On Tue, 18 Jul 2006 06:21:32 -0500, David Maynard
<nospam (AT) private (DOT) net> wrote:




.... and to elaborate, it's not about damaging the pack
(which is already a loss), if they *blow up* they will
likely catch fire, burn violently, and catch anything
adjacent on fire too, risking other people and property.

kony wrote:
Do a little bit of Google: lithium ion battery safety...or pre-apply for
a Darwin award.

Q

Matej M. wrote:

Because the energy density of these disposable cells is relatively low,
and in particular they do not contain metallic lithium! If an alkaline
cell's safety vent opens due to high internal pressure, some poisonous
and corrosive material will come out, which is bad - but not as bad as
what happens when the vents open on a Li cell and expose lithium to the
air.

Experiment for you: Ensure there is nothing flammable close by. Make
sure your will is up to date. Now cut open a Li-Ion cell. Observe (in
the time available to you) the exciting explosion that results.

No. Lithium is a highly reactive metal. "Lithium in its pure form is
highly flammable and slightly explosive when exposed to air and
especially water. Lithium fires are difficult to extinguish, requiring
special chemicals designed to smother them. Lithium metal is also
corrosive and requires special handling to avoid skin contact."
<http://en.wikipedia.org/wiki/Lithium>

It is also used to protect against overdischarge. If a Li-Ion cell is
overdischarged, it is permanently damaged. Allowing the cell to be
recharged in this state is a recipe for explosion. All intelligent
batteries have a safety circuit that will open *permanently* if the
cell voltage goes too low.

If you insist on experimenting with this, please contact me by email as
I will buy you a webcam. All I ask is that you keep in its field of
view while you play with this. I figure I should be able to make
several thousands selling the footage as a snuff movie.

Relatively few batteries enforce a charge counter. It is MUCH more
likely that one of two things has happened:

- the parameter memory in your battery is corrupted, or
- the overdischarge circuit has operated

In a few cases it is possible to revive an apparently dead battery by
resetting the micro, either by identifying the reset pin and asserting
it, or by disconnecting all cells from the controller board and
shorting the micro's power pins to kill any charge in the bypass caps.
It is, however, ill-advised.

zwsdotcom (AT) gmail (DOT) com wrote:
Darwin Award nominee. OTOH, he's ignored every other response, so my
bet might be in the running nonetheless!

Q

Re: "Why we can buy AA cells for TV remote without "the protection
circuit that keeps the pack from exploding" and they dont explode?"

You cannot buy RECHARGEABLE LITHIUM AA cells, precisely because they
could become "bombs". You can buy rechargeable batteries (NiCad and
NiMH (Nickel Metal Hydride). And you can buy one-time use Lithium
batteries (non-rechargeable). But you cannot buy consumer standard size
cells using rechargeable lithium chemistry, for precisely this reason.


Quaoar wrote: