Could a cell explode?

[Cyclomania]

When shorting a cell during a battery build for example.. When the cell is at 3,7 volts before the build. Or when you do something wrong in general that could lead to shorts an so on. Could the cell actually explode? Sending shrapnel into your face and potentially hurt your eyes?

Or is that very unlikely? And a strong fire is more likely?

Was thinking about some good eye protection perhaps? And if someone knows of such a protection mask or something similar, that would protect against an exploding cell.

thanks

 

[lnanek]

The expensive brand name ones have safety vents to release the pressure and avoid that. I've definitely triggered shorts/dented cans prying used packs apart, had the cells quickly heat up, and then start spraying boiling battery solvent around despite that, though. So you trade flying metal fragments for toxic steam - not much better

 

[marty]

You could accidentally poke a screwdriver in your eye. So yes - good eye protection. Safety glasses, face shield, or whatever you comfortable with.

 

[docw009]

In all the pictures and videos of ebike battery fires, the end caps blew off from the pressure. If you were standing around watching a fire, you might get hit with either the casing or the cap. Like Marty said, wear safety glasses.

New cells are generally shipped at 3.4 volts, 30% charge, per UN3480 shipping regulations. IF you look at the specifics of the UN38.3-T5 short circuit test, I believe the cells or a battery that is being shipped must withstand a 100millicohm short w/o going over 160C. They can vent or whatever, as long as they don't get hot enough for combustion. I would suggest building a pack with cells at 30%,

 

[jetpackjbd]

Small explosions do happen on occasion but they’re not really a concern unless your face is right up to it. If you’re working on a full size vehicle battery pack it could be worse but it’s almost always the fire and smoke that are a bigger problem. I’ve accidentally poked through an old iPod battery and in my experience it expanded a bit then created some smoke.

 

[calab]

Big corp battery packs and Apple vs whom, basement builders, ebay, Amazon, Ali's (and the like) sellers ?

Compare Apple corp to apples not Apple corp to wrinkled oranges.

 

[jetpackjbd]

Big corp battery packs and Apple vs whom, basement builders, ebay, Amazon, Ali's (and the like) sellers ?

Compare Apple corp to apples not Apple corp to wrinkled oranges.

Fair point, however it was a cheap Amazon replacement battery so I feel the comparison is close enough.

 

[lnanek]

Wouldn't an iPod battery be a lithium polymer one? Those don't have a metal casing like a 18650 cell, and have much less liquid in them as well. Given stories of certain cell phones catching fire on certain planes, though, I guess they are still energy dense enough to cause fires even if the swelling normally just pops a plastic case open otherwise.

 

[jonyjoe303]

I always wear safety glasses when working on the cells, no need to buy expensive glasses even the cheap ones from the dollar store is better than nothing. The more expensive glasses have better clarity. The biggest hazard is flying pieces when taking cells apart, I once had a sidesnip cutters break and the piece went flying by my face.
The only fire I had was during removal of cells from a battery pack, I shorted the side of the cell and it caught on fire. No flying debris etc. But the fire was comparable to a blowtorch, I had a small bottle of water and kept pouring it on the fire, it would knock the fire down but as soon I remove the water it would flare up again. Eventually the cell ran out of pressure and the fire stopped. The water kept the surrounding cells from heating up.

 

[docw009]

That was a A123 cell which is LiFePO4? I hear they they're more subdued in a fire situation.

 

[Cyclomania]

You could accidentally poke a screwdriver in your eye. So yes - good eye protection. Safety glasses, face shield, or whatever you comfortable with.

Is this enough? Or could it explode through the glass and hurt my eyes badly? Or is this an exaggeration for the most part?

Thanks

 

[fechter]

If you short a single cell, it can explode. More likely, it will shoot out fire like a little rocket motor and fly across the room. Both the flame and high speed projectile could cause injury. With a larger assembly, a short will cause an "arc flash" which sprays out vaporized metal and will burn anything it touches. Look for posts mentioning KFF (Kentucky Fried Fingers) and you can see what damage it can do. Gloves and eye protection are a good idea anytime you work an a pack.