> pulled as soon as it went green
Someone could invent a Rube Goldberg device to do what's needed:
-- photocell watches for green light to go on
-- green light goes on
-- photocell sends signal to solenoid
-- solenoid yanks battery out of charger OR power plug out of wall
Simple, works around the whole problem. Hmmm. Or, fix the problem.
By the way, if anyone's wondering WHY we worry about this kind of thing, the problems have been known for more than fifteen years, for example:
http://catless.ncl.ac.uk/risks/11.95.html#subj7
Sun, 23 Jun 91 11:47:08 PDT
Lauda Air disaster linked to potentially hazardous cargo
" The wreckage also showed evidence of burn marks in one cargo hold, a
phenomenon which specialists initially were unable to explain but later linked
to the watch batteries, the report said.
... a South African Airways Boeing 747 was carrying a cargo of lithium-battery watches when it crashed into the Indian Ocean on a flight from Taiwan to South African in 1987, killing 159 people. Last year, a
Cathay Pacific plane was forced to make an emergency landing after fire broke out in a cargo hold bearing a shipment of watches with lithium batteries..."
Aviation Today :: Lithium Battery Fire Could Burn Through a Cargo Hold
That is the principal finding of a June report of lithium battery fire tests. ... some aircraft fire detection systems are powered by lithium batteries. ...
http://www.avtoday.com/regions/mideast/2802.html
Good advice for anyone contemplating fiddling with a charger or anything else:
----excerpt----
In design or specification:
Do include protective devices such as diodes, limiting resistors and fuses into the
circuits.
Do not allow the failure of one component to create a dangerous situation. In
particular
---> the blocking diode for backup primary cells should be made of
---> at least two individual diodes in series.
Do not join batteries either in series or parallel without first consulting the
manufacturer's advice.
Do not encapsulate lithium batteries without first consulting the manufacturer's
advice.
Do not use more than one lithium battery in the same piece of equipment without first
consulting the manufacturer's advice.
----> Do not install lithium batteries next to a source of heat.
----end excerpt-----
http://www.nerc.ac.uk/about/work/policy/safety/documents/guidance_lithium_batteries.pdf
And remember:
-----excerpt------
Store, and charge, in a fireproof container .....
Charge in a protected area devoid of combustibles.
Always stand watch over the charging process.
Never leave the charging process unattended.
-----end excerpt-----
http://www.rcgroups.com/forums/showthread.php?t=224632
and remember:
from the FAA:
"A relatively small fire source is sufficient to start a primary lithium
battery fire. The outer plastic coating easily melts and fuses adjacent
batteries together and then ignites, contributing to the fire intensity.
This helps raise the battery temperature to the self-ignition
temperature of lithium. Once the lithium in a single battery begins to
burn, it releases enough energy to ignite adjacent batteries. This
propagation continues until all batteries have been consumed.
"Halon 1301, the fire suppression agent installed in transport category
aircraft, is ineffective in suppressing or extinguishing a primary
lithium battery fire. Halon 1301 appears to chemically interact with the
burning lithium and electrolyte, causing a color change in the molten
lithium sparks, turning them a deep red instead of the normal white.
This chemical interaction has no effect on battery fire duration or
intensity.
"The air temperature in a cargo compartment that has had a fire
suppressed by Halon 1301 can still be above the autoignition temperature
of lithium. Because of this, batteries that were not involved in the
initial fire can still ignite and propagate.
"The ignition of a primary lithium battery releases burning electrolyte
and a molten lithium spray. The cargo liner material may be vulnerable
to perforation by molten lithium, depending on its thickness. This can
allow the Halon 1301 fire suppressant agent to leak out of the
compartment, reducing the concentration within the cargo compartment and
the effectiveness of the agent. Holes in the cargo liner may also allow
flames to spread outside the compartment.
"The ignition of primary lithium batteries releases a pressure pulse
that can raise the air pressure within the cargo compartment. The
ignition of only a few batteries was sufficient to increase the air
pressure by more than 1 psi in an airtight 10-meter-cubed pressure
vessel. Cargo compartments are only designed to withstand approximately
a 1-psi pressure differential. The ignition of a bulk-packed lithium
battery shipment may compromise the integrity of the compartment by
activating the pressure relief panels. This has the same effect as
perforations in the cargo liner, allowing the Halon 1301 fire
suppressant to leak out, reducing its effectiveness."
Full text:
http://www.icao.int/anb/fls/dangerou.../WPs/WP.36.pdf
