[NSRCA-discussion] Main battery redundant lead for receiver

Wed Jan 25 05:55:02 AKST 2012

Dave.. Love how you win your discussions.. lol .. ;+}  

    Del
  ----- Original Message ----- 
  From: Dave Lockhart 
  To: 'General pattern discussion' 
  Sent: Tuesday, January 24, 2012 7:07 PM
  Subject: Re: [NSRCA-discussion] Main battery redundant lead for receiver

  2006

  9411sa x2 for ailerons

  8417sa x1 for elevator

  8411sa x1 for rudder

  2009

  Changed to 3517 x2 for elevator (in the same plane)..no change in mah per flight

  2010

  Changed to 8611A on rudder (in the same plane)..no change in mah per flight

  Flight times are about 45 seconds shorter now.

  I still have the Prestige I flew in 2006, so no change to control surface size or throw.

  I'm pretty sure it is the changes in maneuvers flown and higher average watts used by the motor in the course of the flight.  J

  Regards,

  Dave

  From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Peter Vogel
  Sent: Tuesday, January 24, 2012 6:59 PM
  To: General pattern discussion
  Subject: Re: [NSRCA-discussion] Main battery redundant lead for receiver

  Digital servos *definitely* draw more power than non-digitals, but they are much more precise and hold their position better, it's worth the higher draw for pattern.

  Peter+

  On Tue, Jan 24, 2012 at 3:46 PM, Doug Cronkhite <seefo at san.rr.com> wrote:

  I suspect the servos also draw more power than they did years ago.

  Doug 

  Sent from my iPhone

  On Jan 24, 2012, at 3:40 PM, "Dave Lockhart" <DaveL322 at comcast.net> wrote:

    When I first started flying electric pattern...mah per flight was noticeably lower than now, going from 40-60 per flight to 60-80 per flight...flying whatever was the current P/F sequences.  I suspect the increase is due to higher average flight speeds (much more watts at the motor now) and more demanding maneuvers (snaps and KE).

    Regards,

    Dave

    From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Keith Hoard
    Sent: Tuesday, January 24, 2012 11:02 AM
    To: General pattern discussion
    Subject: Re: [NSRCA-discussion] Main battery redundant lead for receiver

    Anthony,

       On a typical flight, I'm guessing the radio only uses around 100-150Mah of power, while the motor is using 4000Mah, so that's about 4% more draw on those two cells.  In practice, I haven't been able to see any difference in the radio cells when I hook them up to my charger at the end of a flight.  Sometimes cells #1 & #2 are the high cells after a flight, so I think the power draw of the radio is negligible to our motor packs.

    The problem with two regulators plugged into the same 10S (or 5S) pack is that you are creating a dead short between the cells thru the ground wires (typically a straight wire thru the regulator).  

    Say you plug Regulator #1 into cells #1&2, and Regulator #2 into cells #6&7.  The regulator's ground wires now have 5 cells of voltage potential (5 X 4.2V = 21Volts) between them since they are plugged into cells # 1 and #6.  When those two ground wires are then plugged into your receiver either thru a switch or direct connection the magic smoke will escape and your retailer will rejoice.

    Also, if you have both of your regulators plugged into your motor pack and the packs eject like Goose in Top Gun, you've lost both of your redundant power sources.  However, if you use a tiny 2S LiPo that is physically separated and secured inside your plane, you have both electrical and physical redundancy.  

    Hmmm, just thought of something . . . maybe we should tie down the receiver so the main regulator can't take the receiver out with it. . . so many contingencies, so little weight . . .

    Keith Hoard
    Collierville, TN
    khoard at gmail.com

    On Tue, Jan 24, 2012 at 8:15 AM, Anthony Romano <anthonyr105 at hotmail.com> wrote:

    Seems like a great idea but I have two questions. Do the packs come down out of balance since two cells are serving extra load? Is there a problem with parallel operation of two regulators?

    Thanks,

    Anthony

----------------------------------------------------------------------------

    From: joddino at socal.rr.com
    Date: Mon, 23 Jan 2012 15:25:00 -0800
    To: nsrca-discussion at lists.nsrca.org
    Subject: Re: [NSRCA-discussion] Main battery redundant lead for receiver

    I've been using this setup for sometime and it is working great.  I have my two cell LiPo charged to 7.5 volts and it is connected to a 6.0 volt regulator into the receiver.  The cable connected to the balance connector on the "bottom" 5S is connected to a 6.3 volt regulator so it supplies all the current to the system and the 2S pack never needs charging.  I'm using an 800 mAh pack but it could be even smaller.   

    Jim O

    On Jan 23, 2012, at 2:09 PM, Scott McHarg wrote:

      Guys,
         Chris Moon just e-mailed me about some leads that were done at the factory.  These leads run off your balance leads to a voltage regulator and allow your main battery pack to be utilized as a redundant receiver battery.  It is NOT meant to be a primary but it will save 20+ grams if you're running 2 rx batteries.  You still have to run the 2nd regulator for true redundancy but you eliminate the 2nd battery.  These leads are factory made and eliminate the need to make them yourself with the concern about plugging in to the wrong cell.  I know in my article, I was pretty much against doing this as a backup but, with Chris having this made at the factory, he has all but eliminated making a mistake by tying to the wrong cell.  I have the link that I'll e-mail you off-list or you can just go to his website.  I don't want to break the NSRCA list rules by advertising for him even though he advertises with the NSRCA.  The leads are only $3.99 each and are found under the Connectors/Adapters listing.

      Thank,
      Scott

      -- 
      Scott A. McHarg

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  Santa Clara County Model Aircraft Skypark

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