Charging concerns/questions with NMP Lithium Ion batteries

[cameron]

Maybe these guys have a good system? Maybe they don't have a track
record of fires & such? 
 I think IF the new precautions are heeded at least if something goes
wrong you only loose an old Barbecue grill!
   Clint Eastwood said it best: "Do ya feel Lucky"
 
 People have known for a couple years about these problems and have kept
quiet about it. Even the companies themselves were worried that the bad
press would ruin there new found Market. I think the most important
questions are:
 How good of a liability insurance policy do I have & Do the companies
pedaling these little firecrackers have ANY insurance?
 
 DO NOT confuse what is in your laptop with what is in your heat shrink
wrapper. SPECIFIC USE BATTERIES HAVE SAFETIES!!!!!!
 DELL GATEWAY  TOSHIBA  And the likes have at least 3 different types of
charge & discharge technology. same as your camera batteries.
  AND THESE COMPANIES HAVE HAD ISSUES!!!!
 
  I know of one failure where the cause was due to the
manufacture/Company, They were having other issues & trying to "recall"
there stuff,Sort of! So don't think that it is ALL user error. But the
potential for error is even worse when you factor in all the things a
user could do to ignite.
 
 Has anyone noticed the big Battery players in the US Will not sell
cylindrical Li-ion raw cells to the public. They usually come from far
east suppliers. 
 
  This is not meant to be a campaign against anyone or any particular
product. I just gotta be able to lay my head on the pillow at night and
KNOW I did everything I could to make others aware. In the event
something really bad happens & we are all wondering why & how. 
 
 IF there are ANY LEADERS in this industry they need to be challenged to
1st Speak the truth even IF they loose $$$. Second that they develop
safe products that are exposed to our lives. There are irresponsible
players out there. Trust me!
 
 "Do ya feel lucky"

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]
On Behalf Of Keith Black
Sent: Friday, May 07, 2004 3:31 AM
To: discussion at nsrca.org
Subject: Charging concerns/questions with NMP Lithium Ion batteries


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. 
 
My question revolves around how the NMP batteries are built and how the
NMP charger works.
 
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. 
 
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.
 
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?
 
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).
 
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.
 
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.
 
 
Here's a link to a good Lithium safety primer on E-Zone:
http://www.rcgroups.com/forums/showthread.php?t=209187
 
Thanks to anyone who can share the details of the NMP lithium system.
 
Keith Black
 

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