devHunter wrote:
... I never use my mac while on the charger.
..
No reason at all to avoid that. The hardware and OS will charge the battery until full, the charging will cease, and you will simply be running off the power adapter.
Rechargeable batteries can quickly drop max charge capacity to a certain point and then last a long time at that state, last a long time near max capacity and then start to loose capacity, or they can just linearly lose capacity from day one and any other possible combinations.
In my opinion, check optimize battery charging and quite trying to micromanage your battery and just use the computer. When you reach a point when your operational time on battery does not meet your needs, then start to worry or simply replace the battery. Otherwise, happy computing.