Charging curves: how to read one before you buy
The area under the curve decides your stop length. The peak on the brochure decides nothing.
A charging curve plots power delivered against state of charge. It is the most useful chart in EV buying and the least often shown.
What a curve looks like
- Rises quickly from low state of charge
- Plateaus at or near the car's peak, briefly
- Steps down in stages as the pack fills
- Falls steeply above 80%
The shape differs markedly between cars, and two cars with the same headline peak can have very different curves.
Why the peak misleads
A car advertised at "350 kW charging" may hold 350 kW for a few minutes, in warm conditions, from a low state of charge.
A car peaking at 150 kW that holds it from 10% to 60% will often add more energy in twenty minutes than the 350 kW car that tapers immediately.
Area under the curve, not the highest point.
The number to compare
10–80% time. It captures the useful window: fast enough to be worth stopping for, and stopping before the slow tail.
Rough guide for a mid-size EV:
| 10–80% time | Verdict |
|---|---|
| Under 25 min | Excellent |
| 25–35 min | Good |
| 35–45 min | Adequate |
| Over 45 min | Long-trip compromise |
What changes the curve on the day
Battery temperature. The biggest variable. Cold packs charge dramatically more slowly — precondition if you can.
Starting state of charge. Arriving at 40% skips the fastest part entirely.
Charger capability. A 50 kW unit caps you at 50 kW regardless of the car.
Shared cabinets. Two bays on one cabinet split its output.
How to use this when buying
If you rarely travel far, the curve barely matters — you charge at home and the shape is irrelevant.
If you regularly do long trips, the curve matters more than battery size. A smaller pack that charges quickly can be the better long-distance car, because you stop briefly and often rather than rarely and forever. That is the same logic as planning a long trip.
Our charge time calculator derates DC estimates for the taper rather than quoting peak, and names which of the car or the charger is limiting you.
In pictures
Common questions
Where do I find a car's charging curve?
Manufacturers rarely publish them. Independent testers do, and the 10–80% time is the summary figure worth comparing.
About the author
ElectraMile EditorialEditorial desk
The ElectraMile editorial team covers charging, running costs and EV ownership for readers in the UK and US.
Spotted something wrong? Tell us — we correct and date every change.
Figures shown for United Kingdom in GBP. Switch market in the header to see local pricing and terminology.
