If you’ve watched a Supercharging session, you’ve seen it: the kW number climbs fast at first, then drops off sharply somewhere past 80%. That’s not a problem with your car, it’s how every EV charging curve works. As InsideEVs explains, a battery naturally resists being pushed toward full charge, and both electrical resistance and heat buildup increase as the state of charge rises, so the vehicle’s battery management system throttles the current to keep temperatures in a safe range.
Tesla confirms the same behavior directly. Tesla’s support page states that “charging speeds slow as the battery charges, so reaching 100% charge will typically take significantly longer than reaching 80%,” and notes that at high-use Superchargers, your car’s charge limit may be automatically capped at 80% to reduce congestion for other drivers waiting behind you.
The practical takeaway differs for daily driving versus a road trip. At home overnight, the slow tail end costs you nothing, you’re asleep, and Level 2 home charging is already far slower than Supercharging, so the curve barely matters. On a road trip, it matters a lot. Charging from 10% to 80% might take roughly 25 to 30 minutes on a modern Tesla, but pushing from 80% to 100% at the same stop can take nearly as long as that entire first stretch.
That’s why Tesla’s in-car navigation typically routes you to your next Supercharger with just enough charge to arrive, rather than filling to 100% at every stop. If you’re planning a multi-stop trip, it’s almost always faster overall to make an extra short stop at 80% than to sit through the slow final 20% once. Let the trip planner calculate the stops, it’s already accounting for this curve when it tells you how long to charge.
Photo by Reinhard Bruckner.