How did you use the watch in this period?..GPS activity?.. was the watch battery flat when you received the watch?.. new batteries may need a few charge cycles to get the best out of them....could you perhaps tell us more?
Sam201176 same issue here. Today, my Fenix 5X went at 50% without any reason after a fully charge of the device. Basically i fully charge it, i went for shopping and came back home after 1 hour and 30 minutes. I did something in my garden for 1 hour and after i run 3km. From 100% went to 50%. It seems that a percentage change every 5 minutes.
These issues are difficult to track. Watch could be more with phone in BT connection at first use for some reason (upgrade downloads...)
It happened to me as well after new software version installation. Sometimes helps just to recharge and all is OK, sometimes helps to do soft reset - hold light button until watch switches off and 20 seconds longer and then normally start again. If it would not help, then would propose to try factory reset and if does not help either, Garmin support will help.
This happened to me also. I found out that my left down button was getting stuck. I became aware of this when I had issues using the button. I followed the Garmin instructions to soak in warm soap water. I don't swim or shower with my watch but had it for close to 3 years now.
