Does using a lower wattage power adapter for a MacBook increase its battery health?

Solution 1:

A low-power charger may not have sufficient power to charge your laptop while you are using it. Even though it's plugged in, the charge level may still go down, or stay at the same level. Or it might go up, but only very slowly. If you have peripheral devices connected that use power, the problem may be worse.

Your laptop draws the power that it needs, according to the power management hardware and software, which Apple spends 'some time and money' on optimizing. Any benefits from using a low-power charger are likely to be minimal, and offset by the inconvenience or other unforeseen problems.

There are so many factors that affect a battery's lifespan -- many of which are out of your control -- that my general advice is: just use your laptop as you need it, and don't try to micro-manage it.