[Elecraft] LiFePO4 battery packs

[JP O'Connor]

According to the product descriptions, both of these battery packs have a
balancing board built into them. The documentation for the board shows that
the board has independent connections to each cell. It protects each cell
from over charge, over discharge, high current discharge, and short
circuit. Thus, you gain the benefit of balance charging while only having
to purchase a lower cost charger, such as the ones suggested for these
packs on their product pages. The larger of these two packs appears to be
very cost effective and a great solution for external power for a KX3,
K2/10, K3/10 or other QRP rig.

A123 branded cells are more expensive, although EP Buddy has them at a very
favorable price. Their packs do not have internal circuitry, however,
requiring purchase of a balancing charger if you want to recharge at higher
rates. See recent KX3 batteries thread on this reflector for discussion.

72/73 de JP WF4Z



On Sat, Jul 7, 2012 at 12:59 PM, Fred Jensen <k6dgw at foothill.net> wrote:

> On 7/6/2012 7:06 PM, Steve Jackson wrote:
>
> > So, what is the opinion of the learned and experienced regarding these
> > battery packs?
>
> Well, there's the obvious ... 600mAh vs 3,000mAh of course.  The LiFePO4
> batteries have a very good capacity to weight ratio, and they are safe,
> you can carry or pack them onto airplanes.  Neither one of them allow
> you to balance the cells however, something that should be done at least
> periodically.
>
> Assuming it is for your K2, you'd probably find that 600mAh was a little
> small.  My K2 draws about 280mA on receive, and at 5W, around 1.5A key
> down.  I use a 4Ah 4S1P LiFePO4 pack that I can balance the cells on
> charge and it lasts about as long as I want to be off in the field
> somewhere.
>
> Li-Poly batteries have a higher capacity to weight ratio which is why
> they are used by RC model folks.  I have one that's about the size of a
> small matchbox, weighs an ounce or so, and is rated at 800mAh, 11.7V.  I
> use it on my KX1.  Li-Poly is somewhat unstable under some circumstances
> and I've had one catch fire while I was using it.  Mine is on a short
> pigtail outside of the rig.
>
> > What's the better deal?  Two of the former?  Anything awful about these
> > packs?  Caveats in their use, other than the obvious?
>
> A123 cells are probably the highest quality, Buddipole sells them, they
> are a bit pricey however.  Whatever you choose, be sure to fuse the
> cable to the rig.  These chemistries can deliver anywhere from 10C to
> 15C or more if shorted.  For mine, that could be more than 60A.  Beware,
> the 12V and RF connectors on the RF board are the same and the cables
> from the KAT2 will interchange quite easily.  I speak from experience
> and now have a jumpered trace on the board that decided to be a fuse. :-(
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the 2012 Cal QSO Party 6-7 Oct 2012
> - www.cqp.org
>
>
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