Ive had a VA3 since June 2018, initially all was well, I then experienced the same horrible battery drain that some of you have also. Since around the v5.4 firmware update, I've struggled to get 2 days out of it... I tried everything I could think of and that had been mentioned in this forum to improved the battery life and thought maybe v5.5 firmware update may solve the issue. Unfortunately nothing did.
I have since raised an RMA with Garmin support and have now received a replacement VA3 that had firmware v5.4 on it and I updated to v5.5 and over the past few days have been using/testing its battery life and all seems back to normal 6-7 days with my usage pattern, over the last 5 days 30-40 minutes running a couple of days (HR and GPS tracking), 30 minutes cardio activity (only HR tracking) a couple of days.
My original VA3 serial no was in the range 5EC0xxxxx, my replacement VA3 serial no. is in the range 5EC7xxxxx so much newer production date.
So I wonder if everyone with a battery drain issue check your serial number and post the beginning 4 characters, maybe there's a pattern to the battery drain issue due to newer firmware versions and earlier hardware???
Either way and albeit with limited testing over less than a week, my personal recommendation to anyone having horrible battery drain is to RMA your VA3 with Garmin and get it fixed/replaced under warranty.