<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2900.2802" name=GENERATOR></HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=2>I think this procedure is essential with NiMh
packs. You can do OK with individual cells (like digital camera applications)
using a charger that shuts down with peak detection. When you charge a set of
NiMh's in series with a peak detector it stops with the first cell peaking. It
doesn't hurt anything, you just don't get a full charge on the pack.
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>It is possible to build a pack charger that charges
each cell individually but it gets cumbersome. Especially when you consider that
an occasional 16 hour charge will solve the problem.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I find the same procedure also works well for
NiCad's. If you reset the peak charger and restart it you will cook the
batteries and suffer short battery life. NiCad's normally fail shorted and you
have enough power to land. NiMh's normally fail open and you will need another
airplane to go with your new battery.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>That is also why I use NiMh in the transmitter and
NiCads in the flight packs.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>John Ferrell <BR><A
href="http://DixieNC.US">http://DixieNC.US</A><BR></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=bob@toprudder.com href="mailto:bob@toprudder.com">Bob Richards</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">NSRCA Mailing List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, February 24, 2006 6:31
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] NiMH
Question</DIV>
<DIV><BR></DIV>
<DIV>The problem with some of the cyclers is that they do a fast charge, then
discharge, then fast charge, etc. without ever "equalizing" the cells.
The problem is that one or more cells in the pack can become depressed more
than others, and without a good equalization charge they will never be topped
off fully since the cells that ARE fully charged will trip the peak
detection when they come up.</DIV>
<DIV> </DIV>
<DIV>I suggest doing a C/10 charge for 16 hours, then cycle the pack and see
what happens.</DIV>
<DIV> </DIV>
<DIV>Bob R.</DIV>
<DIV><BR><BR><B><I>Michael Cohen <precisionaero@comcast.net></I></B>
wrote:</DIV>
<BLOCKQUOTE class=replbq
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">
<META content="MSHTML 6.00.2900.2802" name=GENERATOR>
<STYLE></STYLE>
<DIV><FONT face=Arial size=2>I am cycling my batteries and getting ready for
the flying season. On my initial 5 cycle run at my NiMH batteries, !
both my 1650 mAh packs cycled very low. One pack that I have not used
since end of November only cycled up to 850 mAh and the other pack I have
not used since end of September only cycled up to 1000 mAh. My charger
is set to 5 cycles, charge and discharge are set to .65 amps with a cutoff
voltage at 1.1 Volts per cell. I am now trying 1.00 amp
charge/discharge with a 1.0 volt per cell cutoff and it is looking better,
but I have some questions:</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>1) Did I damage the batteries by letting
them self-discharge too low? I know NiMH batteries have a higher self
discharge rate than NiCD batteries, but I am not aware letting the NiMH
batteries run down could cause damage.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>2) Is this a normal behavior? Maybe
NiMH just need a little more juice at the beginning of the
season.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>3) Is the cold garage a
factor?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thoughts?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Mike
Cohen</FONT></DIV>_______________________________________________<BR>NSRCA-discussion
mailing
list<BR>NSRCA-discussion@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</BLOCKQUOTE><BR>
<P>
<HR>
<P></P>_______________________________________________<BR>NSRCA-discussion
mailing
list<BR>NSRCA-discussion@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</BLOCKQUOTE></BODY></HTML>