I would have to agree that a battery visual aid system is a good project...
Though the beak from Cross the Road Electronics is a FAR better way of checking a battery state than a multi meter. The beak gives the battery voltage, battery percentage of charge, as well as voltages with a few different loads.
The load voltages are a much more accurate depiction of the battery current "health".
I highly suggest one..
Also if you do VEX there is an adapter to test there batteries as well..
I will say it has saved us potential issues in competitions. Yes, finding a dead cell battery in competition is a pit managers feel good moment!
While the rest of the team is out driving, scouting and just out having a good time, you are there quietly testing what many forget...
Also check your battery cables, many work loose after a few matches with big hitters.
Hope your project and season go well..
Aloha!