What you are describing is a race condition!
So let's say your battery is not working at the correct level, what logic would likely kick in to off set the low voltage? That would be the VRM circuit.
But before you dig into the logic you need to first correct the obvious! I would replace the battery first if you think thats the issue. How about checking it using this app! [https://www.coconut-flavour.com/coconutbattery/|CoconutBattery] take a snapshot of the apps main window and post it here for us to see [guide|21499]