Cost
What an EV charge actually costs
You pay for more energy than ends up in the battery, and you rarely get the charger's rated power for the whole session. Both push your real cost above the headline number. The calculator on this site applies both so you can see the gap instead of assuming it away.
The gap between grid energy and battery energy
Every charge loses energy to heat in the charger, the car's onboard charger and the battery. A 10% loss means drawing 40 kWh from the grid to put 36 kWh into the battery. You are billed on the 40.
The loss is not fixed. It is lower on direct current fast charging and higher on slow single-phase AC charging, and it also rises when the battery is very cold or very hot. Treat any single loss figure as a planning assumption, not a measurement of your car. More on losses and charge curves.
Why the last 20% takes longer than the first 40%
As a battery fills, most vehicles reduce the power they accept to protect the cells. A 7 kW wall charger connected to a car that accepts 11 kW will still run at about 7 kW, and the taper means the last stretch of the session runs well below that. This is why a full 20-to-80 percent window usually takes far longer than a flat division of the energy suggests.
What your tariff actually does to the number
Australian households sit on a flat rate or a time-of-use tariff. On a flat rate the tariff is one number and the estimate is straightforward. On a time-of-use tariff the cheap window matters more than the average price, and a charge that straddles peak and off-peak costs something in between. If you are not sure which tariff you are on, ask your retailer before using a specific figure. See what to confirm before you install.
Working out your own cost per 100 km
Once you have one real charge session, divide the cost by the distance you drove and multiply by 100. That gives your real cost per 100 km, including the losses you actually incurred. Using a manufacturer's range figure instead mixes in the car's own optimism, which is why published comparisons often disagree.
What this estimate does not cover
- Electricity plan fixed charges, which do not change with how much you charge.
- Public charging prices, which vary by network, time and membership.
- Depreciation, servicing and insurance, which dominate the true cost of owning a car.
- Any assumption about when or how fast your particular car actually charges.
Figures on this site are planning estimates, not billing advice. Electrical installation must be carried out by a licensed electrician. See sources and about this site.