> when I'm on the desk, I always have the charger in.
Unless the machine specifically handles this scenario, this can artificially wear the battery. Newer MacBooks handle this better with "intelligent" charging (I couldn't say for sure whether a 2012 MBA would have had this feature), but I don't know about other brands.
But the real answer here is that batteries are essentially consumable parts. They won't last forever, and once it drops below holding ~80% of the original charge, it's worthwhile replacing it.
> when I'm on the desk, I always have the charger in.
Unless the machine specifically handles this scenario, this can artificially wear the battery. Newer MacBooks handle this better with "intelligent" charging (I couldn't say for sure whether a 2012 MBA would have had this feature), but I don't know about other brands.
But the real answer here is that batteries are essentially consumable parts. They won't last forever, and once it drops below holding ~80% of the original charge, it's worthwhile replacing it.