[NSRCA-discussion] What do I have?

[Ihncheol Park]

Vince,
 
Yes.  you will want to add balancer connector if you build a 2S pack.  I've
seen them going out of balance much easier than lipo.
If you add a registor to one cell, it works great for glow driver.
 
Ihncheol

  _____  

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
vicenterc at comcast.net
Sent: Tuesday, February 19, 2008 12:43 PM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] What do I have?


Do we need to balance this batteries? 
 
Thanks,
 
--
Vicente "Vince" Bortone
 

-------------- Original message -------------- 
From: "brett terry" <brett.terry at gmail.com> 
The VPX cells are indeed actual A123 cells.  They are roughly half the
size/capability/capacity of the larger cells, expect around 1000 mAh usable
with minimal voltage depression at 10C discharge.  The pack consists of 2
cells in series (2S).

Use the Li-Fe setting (3.6V/cell) to charge. 

I built a few of the larger packs for my IMAC planes and threw together a
smaller pack for ignition, and also a 4S pack for electric planes.  They are
fabulous in terms of actual power output throughout the discharge cycle
because the voltage remains nearly constant.  I can draw 20C current levels
from a deeply discharged pack, right up until they dump.  Of course they
dump VERY fast, so a lot of care is required.  My charger shows the
remaining charge state ! (from 0 % to 100%) when I plug in the battery
(BEFORE it charges).  I just plug in the charger after a couple of flights
and if the remaining charge is under 30%, I just leave it on the charger for
a few minutes to top it off.  These small batteries will charge from
completely dead to fully charged in less than 20 minutes, although they go
to 95% of charge after 7-10 minutes.  I find I can plug them in while
refueling the plane to keep them topped off.

Also, my 50cc planes with big servos draw around 250-350 mAh per flight or
less, so a pattern plane will draw significantly less.  Check out Bob
Pastorello's site (www.rcaerobats.net <http://www.rcaerobats.net/> ) or
RCU/FG for more info. 


On Feb 19, 2008 12:54 PM, John Konneker <jlkonn at hotmail.com> wrote:


I was just in WalMart.  They had the B&D 7v VPX battery packs for $17.88.  I
believe these are A123.  If that is correct what chemsitry should I select
on my BC-6 charger?  I have three ID'd as Lithium:
- Li-Ion shown as max charge 4.1v/cell
- Li-Po shown as max charge 4.2v/cell
- Li-Fe shown as max charge 3.6v/cell
The plastic case it's in is about 3 3/4" long and 1 3/4" wide.  This seems
long.  Is this pack 2s2p?  Anyone taken these apart to build a receiver
pack?
To determine capacity what voltage should the cycle cutoff be set at?
Thanks!
JLK


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