Ultra-Tech Classic VS 4e

[The_Ryujin]

While in 4th ed power cells specific energy were left purposely nebulous in the final version they initially based on Transhuman Spaces's power packs with TL 9 ones having half the energy of the equivalent Transhuman power pack.

That is a TL 9 power cell has a specific energy of 180kJ/lbs. Now you might be saying that seems a bit low but that's because power cells were orginally just advanced capacitors, they have low energy but can discharge effectively instanly making them ideal for devices where power delivery is most important (as in energy weapons). For devices that need endurance over power, orginally as in Transhuman Space there were also going to be batteries (or what Transhuman Space called energy cells for whatever reason) but I don't know the numbers that David used though if I'd have to guess they hold 10x the energy as a power cell but can only discharge 1kW per 900kJ.

Now why do E and D cells hold more energy then the smaller cells? That's because they "HP" power cells, they hold 2.5 times the energy but cost 10 times as much. Technically this option ca. Be applied to smaller cells as well.

This being said, while these are the numbers David used they are not technically official but even if they were in the end they hold however much power you need for game to work.

Also note that that David has since updated his assumptions on how much energy power cells hold and the GURPS vehicles design system energy bank design rules will give results that differ greatly from Ultra-Tech, Space Ships, and The Blaster and Energy Design System. It will also give several upgrade options.