Feníx 5X+ after activity battery drain

I did a run of about an hour on gps only. Standard run profile, the activity itself only drained about 3% and after that I only synced the run then connection to smartphone is off. And it continues to drain at around 1% per hour with a standard watch face one. 

So 1hour gps run and cost around 20%battery for the day. 

This problem has been on going for quite a while. 

Software 8.40

GPS 2.50

What to do?