If you are using the Z1™  or Z2™ and the PowerShell™ with the Battery on AC power during a power outage, the device will automatically switch over to battery power so that you can continue to enjoy a full night of sleep without interruption. 


If you are using your Z2 plugged into an electrical outlet with the Auto Off-On feature engaged (AOFF-ON) and you are also using the PowerShell and Battery, due to the possibility of an electrical outage, if the power does go out, the battery will engage.  When or if the electricity switches back on, your Z2 will automatically begin using the electricity again, because the auto feature is engaged.  


If you are using your Z2 plugged into an electrical outlet with the Auto Off-On feature turned off (AOFF-OFF) and you are also using the PowerShell and Battery, due to the possibility of an electrical outage, if the power does go out, the battery will engage.  When or if the electricity switches back on, your Z2 will not automatically begin using the electricity again.  Your battery will continue to power your Z2 as long as the battery charge allows.