[NSRCA-discussion] Main battery redundant lead for receiver

Mon Jan 23 15:36:52 AKST 2012

Yeah, on my Vanquish even though the sum of all the parts that went into it
came to 4765g, I weighed the whole thing ready to go the other day and
found I was at 5030!  Not a huge deal since I'm in sportsman but I'm still
trying to figure out how one very minor repair to the LG plate and a change
to Secraft canopy locks would have come to 235 grams!  So I started looking
for lighter batteries -- I could get 30g back by switching to the V2 Falcon
props, but that's an extra $27 per prop, almost $1/gram saved.  I'm
currently only running one Rx battery precisely because of weight, so I'm
really liking the idea of being able to use the main as a backup and
switching to a lighter, lower capacity battery for my main Rx bat.

Peter+

On Mon, Jan 23, 2012 at 3:05 PM, Scott McHarg <scmcharg at gmail.com> wrote:

> Peter,
>    To be honest, I'm struggling to make 5000g with my second De Ja Vu that
> I bought from a guy IF I want to run redundant packs.  I use some 800mah
> packs in the primary De Ja Vu but that has no weight issues at 4885.  I
> took off the APC prop, stuck on a Falcon and added an 800mah pack for
> redundancy with a 2nd regulator.  Those items weighed about the same that I
> saved switching to the Falcon prop.   The APC was 128g and the new Falcon
> was 62g.  The 2nd rx battery and regulator was 76g so I'm only 10g heavier
> with redundancy.  On the 2nd De Ja Vu, it has painted wings and stab and
> weighed in at the Nats at 4960g.  I do still need to switch receivers in it
> (I have an 8 ch and a 14 ch receiver).  The 8 ch is in the primary but I'll
> switch that out to save a few grams.  The 2nd DJV was not running a switch
> or an arming switch which I feel is important.  So...to make it all happen,
> a Falcon vs. APC and then am running two 350mah 2S packs (Sky Lipo).  They
> only weigh 26g each.  The 800's were 46g each.  Now, with these pigtails, I
> am under 5000g finally.  WOOT!
>
>
> On Mon, Jan 23, 2012 at 4:56 PM, Peter Vogel <vogel.peter at gmail.com>wrote:
>
>> Ah.  Now that's a good idea + point.  And then, in my case, where I'm
>> running HV, I don't even need a reg.  That would provide true power
>> redundancy for almost no weight penalty, though it does run the risk of
>> yanking your RX out if your main battery ejects, or, even if it doesn't
>> yank the Rx (which is held in by 6 servo leads after all, it could yank the
>> redundant battery lead loose and the main system battery is of course
>> yanking itself, so you are left with no radio...
>>
>> Scott, how do you come up with 20g savings?  What size Rx battery are you
>> running?  My TP 1350's weigh 76g, even 900's are in the 60+g range.
>>
>> Peter+
>>
>> On Mon, Jan 23, 2012 at 2:51 PM, Keith Hoard <khoard at gmail.com> wrote:
>>
>>> Only tap off two cells of your main pack. You can then use a regular
>>> regulator (as opposed to a non-regular regulator).
>>>
>>> Keith Hoard
>>> Collierville, TN
>>>
>>> On Jan 23, 2012, at 16:49, Peter Vogel <vogel.peter at gmail.com> wrote:
>>>
>>> And, of course, with a non-switching BEC off a 10s or even a 5s pack you
>>> would have massive heat issues as it tries to step down the voltage from
>>> 18.5 volts to 7.2 or 6 volts, depending on whether you are running an HV or
>>> standard voltage setup, so the regulator would probably need a fan or heat
>>> sink of some sort, which likely negates any weight savings from not running
>>> with a second battery.
>>>
>>> Peter+
>>>
>>> On Mon, Jan 23, 2012 at 2:30 PM, Scott McHarg <scmcharg at gmail.com>wrote:
>>>
>>>> You have to be careful using the BEC, especially from CC because it is
>>>> a switching regulator which cannot be run in parallel.  It's really best
>>>> not to use the BEC and set up a truly separate system.
>>>>
>>>> Scott
>>>>
>>>>
>>>> On Mon, Jan 23, 2012 at 4:28 PM, George Kennie <geobet4evr at gmail.com>wrote:
>>>>
>>>>> Could a CC BEC also be used instead of a reg.? I don't know how much
>>>>> curent is passed by a reg.
>>>>> Sounds good cause it's a bummer trying to solder an extra lead to the
>>>>> Deans.
>>>>>
>>>>> G.
>>>>>
>>>>> On Mon, Jan 23, 2012 at 5:09 PM, Scott McHarg <scmcharg at gmail.com>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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>>>>>>
>>>>>
>>>>>
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>>>>
>>>>
>>>>
>>>> --
>>>> *Scott A. McHarg*
>>>>
>>>>
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>>>
>>>
>>>
>>> --
>>> Director, Fixed Wing Flight Training
>>> Santa Clara County Model Aircraft Skypark
>>>
>>>
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>>
>>
>>
>> --
>> Director, Fixed Wing Flight Training
>> Santa Clara County Model Aircraft Skypark
>>
>>
>>
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>
>
>
> --
> *Scott A. McHarg*
>
>
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-- 
Director, Fixed Wing Flight Training
Santa Clara County Model Aircraft Skypark
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