The Z1™ and Z2™ battery is designed to be charged and ready for use when you're on the go. To ensure that your battery maintains a full charge, first allow time for a full charge (up to 10 - 12 hours). Be sure that the AC adapter is fully plugged into the PowerShell™ and wall outlet, and that the Z1™ and Z2™ is in 'standby-mode'- meaning when the device is plugged in but NOT in use/ being used for therapy.
Once the battery is fully charged (it will display four solid bars), be sure to disconnect it from the PowerShell™ and store separately, until you are ready to utilize battery power. For travel, we recommend allowing the battery to rest in the PowerShell™ cradle, but not pushing the battery all the way in to connect to the PowerShell™. If the battery does stay connected in the PowerShell™, the charge will deplete within 2-3 days.