[Elecraft] AA primary cell (K1 related) capacity planning

[Steve Jackson]

----- Original Message -----
From: "Mark J. Dulcey" <mark@buttery.org>
 > ... alkaline batteries aren't nearly as good at handling high
> current rates as NiCd or NiMH, so the capacity drops faster at high
> discharge rates.  <snip>  The net
> result is that an alkaline pack would probably outlast a good NiMH pack
> by about 50% in receive-only use, but might actually last LESS time if
> used for a session that included a lot of transmitting.

Now, we're on to the heart of the matter, Mark.  Here goes:

My K1 on RX is in the vicinity of a 60 mA load.  Battery cost aside (a
tradeoff for portable convenience) ... for receive purposes, it seems as if
the alkaline cells make the best choice.

Now, certainly, I'll try and transmit, too!

Figure I have the K1 set to 3 Watts, for example.  I am guessing the draw at
this power level (at 12VDC) is about a half-amp.  That's much less than a
digital camera draws, and in a less onerous duty-cycle.  The advantage again
may well tilt towards the alkalines.

My NiMH charger does a GREAT job, but handles only 4 AA cells at a time.  If
it takes, say, 2 hours to charge one set of 1800 mAh NiMH cells, that's a
minimum of 4 hours to bring two sets back from the discharge state.  Eight
new NiMH cells of this rating would cost me about $25 at a hamfest, 2x that
mail order.

Duracell AA size costs about $1 each at discount retail; that's $8.50 with
tax for an 8-cell pack that may well last 30% longer than an equivalent NiMH
charged set.

Not counting the sunk cost of the 4-cell NiMH charger I already have, and
discounting the inconvenience factor (and the environmental impact of many
dead alkaline cells), I see the apples-to-apples breakeven point at about 4
use cycles.

While this seems like a good argument for rechargeables, I'm still not 100%
convinced.  Am I missing some key coefficient here, guys (& gals)?

Battery power is an issue for QRP operators everywhere, so I appreciate the
only slightly tangential bandwidth this thread is using up.  Nowhere else
can you find an assembly of the sort of analysis brainpower that this
reflector brings to bear.

Steve KZ1X/4
... looking at my K1 which has a fresh set of Energizers in it, but no
antenna hooked up