One Ham's Experience: Good News: The LiPoly I got (local RC hobby
shop) was just great! I did not deplete it on our cruise thru the
Panama Canal, maybe 6 hours operating time (mostly listening and no
CQ's), but I did rag chew a bit with a number of SA stns. Ran a Spartan
Sprint after return without recharging just to see if I could. Voltage
stayed nearly constant until full discharge, at which point it dropped
quickly. As quickly, I recharged it on a MAHA 77.
Bad News: It worked again very well in the next Spartan. Then I got
busy, and didn't check it for perhaps 5 months. At N6A (Alpine County,
CQP), I tried it our before the contest, and it was toast. They are
extremely light (a factor in Spartan, but I wonder in a back pack), they
seem good, but they are expensive, and I've heard they die in a year or
so, regardless of how you use them.
WAYNE: To your basic questions -- I wouldn't spend much (or any) time
adapting the KX1 to LiPo. Mine came with tinned leads on which I put a
coax plug. The expense is a real downer. The difference in power
between 6 and 8 AA NiMH's seems minimal. Yes, Alkaline dry cells do
have a non-flat discharge curve, but you can get an bunch of them at
Costco or Sam's and they're what I generally use. I think the weight of
the additional batteries is overshadowed by the weight of the solar
panel and regulator for those who really do back-pack (I did but I don't
anymore -- too old).
I know you have to keep up with technology and the ever-increasing
demand for "one more feature," but I would caution against messing
around with a success, which my KX1 is right now. Besides, we're
"amateurs," and you have to leave us something to mess around with!
73,
Fred K6DGW
Auburn CA CM98lw
wayne burdick wrote:
We've located a 4-AAA cell battery holder that would fit inside the KX1
(one at each end of the bottom cover, as with the present AA holders). 8
cells would provide 10 or 12 volts, giving you significantly more power
output than 6 of the same cells (as much as 4 watts). The tradeoff would
be in battery life. AAA-size NiMH, alkaline and lithium cells provide
around 1000 to 1250 mA-hours, or around half as much as similar
high-capacity AA cells.
Another option would be to use a small lithium polymer battery. 11 volts
at up to 1450 mA-hours or so might be possible, although these batteries
are very expensive. AAAs might be preferable in a pinch because you can
buy them anywhere. In the field, you can borrow triple-As from
flashlights or other portable electronic devices. The difference in
weight between 8 triple As and a LiPo battery is probably only couple of
ounces, so weight is not likely to be the primary criteria.
You'd probably get five to eight hours of casual operation with NiMH,
LiPo, or lithium cells, which are preferable to alkalines because of
their flat discharge curve. Of course you could recharge NiMH or LiPo
cells in the field with a small solar panel. (Has anyone tried using 8
AAA cells with the KX1?)
We could (in theory) create a new bottom cover option for the KX1 that
would include two 4-cell AAA holders or a LiPo battery, plus a charge
controller that would run from the KX1's DC input jack. The battery
holders and charge controller components could be soldered to a thin PCB
module that runs the full length of the bottom cover. In the case of
AAAs, we'd include a switch to select rechargeable or non-rechargeable
batteries. You might be able to recharge while operating, although this
would have to be tested, since some charge controller generate
significant noise.
Any input on such a product would be appreciated. If there were
significant interest, we'd try to have it ready early next year.
73,
Wayne
N6KR
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