It's also worth mentioning that by using the batch reader, you get the added advantage of not having to fool around with multiplying big numbers and changing your circuit every time you add a battery. This is of course, the main reason to do it this way, but it uses less power and chips as a bonus.

There are *far* simpler designs.
For the least chips, use a batch reader.
Set to read all batteries.
Set to average mode.
Set variable to "ratio".
Hook up console.
Plug in graph display circuitboard.
Program to read batch reader.
Done.
Two pieces... the display will show the fullness of all connected kit batteries as a value from 0 to 1. (1 is full, 0 is empty).

If you need the cute (and more power friendly) led display, it only takes one additional logic writer.
Same as above, except:
Hook up display instead of console.
Change its mode to percent (either with a mode control console or logic chips), but this only needs to be done one time after it's built.
Set up logic writer.
Set to read the batch reader.
Output to display.
Variable is "setting".
Same deal, but one extra chip.