Nasty LiPo fire

[Kepler]

I was helping out a friend setup a new bike today. The bike was being configured to run 20S LiPo on an 18Fet LYEN controller. We were having a bit of trouble getting the hall wires right and were trying a few combinations when suddenly the pack started to smoke. Luckily we managed to get it out of the bike and onto the concrete floor but once this thing had started, it just kept on feeding itself with each cell venting and then going up in flames. The pack burnt for about 30 minutes before it finally went out. Luckily there was no damage to the premise or the bike but it sure was a scary moment and a reality check in relation to the caution required when dealing with LiPos.

Packs were 5000mah 5S Zippys from Hobby King. The controller looks fine internally with no signs of blown Fets or shorts. There is nothing left to check in relation to pack but at this stage we are presuming it was a problem with the pack that caused the catastrophic failure.

Here are a few photos taken on my iPhone. Sorry about the quality.

 

[dogman dan]

New packs? Or old? Even on the wrong combination, that controller shouldn't have been able to stress them that bad. Wow. Shows what happens when one cell decides to go. All the rest then cook off. Scary. All mine have ever done under severe abuse is puff like mad.

 

[Kepler]

Brand new packs fully balanced before use.

 

[full-throttle]

That is one nasty lipo pack prob a bad cell overheated while you were trying out all the combos and started a chain reaction. A SC fault would've been simply blown off

Sorry to hear about your friend's loss

 

[adrian_sm]

Damn. Lucky it didn't do any more damage to the shop. Imagine what would have happened with automatic sprinklers.

Was there any sign of something wrong with the packs? Like a cell that was low when you got them, prior to balancing? Anything in the way you hooked them up they may have contributed.

Anyway. Glad everyone is okay.

- Adrian

 

[Ypedal]

In the first picture..*eyeballs gallons of RC nitro fuel near by !!!!

 

[Doctorbass]

Sorry to hear you lost your entire pack

There is something i want absolutly to know...

I mean.. REALLY REALLY want to know:

What was all the last manouvers or action you made around the pack. .I mean .. EVERY OF THEM !...

Showing lipo fire that appear to be spontanous without reason is always really curious.. and i can't imagine they caugh fire by themself after sitting alone or had to endure little current demand like hall snesor combinaison test with the motor!

There is necessarely something that trigger that.

Cell puncture, balance lead short?, pack was droped to the ground... some sand around the pouch that puncture the layers?

This is REALLY important for us that you examine EVERY last DETAILED action you had in relationship with the pack!


I'm bulk charging my 12x 6s zippy pack for a year now at 1500W DC by just watching the voltage of all cells to ensure they dont go over 4.2V ( usually 4.15V) and never had any sing of puffing or any other problem... I have zero BMS.. no LVc.. I just cut at 3.5V per cell in the controller

Doc

 

[number1cruncher]

Yeah this is not going to help the reputation of Lipo one bit.

Maybe in addition to what Doc Bass has asked for, maybe an understanding of these packs background would also be helpful? Like which HK warehouse did the packs come from? What day where they delivered? Did you guys by chance write down the serial numbers on each pack? Also, were they bottom self like 15C or better?

Glad everything is alright and noone got hurt.

 

[Icewrench]

Wow. That is ugly.

 

[el_walto]

I wonder how long it will take to get that smell out of your garage.

Was there a fuse on the discharge lead? I'm going to guess it shorted somewhere in the controller.

 

[JohnC]

.

 

[Ypedal]

I dont think anything done by or from the controller could result in this, any sort of short would have resulted in instant vaporization of said wire/circuit or battery tab at worst, the cells going off like this have to be caused by something else imo...

edit : Using partially shielded Bullets by any chance ? :lol:

 

[dnmun]

gonna lose your lease on the shop over this.

maybe it would help to have a flat shovel handy to carry the burning pack outside or a metal ash bucket just for fires.

unfortunately i suspect the next one will be on the carpet of an apartment building. in that case the authorities could bring charges too. especially if there is loss involved to others.

 

[Rin]

There wasn't a fire extinguisher in the shop?

 

[John in CR]

For those of us without money to burn I believe it's best to run packs individually through some cycles, and also let them sit at full charge (or maybe even slightly over-charged) before pack assembly. That way you keep losses to a minimum in the event of one bad cell, which seems to be just the luck of the draw.

Other than intentional destruction or charge/discharge errors, the problems are generally coming from bad cells from the factory, not mishandling on our end. Plus we don't know what rough treatment occurred during shipping, but the packs should be able to take anything that doesn't cause a physical deformity of the pack anyway. Instead of this BS of trying to put the blame on the user, and trying to come up with something he might have done wrong, it would serve the community better to come up with a set of procedures to follow to identify bad cells before the packs get combined with other packs where problems are multiplied. We can't realistically expect 100% good cells to come from the lowest cost provider, so how do we protect ourselves in the best manner?

When my unused hard case 4s5ah 20C Turnigy pack spontaneously fried after sitting undisturbed for about a month with an initial 4.15V/cell balanced, I got very lucky. It was the top cell that flamed out, and the cell under it only maximally puffed, leaving the 2 bottom cells still good to go. I had my packs spread a couple of inches apart on a formica covered particle board desk, and the only damage other than the flamed pack was a small hole melted in the side of an adjacent pack. Had the problem started in any other cell in that pack, I believe I'd be talking about our guest house in the past tense, because the flames and heat would have gone sideways enough to spread instead of going pretty much straight up.

John

 

[vanilla ice]

That sucks. How many packs was that?

Running charge bags on bike is one cheap and easy safety step that might help in these rare cases. I think of it like running a proper gastank versus using a plastic bottle full of gasoline on an IC bike.

 

[EBJ]

it would serve the community better to come up with a set of procedures to follow to identify bad cells before the packs get combined with other packs where problems are multiplied. We can't realistically expect 100% good cells to come from the lowest cost provider, so how do we protect ourselves in the best manner?

X2.

My Lipos just shipped today and I am in a tiny 1 bedroom apartment. I have the Hyperion Charger already and was planning on using that to do the "break-in" procedures to each individual battery.
I'd love to know more about "Identifying a bad cell" and what should be done about it. Perhaps someone will start that topic. I have no problem sending back bad packs even if I suspect the slightest problem.

 

[number1cruncher]

the problems are generally coming from bad cells from the factory, not mishandling on our end.

Instead of this BS of trying to put the blame on the user, and trying to come up with something he might have done wrong,

That is why I asked if they wrote serial numbers, so other members maybe could identify if they have packs from a related batch. If the SNs are sequential. I agree that most likely this event was either chemically induced or a bad solder joint or something from the factory. We might be able to fix a bad solder joint, but if the instability was caused by the chemical makeup of the pack, nothing we do could ever help that. Maybe Luke has insight about the chemical aspects?

When my unused hard case 4s5ah 20C Turnigy pack spontaneously fried after sitting undisturbed

I missed that one. I have my ebike lipo all over my house, in "safe" places. Like out of reach of my 5yo. But they are definately not in fire proof places. However, for Christmas, I built my son a Tamiya RC truck and used a hard case 2s 20c Zippy LiPo. If it catches fire, while being used for its intended purpose, things are going to get interesting. At least he is trained to let me hook the battery up and turn it on. He just crashes it into the curb ( ) a lot. Most likely it would go up in flames at a distance. Maybe NiCad wasn't that bad after all. Then again, Jeremy Harris has said that he has had Nicad blow up too.

Imagine if LiPo was in metal cans like NiCad.

 

[Ypedal]

Imagine if LiPo was in metal cans like NiCad.

They are, called 18650 cells, in laptops all over the world ! 8)

 

[liveforphysics]

Wow!


WOW!


WOW!



First JohninCR has a cell randomly go, and now Kepler as well.

After John's incident, I dug through my house and shop through all my totes of RC stuff, gathered up all my puffy packs, ebay packs, and other crap packs and other sketchy packs and had a fun couple hours of overcharging them into fireballs outside (best way to reduce all risk). Then I put my remaining good packs in a concrete corner of my shop with nothing flammable near them.

It seemed a little severe at the time, but now it seems like a good idea.


I have no idea why or how this has happened twice now. It's pretty scary stuff, because it could do it while you're not home, and seems to do it entirely unprovoked.

Can you give us the exact type of pack these were? Were they also hardcase like John's by chance?

 

[neptronix]

For those of us without money to burn I believe it's best to run packs individually through some cycles, and also let them sit at full charge (or maybe even slightly over-charged) before pack assembly. That way you keep losses to a minimum in the event of one bad cell, which seems to be just the luck of the draw.

yup. yup yup...
I give my packs 3 cycles before i OK them for use on anything..
Graph out their per cell discharge and all..

Any funny business and they will not be used. Already seen 2 packs that were not up to par out of 13.

This is why i am always running around telling people to buy quality $ chargers that can do discharge graphs and the like.
( then being promptly ignored. Oh well, their loss )

Sorry to hear about the fire.

 

[dnmun]

i was not trashing kepler. did not mean to seem to diss him, because he is in a jam now. of course if the building had burned down it would be much worse for him, but this coulda happened to a lotta people playing with the lipo packs now. i never had tenants who were there by the end of the month following a fire, usually one day. so i know what he is facing. that is my highest priority now when i screen tenants, evaluating the risk of fire. #1.

i had always understood that the initiation of fires in lipo was caused as the result of thermal runaway during charging that exceeded 4.2V. i had read that when the crust that builds up on the electrode breaks off during the overcharging, then that exposed electrode causes a large amount of heat released locally on the electrode which then continues breaking the electrode apart in a cascade of ever expanding electrode breakup which leads to the ignition of the organic chemicals in the electrolyte and the polymer itself. this is where the lifepo4 dynamics differ because the oxygen is locked in the phosphate so it cannot be released until the temperature of the cathodic material reaches 600o C. this prevents the combustion of the electrolyte.

maybe if there is mechanical shock initiating theses events it could be causing internal shorts following failure of the electrical separation of the electrodes

 

[Lessss]

Did you remember to grab the Marsh-mellows to put the fire to good use?

 

[El_Steak]

Seemingly unprovoked spontaneous combustion like that is really scary.

I'm extra careful when charging, doing so with a cell-level monitoring (dual hyperion 1420i) and temperature cutoff inside the pack. But I never thought this could happen with the pack just sitting there at normal voltage levels.

BTW, would a regular kitchen-type fire extinguisher be of any use on a Lipo fire? I always leave one by the charger alongside a smoke detector.

 

[Ypedal]

From what i read, the fire extinguisher would serve to keep the fire contained and putting out stray flames but the pack will need to burn itself out and run it's course....