An interesting usability issue that affects the people with a color vision deficiency (CVD) – like me :). Here is how Canon and Sony chose to indicate the charging status for 2 battery chargers that I own:

Both chargers have a LED indicator.
Canon LED blinks if it’s charging, and is always on if the charging is done.
Sony LED changes color when the charging is done.
For me, this means that I can tell when the Canon device finished charging, but I have no way to tell when the Sony device finished its job.
GG Canon 🙂