[NSRCA-discussion] Batteries

[Joe Lachowski]

The next Masters schedule is definitely shorter timewise. Same number of maneuvers though.


From: vicenterc at comcast.netTo: nsrca-discussion at lists.nsrca.orgDate: Fri, 14 Mar 2008 20:10:13 +0000Subject: Re: [NSRCA-discussion] Batteries
I could guess that the next Master schedule is going to be electric friendly.  
--Vicente "Vince" Bortone
 
-------------- Original message -------------- From: "Earl Haury" <ejhaury at comcast.net> 


Chad
 
Sure - nothing wrong with going with what provides the highest comfort level. Given the same technology - and often the same manufacturer - the differences between brands can come down to service provided. As you say - they all have their limits. We on the gulf coast are envious of your ambient temps for battery life (you can keep it for human life.) :) I've noted much better life from batts used during our "winter" than the heat of our summer.
 
At least we get a bit of a break with the shorter F3A sequences (the Masters guys need all the capacity they can get). 
 
Earl

----- Original Message ----- 
From: Chad Northeast 
To: nsrca-discussion at lists.nsrca.org 
Sent: Friday, March 14, 2008 10:44 AM
Subject: Re: [NSRCA-discussion] Batteries
Its just my general "feel" from my experience with TP, and witnessing others experience with FP.  I won't go into all the details on the list because I don't want to tarnish any particular company, but I have yet to see any of the 1P packs come close to the longevity of the 4P packs when putting them through the same punishment.I have seen a lot of puffed 5350's, 5300's, 5000's so I guess they all have their limits :)Chad----- Original Message -----From: Earl Haury <ejhaury at comcast.net>Date: Friday, March 14, 2008 9:10 amSubject: Re: [NSRCA-discussion] BatteriesTo: chad at f3acanada.org, NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>> Chad, you have a point, however it's important to factor in that > the 1P > packs are also generally higher C rating. My view when > ! conside ring batteries > initially was that higher cell count provided more failure > opportunities, > both as individual cell failure and connections. I've  > disassembled a number > of  "failed", or no longer pattern suitable packs, and > measured individual > cell characteristics.> > Generally, the cells in a lower C pack tend demonstrate an > increase in > impedance, resulting in lower voltage output for a given current > draw over > their lifespan until no longer "pattern viable". During this > time capacity > diminishes - but most cells with high impedance will still > retain 80+% of > their original capacity. Even though these things generate more > heat than > the higher C packs - they tend to handle abuse (as you've found) > partly > because of the retained capacity and partly because of > "performance > l! imiting " impedance. Post flight imbalance doesn't change too > much as these > packs age - suggesting a similar "aging" of the individual cells.> > Conversely, the high C packs demonstrate very low impedance > initially and > that appears to be retained throughout their life. However, the > cell > capacity appears to drop pretty early and continue to do so over > the pack > life. I've measured some of these with an average capacity loss > of 40% after > 50 flights - that means a 5000 mAh pack is now a 3000 mAh pack. > Even worse - > there is often a good deal of variance from cell to cell. Their > low > impedance will provide little warning (as loss of power) until a > cell is > injured, real easy to do if you try to take 3500 mAh from the > now 3000 pack. > Often one will notice the post flight imbalance increasing as > these packs ! > ag e and it will be greater at higher depths of discharge - a > sure sign some > cells are getting weak. OTOH - for blazing power the high C > packs are the > way to go - but there's a price to pay in life, weight, & $$.> > These observations have led me to surmise that a pack with a > high enough C > rating to minimize impedance losses (and accompanying heat) and > a low enough > C rating to allow good capacity retention should provide the > best value for > pattern. I have no idea just what construction parameters / > chemistry > defines these characteristics. I chose to try the FlightPower > F3A packs > because they are mid-C rating and 5350 mAh capacity. So far they > provide > good power and generate no more heat than the high C packs I've > used. I > expect that the extra capacity (above 5000) offers a little > buffer if th! ere > is a capacity decline over their life. I see little balancer > activity with > these packs regardless of depth of discharge (say 3000 mAh vs > 4000 +) so > far, time will tell - we're all still learning.> > Earl> > Team FlightPower> 



_______________________________________________NSRCA-discussion mailing listNSRCA-discussion at lists.nsrca.orghttp://lists.nsrca.org/mailman/listinfo/nsrca-discussion
--Forwarded Message Attachment--From: ejhaury at comcast.netTo: chad at f3acanada.org; nsrca-discussion at lists.nsrca.orgSubject: Re: [NSRCA-discussion] BatteriesDate: Fri, 14 Mar 2008 16:06:22 +0000_______________________________________________NSRCA-discussion mailing listNSRCA-discussion at lists.nsrca.orghttp://lists.nsrca.org/mailman/listinfo/nsrca-discussion
_________________________________________________________________
Don't get caught with egg on your face. Play chicktionary!
http://club.live.com/chicktionary.aspx?icid=chick_wlhmtextlink1_feb
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20080315/1ccaeca0/attachment.html