[Psi Powers] Power Source as a leveled perk (or Advantage)?

[Prince Charon]

One of the Ergokinesis Perks in the text box of that name in Psionic Powers p35 is called Power Source. In short, it allows the user to substitute for batteries and power cells, up to Medium batteries and B power cells, though anything above Extra Small batteries or AA cells will cost fatigue, and you can't power an energy weapon that way, because it's a perk. Reading it, I wondered whether it would make sense for higher levels of the perk to exist, allowing the user to both substitute for more powerful batteries/cells, and to have an easier time powering devices that the first level could power with difficulty. It also occurred to me that an advantage variant of the perk, perhaps around 5 points per level (same cost as Burning Attack), might be used to power energy weapons, or EK attacks like Lightning (pp33-34), or a hypothetical 'Laser' attack.

So, if a leveled perk, how many levels seem reasonable?

For the advantage, does 5 points per level seem reasonable, or perhaps 4pts/lvl due to the fact that a separate advantage or weapon is required?

My current thinking is that these should be combined, so that once you get to the fourth or fifth level of the perk, it becomes an advantage and you can start powering energy weapons (at 1d/level, of course). Does this seem workable?