After the s/w update for 4.90 on the V3A Music I've noticed considerable battery drain as well. I'm getting a bit over 24 hours off a full charge. I used to make it 2-3 days depending on how long the activities were I was doing with music and gps.
>>SUPPORT PLEASE READ THIS VIVOACTIVE 3 MUSIC SOFTWARE 4.90 HAS A BATTERY DRAIN BUG<<<