I saw a video from dcrainmaker where he compared the fenix 3 and the fr 920 with respect to charging while an activity. The 920 stopped the activity and charged. The fenix 3 could charge while continuing the activity. ( https://www.youtube.com/watch?v=S9haDnwIuSQ Garmin Fenix3 use while charging with USB battery pack)
Do you know how the 735xt works? Is it possible to charge during an activity? (eg during a longer bike trip)