Some of our customers have alerted us to the fact that their Voyager Legend and Edge headsets do not charge when connected to the USB port of a PC running Windows 8.1. They encounter no issues when using the AC charger. The reason for this is that Windows 8.1 introduced new power management profiles, which can cause problems for devices that either charge or are powered from the PC USB port.
Microsoft is aware of the issue and has published an article in their knowledge base that explains it further: http://support.microsoft.com/kb/2900614
Plantronics has released new firmware that corrects the charging problems created in Windows 8.1. The new firmware is available on MyHeadset Updater: http://www.plantronics.com/myheadset-updater