Q: What does Battery Calibration Do?

A: Over time lithium ion batteries will degrade to where it will not charge to 100% of its original capacity. Here is an example of what the calibration does:
You charge your batteries to full but it only shows 70%. This means it has degraded down to only being now capable of charging to 70%. Doing a recalibration will now make it so Windows will now show 100% again instead of 70% when you charge it to full. That doesn't mean it charges to 100% of what it was originally capable of only 100% of what it is now capable of.