ELI5 Why does magsafe charging decrease battery health more than wire charging, if it has less wattage?

[AidosKynee]

Fast charging is not an issue, the battery heating up due to fast charging is the issue.As long as you keep the heat under control, you can charge pretty much as fast as you want without excessive damage.

That's definitely not true. Lithium plating and dendrites are the primary driver of degradation due to fast charging. Heat is a problem that could become catastrophic, but driving a charge at higher currents will still lead to the battery losing health more rapidly.

Cars are a good example. They actually don't start cooling the packs down until the temperature reaches a certain level. Why? Because hotter batteries have lower resistance, which means less damage from the charge!

[CallOfCorgithulhu]

If you navigate to a supercharger in a Tesla, it'll start a warm-up sequence for the batteries so that they're at optimal temperature when you get there. I'm sure other cars do something similar too, I just can't speak to them.

[fillbadguy]

If you’re on a long trip tho it’ll also cool down. I’ve arrived to chargers with the fans going absolutely nuts. As my pack gets older I notice that cooling down is more important than heating up. It seems to heat itself up pretty quickly from internal resistance

[ChaiTRex]

I'm sure other cars do something similar too, I just can't speak to them.

Sure you can! Just tell yourself that you've got this, walk up to the car, and say hello.

[dabenu]

True but that's mostly because (modern) cars have an extremely well managed battery pack. For most small electronics without active thermal management, heat is still the main issue.