it's can be very dangerous !!!!!!

One of the key considerations for safety has to be the positive end.

Ensuring no solder or bits of metal goes in the slits!

rev0 said:
Korishan said:
Yeah, a little piece of metal between those slits in the Pos end is all it takes.

A fire extinguisher. Good question. However, you'd need to get a chemical rated one as the common house is a CO2 one. That won't stop a lithium based fire.


Drat, "after" the video was shut off. Next time remember to keep shooting until you're done for the day, even if that means 16hrs of video recorded :p
Click to expand...

Perhaps we could invest in dashcams, they should be able to do ~6 hours or more on a continuous recording loop depending on the memory card in it. If anything interesting happens, just stop the recording and upload it to YouTube ;)
Click to expand...

Good idea and worth considering imo
 
I get the sense that it turned into a rocket very quickly. Thevideos on youtube ofshorting cells purposefully seem to takequite a long time to really take off, if at all. I wonder if the short was seeing series voltage instead of individual short voltage.

Thank you for sharing. Bet you had quite the adrenaline rush on your way out of the house.


Found this guy charged at 40 volts underwater.

 
I'd love to see that first video with an IR thermometer. I wonder how hot it got before electrolyte came out.
 
I have heated up some cells and in generall it gets above 150-200C before it happens.
 
Wow, that's amazing. I worry when a cell gets over 50C so I mark them as 'hot' and put them away for future testing. Most of my cells test around 32C at 500mA and I have very few that actually went over 50C.
 
Oderus420 said:
Wow, that's amazing. I worry when a cell gets over 50C so I mark them as 'hot' and put them away for future testing. Most of my cells test around 32C at 500mA and I have very few that actually went over 50C.
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Well, there's a difference between safe operating temps, and dangerous temps. The 150+C is the dangerous zone. The <100C is the safe zone. We usually stop it at 50C or so when charging as we don't want stuff melting, like the cell holder or the hot glue holding stuff together ;)

Everythings-stuck-together said:
I get the sense that it turned into a rocket very quickly. Thevideos on youtube ofshorting cells purposefully seem to takequite a long time to really take off, if at all. I wonder if the short was seeing series voltage instead of individual short voltage.
Click to expand...

I doubt that it was a slow build up. Most videos that show a cell going boom from getting hot are applying the heat externally. His was created internally. Makes a huge difference. Also, it wasn't about voltage that caused the issue, but amperage. If the cell was seeing full potential amps, as it was fully charged at time of incident, then the cell could internally generate well over 50A by itself.

@daromer: Perhaps you could do a video on some cells that you "purposefully" put solder under the Pos cap so that it makes contact with the Pos/Neg and see what happens ;)
 
Korishan said:
neurocis said:
Take a look at the very first frame of the video and what is on the towel, and what may happen if something were laid on top of them?
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I think neurocis might be on to something here. I see some metal pieces on the towel. Is it possible that right before the rocketeer event, you laid the pack down on the towel? This could of allowed a piece of metal to make contact with the Pos/Neg on that one cell and start the shorting.

If that is the case, what a small chance of it happening as you'd have to get that piece exactly right on the cell to get it stuck to the cell.
Click to expand...

Exactly, I think the odds align ... cristof should have bought a lottery ticket. Given that a towel is a grunge/shard magnet and the operation in process just above where the pack was laid down involved the stripping, tinning and probably trimming of the BMS wire ends I don't think its outside of the realm of possibilitythat the "rapid disassembly" was set in motion by an errant metal shard.

I would prefer to infer there was a cause as opposed to a spontaneous disassembly. From what I have seen/read so far the 18650 design is amazingly stable and tolerant.

There is the theory of a solder splash short. I don't like the odds of that asit looked like the pack had been assembles for a bit of time and that would have been detected. A further possibility could be an errant fuse pig-tail, but I think that would have burned up pre-rocket. Also the surrounding fuse wires look intact, which leads me to believe it was a single-cell "incident".

I have to give cristof the utmost respect for posting the details of this experience, and that in all respects nothing really bad happened as a result. I want to learn as much as possible from this so that we can all improve our practices and keep our perceptions of "safe practice"in check. Like Pete's incident, there is certainly a testament here to the use ofsafety features (in this case pressure-venting plate).

cristof, I do not know if there are any further details you may be able to give that may shed even further light? I thank you soooo much for your transparency andwhat you have shared so far.

In conclusion, I think the pack was inadvertently laid down on something, that cells positive down, caused a short which simmered in the cell for some unobserved time (right now we have 30 seconds) building pressure until the vent engaged. But as the vent was facing a solid surface, viola, rocket! and a dent in the ceiling as a reminder to keep your work area clear of debris at all times and that maybe it may have a negative net-effect using a towel for a work surface.

Cheers!
 
Well said.
to keep your work area clear of debris at all times and that maybe it may have a negative net-effect using a towel for a work surface.
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Or at least make sure the towel is clean before working on a pack. I actually prefer to work on paper shop towels (the blue automotive type) as they are fairly cheap, strong, and have a good thickness to cushion with, and won't tear very easily.

And I agree also with cristof posting his accident for everyone else to learn about. Even though it was fairly an isolated incident, it shows that accidents can happen. And even having fuses on every cell, it's still possible to get past the fuse to cause an issue (though this is almost always going to be due to some external something falling onto the cell). We can only protect to a certain level. After that, we just need to take precautions and be aware of what is going on around us.

Thankfully for cristof he didn't set the pack down, get a phone call or get distracted by kids/wife/neighbor/etc. It could of easily turned out a lot worse.

Some of this info will make it into the FAQ. So your incident will make notoriety, cristof ;)
 
Hi all,
this incident has show to me how a 18650, even from an old laptop batery pack CAN BE SO POWERFULL !
I have use the "shower towel" for not damaging fuses when the bloc was laid down on the table (as a matelas)
may be it was not a so good idea.
the short circuit may have been very close to cap and minus, big enough, with a very very low resistance, able to give a very hight amperage (A).
I dont want to imagine what will happend if I was not there when it's happend.
all the cells around the rocket one will have explose to, and tonight I will have to sleep in my van, near my burn house.....
:huh:
I have started to repair the batery, must be finish tomorow. But believe me, the batery does not smell flower !
 
cristof said:
Hi all,
this incident has show to me how a 18650, even from an old laptop batery pack CAN BE SO POWERFULL !
I have use the "shower towel" for not damaging fuses when the bloc was laid down on the table (as a matelas)
may be it was not a so good idea.
the short circuit may have been very close to cap and minus, big enough, with a very very low resistance, able to give a very hight amperage (A).
I dont want to imagine what will happend if I was not there when it's happend.
all the cells around the rocket one will have explose to, and tonight I will have to sleep in my van, near my burn house.....
:huh:
I have started to repair the batery, must be finish tomorow. But believe me, the batery does not smell flower !
Click to expand...

Not to downplay this, but in looking at the (minimal IMO)damage to the neighboring cells I do not think this would have cascaded if leftalone,another testament to the 18650 design; If there were a stack tip-to-tail, possibly.

I would have tossed it too though, and I am glad you were there to give it the toss away from othercombustibles for sure!

"I have started to repair the batery, must be finish tomorow. But believe me, the batery does not smell flower !" I guess not ... hehehehe ...
 
Hi all,
I have repair the batery, there is still a few residue on several cells, but now it's finish.
The BMS did not smoke when I have connected it.
No doc for the bms, only a picture how to connect it.
on the bms, there is many LED. Does those LED"shine" only during charge mode ?.
I juste now have to install a pedestal to be sure the batery does not fall down.
I will use it for test. I am waiting for an MPP solar Hybrid MPI serie inverter.
Next step is to built a 14S/80P, but not enough cells today.


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Glad to see that you rebuilt your pack so quickly and didn't discourage, really great job! Did you already check the voltage of each series too see if your bms is balancing them or were they already well balanced? The xt60 seems light for such a big pack but at 48v maybe should handle some basic needs.
The charge controller/inverter you chose looks like a race beast! Very impressed, your setup is promising!
 
Great job on the repair... :)

The led's on that bmsare lit when the connected string of cells are balancing, soonly during charging.
 
sedorikku said:
Glad to see that you rebuilt your pack so quickly and didn't discourage, really great job! Did you already check the voltage of each series too see if your bms is balancing them or were they already well balanced? The xt60 seems light for such a big pack but at 48v maybe should handle some basic needs.
The charge controller/inverter you chose looks like a race beast! Very impressed, your setup is promising!
Click to expand...

Hi, this first batery is most for testing built process, and I need a 48V batery soon for the first inverter test.
Actualy, all series have all same voltage +/- 0,03v, I want said they are balanced, but it's not to bad.
No sun today, but water in the stream.. :)
 
cristof said:
sedorikku said:
Glad to see that you rebuilt your pack so quickly and didn't discourage, really great job! Did you already check the voltage of each series too see if your bms is balancing them or were they already well balanced? The xt60 seems light for such a big pack but at 48v maybe should handle some basic needs.
The charge controller/inverter you chose looks like a race beast! Very impressed, your setup is promising!
Click to expand...

Hi, this first batery is most for testing built process, and I need a 48V batery soon for the first inverter test.
Actualy, all series have all same voltage +/- 0,03v, I want said they are balanced, but it's not to bad.
No sun today, but water in the stream.. :)
Click to expand...

Hydrolectric 800W PELTON Gnrator

This, we have to see. Any videos?
 
@Oderus420: Yes, he has several videos on his youtube channel. Though, all the language is in french ;)
 
I had this happen in a ebike battery build, but it simply vented. I discovered a small bit of solder had dropped down through the slits and must have been almost touching, at some point it moved and touched. I was riding at the time and noticed the pack voltage drop quickly, put two and two together and pulled over. Pulled the pack out and threw it on the dirt. It hissed a few times , Yes I contemplated riding away lol but I stayed until it cooled and the had a hard ass ride home. Lesson learned I'm super careful when soldering the tops . And I keep all cells outside !
 
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