Electrical engineer explains why using a laptop plugged in is safer for the battery than charging

Can you explain why using a laptop while plugged in is less damaging to the battery than charging it and letting it die?

The lithium-ion battery inside is actually a chemical reaction. If you add in electricity, there's some chemical reaction going on and that actually can age the battery. Discharging and charging, it will basically make the capacity slower and slower.

So these are the things that are in our computers, lithium batteries?

Yes.

The more you charge them, the more they degrade.

Yes, but basically when you leave it charging, it will charge you full, right? And after it charges you full, it basically stops charging. There's like this chip inside all of the battery power electronics, we call them battery management ICs. When the battery is 100%, it will actually stop diverging most of the current. When this light turns green, that means the battery is not receiving any current.

It's being powered like a desktop PC.

Exactly, yes. Same thing if you plug your iPhone all the way in.

It's the same with my phone?

Yes. Yes. Oh no.