I am very happy with the battery life of the S20units I have.  There is ample talk time for several days riding (2-4 hours/day) and the units hold charge for weeks in storage.  There is a problem with the battery status reporting.  At the start of the ride the status indicates Battery Level High but 2 hours in I got the Battery Low message, and about 5 minutes later the unit shut down.

I would like the to get the Medium level indicator about 4 hours from end-of-power and the Low level indicator about 1 hour from end-of-power. This would provide some time to either charge the unit or shut down early to conserve power.