EV Charging Curve Comparison

The EV Charging Curve Comparator plots two electric vehicles' DC fast-charging power against state of charge to show which one actually reaches 80% first.

Peak Kilowatts Are a Headline, Not a Charge Time

A spec sheet advertises one number for fast charging, the peak in kW, and it is the number that sells the car. It is also the number a battery holds for the shortest time. A peak is a momentary reading near a low SoC, not the rate that fills a pack from 10% to 80%. What sets that time is the whole shape of the curve: how high the power climbs, how long it stays there, and how early it falls away. Two cars can share a peak and still finish minutes apart.

This tool draws that shape for two vehicles at once, so the relationship is visible rather than implied. The honest single figure is the average power delivered across the window, and it routinely lands far below the peak. A 250 kW headline can average barely over 100 kW in a real 10-to-80% session, while a 233 kW car that holds its power can average close to 190 kW. The car with the smaller headline reaches 80% first, which is exactly why the E-GMP twins and their 800-volt charging behaviour outpace cars that quote bigger peaks.

DC Fast-Charging Curves Compared

The table below is the heart of the tool. Each row takes a real vehicle's representative curve and reports its advertised peak, the state-of-charge band that peak holds, the time to charge from 10% to 80% on a 350 kW station, and the average power delivered across that window. Read the peak column next to the time column to see how loosely the two are related.

Vehicle	Architecture	Peak	Holds peak to	10% to 80% (350 kW)	Average power
Hyundai Ioniq 5 LR	800V	233 kW	~55%	17 min	186 kW
Kia EV6 LR	800V	233 kW	~50%	17 min	188 kW
Tesla Model 3 LR	400V	250 kW	~8% (spike)	30 min	107 kW
Ford F-150 Lightning ER	400V	150 kW	~10%	50 min	105 kW
Chevrolet Bolt EUV	400V	55 kW	~50%	60 min	44 kW

The Tesla carries the highest peak in the table yet finishes behind both 800-volt cars that peak lower, because its curve collapses while theirs hold. Note too that the 150 kW F-150 Lightning and the 250 kW Model 3 deliver almost the same average power, 105 against 107 kW; the Tesla only finishes sooner because its pack is smaller, not because its curve is better. Curve shapes here are representative profiles drawn from EV-Database (Fastned), the P3 Charging Index, and EVKX session logs, and they assume a warmed battery. For a model-by-model figure capped at each car's own limit, you can pull a model-by-model 10-to-80% estimate from the database.

Why the Curve Falls as the Battery Fills

The taper is not a flaw; it is the battery protecting itself. As cells fill, their internal voltage rises and the gap the charger can push current across narrows, so the BMS steps the rate down to avoid heat and lithium plating. Because this is driven by state of charge rather than by pack size, every battery spends roughly the same fraction of the curve in the slow zone, regardless of how large it is.

The cost of the top of the battery is steep. On a 350 kW stall the Model 3 takes about 30 minutes from 10% to 80%, then needs roughly another 32 minutes to crawl from 80% to 100% for far less energy. The last fifth of the battery can cost as much time as the first seventy points, which is why road-trip charging targets 80% and leaves the top for an overnight Level 2 session where a slow rate costs nothing. The same logic explains how a peak kW figure reads on a spec sheet against the real-world numbers.

800-Volt Plateaus Versus 400-Volt Spikes

Architecture is the lever behind the two curve families on the plot. Running the pack near 800 volts lets a car move the same power at half the current, which sheds less heat, so the BMS can sustain a high rate further up the curve. That produces the broad plateau on the Ioniq 5 and EV6. Most 400-volt cars instead spike to a peak at low SoC and decline almost immediately, so their average trails their headline by a wide margin. To place either pattern against the slower charging levels, compare one car across Level 1, 2, and DC fast.

Architecture is not destiny, though. The 400-volt F-150 Lightning holds a gentle, near-flat curve that keeps roughly 90 kW all the way to 80%, so its average sits unusually close to its peak even without the 800-volt trick. A big, well-cooled pack run at a conservative rate can out-sustain a smaller pack pushed hard, which is the same reason a low charge rate relative to capacity protects the cells. For a single specific Tesla and stall, you can run the numbers for a specific Tesla and Supercharger.

Worked Example: Model 3 Versus Ioniq 5 on a 350 kW Stall

Two drivers pull into adjacent 350 kW stalls at 10%, one in a Tesla Model 3 Long Range that quotes a 250 kW peak and one in a Hyundai Ioniq 5 that quotes only 233 kW. The Model 3 needs 52.5 kWh for the 10-to-80% window but averages about 107 kW because its curve falls away early, so it takes about 30 minutes. The Ioniq 5 needs 51.8 kWh and averages about 186 kW because it holds its plateau, finishing in about 17 minutes.

The car with the lower headline reaches 80% roughly 13 minutes sooner. The Tesla peak is genuine, but it lasts seconds; the Ioniq 5 spends most of the session near its own peak. The lesson is to read the average power the tool reports rather than the number on the window sticker, then turn the energy added into a running cost per mile if the stop is on a paid network.

Worked Example: When the Station Is the Bottleneck

The same Ioniq 5 parks beside a Chevrolet Bolt EUV, but the only free charger is an older 50 kW stall. The Ioniq 5 could pull 233 kW, yet the station hands it only 50 kW, so its 51.8 kWh takes about 62 minutes. The Bolt sits just above 50 kW across most of its plateau, so it too is held near 50 kW and its 44.1 kWh also takes about 62 minutes. The premium car and the budget car finish within a minute of each other.

The Ioniq 5's entire advantage lives above 50 kW, and the stall discards all of it, because delivered power is the lower of the curve and the station. A fast curve is wasted on a slow plug, and how the Bolt's 55 kW ceiling stretches each stop shows the same ceiling from the other direction.

Charging Curve

A charging curve is the plot of delivered power against state of charge for a single fast-charging session. It rises to a peak at low SoC, holds for a while, then tapers as the pack fills, and its area, not its height, determines how long a charge takes. Two cars with identical peaks can have very different curves, which is the entire reason this comparator exists.

Average Sustained Power

Average sustained power is the energy added divided by the time taken across a charging window, expressed in kilowatts. It is the most honest single number for a session because it accounts for the whole curve rather than a momentary peak. On a flat-curve car it sits close to the peak; on a spike-and-decline car it can fall to less than half, which is what makes it the right figure to compare.

Battery Preconditioning

Preconditioning is the car warming its battery to an ideal temperature before a fast charge, usually triggered by navigating to a charger. A cold pack cannot accept high current, so without preconditioning the curve starts low and may never reach the plotted peak. The representative curves here assume a warmed battery, so a winter session without preconditioning will run slower than the figures shown.

Peak kilowatts make the advertisement, but the curve makes the charge. Comparing two real curves side by side, against the station you will actually use, turns a misleading headline into the number that matters: how long until you can unplug and drive.