Charging concerns/questions with NMP Lithium Ion batteries

[cameron]

Things can go wrong with "dedicated chargers"! 
 I was unfortunately one of the first to try li-ion for models,Only
because I caught Duralite when they started marketing there replacement
product to li-metal. The awareness of the dangers, The safer handling
practices. Where Just not known to me or others @ that time. We followed
instructions,Talked to the manufacture. And still got bit! They didn't
have a solid product yet. They rushed and put little Bombs out there at
first.
 I will be an advocate for this: IF you follow the AMA's guidelines you
probably wont get hurt. I would not have!
 But this INFORMATION was not out there at my time of use. I have & most
modelers have charged there Futaba stuff overnight for years. And I have
always charged my Li-metal till the light went off on the charger. Even
overnight. My Toshiba laptop, My Samsung Smart PDA Stays in the charger
OVERNIGHT. So does my Makita battery supply IF needed. My house now has
"Dedicated charge areas" Equipped with 2 smoke detectors wired to ALL
the others in the house. But I have never heard of not charging
overnight before this. It WAS a standard practice for EVERYONE I knew at
the time. 
 Predictable Power supply/System  can be achieved by other types of
batteries also. You do NOT have to use Li-Ion to achieve that. But there
out there. Some sort of Li- technology may present itself as the next
rechargeable battery standard, But I have not seen a number of the BIG
U.S. battery players ready to sell NON-specific use Li-Ion raw cells to
the public? Want to guess why? 
 My situation was clearly a faulty manufacture issue. Made worse by the
fact they knew they where having problems & DID NOT warn me. If I have
heeded the current warnings & safe handling practices made available
only recently I could have avoided this. And you guys 2 years ago didn't
know either. Well some did but chose not to say anything in public.
 The real danger of the current li-technology will probably occur when
"Joe newbie" buys "Johnny Quick-snaps" used plane with a pack of these
batteries,Takes it home, Says I can charge this stuff with what I
got-Don't need to spend that extra $$! Or his friend down the street
say's hey buddy don't worry bout buying a charger!! I got this charger I
used when I was into CARS! It works REAL fast!
Let's remember these guys also.
 I hate what happened to me. I really do. But I realize this. Every year
someone dies from a baseball. But we still play baseball. Let's just be
more careful out there. You can throw the ball hard but it doesn't make
you a Greg Maddox. Same as Li-Ion DON'T make you a great pilot. Skill,
Practice, Repetition, Coaching and more practice does that! 
 We know not to fly behind the zero line for Safety reasons, Do we have
good R/C safety "Zero Line" in our homes? That's what this is about!
Just want to do MY part to encourage everyone to wake up tomorrow with a
roof over there head!
 
                                                  Cameron Smith
                                                      770-596-7699

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]
On Behalf Of Troy Newman
Sent: Saturday, May 08, 2004 4:22 AM
To: discussion at nsrca.org
Subject: Re: Charging concerns/questions with NMP Lithium Ion batteries


Dave,

The only failure mode I have seen on the batts is that they do not come
up to full charge after a long period of use like 1yr to 18months. My
original battery pack comes off the charger now at 7.9V not the 8.4 when
it was new. The charger still goes to zero amps....and the battery is as
charged as it will ever get. And its capacity is less as a result. These
batteries seem to be very predictable. That is the main reason I like
them.

I flew about 7-8 flights this morning on the lake bed just back to back
to back...and I was getting exactly 0.15V drop per flight. I was
actually guessing the voltage under load before sticking the meter on
the plane.....I only missed on the last flight and I missed by
0.01V....Last year I was flying before the NATS and found larger current
drains...like double per flight...Guess what I started checking my model
out and found a loose motor mount...Also current drain is directly
related to servo pot and gear train wear! So another reason to have
predictable power system.

As for charger issues...as Jim Oddino stated the charger has an actual
current meter on it. Its an analog meter so you can see the actual
milliamps flowing into the battery pack. As stated by Jim also you get
used to the numbers and if you plug in and see strange values it sets
the alarm off in your brain.

When the battery is charged or taken all it can take then the rules of
electricity are proven on the am-meter. The current goes to Zero! So
unless Ohm's law fails I don't see how the charger will screw up a
battery pack...

Of course anything can happen. Components can fail, I don't know what
the failure issues could be in the charger because I have never seen
one. Same with my Wall wart chargers that came with my radios never seen
a failure there either.....In my 20+ years of modeling I have cooked and
burned up Nicd packs, for various reasons  even had a couple leave a
mark on the table, floor, or in the plane.....I don't stick a battery on
to charge and go to bed. The only exception is the nicads that come with
the TX or my nicads in my B+P starter. These have dedicated chargers
(hummmmm theme
here?) that are designed for this charge overnight at the c/10 rate.


As for Central Hobbies, I have been a customer of Centrals for many many
years. My relationship with them over the years has grown to allow me to
test and help refine some the products they bring to serve the pattern
modeler.

As others have said I am an advocate of their products and service. I'm
not paid, I'm a happy customer. I am also a customer of many other
modeling companies. Looking at my shop, I have Prather med fuel tubing,
Radio South CA hinges, Gator stab adjusters and some Bob Smith CA (both
Thick and thin), and a Hyde Mount on the shelf. I only advocate products
and stuff that I use myself. There are some products that I choose not
to use, in favor of my favorite version. We all have these....the
Ultracote- Monocote, or Zap-BSI, or Coolpower-Magnum....

Those that know me, know that I'm an honest straight shooter....Why
would I want to talk bad about a product that I don't use. There is
enough of this already on this list and in RCU......Product and Company
bashing seems to have grown into a 3 headed monster with the Internet. I
just choose not to play.

Rather I just tell people what I choose to use and why I use it. I never
advocate the use of a product that I don't have personal experience
with. It's your choice to take the advice or leave it.....It's is worth
what you paid for it. I know that when I spend my modeling dollars I
pick the products that I think work the best for me.


Troy Newman

----- Original Message ----- 
From: "David Lockhart" <DaveL322 at comcast.net>
To: <troy_newman at msn.com>
Sent: Friday, May 07, 2004 5:57 PM
Subject: Re: Charging concerns/questions with NMP Lithium Ion batteries


> So what is the degradation/failure mode of the battery, and then what 
> does the charger do?
>
> Thanks,
>
> Dave
>
> ----- Original Message -----
> From: "Troy Newman" <troy_newman at msn.com>
> To: <discussion at nsrca.org>
> Sent: Friday, May 07, 2004 11:02 AM
> Subject: RE: Charging concerns/questions with NMP Lithium Ion 
> batteries
>
>
> >
> > Keith,
> >
> > I can talk about the NMP stuff. I have been using it for a long 
> > time. It works very well and was designed to not have the problems 
> > with other systems.
> >
> > As for over charging using the NMP packs and charger. It is not
possible.
> > The charger is basically a voltage regulator that is set to 8.4V (2
cells
> > means 4.2V per cell)
> >
> > The way the charger works is the pack is say 7.4V and the charger is

> > at
> 8.4V
> > this means current will flow from the charger to the pack. When the 
> > pack reaches its goal voltage...(the setting of the charger) no 
> > current will flow. Therefore it will not overcharge. The charger's 
> > electronics set
the
> > voltage it is not user adjustable.
> >
> > Now if you will look closely at the AMA warning it says they 
> > recommend a dedicated charger to the specific type and brand of 
> > pack. This means no variables, no charger picking cell counts and so

> > on. No picking charge rates.... The NMP charger is exactly this 
> > technology. It will only
charge
> > the 2 cell packs. There is no charge rates to change as you can't 
> > change them.....The pack can only recieve so much energy at once and

> > the design
> of
> > the charger is limited by the battery capacity to accept current. If

> > the battery is at 8.1V it can't take as much current as when it was 
> > at
> 7.1V...so
> > the charger only delivers what the battery asks for.
> >
> > Another analogy is a pair of balloons....ballon #1 is at 8.4psi and 
> > is a certain volume....Balloon #2 is 7psi.
> >
> > The two ballons are attached by a hose and a valve....When the air 
> > valve
> is
> > opened...Balloon #1 will try to inflate #2 right.....If both ballons

> > are equal no pressure will flow between the 2 right?
> >
> > Same thing here....as the voltage comes up on the battery pack the
charger
> > will not deliver the current.
> >
> > This NMP battery system is exactly what the AMA is recommending for
using
> > Lithium batts.
> >
> > Troy Newman
> >
> > >From: "Keith Black" <tkeithb at comcast.net>
> > >Reply-To: discussion at nsrca.org
> > >To: <discussion at nsrca.org>
> > >Subject: Charging concerns/questions with NMP Lithium Ion batteries
> > >Date: Fri, 7 May 2004 02:30:32 -0500
> > >
> > >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
> >
> >
> > =====================================
> > # To be removed from this list, go to
http://www.nsrca.org/discussionA.htm
> > and follow the instructions.
> >
>
>
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