How long an EV charge actually takes
The arithmetic everyone starts with — battery size divided by charger power — gives an answer that is always too optimistic. Here is why, and what to use instead.
Source · OpenStreetMap contributors (ODbL) · Data 2026-08-07 · Reviewed Aug 2026 · Method
Why the simple sum is wrong
A 60 kWh battery on a 50 kW charger looks like a 72-minute job for a full charge. It is not, for three reasons that all push the same way.
The car is often the limit, not the charger. Every EV has a maximum rate it will accept, and on AC that limit is usually far below the post's rating — a 22 kW AC charger delivers 7 kW to a car with a 7 kW onboard charger. Plugging into a faster post changes nothing.
DC charging tapers. Rate falls away as the battery fills, steeply above about 80% state of charge. The last 20% can take as long as the first 70%. This is battery chemistry, not a limitation of the charger, and it is why nobody sensible sits at a DC charger to 100%.
Cold batteries charge slowly. A battery that has not been preconditioned can accept substantially less than its rated peak, which is a real effect on a winter morning in Central Otago.
The 10–80% convention
Because of the taper, the industry quotes 10–80% and so does this site. It is the range people actually charge in on a road trip: you arrive with something left and you leave before the taper makes waiting pointless.
What ChargeMap estimates
Every station page with a recorded power rating shows an estimated 10–80% time for 40, 60 and 80 kWh batteries. The calculation is deliberately transparent: energy needed is 70% of the battery size, and the effective rate is taken as 75% of the post's rating on DC and 92% on AC, to allow for taper and for the car being the limit some of the time.
Those percentages are assumptions, chosen to be realistic rather than flattering. They are not measurements, and a specific car on a specific day will differ. Treat the figures as "about this long", which is all anyone needs when deciding whether to have a coffee.
Why there are no per-model figures here
The obvious next step is a page per car model. It is not here yet, for a boring and deliberate reason: it needs verified battery capacities and maximum DC rates for every model sold in New Zealand, and this build could not source them to a standard worth publishing. Estimating them would produce exactly the kind of confident, wrong, unciteable number this project exists to avoid. It will be added when the specs can be cited.