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<DIV><FONT face=Arial size=2>I'm not trying to start a "heated" debate about the
safety of lithium batteries, but I purchased a couple of these packs just before
the AMA warning and now I have some concerns and questions. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>My question revolves around how the NMP batteries
are built and how the NMP charger works.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>In the past I'd believed that fires with lithium
batteries are primarily due to user error when charging, typically one of the
following errors: 1) Using the wrong type of charger, 2) setting the charger for
the wrong battery type/cell count, or 3) trying to charge cells too
quickly, in excess of 1C. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>However, I did some research on E-Zone and found
that these packs can catch fire even on a slow charger if they are charged
beyond 4.2 volts per cell. This means if your charging a multiple cell pack and
cells differ in voltage by more than 1 volt and the charger keeps charging until
(total cells x 4.2 volts) is reached then even slow chargers can cause a
fire.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Therefore, my question is does circuitry exist
either in the NMP battery pack or in the NMP charger to assure that a single
cell will never be charged in excess of 4.2 volts? If so, how does this
work?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>If this circuitry exists then we can probably
feel quite safe leaving the NMP batteries inside our planes while charging just
as we do with our laptops, cell phones, cameras etc. If not then we're taking a
big chance charging inside our planes, vehicles and houses (as has been pointed
out on this list before).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>FYI, I was shocked when I visited E-Zone and found
that the electric guys have known for a long time that fires are not only a
possibility but have occurred many times. In fact, it's common knowledge in the
electric community that precautions such as charging in a flame proof container,
not charging in vehicles or homes, never leave the battery unattended, etc. must
be observed when charging. I found it very interesting that there are
even numerous people working on various types of fire-proof charge bags made
from things like ceramic fibers.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Obviously the electric guys push things to the
extreme with their batteries, but if such a simple thing as exceeding 4.2 volts
can catch a cell on fire then we should make sure our batteries/chargers have
circuitry to prevent this or we must take the necessary precautions when
charging.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Here's a link to a good Lithium safety primer on
E-Zone:</FONT></DIV>
<DIV><FONT face=Arial size=2><A
href="http://www.rcgroups.com/forums/showthread.php?t=209187">http://www.rcgroups.com/forums/showthread.php?t=209187</A></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thanks to anyone who can share the details of the
NMP lithium system.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Keith Black</FONT></DIV>
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