I've just updated my battery page again, adding a discharge curve (at 300
mA) from an 8-cell pack of AA NiNH batteries sent to me by VE3NFK who has
the same analyzer I do. And NN4CW is sending me a couple of *very* tiny LiPo
batteries to test that he uses in the Spartan Sprint contests with excellent
results. Thanks to both of you for your contribution.
I've gotten a ton of email regarding battery operation w/QRP since making my
initial post a few days ago. Several folks are doing some interesting
experiments involving high-farad capacitors, DC-DC converters & batteries
with solar cells.
In a previous post, there is a link to
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2335
The price and capacity of this battery made me wonder what the "catch" was
since I recently paid $30 more for a slightly smaller battery:
http://www.aeromicro.com/Catalog/thunder_power_pro_lite_3-cell_2100_mah_li-po_pack_4479728.htm
When/If shopping for a LiPo battery keep in mind that batteries of identical
capacities (mAh ratings) can have drastically different discharge ratings.
The battery in the first link has a max discharge rating of 2.5 amps (1C).
The more expensive battery is rated at 31 amps continuous, 50 amps peak.
With our QRP rigs, we will probably never draw 2.5 amps from a battery, so
is there any reason to use the more expensive battery? The main difference
between these two batteries is that the smaller rated battery will have more
of a voltage drop during transmit than the 31-amp battery. This is the
effect that some folks who are experimenting with large capacitors on the
outputs of their batteries are compensating for, with excellent results in
higher output power over simply using the batteries alone.
As it is, I have more than one reason to have the higher-rated battery (R/C
electric planes), but if I was going to use the battery strictly for QRP,
I'd probably go with the less expensive one (and then wonder what tangible
benefits there may be from the other one!) and then start experimenting with
these caps.
http://www.maxwell.com/ultracapacitors/index.html
John Harper AE5X
Portable QRP: http://www.ae5x.com
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