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<DIV><FONT size=2 face=Arial>Trying to intuit battery condition is rather like
trying to figure out how much oil is in an engine, by reading an oil pressure
gauge. However, in most cases, voltage is the easiest and quickest thing
to read. So we use it.</FONT></DIV>
<DIV><FONT size=2 face=Arial>Bill Glaze</FONT></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=joddino@socal.rr.com href="mailto:joddino@socal.rr.com">James
Oddino</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">General pattern discussion</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, August 23, 2010 2:14
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] Scary
night of flying</DIV>
<DIV><BR></DIV>I think if we talk about <B>balancing</B> NiXX batteries
instead of "forming" we will understand what is going on and then we won't
call it false peaking. The reason you want to do the 24 hour C/10 charge
periodically is to make sure all the cells are fully charged. If the
cells are fully charged and fairly well matched you can then fast charge and
all cells will peak at the same time and the charger will turn off when it
should. But let's say the pack has been sitting for a long time and one
or two cells self discharge much more than the others. The other three
cells peak when they are charged and the charger turns off before our two low
cells are fully charged. We fly and all is well until the two that
started low fall off the plateau and the system gets soft. If we are
lucky we land safely. And remember measuring the voltage is not a good
way to know the state of charge of a NiXX pack. It only works if you
know you have matched cells and you started with a fully charged pack.
You know neither unless you do some cycling after a long period of
storage. And by the way the more cells in the pack the worse it gets.
We had a NiCd pack with 50 cells in series in a missile system.
Extended C/10 charging was the only way to know you had a charge.
<DIV><BR></DIV>
<DIV>All of this discussion should make it obvious that Lithium is the way to
go. We balance them every time we charge and there is no false peaking,
there is little self discharge and voltage does give you a good idea of the
state of charge. </DIV>
<DIV><BR></DIV>
<DIV>Jim<BR>
<DIV><BR></DIV>
<DIV><BR>
<DIV>
<DIV>On Aug 23, 2010, at 7:04 AM, Bob Richards wrote:</DIV><BR
class=Apple-interchange-newline>
<BLOCKQUOTE type="cite">
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<DIV>Paul,</DIV>
<DIV> </DIV>
<DIV>For Nicads and NiMh, nothing beats an overnight c/10 charge.
A fast charge once in a while is ok, but it is possible (as others
have said) to get a false peak when doing a fast charge.</DIV>
<DIV> </DIV>
<DIV>If I do want to fast charge my nicads or NiMh, I prefer my
Accucycle Elite. When it finishes the fast charge, it will switch to a
slow charge. You can select the fast charge rate, as well as the slow
charge rate. For my transmitter batteries (about the only thing I
still use Nicads in) I will fast charge at 350 to 500 ma, and set the
slow charge to 50 or 100. It will indicate how many mah capacity it
put back into the batteries during the fast charge. The slow charge
will then equalize the cells. And I do this outside the transmitter
since the internal transmitter wiring and diode will affect the
operation.</DIV>
<DIV><BR>The Accucyle Elite also can cycle Nicads as well.</DIV>
<DIV> </DIV>
<DIV>Some of the fast chargers, or charge-anything chargers, will not
switch to the slow rate, they just shut off. That is why I like the
Accucycle Elite.</DIV>
<DIV> </DIV>
<DIV>Bob R.</DIV>
<DIV><BR>--- On <B>Sun, 8/22/10, Paul LaChance <I><<A
href="mailto:plachance@cox.net">plachance@cox.net</A>></I></B>
wrote:<BR></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: rgb(16,16,255) 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px"><BR>From:
Paul LaChance <<A
href="mailto:plachance@cox.net">plachance@cox.net</A>><BR>Subject:
Re: [NSRCA-discussion] Scary night of flying<BR>To: "General pattern
discussion" <<A
href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</A>><BR>Date:
Sunday, August 22, 2010, 11:37 AM<BR><BR>
<DIV class=plainMail>Hi all,<BR><BR>Thanks for all the advice.
I have to admit I did not cycle the batteries before flying this
time. They were cycled when purchased and were new for the
2008 NATS. I already bought a new battery but wanted to know
if NiCad can be quick charged on a first charging or do they have to
be slow charged like NiMh? Thanks in
advance.<BR><BR>Paul<BR><BR><BR>----- Original Message ----- From:
"Lightfoot" <<A
href="http://us.mc11.mail.yahoo.com/mc/compose?to=lightfoot@sc.rr.com"
ymailto="mailto:lightfoot@sc.rr.com">lightfoot@sc.rr.com</A>><BR>To:
"'General pattern discussion'" <<A
href="http://us.mc11.mail.yahoo.com/mc/compose?to=nsrca-discussion@lists.nsrca.org"
ymailto="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</A>><BR>Sent:
Sunday, August 22, 2010 11:13 AM<BR>Subject: Re: [NSRCA-discussion]
Scary night of flying<BR><BR><BR>> Might well have been a case of
NiCad "memory". I wouldn't have thrown them<BR>> away unless
after cycling them twice they showed to be weak. Periodic<BR>>
cycling is a must!<BR>> <BR>> Jay Marshall<BR>>
-----Original Message-----<BR>> From: <A
href="http://us.mc11.mail.yahoo.com/mc/compose?to=nsrca-discussion-bounces@lists.nsrca.org"
ymailto="mailto:nsrca-discussion-bounces@lists.nsrca.org">nsrca-discussion-bounces@lists.nsrca.org</A><BR>>
[mailto:<A
href="http://us.mc11.mail.yahoo.com/mc/compose?to=nsrca-discussion-bounces@lists.nsrca.org"
ymailto="mailto:nsrca-discussion-bounces@lists.nsrca.org">nsrca-discussion-bounces@lists.nsrca.org</A>]
On Behalf Of Paul LaChance<BR>> Sent: Saturday, August 21, 2010
10:57 PM<BR>> To: General pattern discussion<BR>> Subject:
[NSRCA-discussion] Scary night of flying<BR>> <BR>> Hi
all,<BR>> <BR>> I finally flew my Prestige tonight after not
flying it since the NATS 2008.<BR>> I have not flown it or ANY
planes for 2 full years. I charged everything up<BR>>
<BR>> and all seemed well. Flew my first flight and landed
without incident. I<BR>> checked the plane over and checked
all my batteries and all looked well.<BR>> <BR>> Flew flight
2, all was going well. Flew the Advanced pattern twice
and<BR>> landed. Checked my batteries again and they still
read over 6 volts.<BR>> Engine was running great and all was
well.<BR>> <BR>> Flew flight 3 and that is where things got
scary. I flew the sequence once<BR>> and everything was
going well. When I started my second sequence the
plane<BR>> got sluggish and was not feeling right. I landed
ASAP and as soon as the<BR>> wheels tounched down, I went to add
rudder to stear towards the pits and had<BR>> <BR>> no rudder,
no elevator, and only one aileron was working but it barely
moved<BR>> <BR>> and was very sluggish. I shut the plane
off and checked the batteries and<BR>> they were barely reading
4.5 volts. This was a 5 cell nicad pack. I guess<BR>>
I had a cell short and kill the pack. I was just amazed and am
very lucky<BR>> to have been able to get the plane back on the
ground before the battery<BR>> completely failed.<BR>>
<BR>> Has anyone had this happen before? What would cause
this? I am going to<BR>> get a new pack in the morning and
try to fly again tomorrow evening.<BR>> <BR>> Thanks in
advance for the help,<BR>> <BR>> Paul<BR>> <BR>>
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