[NSRCA-discussion] What do I have?

[brett terry]

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) 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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