[NSRCA-discussion] AAA NimH batterys

[Steven Maxwell]

 Jerry wasn't that your Webra setup??
 Steve Maxwell


> [Original Message]
> From: Jerry Budd <jerry at buddengineering.com>
> To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
> Date: 1/28/2006 4:02:45 AM
> Subject: Re: [NSRCA-discussion] AAA NimH batterys
>
> For the 2002 Nats I switched to a AAA 700 mAh NiMH battery pack to 
> make weight.  While practicing at the Kokomo field I discovered that 
> the pack was good for about 1-1/2 flights (don't ask me how I know 
> that!).
>
> Fortunately, I got control back (well - partially) after the 1-1/2 
> downline snap and was able to coax the plane back onto the ground. 
> Not fun.
>
> At the post-flight debrief I figured out that the AAA cells simply 
> had too high of an internal impedance to deliver enough current to 
> keep the voltage above the receiver/servo cut-off level when all the 
> servos needed to move at once.  I was using JR 7000 Super Servos for 
> aileron which went slow/shut off at 4.6V whereas the other JR servos 
> kept on working down to 4.2V.
>
> Jerry
>
>
> >Ed is right.  The smaller the cells the higher the internal resistance. 
Run
> >them down to 20% remaining capacity and put a heavy load, like 5 Amps on
> >them and read the voltage.  You will probably not like what you see.
> >
> >Jim O
> >
> >
> >----- Original Message -----
> >From: "Ed Alt" <ed_alt at hotmail.com>
> >To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> >Sent: Thursday, January 26, 2006 3:06 PM
> >Subject: Re: [NSRCA-discussion] AAA NimH batterys
> >
> >
> >>  Ed:
> >>  You might get disappointing results due to the inherently high
internal
> >>  resistance of NiMH.  Going with AAA cella and such a low capacity
might
> >mean
> >>  that you don't get as many flights as you expect before a voltage test
> >under
> >>  load dips below an acceptable value.
> >>
> >>  Ed
> >>  ----- Original Message -----
> >>  From: "Ed Miller" <edbon85 at charter.net>
> >>  To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> >>  Sent: Thursday, January 26, 2006 9:05 AM
> >>  Subject: [NSRCA-discussion] AAA NimH batterys
> >>
> >>
> >>  > Is anyone using AAA NimH batteries for a RX pack ??. I am looking at
> >>  > Batteries America ( EHYOST ) and they seem to have AAA NimH's in
720,
> >800
> >>  > and 900mah ratings. I currently use their 2/3A 5 cell NimH pack at
> >1100mah
> >>  > and a weight of 3.85 ounces complete with the long lead I have on
the
> >>  > pack.
> >>  > Going to their AAA 5 cell pack looks like I can save about an ounce
or
> >so.
> >>  > Mah isn't an issue, I can get in excess of 7 to 8 flights on the
1100mah
> >>  > pack I use now before charging so going to 900mah shouldn't be a big
> >hit.
> >>  > Don't suggest Lithium anything as lighter, want to continue to use
my
> >>  > Alpha
> >>  > 4 charger and am not convinced those new batteries are safe.
> >  > > Ed M.
>
> -- 
> ___________
> Jerry Budd
> Budd Engineering
> (661) 722-5669 Voice/Fax
> (661) 435-0358 Cell Phone
> mailto:jerry at buddengineering.com
> http://www.buddengineering.com
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