Alt-BEAM Archive
Message #02070
To: Steven Bolt sbolt@xs4all.nl
From: "Paul B. Webster VK2BZC" pwebster@clinipath.com.au
Date: Wed, 07 Apr 1999 13:15:00 +1000
Subject: [alt-beam] Re: Microcore memory for 100Farad caps.
Steven Bolt wrote:
> Make the calculation. 1 ampere * second = 1 farad * volt
> Let's say 3V: 100 * 3 = 300 ampere * second
> Translate that to wattsecond by again multiplying by volt: 900ws
> Convert that to milliwatt-hour: 900 * 1000 / 3600 = 250 mAh
> Which equates to two AAA nicads.
Eh? Let me try that. 100 Farad is it? It=CV
Let's say that we can afford a drop from 3V to 1V, so C*V = 100 x 2
which is 200 Ampere-seconds. Divide by 3600 to get Ampere-hours and
scale up by 1000 to get milliampere-hours, gives 83 mAh.
Probably comparable to the AAAA (or whatever) Ni-Cds out of a 9V
"213"-style battery. Two of these would supply 2.5V fully charged and
you would run them down to 2.2V or 2.0V.
The big question is indeed internal resistance. While Ni-Cds are only
about 50% efficient at energy storage, these capacitors might be little
better or a lot worse at currents above a couple of milliamps.
--
Cheers,
Paul B.
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