[NSRCA-discussion] Main battery redundant lead for receiver

Tue Jan 24 07:50:59 AKST 2012

I'm a big A123 fan myself, and have several 2S-1100 mah packs.  I was using
them in my Integral for the radio and was still well under the 5K limit.

I switched over to using the motor batts for the radio not because of
weight, but for simplicity (read - laziness).  Using the motor batteries
eliminates another charger (w/power supply) that I have to drag to the
field and another battery that I have to manage / worry about.

Now the only two batteries (and chargers) that I have to be concerned with
are the motor batteries and my transmitter batteries.  The little 2S backup
gets charged at the beginning of the day and is just along for the ride.

Keith Hoard
Collierville, TN
khoard at gmail.com

On Tue, Jan 24, 2012 at 11:30 AM, Wayne Galligan <wcgalligan at att.net> wrote:

>   After all this discussion about extra wire connectors and regulators,
> etc., etc.   Interesting as it seems.
> Why not use an 1100 mil A123 pack for the receiver without the regulator.*
> *I haven't weighed the difference but it couldn’t be that much.
> Sounds like your going for a lot extra work to save a few “Grams”.
>
> Simplicity rules.
>
> Wayne Galligan
>
>  *From:* Keith Hoard <khoard at gmail.com>
> *Sent:* Tuesday, January 24, 2012 10:01 AM
> *To:* General pattern discussion <nsrca-discussion at lists.nsrca.org>
> *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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