> - need to establish a system of keeping track what's charged

This seems to be the root of all of your problems.

Just charge all of the cells that aren’t in use.

When you take drained cells out of something, they go in the charger.

Charger is always plugged in and right next to where you store the cells.

If there’s ever any question, just stick the cells in the charger. Don’t bother playing all of the games to avoid “memory effect”. It’s much better with modern cells and not worth the hassle to try to work around.