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AA Cells in Various Chemistries
AA batteries are available everywhere. They're
cheap, convenient to use and are available in a variety of chemistries:
rechargeable NiCad and NiMH; non-rechargeable alkaline and lithium.
NiCads are essentially obsolete now that NiMH's are on the scene
with more capacity and less weight. So the relevent characteristics
of the other three types, each with their own advantages and
disadvantages, are shown here graphically.
The Energizer e2 Lithium batteries pack a mean,
but expensive punch. The 8-cell pack represented here cost $24
and they are non-rechargeable! They are lighter than
normal AA alkalines and maintain their voltage under load more
consistently than alkalines. But their expense renders them
unsuitable for QRP (at least at my QTH!).
The capacity of rechargeable NiMH in AA-size
has incresed in resent years and are now available in advertised
capacities of 2500 mAh. Shown here are two smaller capacity
sizes of 8-cell packs of these batteries. An 8-pack of the 2500
mAh batteries costs around $20 making these batteries the best
choice for those needing standard sized batteries in their K1's,
KX1's or external standard-sized battery housing. They are advertised
as having over 100 recharge cycles. NiMH cells have a nominal
voltage of 1.2V compared to 1.5V for alkalines so users of these
batteries may wish to use a 10-cell pack.
Alkaline batteries were my favorites for a
long time. This was mainly due to their convenience - I could
buy a fully chraged, ready to go set on my way to an outdoor
event and not worry about memory effect or whether or not I
fully charged them the night before. I knew that their voltage
decreased almost immediately after applying a load - what I
didn't know was how steep this decrease was. I no longer use
alkaline batteries for QRP.
Name Brand vs. Off-Brand - 8 Non-rechargeable
Lithium AA's
Steve KA9QOA recently posted a source for lower
priced generic lithium AA cells to the Elecraft mailing list.
The source was BatterySpace.com
and the batteries cost half the price of the Energizers. Wondering
if the old adage "you get watcha pay for" holds true
in this case, I ordered a set & compared them with the more
expensive Energizers.
The graph below represents an 8-pack of each
brand and shows that the generic batteries last about 90% as
long and provide about half a volt less output throughout their
discharge curve as the Energizers. But at half the price, this
seems reasonable to me.
Energizer
e2 Lithium AA's | Energizer
NiMH Reachargeable AA's (pdf)
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