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<DIV><SPAN class=873440221-24012005>Hi Keith,</SPAN></DIV>
<DIV><SPAN class=873440221-24012005></SPAN> </DIV>
<DIV><SPAN class=873440221-24012005>I don't receive the K-Factor - different
country - so I'm not familiar with Lance's approach ? I'm interested in the
voltage regulators you using - are they DIY or off the shelf ? </SPAN></DIV>
<DIV><SPAN class=873440221-24012005>After a good flying session, have you tested
the capacity of both battery packs to get a feeling of what's actually happening
in flight ie. is the 2'nd battery pack being used during high current loads,
somewhat unexpected but entirely possible ? </SPAN></DIV>
<DIV><SPAN class=873440221-24012005></SPAN> </DIV>
<DIV><SPAN class=873440221-24012005>Cheers,</SPAN></DIV>
<DIV><SPAN class=873440221-24012005>Hitesh</SPAN></DIV>
<DIV> </DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV align=left class=OutlookMessageHeader dir=ltr><FONT
face=Tahoma>-----Original Message-----<BR><B>From:</B>
discussion-request@nsrca.org [mailto:discussion-request@nsrca.org]<B>On Behalf
Of </B>Keith Black<BR><B>Sent:</B> 24 January 2005 09:26<BR><B>To:</B>
discussion@nsrca.org<BR><B>Subject:</B> Re: any merit in running dual battery
packs ?<BR><BR></DIV></FONT>
<DIV>Though it's true that most planes flown use only one battery, and if
maintained correctly a pilot can go years without loosing a plane for power
reasons if he's lucky, there are still several failure points that can turn a
two to three thousand dollar model into firewood. I personally know of at
least four pattern planes that have been lost due to power issues. The failure
points include bad wiring, faulty regulator (if used), switch, battery going
bad, false peaks, battery becoming dislodged and unplugging, and probably some
others that I haven't thought of. </DIV>
<DIV> </DIV>
<DIV>I think having a backup battery is a very good idea if you can afford the
additional weight. I personally prefer the second battery even if it makes me
a few ounces over weight for the majority of my flying which is practice. A
centrally located backup battery can be removed for contests to make the
weight limit. </DIV>
<DIV> </DIV>
<DIV>A backup battery can be done as described in Lance's article in the
December K-Factor or there are other approaches that can be used. The method I
use is two five cell packs, one primary (pick your battery type or size)
and one a AAA 750 mha NiMH pack, both going through their own switch and
regulator into different channels in the RX. The regulator on the primary
battery is 5.8 volts and the regulator on the backup battery is 5.5 volts.
This will cause the voltage to be drawn from the primary battery and not the
backup battery. Voltage will only be pulled form the backup battery when the
primary battery voltage drops below 5.5 volts. The regulators also perform the
task of preventing reverse charging (like a diode). </DIV>
<DIV> </DIV>
<DIV>This approach is slightly heavier than Lance's approach since it requires
two regulators and an additional cell, but for me it worked well and was
easy.</DIV>
<DIV> </DIV>
<DIV>Keith</DIV>
<DIV> </DIV>
<DIV>----- Original Message ----- </DIV>
<BLOCKQUOTE dir=ltr
style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A href="mailto:Rcmaster199@aol.com"
title=Rcmaster199@aol.com>Rcmaster199@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
href="mailto:discussion@nsrca.org"
title=discussion@nsrca.org>discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, January 24, 2005 10:16
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: any merit in running dual
battery packs ?</DIV>
<DIV><BR></DIV><FONT color=#000000 face=Arial id=role_document>
<DIV>
<DIV>In a message dated 1/24/2005 7:19:07 AM Eastern Standard Time, <A
href="mailto:hitesh@salt.ac.za">hitesh@salt.ac.za</A> writes:</DIV>
<BLOCKQUOTE
style="BORDER-LEFT: blue 2px solid; MARGIN-LEFT: 5px; PADDING-LEFT: 5px"><FONT
color=#000000 face=Arial style="BACKGROUND-COLOR: transparent">
<DIV><FONT color=#0000ff face=Arial><SPAN
class=095360912-24012005>Hi,</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial><SPAN
class=095360912-24012005></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial><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 color=#0000ff face=Arial><SPAN
class=095360912-24012005></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial><SPAN
class=095360912-24012005>Cheers,</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial><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></BLOCKQUOTE></BLOCKQUOTE></FONT></BODY></HTML>