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<DIV><SPAN class=746360619-24012005><FONT face=Arial color=#0000ff size=2>Hi
Ron,</FONT></SPAN></DIV>
<DIV><SPAN class=746360619-24012005><FONT face=Arial color=#0000ff size=2>Nickel
tends to fail short. That's actually good. Once upon a time, Orbit sold its
packs with diodes across each cell to protect against failed-open
cells.</FONT></SPAN></DIV>
<DIV><SPAN class=746360619-24012005><FONT face=Arial color=#0000ff
size=2> Try the Smart-Fly BATshare ... same bat time, same bat
channel!</FONT></SPAN></DIV>
<DIV><SPAN class=746360619-24012005><FONT face=Arial color=#0000ff size=2><A
href="http://www.smart-fly.com/Products/BatShare/batshare.htm">http://www.smart-fly.com/Products/BatShare/batshare.htm</A></FONT></SPAN></DIV>
<DIV><SPAN class=746360619-24012005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=746360619-24012005><FONT face=Arial color=#0000ff
size=2>later,</FONT></SPAN></DIV>
<DIV><SPAN class=746360619-24012005> <FONT face=Arial
color=#0000ff size=2>Dean</FONT></SPAN></DIV>
<P><FONT face="Times New Roman">Dean Pappas</FONT> <BR><FONT
face="Times New Roman">Sr. Design Engineer</FONT> <BR><FONT
face="Times New Roman">Kodeos Communications</FONT> <BR><FONT
face="Times New Roman">111 Corporate Blvd.</FONT> <BR><FONT
face="Times New Roman">South Plainfield, N.J. 07080</FONT> <BR><FONT
face="Times New Roman">(908) 222-7817 phone</FONT> <BR><FONT
face="Times New Roman">(908) 222-2392 fax</FONT> <BR><FONT
face="Times New Roman">d.pappas@kodeos.com</FONT> </P>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> discussion-request@nsrca.org
[mailto:discussion-request@nsrca.org]<B>On Behalf Of
</B>ronlock@comcast.net<BR><B>Sent:</B> Monday, January 24, 2005 1:40
PM<BR><B>To:</B> discussion@nsrca.org<BR><B>Subject:</B> Re: any merit in
running dual battery packs ?<BR><BR></FONT></DIV>
<DIV>I wanted redundancy in the power system for my pattern birds, but without
ANY new potential points of failure. My confinguration is:</DIV>
<DIV>Two 700mah 5 cell batt packs. Each pack direct to a
switch, direct to Receiver.</DIV>
<DIV>No regulators, diodes, etc. </DIV>
<DIV>I'm more concerned about connector, switch, and solder
joint failures in the pack, than failure of a battery cell. This
config gives me redundancy in those areas.</DIV>
<DIV>When things go normally, I have 1400mah available with only a slight
weight gain over a single larger pack, switch & wiring.</DIV>
<DIV> </DIV>
<DIV>I understand cells more often fail open, than short. But in
case of a short, (the worst case for this config) the good pack must fly
the plane, and charge the "bad" pack for duration of the
flight. After research & discussion with others, it's my belief
the good pack will tolerate the load of charging the bad one (which won't
be at a very high rate) and finishing a flight. </DIV>
<DIV> </DIV>
<DIV>A potential failure point is me. (darn humans!)
My duties as crew chief include checking both batts before every flight,
and turning on both before flight.</DIV>
<DIV> </DIV>
<DIV>Later, Ron Lockhart</DIV>
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style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">--------------
Original message -------------- <BR>
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<DIV>
<DIV>In a message dated 1/24/2005 7:19:07 AM Eastern Standard Time,
hitesh@salt.ac.za writes:</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><FONT
style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 size=2>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=095360912-24012005>Hi,</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=095360912-24012005></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=095360912-24012005>Now that we all using high powered digital
servo's with incredible holding power etc - is there any merit in running
2 battery packs, say 1 Ah each as opposed to 1 high capacity
pack thereby eliminating the single point failure ? If I did want to
run 2 packs, is a diode necessary to prevent 1 pack from possibly charging
the other if 1 pack were to go bad ?</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=095360912-24012005></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=095360912-24012005>Cheers,</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=095360912-24012005>Hitesh</SPAN></FONT></DIV></FONT></BLOCKQUOTE></DIV>
<DIV> </DIV>
<DIV>Hitesh, a 1500 to 2000ma battery is all you need. There's little
advantage to redundancy unless you are planning to fly more than 5-7 flights
(res) on any given day. But then again, I use NiMH on the airborne and only
Sanyo packs, which have proven extremely reliable for several years now.
As such, a redundant power source isn't really necessary in pattern
models and you can avoid some unnecessary weight build up. </DIV>
<DIV> </DIV>
<DIV>What has been done in large models is to add another battery
and switch harness to an unused channel on the receiver, which
provides adequate redundancy. The extra weight on such models isn't as
critical as it is in pattern models. Both switches "on" at take-off
please.</DIV>
<DIV> </DIV>
<DIV>Of course, if you just have to have the extra battery and you have
enough weight margin and room, the above is one way to do it. There are
other ways, but this is simple and reliable.</DIV>
<DIV> </DIV>
<DIV>MattK</DIV></FONT></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>