Charging is not one speed. The same car can add five miles in an hour at a wall outlet, twenty-five at a home charger and a hundred in twenty minutes at a highway stop. The difference is power, and the car is usually the limit rather than the station. Move the sliders below and the rules stop being abstract.
Playground · no wrong answers
Build a charging stop
1 · Pick a car
2 · Pick a charger
3 · Drag the battery
10% → 80%
Time plugged in
28minutes
10% → 80% · 55.3 kWh · 194 miles
- Miles / hour
- 415
- Average power
- 118 kW
- Power at the end
- 46 kW
Who is the bottleneck
The car is the limit. The post has more to give, but the car will not take it. A bigger charger would change nothing.
An estimate, not a measurement: a typical taper curve, scaled to each model's published 10–80% time, at 3.5 miles per kWh. Real sessions move with temperature, charger sharing and the car's own software.
The three numbers that decide it
Every stop is a negotiation between three ceilings. Whichever is lowest sets the pace — and the lowest one moves as the pack fills.
Power
The post
1.4 kW at a wall outlet, 350 kW at a fast site. A station's rating is a peak, not a promise — a shared or throttled post delivers less than the sign says.
Limit
The car
One ceiling for AC, another for DC. A 150 kW car will not charge faster on a 350 kW post, and that ceiling is often the lowest of the three.
State of charge
The battery
A nearly empty pack takes almost anything. A nearly full one takes very little, and the drop above 80% is deliberate.
One change at a time
Change the charger and leave the car alone: the time stops falling once the post is faster than the car. Then change only the battery window: the last 20% costs more than the 20% before it. Two experiments, two different ceilings.
Why the last 20% is slow
A lithium-ion pack cannot take its peak rate at every state of charge. The battery management system tapers the current as the cells fill — gently at first, steeply above roughly 80% — to protect the cells and keep the temperature under control. The cost is not small.
10% → 70% · 60% of the pack
20 min
47.4 kWh in, 145 kW average
80% → 100% · 20% of the pack
36 min
15.8 kWh in, 27 kW average
On that car the first 60% of the pack takes about half as long as the final 20%. That is why road-trip advice is to stop at 80% and move on: the last fifth buys range at a fraction of the speed, and it holds the charger while it does it.
Now guess one
Three real stops. Set the slider before you look — the gap between your instinct and the number is the part worth learning.
Guess the time
How long do you think?
1 / 3
Tesla Model 3, 10% to 80%, on a 350 kW DC fast charger.
79 kWh pack · 250 kW DC peak
A realistic charging-time table
| Charging level | Typical power | Miles added per hour | Best for |
|---|---|---|---|
| Level 1 (120 V) | 1.4 kW | 4–6 | Overnight at home, last resort |
| Level 2 (240 V) | 7.2 kW | 20–25 | Home, work, hotel |
| Level 2, high-power | 11.5–19.2 kW | 35–60 | A car with a large onboard charger |
| DC fast | 50–149 kW | 150–400 (peak) | A top-up on a route |
| DC fast, 150 kW+ | 150–350 kW | 450–1,000 (peak) | A road-trip stop |
Miles assume 3.5 miles per kWh, the same figure the playground uses. Peak figures are not the average over a session; a car may accept less than the station can deliver.
What a 10–80% stop looks like
The industry quotes 10–80% because it is the useful part of the curve and the part that avoids the slow top of the pack. These are the models in the vehicle guide with both a DC peak and a published 10–80% time.
| Model | Battery | DC peak | 10–80% |
|---|---|---|---|
| Bugatti Rimac Nevera | 106.8 kWh | 500 kW | 16 min |
| Lucid Gravity | 123 kWh | 400 kW | 26 min |
| Volvo EX60 | 91 kWh | 370 kW | 19 min |
| Polestar 3 | 102 kWh | 350 kW | 23 min |
| Mercedes-Benz EQS | 112 kWh | 330 kW | 26 min |
Catalogue figures for the matched trim; US trims can differ. The time is the maker's 10–80% claim, not a measured session at every station.
Home and public charging are different jobs
A Level 2 charger at home or work is for the hours a car is parked. A DC fast charger is for a route, where the stop is measured in minutes. Neither replaces the other, and a car with no home charger is a different ownership experience from one with a driveway.
At home · hours
7–9 hr
A 7.2 kW box refills most cars overnight. You sleep through it, so the speed barely matters.
On a route · minutes
20–40 min
A DC stop to 80%. Here every kilowatt counts, because you are standing next to the car.
- Level 2 stations
- 3,808
- DC fast
- 749
- 150 kW+
- 221
- Median price
- $0.35
The directory has 3,808 Level 2 stations and 749 DC fast stations; the speed hubs split them by power, and the cost-per-mile guide turns the price side into a number you can compare.
The whole page in four lines
- 1The lowest of post, car and battery sets the speed.
- 2A faster post only helps a car that can take it.
- 310–80% is the useful window; the last 20% is slow on purpose.
- 4Home is hours, public is minutes. Both are normal.