[Elecraft] KX1 on AAAs or Lithium Polymer?

[wayne burdick]

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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