EV charging at home vs public — cost breakdown

Why this matters when you buy

EV marketing often quotes cents-per-kilometre figures based on home charging at the cheapest available tariff. If your actual routine involves workplace top-ups, shopping-centre AC chargers, or highway DC stations, the effective rate rises. Over five years and tens of thousands of kilometres, the gap between best-case and realistic charging cost can be thousands of dollars.

How CarCostIQ models it

CarCostIQ applies a blended electricity rate. You set home c/kWh and the home-charging percentage; the remainder is priced at a public-charging multiplier (default 2.5× home rate, reflecting typical commercial station margins). The blended rate feeds into the annual energy line. If you charge 100% at home, you get the lowest possible cost; at 0% home, you pay the full public premium.

Real-world caveats

Public charging prices vary widely — from free destination chargers at shopping centres to $0.60+/kWh at highway ultra-rapid stations. The 2.5× multiplier is an average starting point; override it if you know your regular station's price. Subscription plans from charging networks can lower the effective public rate. Workplace charging may be free or subsidised — model it as home rate if the cost to you is similar.

Simple practical example

Suppose home electricity is 30 c/kWh and you charge 80% at home and 20% at public stations (at the default 2.5× multiplier = 75 c/kWh). Your blended rate is 0.80 × 30 + 0.20 × 75 = 39 c/kWh. For a vehicle using 15 kWh/100 km over 15,000 km/year, that is $877/year in energy. At 100% home charging the same scenario costs $675/year — a $200/year difference, or $1,000 over five years. Run your exact mix in the calculator to see the impact on your pair.

Common misunderstanding

Many buyers assume 'I will always charge at home' and never test the sensitivity. Even occasional road trips with DC charging can shift the effective rate. Conversely, some buyers overestimate public charging dependency — if you have a garage with a standard power point, overnight trickle charging covers most daily commutes at the lowest rate.

What to override in the calculator

In the calculator's advanced fields, adjust the home-charging percentage and your home electricity c/kWh. If you know your public station's per-kWh price, divide it by your home rate to estimate the multiplier. Try scenarios at 100%, 80%, and 50% home charging to see where the break-even shifts.

Frequently asked questions

What is the default charging mix in CarCostIQ?

80% home charging by default — most Australian EV owners do the bulk of their charging at home, with the remainder priced at the regional public rate. Open advanced fields to change the home-charge percentage and see how public charging affects total cost.

How much does public DC charging cost in Australia?

Prices range from $0.40 to $0.65+ per kWh depending on the network, speed, and location. Some networks offer subscription plans that reduce the per-kWh rate.

Can I model free workplace charging?

Yes — treat workplace charging as home-rate charging (or lower your home c/kWh to reflect the blended cost of home + free workplace).

Does charging speed affect cost?

In my model, cost depends on c/kWh, not charging speed. In practice, faster DC stations tend to charge more per kWh than slower AC stations.

What if I have solar panels?

Lower your home c/kWh to reflect the effective cost of solar self-consumption (often 0–10 c/kWh). This significantly improves the EV's cost advantage.