An anthology of lithium-chemistry failures in flash lights

Gauss163

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All that is interesting, and I get your point is that in the grand scheme of things flashlights are pretty safe. But I really hate it when people try to (mis)use statistics. Those stats say nothing about how many people use a flashlight with lithium-ion batteries, how often they use it, what conditions they use it in, etc

Speaking of which, there are surely hundreds (or thousands) times as many laptops in use as there are Li-ion flashlights. Yet it seems, based on media reports, that the number of safety incidents in recent years are roughly comparable for the two. Do you think that this implies that laptops are hundreds of times safer than Li-ion lights?
 

WalkIntoTheLight

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I find the thread of interest.
All issues were with multi cell lights
Some issues with primary cells in multicell lights

Take away - good quality (battery) single cell light is much lower level of risk.

Yes, that seems to be the moral of the story. Stick with single-cell lithium lights and you're probably not ever going to run into problems during use. (Charging may have issues.)

However, most of the ultra-bright lights use several lithium-ion cells. I think that's a concern, especially for newbies that might buy cheap cells and chargers. I know where I live it's tough to find lithium-ion cells (and they're expensive when you do find them), so ordering from some cheap site might be tempting.
 

tandem

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Just look at all of the redundant posts here asking about whether this is a good cell/battery, or is that a good charger?

I agree with you. I'm tempted to point most of those folks to an AA Eveready flash light from Home Depot because they are looking for consumer friendly simplicity in purchasing.

Consider the video showing flour, yes flour, in a counterfeit 18650 UltraFire cell that had a ~70mAh "cell" inside. Mix that into a multi-cell light and see what happens. Or charge at what you think might be 1C (say 2400mA to be safe) but is actually a 37C charge rate.

It's a minefield out there.

A little fear over some of the crap and utter frauds out there is a good thing.

PS: If it wasn't so dangerous it'd be hilarious that crap cells are being counterfeited.
 
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WalkIntoTheLight

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Consider the video showing flour, yes flour, in a counterfeit 18650 UltraFire cell that had a ~70mAh "cell" inside. Mix that into a multi-cell light and see what happens.

Sounds like you'd get bread!


Anyway, it almost seems like it's more trouble and expense to produce a fake cell like that, than just sell a "real" crap cell.
 

thedoc007

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Speaking of which, there are surely hundreds (or thousands) times as many laptops in use as there are Li-ion flashlights. Yet it seems, based on media reports, that the number of safety incidents in recent years are roughly comparable for the two. Do you think that this implies that laptops are hundreds of times safer than Li-ion lights?

"Media reports" are not a source of statistics. In fact, often they lead to misconceptions.

http://www.ted.com/talks/hans_and_ola_rosling_how_not_to_be_ignorant_about_the_world?language=en
 

Gauss163

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"Media reports" are not a source of statistics. In fact, often they lead to misconceptions.

Of course, but reports from the media, web, etc are the only stats generally available. Probably the majority of these incidents are not recorded anywhere.

I think that it is highly likely those very limited data points do extrapolate, i.e. laptop battery systems are indeed hundreds of times safer than Li-ion lights + chargers, because - as I elaborated above - laptop battery systems are designed to meet much higher safety standards than are Li-ion lights + chargers.
 
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thedoc007

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I think that it is highly likely those very limited data points do extrapolate, i.e. laptop battery systems are indeed hundreds of times safer than Li-ion lights + chargers, because - as I elaborated above - laptop battery systems are designed to meet much higher safety standards than are Li-ion lights + chargers.

You can choose to believe that if you like. I can't say one way or the other. But I'd encourage you to watch the video I linked (at your leisure). The news can be extremely misleading, and if you think that is reliable data that can be generalized/extrapolated, you are going to be misinformed more often than not. Anecdotes are an extremely poor substitute for statistics.

I also think that the safety of li-ion in lights is highly dependent on the competency of the user. Whereas laptops are designed to be idiot proof (with limited success, obviously) it is up to the consumer to ensure safety with lights. An attentive, informed user, with high-quality cells, is an entirely different situation than a clueless person running fake Ultrafires in series.
 
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Gauss163

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You can choose to believe that if you like. I can't say one way or the other. [..] The news can be extremely misleading [...]

I also think that the safety of li-ion in lights is highly dependent on the competency of the user. Whereas laptops are designed to be idiot proof (with limited success, obviously) it is up to the consumer to ensure safety with lights. An attentive, informed user, with high-quality cells, is an entirely different situation than a clueless person running fake Ultrafires in series.

My beliefs are not primarily founded on news reports but, rather, on extensive knowledge of the design of laptop battery systems.

No doubt that the average Li-ion light user is more technically competent than the average laptop user. But that does not help much when the user is a newbie (e.g. recent incident), or when a user makes the inevitable human error.
 
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tandem

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laptop battery systems are designed to meet much higher safety standards than are Li-ion lights + chargers.

Hundreds of times safer? That doesn't sound very scientific at all.

When it comes to core functionality there's very little that is inherently safer about a laptop battery system vs good individual cells and a properly designed standalone cell charger. Both will avoid over-charging cells. Both will alert the operator if there is something dreadfully wrong that the system cannot deal with. Both will monitor temperature.

Yet still laptops catch on fire.

The laptop battery management system was designed around a known set of requirements, not as a general purpose solution that has to deal with multiple types and capacities of cells not to mention a varying stream of sources. In this comparison the laptop BMS has it easy.

Yet still laptops catch on fire.

Two aspects of many but not all laptop battery management solution implementations that do go beyond the capability of a simple drop-in charger are battery health monitoring and end-user accessible flexible state-of-charge tuning. If the owner of a self-assembled flash light power system wants that level of system assurance they need to, and can, take on those management tasks themselves, whereas a laptop battery system can incorporate that and more with full automation.

+1 for laptops but still laptops catch on fire.

The modern laptop battery system is without doubt a safer tool in the hands of the average consumer than some user-assembled flash light systems, I've no argument with that.

A laptop battery system, sourced from the OEM not the underworld of third-party suppliers, should as a matter of course be a safer consumer friendly solution than individually assembled "systems" from a virtually infinite world of suppliers.

For us as individuals if we want to meet or beat the laptop safety track record, we need to take on responsibility for designing (purchasing) a system with safety in mind from the start, and we need to take on some of the responsibility for managing the power solution that is automatically provided by the laptop battery system. Many responsible flash light system users have done just that, and it is not these sorts of individuals that you find in problem reports on this site and others like it.
 

Gauss163

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The modern laptop battery system is without doubt a safer tool in the hands of the average consumer than some user-assembled flash light systems, I've no argument with that.

Agreed (as I argued at length above). Note that I never claimed that knowledgeable users cannot (partly) reduce the risks of inherently less safe systems such as Li-ion lights + standalone chargers.

When it comes to core functionality there's very little that is inherently safer about a laptop battery system vs good individual cells and a properly designed standalone cell charger.

Not true. Read what I what I wrote above and follow the links to the literature if you wish to learn more about the design of laptop battery systems.
 

HKJ

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Not true. Read what I what I wrote above and follow the links to the literature if you wish to learn more about the design of laptop battery systems.

Laptop battery pack may contains many safety systems, but that does not make them safe. All the recalls was not due to faulty safety system, but faulty batteries and that could not be handled by the safety system.
Anyway the energy in a laptop battery pack is fairly limited, the problem is when it gets released in a short time. This is nothing new, it is always problematic when the energy, in a energy storage, is released in a short time.
 

Gauss163

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Laptop battery pack may contains many safety systems, but that does not make them safe.

It certainly makes them safer. The multiple redundant safety mechanisms guard against many possible types of failure (but certainly not all types, such as failures internal to cells).

All the recalls was not due to faulty safety system, but faulty batteries and that could not be handled by the safety system.

Of course. Nobody claimed that any system is 100% safe. The arguments are about relative levels of safety.
 

tandem

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It isn't only buyers of lithium-ion cells for flash lights that can land themselves into trouble. Folks that seek out the best price laptop battery pack may find themselves the proud owner of an incendiary device.

http://www.cpsc.gov/en/Recalls/Reca...TG-Replacement-Batteries-for-the-MacBook-Pro/

Best Buy Recalls ATG Replacement Batteries for the MacBook Pro Due to Fire, Burn Hazards (Recall Alert)

The firm has received 13 reports that the battery caught fire, including one report of a serious burn to a consumer's leg.


IEEE Standards mean nothing in the marketplace.

Edit: Any optional standard has less value.
 
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Gauss163

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It isn't only buyers of lithium-ion cells for flash lights that can land themselves into trouble. Folks that seek out the best price laptop battery pack may find themselves the proud owner of an incendiary device.

Of course, there are low quality laptop batteries by fly-by-night third party manufacturers that cut corners on QA, safety, etc. just like there are low quality xxxfire cells. That's why I preface my remarks with "reputable". But it is easy to prevent use of counterfeit batteries by requiring authentication, e.g. from TI's literature

TI said:
Using SHA-1 in bq20zxx Family of Gas Gauges

Battery counterfeiting is a major problem confronting original equipment manufacturers (OEM) today. One of the most effective methods to counter this issue is with the use of SHA-1 authentication routines in battery designs. Using this approach ensures that the OEM can track the suppliers for battery replacements. With this anti-counterfeiting algorithm, only battery packs manufactured by authorized subcontractors using the bq20zxx Impedance Track™ gas gauge IC with the SHA-1 can be integrated into OEM system designs. The SHA-1 authentication key in the bq20zxx can be regulated and tracked by the OEM. Multiple subcontractors can be supplied with different authentication keys for even greater security and regulation.


IEEE Standards mean nothing in the marketplace. Edit: Any optional standard has less value.

Various international standards are followed by all reputable laptop manufacturers. These standards have played a major role in greatly improving the safety of laptop battery systems.
 
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tandem

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The lithium-ion powered flash light safety mantra I'm fond of repeating includes:


  • single cell lights (these are going to be intrinsically safer than multi-cell configurations regardless of chemistry)
  • known good chargers (utilizing the correct charging algorithm, rates, cut-offs thermal and other protections)
  • known good lights (designed to protect against accidental short, thermal overload, over-discharge)
  • known good cells (of appropriate capacity and discharge characteristics that also incorporate over-charge/discharge protection or utilize chemistries less prone to failure when so abused)

Such a system manages the single cell whether in use or under charge in a safe manner. A single cell light has fewer dangerous points of failure. A single cell under charge likewise avoids one of the points of failure a battery management system must account for.

The reason for the re-hash of the above is I keep meaning to point out the title of IEEE Standard 1625:

Standard for Rechargeable Batteries for Multi-Cell Mobile Computing Devices

The inference here is the IEEE recognizes that multi-cell configurations pose a higher degree of failure risk than single cell devices.

Who would disagree with that?
 

HKJ

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The inference here is the IEEE recognizes that multi-cell configurations pose a higher degree of failure risk than single cell devices.

There is also a standard about single cell applications.

The problem is many people here focus on laptops and phones, they are computers and can do a lot of analysis and show information about the battery. This is not necessary to keep the battery safe.
My Bosch cordless drill with LiIon batteries does not have all this stuff, but I expect that it is safe anyway.
 

Gauss163

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@tandem What precisely do you mean by a "known good" charger, light or cell, and how do you certify it as "known good"?
 
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