Vivoactive 3 battery charge level indicator accuracy

I have had my Vivoactive 3 for about 3 years. About a year ago I got a Venu Sq 2 because of the advertised battery life. The battery life on the Vivoactive 3 was approximately 48 to 56 hours on a full charge. I really like the Vivoactive 3 so I watched some videos on how to change the battery and purchased a battery and replaced it. The battery life with the new battery is no better. I'm wondering if the battery charge level on the Vivoactive 3 is accurate and if I should keep charging it after is says 100 % full charge. Or is this just that the Vivoactive 3 sucks up power on the battery and the battery life will always remain at 48 to 56 hours of life on a full charge. I know there are a lot of posts about poor battery life on the Vivoactive 3.  Any input will be appreciated.

FYI, the Venu Sq 2 will run for over 8 days on a full charge.

Thank you very much.

Norm