[TenTec] which power supply setup?

[Lee]

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 at arrl.net>
To: "Discussion of Ten-Tec Equipment" <tentec at 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