The earbuds are charged from the charging case simply by placing them in the charged case. Even if there is no access to power when on the go, the earbuds can be charged.

Place the earbuds in the charged case.

If you open the lid of the charging case, the status LED displays the amount of charge remaining in the charging case. link

When you open the lid with the earbuds inside the charging case, the status LED displays the remaining battery charge of the earbuds. If both left and right earbuds are in the charging case, it displays the charge of the one with less remaining battery.

Close the lid of the charging case.

Charging begins.

If you close the lid of the charging case, the status LED displays the amount of charge remaining in the charging case. link

A fully charged case can recharge earbuds that have zero remaining charge three times.

It takes approximately 3 hours to fully charge the rechargeable battery from the state of no remaining battery power.

When the rechargeable battery built into the earbuds is low, a notification sounds. Charge the earbuds.

Even if you place only one earbud into the charging case, it can be charged.

NOTE

If the charging ports of the earbuds and charging case are dirty, charging may not be possible. Wrap a clean cloth soaked with anhydrous ethanol around a toothpick and gently wipe the ports regularly.

If the earbuds get any moisture, thoroughly wipe it off before placing them in the charging case.