Use The Charge Case - Plantronics Voyager Edge series User Manual

A fully charged case can supply an additional 11 hours of headset talk time.
IMPORTANT
Fully charge the charge case prior to use.
Check the charge case or headset battery status by swiping either the case or headset icons.
The LEDs indicate the battery status.
Battery status LEDs for charge case and headset
Battery high
Battery medium
Battery low
Battery critical; Recharge case/headset