Fenix as USB storage on Android
The USB access to Fenix GPS watches makes it really easy to view activities and tracks on a laptop: just plug in the USB cable and you’re done.
But on a phone it requires something extra: a powered USB hub. Fortunately, there are very small ones around.
You need a powered hub, because without it, using only an OTG cable, the Fenix will start charging from the phone, the voltage drops and you have a good chance of damaging the filesystem.
Symptoms of a damaged filesystem on a Fenix (2) are: inability to save an activity, crashing when accessing the history, rebooting when trying to access waypoints. Not fun when there is no laptop or PC anywhere around.
A Fenix 3 has a chkdsk routine built in, so it mostly fixes itself, but you might lose files.
The hub can be powered from a USB powerbank if no wall sockets are around.
Shown in the image are all required components; phone, powerbank, hub, charger, regular USB cable, Fenix on Fenix USB cable.
After having everything connected (Fenix last), the activities are accessible on USB storage in \Garmin\Activity.
Simply copy them to the phone’s local storage and then, very important: safely remove the Fenix storage.
After this you can disconnect everything (Fenix first), and view the FIT file in one of the -unfortunately- not many Android apps that support this (EdgeScope is one).
But if you have a Fenix or Fenix 2, you can save the FIT files as GPX on the device. They will be stored in \Garmin\GPX. There are many apps that can display GPX tracks.
The hub itself is widely available from many sources, search for “powered micro USB hub OTG”. Brand names vary. There is a small switch on the side that selects between “Charge” and “OTG”. Charge is for when you want to charge your phone via the hub. There are more compact ones with only one connection too.
Note for Fenix 3 users: activity files can easily be saved on the phone and later uploaded to Connect if so desired, “monitor”-files (that store activity tracking data such as steps and sleep data) are not kept forever, the oldest files are deleted after some time.
You can “rescue” them on your phone, but if you write them back in \Garmin\Monitor it is not sure at all if they will sync to Garmin Connect. As far as I know, nobody has tried that yet.
To store activity tracking data on the watch for longer, switch off BLE on the Fenix 3 or on the phone. Instead of writing 1 monitor file every 15 minutes and keeping only 3-4 days or so, they will be written every 24 hours and kept for a week, probably longer, and then they will sync as normal.