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<DIV><FONT face=Arial size=2>Bob, that sounds like a good solution.
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Since the diode consumes some energy what voltage
is seen by the receiver? </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Do you just purchase a diode from an electronics
store and solder it in yourself, or is there one marketed specifically for use
in our applications (proper connectors etc.).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Can you share the specifics of the one you use
(maybe even a model number and where you purchased it)?</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>
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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=WHIP23@aol.com href="mailto:WHIP23@aol.com">WHIP23@aol.com</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, March 28, 2003 5:00
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re two batteries, was Miracle
switch failures</DIV>
<DIV><BR></DIV><FONT face=arial,helvetica><FONT lang=0 face=Arial size=2
FAMILY="SANSSERIF"><BR>Ok third try, I must be e-mail challenged!!<BR><BR>
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<BLOCKQUOTE
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TYPE="CITE"><BR>Hi Guys<BR><BR>
<BLOCKQUOTE
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TYPE="CITE">All the "battery backup systems" I have seen put something
of unknown reliability/untested in the critical path. The best
setup is two batteries diode orred (sp?) together (diode in each path
from switch to receiver) through two switches (must be 5 cell to allow
for the diode drop) fully redundant, you would have to have a failure in
both paths at the same time to loose control due to battery.
Assuming you check things every flight the odds of a failure in both
paths is too remote to consider. There is little weight penalty,
run two batteries 1/2 the size you would normally run. Being a
worrier I also make a point of never running either pack down too far
(if I happen to be running on one pack I want enough charge in that one
pack to last a long flight). The diodes must be in the path from
the switch to the receiver (if you put them between the battery and the
switch, as once got printed incorrectly, with MY name attached, you
won't be able to charge in this configuration) I've been doing
this for about 10 years with no problems and it has saved me an
airplane, both batteries good on take off one was bad (open) on landing,
if only one battery, bye bye airplane. Guess you could argue that
the bad battery might have been in someone else's airplane VBG. It
is a little more complex, two switches (one of the biggest failure
items) two charge jacks, two batteries. Assuming you have an
unused channel you can plug the battery into any unused channel
(preferred) if not then I would wye it to a non mission critical
channel, last choice would be to wye the two batteries together (the wye
is then mission critical, I told you I was a worrier) There is
also good evidence that the diodes are not necessary, that a 5 cell pack
won't charge a 4 cell pack (one shorted cell), sounds right and I've
used this scheme, but I have never tested it with a cell shorted so I
have no first had experience. I'm not sure I could sleep at night,
anymore, with only one battery pack and switch, just seems like
unnecessary risk.<BR><BR>Flame suit on,
Bye<BR><BR>Bob<BR></BLOCKQUOTE><BR></BLOCKQUOTE><BR><BR></BLOCKQUOTE><BR></FONT><FONT
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