 2 cells, so cut the connections with a angle grinder, pulled out the effected cells and put them outside, then sprayed water over them. That's when I noticed a hole on one cell and put some water into it, which stopped it smoking.

Went back and tested all the cells, finding them all at 3.45v. Checked the 2 removed cells, to find one at 3.4v and the other bulging stuffed at zero. The neighbour was distraught as he had 2000ah of cells and thought they would all be buggered. Once I reassured him and his always doubting wife that wasn't the case as he technically had only lost one cell, the result was he would lose 40ah and have 2-3 spare cells, depending on whether the other cell lost its charge. Which made him much happier.

Turns out he decided to put his battery box on a stand and drilled into the box to attach it, thinking the ply inside would stop the drill before it hit the cells. First hole he drilled, went straight through and into a cell, creating a spark and setting it on fire. He said at first all it did was hiss and smoke jetted out of the cell, that's when he rang me. Then it caught on fire which seemed to spread across the pack but was only the burning fumes.

So we took out one cell line and everything seems to be functioning properly, but had to rewire the BMS back in. Other than that, everything is fine. Will keep an eye on his system for a few days to make sure its alright and believe the pack will now stay where it is.

Here's a couple of photo's of the two removed cells, one still has 3.4v and will be used to see how much or if any damage has been done to it. If that had happened with LA, doubt there would be anything worth saving and it does show the safety of these things and how easy it is to start and put out a fire in them. You can see the drill hole in the upper left of the buggered cell, good lesson on why you shouldn't use a drill around them.

[bagmaker]

Nice work but watch your health, slowhand.
ANY signs of respiritory issues for a day or two and straight to emergency for you, OK?

Ol mate of mine has a permenant scar on his L ring finger, R index and thumb.
Arced his ring across LA battery terminal and it glowed to an orange color in an instant.
Pulled it off with other hand, had little choice.
We forget how much power is being messed about with, sometimes.

Are they copper terminal strips?

[dapope]

Tough little beggars. Shorted a couple of mine at times, holes in the spanners or washers
Bet your neighbour doesnt do that again!

[norman]

I was under the impression that lipo and water will start a fire not put it out...

[BruceS]

Norman I had to recently cut an anode with an angle grinder ........... ever seen what they throw out of helicopters when a missile attack is likely/suspected??
Next time I'll persevere with the hacksaw!!

[slowhand]

My neighbour just dropped in, brought me a heap of veggies and a box of Williams organic beer, which we think is the best beer on the planet as unlike all packaged beer, it doesn't contain glycol. Told him I'd keep the beer on ice until we can be sure his pack has survived, which should take a few days for anything adverse to raise its head. He certainly had a shock and won't be drilling or doing anything with his pack, but leave it where it is.

G'day Normam, smothered the flames because wasn't sure what would happen if water was thrown over them, including shorting out and destroying the entire pack. It was only after I got the cells outside that I fine sprayed them to cool and quell the smoke, When I squirted water into the cell, it stopped smoking and that was also to see what would happen, as the cell was buggered any way.

Ripped the BMS out as didn't want it to burn, the flames were moving to the front of the pack when I went in, so the only thing to do was smother it, even though he had a chemical fire extinguisher in the shed. When I asked him why he didn't use it or smother the flames, he just shrugged and said, it happened so quickly didn't have time to think and just bolted out of the shed to call me. Going to surprise him tomorrow, have some spare 40ah cells so will give him a couple to replace the damaged and sus ones.

Bagmaker, they are copper strip correctors, 3mm thick by 18 or 24mm wide. You get it in 4m lengths and they make excellent connectors and heaps cheaper than buying retail ones. When experimenting with cells, decided to make a starter battery and discovered the braided and other retail connectors, don't handle big load currents, so did what the military does and connected them with coper bar. Started the land cruiser and earth mover easily, so turned it into and 40ah auxiliary for the Sahara so can run the laptop and TV stereo in it without worrying about flattening the start battery.

As for health, am watching myself and feel I didn't get any fumes as was in and out fast each time I went in until got the cells outside. Will have to look up what sort of fumes are given of when lifepo4 burns and have done lots of deep breathing to clear my lungs of any residue hopefully.

Will make some start batteries out of my spare cells for the bus cars and machinery once I've worked out the best BMS for that job.

Bruce, can assure you the sparks flew when I cut through the connectors and it's something I wouldn't recommend doing, expect in an emergency. There was no chance of disconnecting the cells any other way at he time.

[Dot]

I reckon I would have a go at putting out a fire if I got a box of FRESH vegies other than the crap we get from the shops these days.

[jon_d]

Q: Was it a chemical/catalyst fire triggered by the reaction with the air, or an electrical fire triggered by a short in the battery?

[dapope]

I reckon it would be the short. Drills into batteries shouldnt go.

[T1 Terry]

Great work Slowhand, quick thinking saved the day, those beers will help cleanse the system
Just as a note regarding the safety level with these cells. As part of the military testing for a manufacturer to sell to the Chinese military there is a series of military type tests they perform on them and they are not allowed to explode or catch fire as a result of these tests. They shoot holes in the batteries and they don't catch fire, they shoot holes in them and chuck them in river water and they don't explode or burst into flames. They connect cables between the positive and negative terminals and the cells don't explode or catch fire, just vent their electrolyte.
An LiFeP04 cells doesn't make oxygen when it boils it's electrolyte, just a petrol like vapour that is flammable while in the vapour state. I'm guessing the arc from the drills brushes ignited the vapour and the boiling electrolyte fuelled the fire outside the cell where it could mix with oxygen. The vapour being heavier than air would have settled onto the other cells carrying the fire on to the plastic cases.
there are pros and cons of using heavy cell links, the copper link straps we use fuse at around 400 amps, a shorted cell like that would pull a lot more than that from the other cell it's paralleled with so the link would normally fuse isolating the pack from the shorted cell. 400 amps is more than most house battery systems would pull from a cell, but electric vehicles can pull 1,000 amps for short periods so they need much heavier links.
Real scary stuff when they short like that, he sure must have stuck that drill in deep, there is a good 6mm of plastic case to get through with the Winston and Sinopoly cells, well 3mm on the inner ribs, but still 6mm all together before you would reach any active plates.

I guess you have read the story of how Plasma Boy got his name http://www.evdl.org/pages/plasmaboy.html and they were lead acid batteries, imagine what would have happened if he had lithium batteries Real scary power available in any battery.

T1 Terry