Battery puffed due to faulty charger please help!

[Raichuboy18]

Ok, so my charger ended up showing a lower voltage than was really there, causing it to over charge the battery. I used a SkyRC RS16. My batteries puffed (see picture) and are WAY over voltage (17.60 and 17.80). I currently have them outside in a hard metal trash can. I'm pretty sure I am going to dispose of them but I wanted a second opinion. I am scared to death but I don't want to lose 100$+ (I also don't want to lose my house to a fire either). One that I wasn't charging is on the right for reference.

 

[Sunder]

Although puffed batteries can be used, its pretty dangerous to do so. That's hydrogen gas in those puffs.

Best you drain them as fast as possible, then throw rhem into a plastic bucket full of salt water, away from the house. Keep them there until just before garbage collection, and dispose of them then.

 

[Raichuboy18]

That's what I thought... Thanks for the second opinion.

 

[wesnewell]

Assuming they are 4s packs, they should shrink when you discharge them to 16.8V. I've over charged a 4s pack to 17.9V before and never had a problem with it once I brought it back down to 16.8V. The dangers of puffed cells are vastly overstated. Better to have a pouch cell puff than to have an 18650 can cell that will just explode. I've made holes in a many a puffed cell and resealed them and used them for years without a problem.

 

[Syonyk]

First, an 18650 won't "just explode." They're designed to vent safely, and many of them can contain a good bit of pressure without a problem before venting.

Second, $100 vs the cost of a house seems a reasonable tradeoff to me. I don't mess around with damaged cells.

Either keep those in a fireproof enclosure at all points, or discharge and scrap. IMO.

 

[wesnewell]

Tell that to the people that have been seriously injured when the exploded in their pockets.

 

[Syonyk]

Tell that to the people that have been seriously injured when the exploded in their pockets.

I suppose I should have specified "A competently built 18650, not recycled garbage, not contained in a pipe bomb short circuit." I keep forgetting that's not a common assumption one can make around here.

 

[Hillhater]

^^^ sorry but the myth of "safe 18650s". Went up in the smoke of the Tesla pack going off like a big firecracker on UTube !
Pouches dont explode either, they just vent and burn fast n nasty, but those 18650s , once they get overheated... (for whatever reason ,.. short, overcharge, damage, etcetc) ...then they "pop" and launch like flaming projectiles.
Of course, this is not a fault of the cell, its invariably user abuse, same as most of the pouch cell problems.

 

[Syonyk]

And we're talking about a lipo cell that's just gone through user abuse.

Though, really, the problem here is pack builds that don't use a competent BMS with overvoltage protection.

 

[Hillhater]

This was the Tesla module i was refering to.
It went thermal after the guy accidentally shorted one cell.
[youtube]QXHecPqFDB8[/youtube]
https://youtu.be/QXHecPqFDB8

And, like many others, i have had "puffed"lipo due to accidental abuse, and cooled, compressed, pricked, and deflated them. They ran fine for many years after , eventually only failing due to "solid swelling" ...which is very different to gas puffing.
But with the price of Multistar type lipo these days, its hardly worth the effort/ risk

 

[TristanP]

It went thermal after the guy accidentally shorted one cell.
https://youtu.be/QXHecPqFDB8

Actually he damaged one cell using his dremel. Then over a 90-minute period the fire propagated from one cell to the others, as shown in the video. A typical undamaged Panasonic cell will probably not burn nor explode if you short it.

 

[Syonyk]

The Tesla pack is certainly outside expected operating conditions - normally it would have coolant flowing through it, and I expect that if the coolant can take the heat of a 120+kW supercharge, it can cool a single runaway 18650.

But, yes, most of them put out enough heat in a runaway event to heat local cells to runaway.

The difference is that it's hard to get a quality, OEM 18650 into a runaway event without seriously damaging it, shorting it, or otherwise abusing it. Lipos seem to burst into flames of their own accord far more than I think is reasonable.

An 18650 based pack composed of high quality OEM cells, with a BMS that limits both overcharge and overdischarge, is likely to live its life without ever getting exciting. A good BMS simply will not let you overcharge the cells by much if you hook up the wrong charger, and should also attempt to bleed them back down after it cuts off the charger. A faulty charger should not be able to push the cells to 4.45V/cell through a good BMS. Period.

 

[Hillhater]

And im sure good quality pouch cells pack with a quality bms that protects from overcharge and overdischarge, will equally live its life without getting over excited !
The reason we see so many lipo fires is well documented..
Cheap , low quality cells
Poor pack construction alowing pouch damage
No bms used
Cheap unreliable charger systems
Un professional/ amature Users (The RC hobbyists, Ebikers, Eskaters etc)
High damage risk usage..RC flying, cars, etc

The fact remains that both pouch and can cells will flare up if abused.
Remember the Sony/Dell laptop fires and the recent saga of the "Hoverboards" ?