While using Doors CS 7.4 on my TI-84 Plus SE, I noticed that the battery indicator seemed inaccurate. After some experimentation, I found that the meter was closely correlated to the contrast of the calculator's screen. When I set the OS contrast level to ≤5, DCS shows a full 100% battery in the bottom right. Setting the contrast to 6 yields a mostly full battery, and 7 shows the battery to be half-empty. A contrast of 8, though difficult to read due to the dark screen, shows a low (approximately 25% full) battery. I didn't go any lower as I could not read the screen.
My question is this: is DCS's battery meter correlated to the contrast? Is this only my calc, or is it a bug in DCS?
By the way, I have a TI-84 Plus SE on OS 2.55MP with Axe, Celtic 3, and zStart installed.

As discussed previously, yes the battery meter uses the current display contrast as a proxy for any actual battery reading. The calculator's hardware only provides a "low battery" flag (presumably for when the battery voltage drops below a certain point) so providing any objectively correct reading is impossible.