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<DIV><FONT face=Arial size=2>Bob</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>NiMH & Li are both viable and offer advantages
over NiCad in capacity, maintenance, and weight. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The internal impedance of the present day NiMH
results in slightly more voltage drop for a given current than NiCad (or Li),
but the price / capacity / weight value is hard to beat. Mechanical
durability is as good as NiCad. I use a Sanyo 1650 mah 5 cell pack (5 cells
to minimize the volt drop effect) with a regulator ) <$20 &142 gr. I've
logged more than 1000 flights on these with no problems (generally renew the
pack annually). I use the same cells in my xmtr. Slow
charging is no problem except that the higher capacity takes longer if they're
discharged fully. The advantages over Li are cost and the acceptance of fast
charging. Some peak detect fast chargers don't do well with NiMH, I've found the
Sirius Pro to be excellent.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>However, I am changing to Li (the hard case of the
Li-ion makes them a bit more mechanically durable than LiPo). Low impedance
provides minimal voltage drop at high current loads. The real advantage is the
weight / capacity ratio, a 2400 mah Li-ion weighs less than 100 gr. with even
less weight for LiPo. The disadvantages are that a volt reg is
necessary, their inability to accept fast charging, and higher cost. I use
the NMP charger from Central (Jim Oddino designs are reliable). </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Earl</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></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=bob@toprudder.com href="mailto:bob@toprudder.com">Bob Richards</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> Thursday, October 06, 2005 7:40
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Airborne batteries</DIV>
<DIV><BR></DIV>
<DIV>Guys,</DIV>
<DIV> </DIV>
<DIV>I'm needing to replace several nicad airborne packs for my radios (as
well as a couple of transmitter packs). I'm wondering what has changed in the
technology in the past 8 years. </DIV>
<DIV> </DIV>
<DIV>NiMh packs had just hit the market about 10 years ago, and as I recall it
seemed that they did not stand up well to vibration - several inflight
failures being reported. Seemed they were ok for transmitters. Has that
changed?</DIV>
<DIV> </DIV>
<DIV>I know Li-ion and Li-poly are now available, but what type of charging
apparatus am I looking at investing in? I also think I need to use a regulator
with these?</DIV>
<DIV> </DIV>
<DIV>I don't presently have a fast field charger and would like to have one,
is there one that covers all the above bases?</DIV>
<DIV> </DIV>
<DIV>Thanks in advance,</DIV>
<DIV> </DIV>
<DIV>Bob Richards.</DIV></BLOCKQUOTE></BODY></HTML>