NIMH TX pack

[PENNISI Peter]

Is there any truth in the matter that a possible mode of failure in a NiMH
pack is for cell or cells to go open circuit. If this is the case you will
crash because you will immediately have 0 volts. Where as when a nicad cell
fails the cell normally shorts which results in less voltage which means you
will probably crash unless you are using 5 cells.
 
I would be interested to hear if this has any truth from any experts out
there.
 
Secondly if you look at Red Schofield's website (don't have the link handy
at the moment) he does not recommend NiMH for our application.
 
Peter 

-----Original Message-----
From: Bob Pastorello [mailto:rcaerobob at cox.net]
Sent: Friday, 10 October 2003 11:26 AM
To: discussion at nsrca.org
Subject: RE: NIMH TX pack


FWIW - my experience parallels Matt's exactly, even down to the same
supplier for my TX NiMH battery.  I've had zero problems, and use the Sirius
almost exclusively now.  Only NiMh batteries in all my applications.  I
really like the long shelf life, and not losing any charge.  Having more
capacity per ounce than comparable NiCads is a good side benefit, too.
 
Charge at the .1C rate the first couple cycles, like Matt sez...it'll work
just fine.
 
Bob P.

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On
Behalf Of Rcmaster199 at aol.com
Sent: Thursday, October 09, 2003 7:39 PM
To: discussion at nsrca.org
Subject: Re: NIMH TX pack


Derek,

On Earl Haury's suggestion I bought my first NiMH airborne pack from Radical
RC in Georgia, about 2 seasons ago. The fellow who runs Radical appears to
really know his stuff. He is the real deal. He has written a pretty good
article (on his website)
, regarding the care and feeding of NiMH bats, that is worthwhile reading. 

The key thing he talks about is setting the battery capacity when the
battery is new, uncharged. He stresses to charge the battery at the 0.1C
rate the first couple times. Thern fast charging isn't a problem and is
actually recommended

Earlier this year I also bought the TX bat to go with the airborne. I
followed that expert's advice to the letter and have been very happy with
the results, (some 70 chrge cycles later on the airborne)

About the only thing I do now is place the bats on charge on the SIRIUS
Charger, on the way to the field, and by the time I get there, they are
charged (1000 ma charge rate)

Matt K



Subj:NIMH TX pack 
Date:10/9/2003 4:54:57 PM Eastern Daylight Time
From: derekkoopowitz at earthlink.net <mailto:derekkoopowitz at earthlink.net> 
Reply-to: discussion at nsrca.org <mailto:discussion at nsrca.org> 
To: discussion at nsrca.org <mailto:discussion at nsrca.org> 
Sent from the Internet 



I just ordered a new (replacement) TX NimH battery pack from Cermark.  It is
a 1650mah pack.  I've never had a NimH pack before so I'd like to find out
from the experts out there if there is anything I need to do differently
than a standard NiCad pack.  Can I use my Alpha 4 to charge it?  I do have a
Dymond charger that I can use and I know that it does support NimH but I'd
prefer to use the Alpha 4 because of its AC/DC versatility.


Thanks.





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