[NSRCA-discussion] Main battery redundant lead for receiver

Tue Jan 24 14:59:21 AKST 2012

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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-- 
Director, Fixed Wing Flight Training
Santa Clara County Model Aircraft Skypark
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