I do have a more serious question though. I assume stated shield power levels remaining in a given situation work the same as present day chemical batteries, which maintain output at or near stated voltage even as they approach total discharge. So shields at say 18% can still repel the same magnitude of firepower they can at 100%, but are 82% closer to collapsing. Is this the consensus out there?
Well, you're not really accurately stating the whole deal with batteries. (FYI, in case anyone's interested, I changed jobs several months ago, and am now the senior mechanical engineer with Valence Technologies, a high-tech battery manufacturer focusing mainly on the electromotive vehicle marketplace... so I'm fast becoming a bit of an expert on this topic.)
It's true that electrochemical batteries provide a near-constant VOLTAGE... but that's not the same as saying that they produce a near-constant OUTPUT.
Output is typically rated in either "amp-hours" or in "watt-hours" (which is simply amp-hours multiplied by the voltage... which, as stated, remains essentially constant). This is normally what's referred to as "output," not the voltage. And during the discharge cycle, the battery's available-current-per-unit-time decreases much more significantly than the battery's voltage does (though it's by no means linear, of course).
Think of it using the water-flow analogy... voltage is the difference in height between two pools of water. Amperage is the speed at which the water flows from the higher one to the lower one. In the case of a battery, this flow rate constricts as the battery discharges.
In other words, in a fully-charged battery, you may be operating at 14V and may have a lot of power being provided, while in a heavily-discharged battery, you may still have 14volts but not be able to get very much POWER out.