Does the user receive a warning when a SensoNODE Gold sensor's battery is low?

Answer

Yes, if the site administrator sets up a battery alarm.  As an example, a sensor reporting to the collection server once every 15 seconds can have an alarm value set at 2.80V.  A user can be notified when the battery voltage drops below the aforementioned value.  This will provide approximately 10 days of notice before the battery has no charge.