[Spaceships] Where are the Capacitors?

[capnq]

Originally Posted by Peter Knutsen

A simpler solution would be to invent a new category of ships, separate from the one that can be built with the core Spaceships rules. This category is the short-occupancy ship, created according to modified parameters, but gifted with more efficient energy systems (since they are batteries or capacitors, rather than reactors) and needing to connect with a mothership or space port very often. Perhaps every 8 hours.

That isn't a "solution" at all, if you're trying to design a FTL-drive ship that takes days or weeks to cross interstellar distances.

My theroretical "first steps to space" campaign involves a prototype jump drive that requires a lot of power dumped into it all at once to trigger the jump. The ship I designed (with the GURPS Space 1st ed. rules, IIRC) Jumps .2 light-years in 2 seconds, then needs over 16 minutes to recharge the capacitors. The ship's maiden voyage to Proxima Centauri will take nearly six days, if nothing goes wrong.

[SuedodeuS]

This thread had some information on capacitors, with stats based on the fuel cells. You might want to take a look at it.

[jacobmuller]

I keep seeing Fuel Cells referred to as requiring fuel. I must be misreading the "closed system" bit. I think of them as burning their stored H-LOX and requiring outside power input to turn the exhaust water into H-LOX. Rechargeable batteries? Refueling would be faster but, to my mind, that isn't a closed system; Physics: "a closed system can exchange energy, but not matter, with its surroundings." This is how batteries work.

Turning it into a powerplant/capacitor system...
Csomic power level weapons and shields using standard powerplants. The Fuel Cells would be your capacitors and they'd be 1,000 of the size required. For a 20sec turn, a 24hour fuel cells becomes a 4shot battery. Recharging the capacitors from a power plants/solar units logically takes more power than they produce.

You'd have to find a scale below Cosmic for a playable rate of use; perhaps make your power systems a mix of capacitor/generator on a ratio that gives a decent recharge rate. A bit of number-philia will get you there.

[Anaraxes]

The thread to which Ulzgoroth linked mentions that there's not much difference between a closed-system regenerative fuel cell and a rechargable battery. Electrical input to either reverses the chemical reaction that gave you electricity in the first place. Run the chemical reaction again, and you get electricity while the battery discharges / the fuel cell consumes fuel.

Capacitors don't store energy as chemicals, though, so they have a fundamentally different mechanism. They might well have different efficiency per unit volume.

That gets into questions speculating about future super-tech, the relative improvements in each technology, and the metagame questions of what happens to balance if one technology is clearly dominant. So perhaps it's best simply to file off the names and use about the same stats for all three. You might build in a preference at different sizes -- say, capacitors have the least overhead, so they're best in small applications (like current electronics) while batteries have better power density at medium sizes (like current batteries) and fuel cells are best at large sizes that can make up for all the extra stuff to produce the power (like current fuel cells). The piecewise curve along the "best" line for each size is the tech you're actually going to see in the optimally designed ships, and so that curve should be the one you balance.

[ericbsmith]

In 3e Vehicles/GURPS Space:

Excluding the "Power Core" of the power plants,
1 ton of Fusion Plant provided 10 MW
1 ton of Antimatter Plant provided 20 MW
1 ton of Power Cells provide 12.5 MWh

The biggest advantage of Power Cells in 3e Vehicles/Space was that they were extremely compact compared to the Power Plants - in the space of a 1 ton Antimatter Reactor you could fit 6 tons of Power Cells providing 75MWh of power, making them slightly favorable to installing a Power Plant in some circumstances. I'm not sure how you could map that kind of volumetric efficiency into the Starships 4e system (which is solely concerned with Mass, not Volume).

Probably the best way is to ignore mass and look at effect - In 3e a given volume of Power Cells provided about 4x the MWh as the output of an Antimatter Power Plant in MW. In Starships 4e a slice of Antimatter Plant provides 4 PP, so an equivelent slice of Power Cells ought to provide approximately 4x that, or 16 PP hours. In 3e Power Cells were also extremely expensive - something like 25x the cost of a Power Plant of equivelent volume.

[Pomphis]

But note that 4e powercells are much less efficient than 3e powercells were. Compare UT4e p.19 with VE2 p.88.

If you introduce 3e powercells in 4e, they will also be used for other applications, like in handheld weapons.

[vicky_molokh]

Originally Posted by jacobmuller

. . .Fuel Cells . . .

IMO Fuel Cells provide very little PPs compared to reactors to be counted as capacitors.