The charging/charged status in your Z-Wave hub's app will show as on and off. "On" means the connected phone or tablet is charging, and "off" means it is charged.
When charging a device with the USB ports, it's best to keep the device off. Otherwise, it may start drawing power shortly after it's charged and send confusing reports to your hub.
The maximum load for both USB ports is 2.1 A combined, so it's not recommended to exceed this capacity.