[Elecraft] Alternative battery for K2?

[Chip Stratton]

I had a 4 cell LiFePO4 battery inside my K2 for quite a while. It was about
the same size as the original SLA.

I found that I was able to charge it with the built-in SLA charging circuit
as a matter of routine and the cells remained in balance, as verified by an
occasional balance charge with a CellPro Multi4.

The reason this worked well was because the cells in the pack were all of
good quality, the discharge rate was not excessive, the built-in K2 charger
charged at low current, and I was careful not to leave the charging circuit
on for prolonged periods. LiFePO4 will  tolerate limited low current
"overcharging" fairly well and without the danger associated with doing the
same with regular Li-Poly chemistry, and in my experience without damaging
the cells. Of course, ultimate cell life may be only 500 cycles instead of
the 2000 you might expect with good LiFePO4 cells and use of a quality
balance charger, but I never found any degradation.

I agree with others that have replied, however, that just using an external
LiFePO4 pack entails little disadvantage, and that is what I do now myself.

Chip