[Elecraft] Dead Battery

[Jeff Burns]

This year I started field day of running my K2 from the internal battery.
Since the club was 5A I cranked the power up to 15w. Within a few minuets I
had a strange modulation of my side tone. The two-meter station even heard
me, and I was on 15m CW. It took me an hour to figure out that the battery
voltage was dropping below 8v causing the radio to reset with each dit and
da. This was a surprise because the battery is less than a year old and is
left on float charge all the time. Switching to an external battery fixed
the problem.

When I got home I charged the battery and measured the charge voltage at the
battery terminals. When the charger was first connected the voltage was
13.04V. After a day of charging it was at 13.89V. That looked good to me,
but the battery will not hold a charge. If I leave it unplugged for a few
hours it does the same thing it did on FD. Looks like I have a bad battery.

Now my question is what caused this battery to fail in less than a year? The
battery was purchased from a battery supply house I found on the Internet,
rather than Elecraft. For a charger I use a laptop computer supply rated 19v
and 2.64A (only cost $3). I made a box with a LM350AT voltage regulator to
drop the 19v to 14v. Anything wrong with this setup?

A higher amperage supply would be nice so I could run the K2 at full power
with out the battery. I have also been tempted by the MFJ Miniature
Switching Power Supply because of it would not need the voltage reducer. Any
thoughts?

I will order a new battery in a few days, but do not want to have it suffer
the same fate as the last on.

Jeff Burns

AD9T