[Elecraft] [KX1] A LiFePO4 internal battery option

[Chip Stratton]

I found some LiFePO3 batteries that fit well within the KX1 case, and
thought I would share:

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14075

These are a different Lithium chemistry (same as A123 cells) than the more
common LiPoly cells. Their fully charged voltage is 3.6 V and they are
essentially fully discharged at 3.0 V. They are more tolerant of overcharge
and over-discharge than normal LiPoly cells too. I put two packs in series
in place of the AA cell holders in the KX1, to give a 14.4 V pack fully
charged, while taking up less space and weighing less. They are also almost
incredibly inexpensive. Downside is you only have 700 mAh to work with, and
with the higher voltage the KX1 will drink more heavily from your battery.
Still, this solution should give at least 3 hours or more of normal use -
plenty for me for an afternoon out.

The downside is that you need an appropriate LiFePO4 battery charger with
the appropriate "balance" charge connectors. I use a Cellpro 4S with a JST
type adapter board (to match the connectors).

Chip
AE5KA