Originally Posted by Johnny1A.2 (Post 2146745)

The thing to remember about a Smithian accumulator is that it isn't a capacitor or a battery. It's a totally different technology, probably based on physics we don't understand, like a lot of the rest of their tech.

An accumulator is defined not by how it works, but by what it does, i.e. store large amounts of energy with the ability to release it very fast. How it does it matters less than what it does.

How much energy does a Smithian accumulator store? He never gives hard figures, but lower bounds can be estimated by observing what the technology does. The answer is 'a freakin' lot'. They can power hand weaponry with more than enough juice to vaporize large masses like humans, or sections of walls. (It takes far more energy to vaporize a human than it does to kill one.)

The shipboard accumulators can store significant amounts of energy relative to their total-conversion based power plants.

Remember the old Star Trek TOS trope of the phase pistol set to turn into a bomb? There were a couple of incidents where it was shown that this could be done, and Kirk says at one point (paraphrasing) that such a pistol bomb could have blown the side of the ship out if they hadn't stopped it.

That's completely realistic, given the displayed performance of the phaser pistols (rapid vaporization of large masses, etc.). That much energy packed into a small space will make a dandy bomb if it gets released instantly.

The Smithian accumulators have similar storage densities, or higher.

Originally Posted by gruundehn (Post 2146777)

You are not making your case that accumulators are neither capacitors not batteries. Capacitors are active storage devices and batteries are passive ones. Unless accumulators store energy in some fashion that is neither active nor passive, they are one or the other.

Originally Posted by gruundehn (Post 2146777)

You are not making your case that accumulators are neither capacitors not batteries. Capacitors are active storage devices and batteries are passive ones. Unless accumulators store energy in some fashion that is neither active nor passive, they are one or the other.

Originally Posted by Ulzgoroth (Post 2146781)

A superconducting induction ring is neither a capacitor nor a battery, but it stores energy.

Originally Posted by gruundehn (Post 2146868)

I am not familiar with that technology. Does the device have to be part of a circuit or can it be left by itself? If it has to be part of a circuit, it is a capacitor. If it can be removed from the charging circuit and stored, it is a battery.

The function does not change even when the technology does.

Originally Posted by Ulzgoroth (Post 2146871)

'Battery' and 'capacitor' are not as abstract terms as you seem to want them to be.

Also, a capacitor can be removed from the charging circuit and stored. They do tend to lose their charge over time, though that might be more a feature of modern tiny ones than bulkier types like leyden jars. But then some electrochemical batteries also break down in storage...

Originally Posted by Anaraxes (Post 2146876)

I don't understand the passive / active distinction. A capacitor stores energy in an electric field. A battery stores electrical energy as chemical energy. If anything, the battery seems the more "active" of the two in that more has to happen to get electricity back out. But they both have to change something about their state.

"Accumulator" is a general term for something that stores energy; by that definition, both batteries and capacitors are types of (electrical) accumulator. I've also seen that term used for non-electrical energy storage, as in hydraulic systems, so it seems the broadest of the three, and thus appropriate enough either for purposes of the OP or of Doc Smith.

Originally Posted by gruundehn (Post 2146900)

I am not using the terms in any abstract sense but in a technical sense. A capacitor must be kept charged actively in that current must always be supplied in order for the charge to stay. A battery does not need constant recharging. Yes, there are capacitors that can store a charge outside of a circuit but not generally, old style Leiden jars hold a charge, for example, but not over a long period of time. Hours, or maybe days rather than years or even decades.

There are other differences between the two types of electrical storage but the need to recharge over a short period rather than a long period is the one I started with and stay with.

Originally Posted by gruundehn (Post 2146902)

A capacitor stores electrical energy on a physical surface and a battery stores electrical charge (sort of) in a chemical solution. I say sort of because a battery does not store electrical energy but chemical energy which due to chemical action, releases electrical energy.