denton sprague wrote:
"wonder if there is a conversion factor going from farads to amp-hours?
one of my pet on line research is on those super capacitors and at which
point they can have the storage capacity of a sealed lead acid battery."
and Spencer replied:
"here is a link to a 2000F capacitor
http://www.koldban.com/Kapower_Specifications_s/29.htm";
My reply:
Super caps have a long way to go to reach the storage capacity of a SLA
battery. The KApower super cap (and other super caps) have very high
pulse power ratings but very low storage capacity.
Using the relationship IT = EC we can do a quick analysis to see what I
mean. I - current in amps, T - time in seconds, E - voltage change in
volts and C - capacitance in farads.
To keep things simple I like to use what I call a " first
approximation". We'll use an Argonaut VI to keep the discussion Ten-Tec
:-) Receive current 0.5 amps and allowable voltage change 14 volts to
10 volts or 4 volts change.
So....the question is how long will a 2000F capacitor run an Argonaut on
receive?
Using T = EC/I, T = (4 * 2000)/0.5 which results in 16000 seconds run
time. In hours that is 4.4 hours from a 62 pound "battery" in a 1329
cubic inch package at who knows how much cost! Transmit at 10 watts cw
will require approximately 5 times as much current so we reduce the run
time to 4.4 / 5 or 0.9 hours key down! For comparison, a LiFePO4 6 Ah
12 volt battery weighing 1.4 pounds in a 26 cubic inch package and
costing $80 would run the Argonaut on receive for 12 hours and 2.4 hours
key down CW transmit. A SLA would reduce that cost considerably but
would be larger and heavier. I've not considered the 30mA self
discharge rate for the KApower capacitor. Let's do that. T = (4 *
2000)/0.030 = 267,000 seconds or 74 hours!
Super caps have come a long way but still have a long way to go to come
anywhere near the performance of a rechargeable battery for powering our
rigs. Doubt it will happen in my lifetime (I'm 73) if ever. But there
is a place for super caps in short term/high current applications.
73 all,
-Lee-
WA3FIY
------ Original Message ------
From: "Spencer" <w1gak@arrl.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: 8/19/2016 12:49:59 AM
Subject: Re: [TenTec] which power supply setup?
denton sprague wrote:
wonder if there is a conversion factor going from farads to amp-hours?
one of my pet on line research is on those super capacitors and at
which point they can have the storage capacity of a sealed lead acid
battery.
here is a link to a 2000F capacitor
http://www.koldban.com/Kapower_Specifications_s/29.htm
That is a lot of electrons
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