Phil,
It appears that there are three types of batteries with lithium in their
names ... Li-ion, Li-poly, and LiFePO4. Li-ion, in one or another of
the variants, usually power laptops, cell phones, and Tesla's. They're
pretty stable, you can take them on aircraft although there are some
limits on total weight and packing.
Li-poly are very small and light with a high energy density and are used
mainly by RC hobbyists. I have a 750 mAh one for my KX1, it's a little
smaller than a small matchbox and weighs an ounce or so. They're
somewhat unstable, I wouldn't recommend internal mounting. I had one
catch fire while I was operating, it was on a pigtail which I pulled
loose and tossed it over the deck rail onto our gravel driveway. I
always charge my current one outside.
LiFePO4 seem to be very stable. I have a 4S1P A123 2.5 Ah pack for my
K2. At full charge, it is almost 14 V which drops quickly to around
13.5 where it pretty much stays until almost depleted. With my K2 on CW
in QRP field contests [flight of the bumbles], it has powered 3-4 hours
of steady operation. So far, I get tired and hungry faster than I can
run it down. It does require a cell-balancing charger, mine is a
CellPro-Multi4 which will charge a variety of chemistries. Considering
all, LiFePO4 seems to be the best choice ham use.
Use great care with Li batteries of any flavor. They have an incredibly
high energy density for their size and weight, and incredibly low
internal resistance, so fuse the leads and don't ever short it. My 2.5
Ah pack will easily deliver 10 to 15 times that [25 - 40 A] into a
short. You can spot weld with them and some of the larger ones would
probably start my truck.
73,
Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org
On 5/26/2015 11:42 AM, Phil Hystad wrote:
Thanks Jim,
I took a look and they appear to be cheaper than the A123 packs (the
brief scan I did) — I may buy one or two. But, with my two 4S1P A123
battery packs have performed very well with the KX3 so far.
Although, this is a KX3 running QRP to 10 watts.
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