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<DIV><FONT face=Arial size=2>Ed,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>In my current Aries I run two NiMH battery packs,
the new Li-Ion packs were "going" to go into my new plane.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Here's my current setup: One five cell double A
1680 mah NiMH pack (5.2 oz.) on a 5.7 volt regulator, and one five cell triple A
400 mah NiMH pack (about 2.5 oz) on a 5.4 volt regulator. Power is always
pulled from the 1680 mah pack unless it drops below 5.4 volts. Therefore, the
400 mah battery only kicks in if needed (due to a failure or dead primary
pack). </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I can fly until I'm tired on the fully charged 1680
mah pack, I'm guessing safely 6 or more 20 minute flights.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I derive a level of comfort from having the
redundant battery setup after hearing all the horror stories and seeing Lance's
beautiful Aries #2 go in due to lost receiver power.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>With my current setup I'm carrying around almost
eight ounces of battery weight, which is why the Li-Ions looked good to me. I
could drop 1.8 oz by going to the Li-Ion batteries AND increase flying time
(though flying time isn't an issue).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>However, given the issues with Li-Ion packs I feel
that I should either A) stick with my NiMH batteries or, B) install the Li-Ion
in a location that it can be removed for each charge.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Keith Black</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=divesplat@yahoo.com href="mailto:divesplat@yahoo.com">Ed Deaver</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, May 07, 2004 8:34 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Charging concerns/questions
with NMP Lithium Ion batteries</DIV>
<DIV><BR></DIV>
<DIV>OK, Ive had Duralite and subsequently Powerflites for about 5 years
now. Because of the fire hazard, everyone is recommending going back to
reg batteries or NMhd(which my charges probably won't support)</DIV>
<DIV> </DIV>
<DIV>So for 3 digital, 1 4721 and a mini throttle servo, how many mah should I
look at buying in old style batteries? I would only go with 5 cell
pack.</DIV>
<DIV> </DIV>
<DIV>Thanx</DIV>
<DIV> </DIV>
<DIV>ed<BR><BR><B><I>Keith Black <tkeithb@comcast.net></I></B>
wrote:</DIV>
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<DIV>
<DIV><FONT face=Arial size=2>Thanks for your reply Jim. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I do like design of the NMP charger and the way
it shows how much current is being feed to the battery. This is clearly an
excellent design feature. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>What I gather from your response is it is
"possible" for a cell to be charged beyond the safe limit if another cell is
either out of balance or defective. Also, I understand your point that one
may be able to spot a bad cell after becoming familiar with the charger.
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>As it relates to the cells being unbalanced,
will lithium batteries equalized each other via a "trickle" as is the case
with NiCad batteries?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Jim, I really appreciate your always candid
responses and willingness to assist others on the list.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thanks,</FONT></DIV>
<DIV><FONT face=Arial size=2>Keith</FONT></DIV></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=JOddino@socal.rr.com
href="mailto:JOddino@socal.rr.com">JOddino</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, May 07, 2004 10:30
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Charging
concerns/questions with NMP Lithium Ion batteries</DIV>
<DIV><FONT face=Arial size=2></FONT><FONT face=Arial
size=2></FONT><BR></DIV>
<DIV><FONT face=Arial size=2>Hi Kieth,</FONT></DIV>
<DIV><FONT face=Arial size=2>I believe the NMP solves most of the problems
we have all read about. 1) it is the right type of charger for
Li-Ions and is dedicated to that chemistry by limiting the current and the
voltage. 2) it is set for two-cell packs and that cannot be changed by the
operator or on its own. 3) it limits the current to less than the 1C rate
(for 2000 mAh packs).</FONT></DIV>
<DIV><FONT face=Arial size=2>Probably its best feature vs. the other
chargers is the meter that tells the operator what is going on.
After you use it a few times you will be able to predict the current at
the beginning and during the charge cycle depending on how many
flights you had. If something is wrong, like a cell way out of wack,
it will give you an indication. Of course it tells you when the pack
is charged and if for some reason it was taking too long you would figure
it out. In other words you will learn what is normal proper charge
current vs. time and could spot an unbalanced pack. It cannot assure
you a cell will not be overcharged if the cells are not matched but I
believe you would spot it.</FONT></DIV>
<DIV><FONT face=Arial size=2>I've been using it for over a year and always
charge the packs in the plane. The total charge time is relatively
short so you can monitor it, but I have left them plugged in over
night. </FONT></DIV>
<DIV><FONT face=Arial size=2>I have only seen one pack (a Duralite which
was in a plane I bought) with a slight unbalance. It was a 2S2P
configuration and I don't have much experience with that
configuration. I have never seen a simple 2 cells in series pack
unbalanced.</FONT></DIV>
<DIV><FONT face=Arial size=2>Where you really need to worry about this is
in long strings like those used in electric flight. I talked to Fred
Marks (FMA) about bringing out each node so each cell could be checked and
charged individually if required. He said they plan to do that in
the future.</FONT></DIV>
<DIV><FONT face=Arial size=2>In the mean time, I believe one could stick a
pin through the heat shrink to check the cell balance. I'll try that
today and get back to the list.</FONT></DIV>
<DIV><FONT face=Arial size=2>Regards, Jim</FONT><FONT face=Arial
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