Elon Musk explains why charging your EV to 100% on a road trip is a mistake: On a road trip, your instinct is to fill the battery all the way up. That's how you'd treat a gas tank. But a battery doesn't work like a gas tank. Charge to about 80%. Drive it down to 10% or less. Repeat. This is just for long trips, when you want to spend as little time at the charger as possible. Elon: "Getting from 80 to 100, it takes about as much time as getting from 0 to 80." The reason is what's happening inside the battery. Lithium ions travel from one side to the other, looking for a place to settle. Think of them as cars hunting for a parking spot. When the lot is empty, they zip right in. As it fills up, they have to circle around, like at a packed mall. So the closer the battery gets to full, the slower it charges. The last few spots take the longest to find.