[NSRCA-discussion] Receiver packs

James Oddino joddino at socal.rr.com
Sat Feb 14 12:55:38 AKST 2009 

I'll second that.  I see a bunch of folks that are not near as  
knowledgeable as pattern folk flying all kinds of aircraft and they  
don't seem to have problems with LiPos.  I believe the loss of planes  
due to NiCds and NiMHs was/is a lot higher than those lost to Lithiums  
(excluding those early Duralites).

Jim O


On Feb 14, 2009, at 1:26 PM, Ed Alt wrote:

> Jerry:
> Using A123 batteries requires extra vigilance, since they have a  
> very flat discharge curve for most of their capacity (after an  
> initial quick drop), right up to the point where you have little  
> usable capacity left.  As a result, you won't be able to gauge  
> remaining capacity with a meter, although you can estimate it once  
> you can experience with typical discharge characteristics.  As long  
> as everything with your servo current drain remains consistent and  
> healthy, you can pick a reasonable quitting point after X flights.   
> I'm not sure what the appeal of these batteries is for a flight pack  
> application. One drawback is that you run the servos at a fairly  
> high voltage, which might damage some servos.  If you add  
> regulators, that problem is alleviated, but overall you have a  
> heavier solution than with a LiPo set.  Enhanced charging safety is  
> really all that you are buying.
>
> I think the thing that should be realized is that a set of 2 cell  
> 480 or 730 mAh LiPo's have an extraordinarily easy life when all  
> they are doing is powering a flight pack.  You can get many more  
> cycles out of then than NiCad or NiMH packs and they have much  
> better end of life performance.  I just don't see what the concern is.
>
> Ed
>
> ----- Original Message -----
> From: Jerry Voth
> To: General pattern discussion
> Sent: Saturday, February 14, 2009 4:11 PM
> Subject: Re: [NSRCA-discussion] Receiver packs
>
> Richard,
>
> I was thinking more about using A-123 batteries. They're supposed to  
> be safer. My memory is what scares me about Lipos.
>
> Also, what would the effect be on an ESC using A-123 batteries in  
> place of Lipos? I've read there are some issues.
>
> Jerry
> ----- Original Message -----
> From: Richard Strickland
> To: General pattern discussion
> Sent: Saturday, February 14, 2009 12:37 PM
> Subject: Re: [NSRCA-discussion] Receiver packs
>
> Jerry--just a couple thoughts:  I will probably never use a battery  
> for a receiver/flight pack again that I haven't been in charge of  
> its history.  If you've been paying attention to its characteristics  
> since new, we can generally tell when they start to lose capacity-- 
> and for me, there was a point on the ESV when it got there, I got a  
> little nervous about going up 'one more time'.  When it would  
> approach that point after about five flights, then I would figure it  
> was 1. if early in its career--then to cycle and 2. if in to the  
> second or third year(sometimes longer) it was time to retire it.   
> Nicads for me have been pretty reliable that way and I've been  
> comfortable running one pack.  You can still go to five cells in  
> nicads for additional capacity and power with a regulator and still  
> have that reliability.  I think most of the guys that have gone to  
> lipos can enjoy the increased capacity and power along with an  
> increased discharge rate in a smaller, lighter package.  But I don't  
> get the impression that they trust them like nicads.  Probably the  
> best thing to do is monitor your batteries of any type with a good,  
> loaded ESV to keep an eye out for any unusual battery behavior.  The  
> two battery debate is a little like the single versus twin debate in  
> full scale airplanes--some guys think twins just have double the  
> chances to fail.
> All that said, I understand some of the new receivers are a little  
> touchy regarding low voltage situations.  I had an older receiver in  
> an airplane that I bought used with a 'new' battery--turned out the  
> battery was bad--but got a warning(hold) and was able to land--but  
> showed NO volts afterward.
> Chances are with the newer stuff, it may not have made it back on  
> the ground in one piece.  So using a 5 cell nicad or 2 cell lipo  
> with regulator may not be a bad idea and monitor with a good loaded  
> ESV.
> FWIW
> Richard
>
> From: jjvoth at mtelco.net
> To: nsrca-discussion at lists.nsrca.org
> Date: Fri, 13 Feb 2009 20:32:46 -0600
> Subject: Re: [NSRCA-discussion] Receiver packs
>
> Thanks for the info guys
> ----- Original Message -----
> From: Vicente "Vince" Bortone
> To: General pattern discussion
> Sent: Friday, February 13, 2009 8:28 PM
> Subject: Re: [NSRCA-discussion] Receiver packs
>
> Hi Jerry,
>
> I have been using two li-po using the tech-aero double regulator http://www.tech-aero.net/plr5-dr2.htm 
>   The capacity I am using now is 930 mah, 2 cells  batteries.  I  
> know that I can fly at least 6-8 times.  After that, I am brain dead.
>
> VB
>
>
> ----- Original Message -----
> From: "Richard Strickland" <pamrich47 at hotmail.com>
> To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
> Sent: Friday, February 13, 2009 8:01:03 PM GMT -06:00 US/Canada  
> Central
> Subject: Re: [NSRCA-discussion] Receiver packs
>
> Jerry, I think the short answer is no.  But there has been much  
> discussion regarding dual packs for back-up.  An example ot single  
> pack usage is using a 2 cell lipo at around 780-800ma for practice  
> and 340-380ma for contests to make weight.  These are used with  
> voltage regulators with variing outputs.
> RS
>
> > From: jjvoth at mtelco.net
> > To: nsrca-discussion at lists.nsrca.org
> > Date: Fri, 13 Feb 2009 17:32:25 -0600
> > Subject: Re: [NSRCA-discussion] Receiver packs
> >
> > Sorry, I said that wrong. I meant are two packs needed to power  
> the flight
> > pack.
> > ----- Original Message -----
> > From: "Jerry Voth" <jjvoth at mtelco.net>
> > To: "NSRCA" <nsrca-discussion at lists.nsrca.org>
> > Sent: Friday, February 13, 2009 5:23 PM
> > Subject: [NSRCA-discussion] Receiver packs
> >
> >
> > > This has probably come up many times but I'd like to know if it's
> > > necessary
> > > to use two Li-Fe packs for the radio and servos
> > > _______________________________________________
> > > NSRCA-discussion mailing list
> > > NSRCA-discussion at lists.nsrca.org
> > > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
> > >
> >
> >
> >  
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