[NSRCA-discussion] "Sick" Lipo Packs

[Robert Campbell]

Ron,

We're going to start calling you Dr. Frankenstine.


Rob


----- Original Message ----- 
From: "Ron Van Putte" <vanputte at cox.net>
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Sent: Saturday, December 04, 2010 5:45 PM
Subject: [NSRCA-discussion] "Sick" Lipo Packs


> Those of you who use lithium polymer battery packs to power their  
> competition airplanes are familiar with "puffed" packs.  I recently  
> had four elderly 5S packs "puff".  We all know that's not good, but  
> what I'd like to know is what's actually happening.
> 
> I know it's probably not wise for consumers to take lithium polymer  
> packs apart, but that's exactly what I did with four packs.  I  
> discovered that in three of the "puffed" packs, only a single cell  
> was "puffed".  In the last pack, there were two "puffed cells.  I did  
> a little arithmetic and quickly discovered that I could make three  
> "unpuffed" packs from the good cells I had.  So, I unsoldered the  
> "puffed" cells from the four packs and cannibalized one pack to make  
> three 5S packs from what I had left.  This process is obviously for  
> the timid or the careless.  I was careful and had no mishaps.   
> However, I would suggest that anyone who says "Oops" a lot should not  
> attempt doing this.
> 
> The three 5S packs I have left are "rock solid".  Experienced  
> electric-pilots will know just what I mean.
> 
> I have flown these packs and they seem to perform just as they did in  
> their "youth".
> 
> My questions are:  Why do lithium polymer cells "puff"?  What is the  
> likely future of my recovered 5S packs?
> 
> Ron VP
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>