The highest number briefly shown on a charging display rarely describes the entire charging stop.
Reading a charge curve
A charging curve plots delivered power against battery state of charge or time under specified conditions. Many vehicles accept their strongest DC power only over part of the session. As state of charge rises, battery cells approach voltage limits and the BMS reduces current. A quoted peak kW is therefore a short-duration maximum, while average kW across a specified state-of-charge window is more directly related to how long a journey stop takes.
Why one number never predicts charging time
Elapsed time depends on the usable energy moved between the start and end charge percentages, the curve at the pack's current temperature, station power capability, vehicle voltage, cabling limits and auxiliary loads. A charger rated for more power than the car can use will not force faster charging. Equally, a vehicle with a strong advertised peak can be slower across a broad window than a competitor with a flatter curve.
A defensible comparison protocol
Require the same type of metric for both vehicles: minutes from 10% to 80%, preferably under manufacturer-defined battery temperature and station conditions, or independent instrumented data with explicit methodology. 'Added miles in 15 minutes' can only be compared if the underlying range-test procedure and assumed efficiency match. Avoid mixing a marketing WLTP-distance claim with an EPA-distance claim.
The practical stopping strategy
Some routes are faster with several moderate top-ups than charging each time toward full. But whether this is true depends on station spacing, charger queues, vehicle curves and departure requirements. Treat planning software estimates as scenarios, not test results. A chart should distinguish measured power from an illustrative curve, and never invent point-by-point data to fill gaps.
A worked reasoning example without invented test figures
Two cars can briefly reach different peaks and still require similar overall charging stops. The first might reach a high power early but sharply taper as SOC rises; the second might peak lower and remain closer to that level over a larger SOC interval. Charging time comes from the integral of energy transferred divided by instantaneous power, not a division using the highest observed number. The only fair comparison is an equally defined measurement window under documented battery temperature, station power and battery condition. This is why one isolated screen capture showing an impressive kW figure has very limited editorial value.
What to record during a test
Log time stamps, initial and final SOC, energy delivered by the station, vehicle and charger identifiers, battery preconditioning status, ambient temperature and any competing charging load at the site. Power-versus-SOC points should come from instrumented readings and clearly label whether SOC is displayed or inferred. If a vehicle's charge curve changes after a software update, preserve the version history. Never draw smooth 'measured' curves from marketing 10–80% minutes or fabricate missing measurements.
Focused Reader Questions
Why compare 10–80% instead of maximum kW?
A defined SOC interval captures more of the charging curve. Compare it only when test conditions, usable pack and power-source methodology are provided.
Can two cars with equal peaks charge at different speeds?
Yes. Different tapers, energy capacities, thermal limits and accepted voltage create different average rates over a charge window.
Does the charger power label prove delivery?
No. It is an equipment class or limit; actual current, voltage, BMS and possible stall sharing can reduce observed delivery.
Can a charging curve be inferred from a time claim?
Not uniquely. Many possible power shapes can yield the same total time, so generating invented measurements would be misleading.
Sources and Further Reading
Scope: 2020–2026 vehicles and the regions identified above. Charging access, legal obligations, warranties and vehicle equipment must be checked for the particular market, model year and date.