Neither model is always cheaper — your car decides. Per-kWh pricing charges for the energy your battery takes, so the bill is the same however fast or slow the session runs. Per-minute pricing charges for time plugged in, so a fast-charging car in mild weather can pay less, while a slow session — a cold battery, an older car, the slow top of the charge — pays more for exactly the same energy.
Key Takeaways
- Per-kWh pricing charges for energy; per-minute pricing charges for time, so session speed sets your real price.
- The taper, a cold battery, a low car ceiling and shared posts all make per-minute sessions dearer per kWh.
- On a per-minute tariff, unplugging near the top of the fast part of the charge saves the most money.
- Check the pricing model on the screen or app before you start — the rates are shown up front.
How the Two Models Work
With per-kWh pricing, the meter is the product: you pay for each kilowatt-hour delivered, and the charger and car can take as long as they take. With per-minute pricing, the clock is the product: the rate runs from plug-in to unplug, whether power is flowing at full speed or tapering to a trickle. Some stations combine elements — a per-minute rate, sometimes with a session fee to start — which is why our explainer on whether charging stations cost money lists time-based pricing among the standard models. The model in use is shown on the station screen or in the network app before the session begins.
The Same 30 kWh, Three Different Bills
The numbers below are worked examples with labelled prices, not quotes — your station’s rates will differ. They show what changes the bill: not the energy, which is 30 kWh in every row, but the average speed of the session under time pricing.
| Session | Per kWh at an example $0.45/kWh | Per minute at an example $0.30/min |
|---|---|---|
| Fast session, averaging about 60 kW (about 30 minutes) | $13.50 | About $9.00 |
| Slow session, averaging about 25 kW (about 72 minutes) | $13.50 | About $21.60 |
Read the table as a rule: under per-minute pricing, everything that slows a session down raises the price of every kilowatt-hour in it. Under per-kWh pricing, a slow session is merely slow.
Why Your Car and the Weather Set the Winner
- The charging taper. EV charging slows as the battery fills, sharply so in the last part of the charge. On a per-minute tariff, those slow final minutes are the most expensive energy of the session; on a per-kWh tariff they cost the same as the fast minutes.
- A cold battery. A cold pack accepts power slowly at first, so a winter fast-charge takes longer — and costs more per kWh on time pricing.
- Your car’s ceiling. The U.S. DOT puts DC fast charging at 50–350 kW, but each car has its own maximum. A car with a modest maximum, or a plug-in hybrid on a Level 2 post billed by time, fills slowly and pays for every minute of it.
- Shared posts. Where two cars share one charger’s power, both sessions slow down — and on per-minute pricing, both drivers pay for the sharing.
Charging at Home Sidesteps the Question
At home there is no pricing model to game: you pay your electricity tariff for the energy used, at a U.S. average residential price of 18.31 cents per kWh. A home unit such as the EV-ACT5006T 48A Level 2 wall charger, or the EV-ACS4005T 40A NACS portable charger on a NEMA 14-50 outlet, makes public pricing an occasional trip cost rather than your everyday rate — which is the larger saving behind why public charging costs more.
Frequently Asked Questions
Why do some stations charge by the minute at all?
Time-based pricing has been used where selling electricity by the kWh was restricted, and operators also like that it discourages cars from sitting on a fast charger. Either way, the model transfers the risk of a slow session from the operator to you.
How can I tell which model a station uses before I plug in?
The price is displayed on the station or in the network app before you start. At federally funded corridor stations in the US, chargers must also accept contactless card payment with no membership required, so the rate is visible without signing up first.
Is a per-minute fee the same as an idle fee?
No. A per-minute rate runs while you are charging. An idle fee starts after charging has finished, to free the space for the next driver. A station can have either, both, or neither — check both lines of the price display.
Related Reading
- Do EV Charging Stations Cost Money? Free vs Paid Charging Explained
- How Much Do EV Charging Stations Charge?
- Why Is EV Charging So Expensive at Public Stations?
- Where to Find EV Charging Stations: Maps, Apps and Tips
