When is the cheapest time to charge an electric car?

The useful comparison is the electricity bought or diverted into the car. That can be a little more than the energy added to its battery.

Compare the same charging session

Suppose a car has a 60 kWh usable battery and you want to move from 20% to 80% charge. You need to add 36 kWh to the battery.

For this example, assume 90% charging efficiency. The charger would draw 40 kWh to put that 36 kWh into the battery. The remaining energy represents charging losses and overheads. Actual efficiency varies.

The solar figure is lost export income, rather than a new electricity charge. It assumes the whole 40 kWh comes from surplus solar that would otherwise have been exported. If some electricity comes from the grid, price that portion separately.

These worked examples exclude existing supply charges and other plan costs. For an ordinary day, replace the energy needed for your driving; you do not usually need to charge from empty to full. Check whether a consumption figure is measured at the battery or the wall before adding a separate allowance for losses.

Can I charge my electric car for free at home?

Offer details checked 13 October 2026: our evEnergy Saver plan (opens in a new tab) offers 12 cents per kWh from midnight to 6 am AEST for eligible ACT residential EV owners with a smart meter. Its free grid-electricity periods are noon to 2 pm AEST on Saturdays and Sundays. Controlled load is excluded; terms and fair use apply.

Those weekend periods are two separate two-hour windows. A car drawing 7 kW for two hours can take about 14 kWh from the charger, before charging losses. It cannot fit the example’s full 40 kWh into one such window.

Check the clock as well. During daylight saving, midnight AEST is 1 am local time.

Offer details checked 13 October 2026: eligible NSW customers can opt into the Solar Sharer Offer, with the first 24 kWh free between 11 am and 2 pm local time each day. A smart meter is required. Embedded networks are excluded, and other charges continue.

Check what the rest of the house pays

An EV plan can change what the rest of the household pays. Compare the home and car together using the same annual usage. Include the daily charge, demand charges where applicable, solar credits and any electricity that must be bought outside the cheap window.

Also check your vehicle’s maximum AC charging rate. A more powerful wall charger cannot force the car to accept power above that limit.

Should I charge from my home battery?

Stored electricity has a cost and another possible use. Energy sent to the car is no longer available for the home later. Compare grid-charging cost, charging losses and the value of keeping that energy for household demand before counting battery-powered charging as free.

Ask how the car charger and home battery interact. If a cheap grid-charging period is the plan, check whether the battery supplies the car automatically and which supported settings can change that behaviour. The right setup depends on the equipment and its controls.

Use the car’s or charger’s scheduling controls, set a charge target suited to your driving and confirm that charging begins and ends when expected. If you leave early or park elsewhere during the cheap period, choose a schedule that reliably gets you ready.

Compare a normal week of driving with the car’s parking hours and your actual rates. Set a realistic charge target and check that it is reached. A schedule change may be enough; faster equipment is worth considering when it solves a charging-time or convenience problem you actually have.

As a separate illustration, adding 18 kWh to the car at 90% efficiency needs 20 kWh from the supply. At a steady 2 kW, that takes ten hours. A six-hour cheap period covers 12 kWh of that input; the remaining 8 kWh needs another period or more charging power. Price those portions separately instead of applying the cheap rate to the whole session.

Related advice: Do I need a dedicated EV charger at home? · When is off-peak electricity?

Find a plan that fits your charging

If you’re an ACT EV owner, start with the eligibility and current terms of our evEnergy Saver plan (opens in a new tab). In NSW, compare the plans available for your address (opens in a new tab). You can use the household-cost comparison in this guide whether you’re already with us or another retailer.

Review your electricity plan after an upgrade