When calibrating the battery, would it be bad to use the fast charger?

Hey. I’ve heard so many conflicting opinions on the matter. Everyone says different things and there is no definite answer anywhere really. But using the fast charger does cause the internal circuitry of the battery to dissipate more heat,so it puts more thermal stress on the battery. Based on my research,using a slower charger is better than a fast charger in the long run. It isn’t as stressing to the battery as fast charging. But keep in mind the battery and charger are designed for each other. The phone is designed to accept higher current. So it is safe and will work well.

With my iPhone 6s Plus I charge with a 2 amp charger instead of 1 since by the time the battery goes bad I’ll probably get a new phone.

For calibrating,it technically would be best to use a slower charger,but in practice it really isn’t worth worrying about.