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<DIV><FONT face=Arial size=2>Digitals do not draw any more peak current at start
or at stall. That current is basically the applied voltage divided by the
resistance of the motor winding. Three Ohms is typical so the current
would be 6 volts divided by 3 Ohms or 2 amps. As soon as the motor starts
moving it generates an emf, like a generator that bucks the input voltage and
reduces the current. however if you get a bunch of servos buzzing you can
draw a lot of current.</FONT></DIV>
<DIV><FONT face=Arial size=2>What makes the digitals draw more <U>average</U>
current is the fact that they send more pulses to the motor with very little
error signal. In other words if you press on the elevator to create an
error between commanded position and true position, the digital will send more
average current than the so called analog trying to get back to the commanded
position.</FONT></DIV>
<DIV><FONT face=Arial size=2>Jim.</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=gene.maurice@comcast.net
href="mailto:gene.maurice@comcast.net">gene.maurice@comcast.net</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> Wednesday, August 25, 2004 6:06
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: NMP 7.4v 2Amp Battery
Packs</DIV>
<DIV><BR></DIV>
<P>Adam<BR>I think that if you were to put a fairly fast amp meter in the
power circuit on an all digital plane, you'll find the peak draws MUCH higher
than 1 amp. A local guy has an EagleTree system in an all digital plane
(sample response time is only about 1/10 of a second, pretty
slow) and it shows AVERAGES of 1.0 - 2.0 amps with peaks up in the 3 - 4
amp range. These peaks are very short in duration but require a battery
capable of delivering that sort of amperage none the less.</P>
<P>Digital servos draw large amounts of current when asked to
move, especially under aerodynamic loads. In addition, their holding
power will draw as much current as it takes, or is available, to maintain a
position. </P>
<P>Check it out, I think you'll be surprised. </P>
<DIV class=signature id=signature>--<BR>Gene Maurice <BR>AMA 3408 NSRCA 877
<BR>Plano, TX <BR>gene.maurice@comcast.net</DIV><BR>
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Original message -------------- <BR><BR>> Dieter Rozek wrote: <BR>>
<BR>> > I just purchase these battery packs and according to the
included <BR>> > instructions is mentions to "Only use NMP's Lithium
charger to charge <BR>> > these packs." I was wondering if anyone
might know why this would be <BR>> > the case. Shouldn't any Li
battery charger work? I already have a <BR>> > Kokam Li battery
charger which allows me to charge at various rates. <BR>> > Is there a
legitimate reason why I should buy their charger or should <BR>> > any
Li charger work? Also, I was surprised at the diminutive size of <BR>>
> the pack. Does this pack have enough juice to power 3x JR9411, 1x3412
<BR>> > and 1x8411 in a Temptation? At 2A I would assume that this
would be <BR>> > more than plenty? I would be interested in hearing
anyo! ne's <BR>> > experience with these packs. <BR>> > <BR>>
> Thanks <BR>> > <BR>> > DIeter <BR>> > <BR>> >
===================================== <BR>> > # To be removed from
this list, go to <BR>> > http://www.nsrca.org/discussionA.htm <BR>>
> and follow the instructions. <BR>> > <BR>> I'm estimating our
peak draw with a fully digital plane is around 1amp, <BR>> so any lithium
battery over 250mah shouldn't have a problem staying <BR>> above 6.0v
during those draws. <BR>> ===================================== <BR>>
# To be removed from this list, go to http://www.nsrca.org/discussionA.htm
<BR>> and follow the instructions. <BR>>
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