Obvious solution to make Note 7's 'safe' for transport?

[johnpjackson]

Not that this would be practical to enforce, but, couldn't you make the Note 7 guaranteed not to be able to self-ignite if you fully discharge the battery? I would bet money that a fully discharged battery, even directly short circuited, would be able to generate enough heat to even be noticeable, let alone create a hazardous condition.

Of course, there's no way to instantly discharge the battery (other than the short circuit flaw that results in this whole overheating, bursting, and bursting into flames debacle, of course). So, aside from having to change the rules that have been made completely banning the Note 7 from being flown, etc., if you wanted to make your Note 7 safe to fly, or ship back to Samsung, etc., you'd have to let it run until the battery was drained. And then, boot it another time or two until it won't even power on at all.

That would work, wouldn't it?

 

[dontpanicbobby]

Nope. Fire-proof box.

 

[johnpjackson]

Nope. Fire-proof box.

Why? I mean, yes, a fireproof box is a way to partially deal with the issue in general. But specifically, my point is, I believe a fully discharged battery would be incapable of generating any appreciable heat, and thus, burst, burn, etc. Correct?

 

[dontpanicbobby]

Because it could catch on fire. Samsung has no idea what the problem is.

 

[johnpjackson]

Because it could catch on fire. Samsung has no idea what the problem is.

Samsung may still not have an explanation for what's causing the battery short, but, I believe it's correct to say that a fully discharged battery can not cause any problems, even if you short circuit it at that point.

 

[dontpanicbobby]

Okay I'll give you that theoretically but to me that sounds like "drain it and hope it doesn't burn." No offense John but those phones are really scary.

 

[johnpjackson]

Okay I'll give you that theoretically but to me that sounds like "drain it and hope it doesn't burn." No offense John but those phones are really scary.

No offense taken It's not a matter of hoping it doesn't burn. The whole reason a battery can create heat at all arises from the fact that it chemically stores potential energy that is dissipated in the form of electrical energy when you complete an electrical circuit with it. When all the chemical potential energy has been dissipated, it really is accurate to say the battery is 'dead'. It means there's no more chemical potential energy remaining in it. If there were, it wouldn't be 'dead' and could keep powering your device until it was.

A dead battery can't develop enough heat to cause any problems. As a practical matter, fully discharged is a relative term. Even if you discharged your device until it would no longer power on, you'd still be able to find a detectable amount of electrical output available from it. But, since that amount isn't enough to even operate the device, it is proof there's isn't enough to generate enough heat to be dangerous.

The problem I see with this 'solution' is that it wouldn't be simple for anyone to implement it on the spot. I would take planning ahead. In the case of wanting to ship the device somewhere, someone reliable and trustworthy would have to be on the hook for verifying the device was fully discharged before allowing it to enter the shipping and handling/transportation system.

 

[kate]

Draining the battery might help, although it's hard to say without knowing the cause. But even if it did help, I don't think lawyers at Samsung would let them say that.

They can't tell people "use this device, that might explode, for a little while longer to empty the battery."

 

[dontpanicbobby]

You forgot about the capacitators. They hold power from the battery until needed. Any Electrical Engineers here?

 

[johnpjackson]

Draining the battery might help, but it's hard to say without knowing the cause. But even if it would help, I don't think lawyers at Samsung would let them say that.

They can't say "use this device, that might explode, for a little while longer to empty the battery."

Actually, yes, when it comes to lawyers, I'd say that's correct. Practically speaking, if the odds of any one person's device self-igniting are already very small (which they are), then the odds of any of that subset of devices self-igniting right now, right after someone decided they were simply going to let the device run until the battery was fully depleted are exponentially smaller again. But, sure, to make the lawyers happy, you could make the instructions require it be done somewhere safe, like in a sink, or a baking dish, or outdoors on a non-flammable surface, etc.

I'm not trying to suggest this is something that Samsung or any organization could practically request or require of people. I'm saying that if an individual was looking for a way themselves to guarantee their device could not self-ignite, this is a way that could be reliably be accomplished. I was looking for others who understand the physics to also offer an opinion, among anyone else too

 

[johnpjackson]

You forgot about the capacitators. They hold power from the battery until needed. Any Electrical Engineers here?

Capacitors

There aren't any capacitors inside the phone capable of storing enough energy to generate any appreciable quantity of heat. The battery is the source of any and all such amounts of energy. Empty the battery's stored energy and you have emptied its ability to create the quantities of heat responsible for the problem in this matter.

 

[dontpanicbobby]

Well I was thinking these lithium ion batteries were like jelly... a spark could ignite them. That would explain the smoke: They don't explode, they burn really quick.

 

[johnpjackson]

Well I was thinking these lithium ion batteries were like jelly... a spark could ignite them. That would explain the smoke: They don't explode, they burn really quick.

The electrolyte in the batteries is a flammable liquid substance, yes. But the only way the electrolyte can be ignited is by being raised to ignition temperature in the presence of oxygen. There's no way for the electrolyte to become hot enough to expand and burst out of the battery case, and then burst out through the phone's case to reach the atmosphere, still hot enough to begin combusting, other than to short circuit the battery itself, while it has an appreciable amount of chemical potential energy residing in it. That's probably a clue about how Samsung decided that limiting the battery's charge to 60%, initially in the defect incident, was a helpful mitigation step. It could be that a new battery with less than 60% of a full charge in it just wouldn't have enough capacity to create the amount of heat required to precipitate the catastrophic failure condition.

 

[johnpjackson]

I would give my infant a fully discharged Note 7 to snuggle her cheek against, unattended. There's just no way a discharged battery can pose an overheating and spontaneous combustion hazard. Remember the Toyota unintended acceleration drama? How concerned would you be, sitting in one of those Toyota's, if the gas tank was confirmed to be empty?

 

[dontpanicbobby]

I was thinking Corvairs not Toyotas.

 

[lunatic59]

Would you give your infant a fully unloaded Glock to snuggle?

Theoretically, you are absolutely correct. Without a charge, there is no possibility of the ignition source being the battery.
Technically, even discharging a partially charged Li-Ion cell it to discharge it could generate enough heat to ignite.
Statistically, it's highly unlikely that ANY note 7 is going to spontaneously ignite, regardless of charge. How many phones actually caught fire?

Samsung has received 92 reports of the batteries overheating in the US, including 26 reports of burns and 55 reports of property damage, including fires in cars and a garage, the CPSC said.

Source

Out of the 1,000,000 sold in the U.S. that's a 1:10,000 chance. And that's with NO due diligence.

Practically, I'm not sure there is a way to measure a complete discharge without removing the battery. Assuming that the battery is completely discharged just because it won't boot the phone is probably not true. What they haven't said is exactly how much of a charge is necessary to ignite one of these things.

 

[johnpjackson]

Practically, I'm not sure there is a way to measure a complete discharge without removing the battery. Assuming that the battery is completely discharged just because it won't boot the phone is probably not true. What they haven't said is exactly how much of a charge is necessary to ignite one of these things.

If there wasn't enough charge remaining in the battery to power up the device for even a moment, that's a fool proof way to demonstrate there's not enough charge in the battery to create enough heat to burst, much less ignite the battery. If there were enough potential energy in the battery to create that amount of heat, at all, that would be enough energy to power up the device.

And sure. If you gave me a Glock and allowed me to remove all the rounds from the clip and the chamber, I'd let my infant daughter put the barrel in her mouth. Eeeesh. Not that it wouldn't still horrify me.. But that's the point - facts are facts. If there's no doubts about them, you can rely on them.

 

[lunatic59]

If there wasn't enough charge remaining in the battery to power up the device for even a moment, that's a fool proof way to demonstrate there's not enough charge in the battery to create enough heat to burst, much less ignite the battery.

I intend on submitting this to Mythbusters for an upcoming episode.

 

[dontpanicbobby]

YES!

 

[lunatic59]

They do like blowing stuff up.

 

[dontpanicbobby]

YES!

 

[Slug]

facts are facts. If there's no doubts about them, you can rely on them.

One problem with that assumption is that you are in possession of all the facts.

No offence, but do you honestly think that you know better than the company who manufactured, tried and failed to find the problem? Or indeed those whose reputation (and legal liability) depends on safely shipping stuff around the world?

p.s. Even if discharged a li-ion cell that has been overcharged may continue to produce gas due to electrolyte decomposition, raising the cell's internal pressure and risking rupture.

 

[johnpjackson]

p.s. Even if discharged a li-ion cell that has been overcharged may continue to produce gas due to electrolyte decomposition, raising the cell's internal pressure and risking rupture.

Are you saying such a discharged cell would in some way still retain an amount stored chemical energy necessary to create the heat required to cause cell and device case ruptures, and self-ignition that we've seen in this situation? I'm still going to assert that can not be the case. If you have information that explains otherwise, sure, I'd love to see it. Learning anything else I might be able to, from attempting this discussion, is what prompted me to do so.

 

[mikedt]

You forgot about the capacitators. They hold power from the battery until needed. Any Electrical Engineers here?

I'm not an electric engineer but I think nucular bombs use capacitators.

Whole discussion is academic and theoretical anyway, sure not going to convince the FAA and airlines of it. Note7 just does not go on planes, end of!

 

[dontpanicbobby]

Gas can blow up. Could be, hope they're listening