[NSRCA-dist7] LiPo cell configuration

[Scott]

Yes, I want to see this (your testing). I will also talk to my contacts at
TP and see why they are not recommending this pack. TP specifically told me
the 5200 pack (5s2p) is best for pattern.. but I wonder why. I'll find out.
 
sc

  _____  

From: nsrca-dist7-bounces at lists.nsrca.org
[mailto:nsrca-dist7-bounces at lists.nsrca.org] On Behalf Of James Oddino
Sent: Wednesday, September 17, 2008 9:40 PM
To: CA, AZ, HI, NV, UT
Subject: Re: [NSRCA-dist7] LiPo cell configuration


TP does have a 10s1p 5000 V2.  I borrowed one and flew a few flights on it,
but it was before I had the CellPro.  It's performance was very good but it
did seem to have balance issues on the TP 1010/210.  I'm going to be out of
it for the next two weeks but I'll try to test it again when I get back.
Perhaps the CellPro will keep it in better balance. 

Jim


On Sep 17, 2008, at 9:04 PM, Scott wrote:


Hey Electric Guys,
 
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.
 
I'd be interested in your opinions on this topic.
 
Scott
 
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