When Stryd is not in use, it is in energy saving mode. Its sensors and ANT+ signal will be disabled to save energy, but Bluetooth will remain enabled so that you can still connect to it with your phone. When not in use, the battery will last for several weeks.
As soon as Stryd detects motion, such as shaking your Stryd or walking around with it before your actual run, it will activate itself and start recording data. It will continue to record data until it stops detecting any motion for a few minutes. The battery will last about 20 hours when Stryd is active.
When syncing data to Stryd PowerCenter using your phone, you will upload all data stored on Stryd. This means there data from before and after your runs will appear in PowerCenter. The development team is considering a feature to allow runners to crop their run and cut off this data. When using a compatible sports watch such as Garmin, PowerCenter will rely on the data stored on the watch and the data in PowerCenter will match with the time recorded by the watch.
If you have additional questions, contact firstname.lastname@example.org.