Re: Question: capacitors as special use batteries?

On Fri, 11 Jul 2008 08:16:36 -0700 (PDT), BobG <bobgardner@xxxxxxx>
wrote:

Tecate sells the Maxwell Boostcaps that are the size of a D-cell,
2.7V, 350 Farads. Its takes several minutes to charge one up on the
lab supply supplying 2.5V 3A. Several 1000 watt-sec.

You're not going to get more power out, on average, than you put in.
Drills use a lot of power, so if a 2-minute charge yields 2 minutes of
drilling, it's going to be a *big* charger.

Batteries aren't as efficient as caps (joules in:out) but batteries
tend to run constant-voltage during use. Caps lose voltage linearly,
so will need downstream electronic switching regulators to keep up the
load as they discharge.

John


.

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