How does battery calibration work on Android with multiple batteries?

[fuzzybabybunny]

I've got the S5 with a few batteries, all of them different brands (Samsung, Anker, no-name).

Does battery calibration measure the battery so that the phone knows how to accurately represent the charge level in percent?

If so, wouldn't each battery need a separate calibration log / table or something? I could run calibration for Battery #1, but when I swap in a different battery, it'll still be using the calibration table for Battery #1, right? Unless each battery had some sort of unique ID number that it reports to the phone...