Counterfeit batteries could result in TSA ban on all Li packs
- From: testing_h@xxxxxxxxx
- Date: Mon, 8 Sep 2008 12:47:33 -0700 (PDT)
Hi all.
Seems that there are serious concerns about the risk of a catastrophic
laptop fire on board an aircraft. The current consensus is that the
existing regulations are adequate to ensure that a lithium battery
fire can be contained with existing extinguishers.
However, this is for a correctly assembled pack with all safety
measures intact including cell partitions (where found) and vents, as
well as thermal shutdown system.
I've done some research of my own including purchasing and testing
spare batteries, and found that the counterfeit cells being sold as
cheap replacements (especially for older laptops considered obsolete
by the manufacturers) are badly designed, and in fact many do not even
include a thermal cutout or even cell vents as specified under the
relevant CE and UL certifications-.
In some cases, the "safety circuit" has been replaced with a custom
chip that reports false values to the laptop to allow charging to take
place without even measuring the imbalances between cell pairs. A
typical example being one I purchased online for a Sony Ericsson T68i
phone where the Li-Poly cell had been replaced with a Li-Ion of
greater capacity, haing recycled a "dead" pack for the controller -
later packs skipped this step and replaced the safety circuit with a
resistor to generate plausible values for the phone's charging
circuit.
Especially dangerous are the "extended capacity" packs that use high
capacity cells- these reduce the separator thickness resulting in the
cell being far more unstable when heated by an adjacent internal
shorted cell to the point that the entire pack could explode in the
event that even a single cell fails. due to the series/parallel
configuration.
It is possible that even a sustained burst from a water extinguisher
might not reduce the overall pack temperature below that required to
prevent additional runaway events and an uncontrollable toxic fire.
Additionally, these countertfeit packs may use banned fluorine-
containing polymers in their construction, in the event of a fire
releasing HF neurotoxic gas into the cabin as well as highly irritant
smoke.
I wouldn't be surprised if the TSA declare counterfeit batteries to be
a security risk and enforce an outright ban in the next few weeks/
months.
See http://www.zpowerbattery.com/technology/safety.htm for more
information, as well as numerous Youtube videos including one this
year.
The problem is that people don't quite realise how much a risk they
are taking by purchasing "bargain" packs from less than reputable
dealers. Maybe if insurance companies actually stated that they will
not cover fires caused by laptops/etc containing Li cells then the
Govt might finally take action and deal with these unscrupulous
companies selling dangerous goods.
.
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