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<DIV dir=ltr align=left><SPAN class=965342908-18092008>Don, I have 4 5300's that
are the one's I have been using for a long time (years). Mine too, pull my plane
well, but comparing them to new packs, the drop off in performance over time has
been so subtle I notice little difference until I compare them to new packs. The
difference is very evident. However, my larger concern is fire.. as I place more
demand on cell BANKS that may be bad (or going bad), the heat builds up much
more.. and the potential for fire, in my mind, increases. This happens when
charging and discharging (flying). Imagine a cell or TWO being puffed inside a
4s BANK of cells inside the black heat shrink. There is a chance you would not
see this unless you are looking close.. which I have done, and have replaced
these packs. The stress on the remaining good cells within the 4s bank is
extreme. Things have been pretty quiet lately regarding fires with LiPo, but we
must not forget the potential is still there and using old packs (any packs for
that matter), where the IR has increased, is concerning to me. I have 2 packs
(5300) that run hot and I don't think I'd fly them in 90 degree plus outside
temps as they would really come down hot after a flight. The new packs (5200's)
are not even warm to the touch. Oh, just FYI, I have replaced my 5000 V2 Extreme
pack with the new 5200 cells. I am not recommending the 5200's yet, they are too
new yet, but it seems they have good potential. Also, here is San Jose,
the outside temp's are rarely over 90.. but up in Sac or AZ, this happens much
more often. If I lived in these areas I'd be a bit more concerned. </SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=965342908-18092008></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=965342908-18092008>sc</SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma><B>From:</B> nsrca-dist7-bounces@lists.nsrca.org
[mailto:nsrca-dist7-bounces@lists.nsrca.org] <B>On Behalf Of
</B>AtwoodDon@aol.com<BR><B>Sent:</B> Wednesday, September 17, 2008 9:31
PM<BR><B>To:</B> nsrca-dist7@lists.nsrca.org<BR><B>Subject:</B> Re:
[NSRCA-dist7] LiPo cell configuration<BR></FONT><BR></DIV>
<DIV></DIV><FONT id=role_document face=Arial>
<DIV>Scott, like you, my TP5300s (4P) configuration have lasted into my 3rd
season flying electric. Yep, they are tired but will still pull my plane
vertical as far as I need, just not quite as much gusto. All my other
batteries are 1P configurations but I have not seen that show significantly
better or worse balancing challenges. I agree, the 1P configuration would
make it easier to detect a single cell developing higher IR.</DIV>
<DIV> </DIV>
<DIV>I have one FP5350 (2 5S packs) as well as 2 TrueRC 5000 mah packs (each 2
5S packs). The FPs have been solid with about 75 flights, no issues,
pretty easy to balance while charging. The 2 TrueRC packs need a little
more balancing during charge but everything finishes out fine. They have
less than 30 flights each.</DIV>
<DIV> </DIV>
<DIV>I did check one of the TrueRC packs on Jim's Cellpro and all 10 cells were
in the 3.5 milli ohm range, one cell was slightly higher at about 4 if I
remember correctly. The new Cellpro 10s is interesting and there is a
very good review and subsequent discussion about it on RC Groups.</DIV>
<DIV> </DIV>
<DIV>Don</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>
<DIV>In a message dated 9/17/2008 9:05:48 P.M. Pacific Daylight Time,
scottcov@comcast.net writes:</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><FONT
style="BACKGROUND-COLOR: transparent" face=Arial>
<DIV><SPAN class=279212203-18092008><FONT face=Arial>Hey Electric
Guys,</FONT></SPAN></DIV>
<DIV><SPAN class=279212203-18092008><FONT
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=279212203-18092008><FONT face=Arial>I'd be interested in what
LiPo battery configuration you are using.. 5S2P, 5S4P, 5S1P... other. Why?..
read on. I believe the less "P" you have in the battery the easier to balance
and possibly the longer life you will get due to better cell balancing before
charging. I have recently converted to a new cell by TP, some of you saw this
at the Hollister contest. The 5S2P, 5200 pack, is working great. Jim Oddino
and I checked the internal cell resistance, which was around 3milli-ohms (if I
recall correctly). This battery puts out 156A burst, the older 5s4p, 5300 pack
put out 109A burst. My thinking is this, the lower "P" pack you have the
easier to keep the battery in balance. If you have a 4p pack, any one of the
4p cells can degrade over time, causing the 4p 'bank' to not supply as much
sustained current - causing the whole battery to be weaker. Jim and I played
with a Cellpro 10S charger, and I think we concluded that it would be
difficult for any charger to determine if any one cell in a 4p bank
was going bad (you can only monitor the bank IR, not the individual cell
within the bank). However, if you had a 1p 10S pack, you could easily tell if
the cell was gaining resistance as it aged. On a 2p pack, the resistance
CHANGE may not show up as easily as a 1p pack but much easier than a 4p pack.
We are trying to determine here when a 5S pack is getting weak (yes, we can
see as we fly - but if we could determine as it happens, perhaps we can
correct this by charging differently). Jim O mentions he has not seen a
battery with as low of internal resistance readings as the new TP pack, which
equates to more power, less heat in use, and I hope longer life. I will
mention here that my 5300, 5s4p packs have lasted 2-3 years and many,
many flights, but they are getting old.. and the new packs may last
3-4 years.. they are also around $250 each.. a reduction in price from the
5s4p packs. I believe even newer technology will soon show us a 10s1p
pack from TP - and some may have this now from other
manufacturers.</FONT></SPAN></DIV>
<DIV><SPAN class=279212203-18092008><FONT
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=279212203-18092008><FONT face=Arial>I'd be interested in your
opinions on this topic.</FONT></SPAN></DIV>
<DIV><SPAN class=279212203-18092008><FONT
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=279212203-18092008><FONT face=Arial>Scott</FONT></SPAN></DIV>
<DIV><SPAN class=279212203-18092008><FONT
face=Arial></FONT></SPAN> </DIV><BR><BR>_______________________________________________<BR>NSRCA-dist7
mailing
list<BR>NSRCA-dist7@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-dist7<BR></FONT></BLOCKQUOTE></DIV></FONT><BR><BR><BR>
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