[NSRCA-discussion] AAA NimH batterys

[Chris Moon]

I have several ni-mh packs from No-BS (Hangtime Hobbies) and they are 
excellent.  If you are worried about voltage drops w/ ni-mh packs then 
just go to a 5 cell pack.  Another option is li-ion packs.  I just 
switched late last yr to the Fromeco 2400 li-ion @ 3.3oz plus a 6V 
regulator from the good people at Jaccio (Jim Oddino). Tons of flight 
time and no problems w/ voltage drop during maneuvers.

Chris

Dean Pappas wrote:

>Hi Gang,
>Don't equate the typical NimH with horrible cell resistance to the good ones with low resistance. They really are different animals. Look at the "H" series on the SR site, then compare cell resistances. In most cases, you can't even find the numbers, on most cells you buy, because they are so horrible. Don't throw the baby out with the bath-water.
>Low resistance NimH cells are, no doubt, available from elsewhere, too. I'd check NoBS batteries first.
>Dean
>
>	-----Original Message----- 
>	From: nsrca-discussion-bounces at lists.nsrca.org on behalf of Jerry Budd 
>	Sent: Sat 1/28/2006 4:02 AM 
>	To: NSRCA Mailing List 
>	Cc: 
>	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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