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The transition to electric mobility is no longer a mirage of the future; it is the reality of the roads today. However, for those who have been used for decades to looking at the illuminated totems of gas stations and knowing exactly the price of a liter of gasoline or diesel, the shift to kilowatt-hours (kWh) can seem like a real puzzle. The question echoing in the minds of all potential buyers is always the same: after all, how much does it cost to charge an electric car?
The short and honest answer is: it depends. It depends on where you charge, what time you charge, how fast you charge, and what electricity contract you have. While filling up a fossil fuel tank has a relatively uniform cost across the country (with variations of a few cents), filling a battery with electrons can cost anywhere from zero euros (if you have solar panels at home) to amounts approaching the cost of gasoline (if you use ultra-fast chargers on highways without the proper card).
In this comprehensive and exhaustive guide for AUTO.MOTO.pt readers, we will demystify all the variables, present real calculations, and show you how to optimize your costs, especially if you are considering purchasing electric used cars, where calculating the return on investment (ROI) is fundamental.
1. Basic Math: Understanding the Kilowatt-hour (kWh)
To understand the cost, we first need to understand the unit of measurement. In combustion vehicles, we measure tank capacity in liters. In Electric Vehicles (EVs), we measure battery capacity in Kilowatt-hours (kWh).
An electric car's consumption is typically measured in kWh per 100 km (kWh/100 km), in the same way we measure liters per 100 km (l/100 km).
- An efficient city EV might consume between 12 to 15 kWh/100 km.
- A large electric SUV might consume between 18 to 24 kWh/100 km.
The Fundamental Calculation: Charging Cost = (Battery Capacity in kWh) x (Price per kWh).
Imagine you have a vehicle with a 60 kWh battery (a very common capacity in today's market) and the battery is completely flat (0% to 100%). If the cost of electricity is €0.15 per kWh, the calculation is: 60 kWh x €0.15 = €9.00 for a full charge.
With this 60 kWh battery, assuming an average consumption of 15 kWh/100 km, you will be able to travel about 400 kilometers. Therefore, you spent 9 euros to travel 400 km. This is the baseline scenario, but let's now dive deeper into the different charging methods.
2. The Ideal Scenario: Home Charging
The vast majority of EV users (about 80 to 90%, according to various industry estimates) charge their cars at home, overnight. This is, by far, the cheapest, most convenient, and most efficient way to keep your vehicle running.
2.1. Electricity Tariffs in Portugal
In Portugal, the cost of home charging is closely tied to your energy supply contract. To check current average tariffs and free market options, the ERSE (Energy Services Regulatory Authority) provides crucial simulators for consumers.
There are different types of tariffs:
Simple Tariff (Tarifa Simples): The price of kWh is the same at any time of day or night. It averages around €0.16 to €0.18 (including taxes).
Dual-Rate Tariff (Tarifa Bi-horária): The price varies depending on the time. During off-peak hours (usually at night and weekends), electricity is substantially cheaper, dropping to figures around €0.09 to €0.11 per kWh. During peak hours, the price is higher.
Practical Example (60 kWh Battery on Dual-Rate Tariff): If you charge the same 60 kWh overnight (off-peak hours) at €0.10/kWh, the total cost will be: 60 x €0.10 = €6.00. Cost per 100 km = €1.50. (An unbeatable figure compared to any combustion vehicle).
2.2. The Importance of a Wallbox
Although you can charge your EV from a standard domestic socket (Schuko plug), this is highly discouraged for daily use. It is extremely slow (it can take 24 to 30 hours for a large battery) and can cause overheating in your home's electrical wiring. The solution is to install a Wallbox (a dedicated wall charger). This involves an initial investment (between €500 and €1200, including installation), but it allows charging at powers of 3.7 kW, 7.4 kW, or even 11 kW (if you have a three-phase setup), fully charging the car safely during a night's sleep.
3. The Urban Jungle: The Public Charging Network (Mobi.E)
When you leave home or need to make long trips, you will have to resort to the public network. In Portugal, the network is managed by Mobi.E, a model that is innovative at a European level but can be complex to understand initially.
On the Mobi.E network, you do not pay directly to the charging station. The cost is billed by your CEME (Electricity Retailer for Electric Mobility), via an RFID card or app, and comprises several components:
- The Energy Component (CEME): The price your retailer charges per kWh or per minute.
- The Station Component (OPC - Charging Point Operator): The fee charged by the company that installed and maintains the physical station on the street (like Galp, EDP, Ionity, etc.). This can be charged per minute, per kWh, or a mixed activation fee.
- Taxes and Fees: The EGME fee (Electric Mobility Network Managing Entity) and VAT.
3.1. Normal Charging (AC - Alternating Current)
These are the most common street chargers, generally offering powers of 11 kW to 22 kW. They are ideal for when you go to the mall, the gym, or leave your car parked on the street during the workday.
- Average Cost: Around €0.25 to €0.35 per kWh (depending on the CEME + OPC combination).
- Cost to fill 60 kWh: About €15 to €21.
- Cost per 100 km: About €3.75 to €5.25.
3.2. Fast and Ultra-Fast Charging (DC - Direct Current)
Found mainly on highways and service stations. They charge the battery from 10% to 80% in 20 to 40 minutes (powers of 50 kW, 150 kW, or even 350 kW). Convenience comes at a high price.
- Average Cost: Can vary drastically, but is normally between €0.45 and €0.79 per kWh.
- Cost to fill 60 kWh: Can range from €27 to €47.
- Cost per 100 km: Between €6.75 and €11.85. (In this scenario, the cost per kilometer begins to approach the cost of an efficient diesel car).
4. Variables That Affect Cost and Efficiency
The cost of charging is not static; it is influenced by how and where you drive. The International Energy Agency (IEA)has published detailed reports on how external factors impact the overall efficiency of electric vehicles.
- Outside Temperature: Lithium-ion batteries do not like extreme cold or extreme heat. In winter, the car needs to use battery energy to heat the battery itself and the cabin, which can reduce range by 15% to 25%. Consequently, you will spend more kWh to travel the same distance.
- Speed: In combustion cars, the highway is often where they are most efficient. In EVs, it's the opposite. The absence of a multi-ratio gearbox means that driving at 120 km/h consumes exponentially more energy due to aerodynamic drag than driving at 50 km/h in an urban circuit.
- Driving Style: Utilizing regenerative braking (which charges the battery as you slow down) on urban routes or mountain descents can recover a surprising amount of energy, lowering your effective cost per kilometer.
5. The Impact on the Used Car Market
The issue of charging and battery health is undoubtedly the primary concern for those navigating the market looking for opportunities. And this is where correct evaluation comes into play.
Buying electric used cars is an excellent way to enter zero-emission mobility without the exorbitant upfront cost of a new vehicle (which usually suffers steep depreciation in the first three years). However, when an experienced buyer evaluates the vehicle, the focus is not so much on the engine's mileage, but on the State of Health (SoH) of the battery.
The SoH indicates the maximum charge retention capacity of the battery compared to when it was new. A used car with an SoH of 90% means its battery has lost 10% of its capacity. If the original battery was 60 kWh, it can now only store 54 kWh. This affects the user in two ways:
- You will have less total range.
- The charging cost to go "from 0 to 100%" will be slightly lower (because the physical capacity has decreased), but you will have to charge more frequently to cover the same kilometers over the month.
Organizations like the UVE - Electric Vehicle Users Association always recommend demanding a certified battery health report before finalizing any deal. If the battery is in good condition, electric used cars represent colossal long-term savings, not only in electricity compared to fossil fuels but also in maintenance (no oil changes, fuel filters, timing belts, and much less brake pad wear).
6. Direct Comparison: Electric vs. Combustion
To put things in definitive perspective, let's compare the annual costs for an average Portuguese driver who travels 15,000 km per year.
Scenario A: Gasoline Car (Consumption 6.5 l/100 km at €1.70/liter)
- Cost per 100 km: €11.05
- Cost for 15,000 km: €1,657.50 / year.
Scenario B: Electric Car charged 100% on Fast Public Network (Consumption 15 kWh at €0.55/kWh)
- Cost per 100 km: €8.25
- Cost for 15,000 km: €1,237.50 / year. (Saves money, but the margin isn't giant).
Scenario C: Electric Car charged 90% at Home (Dual-rate €0.10) and 10% on Fast Public Network
- Mixed cost per 100 km: (0.9 * €1.50) + (0.1 * €8.25) = €1.35 + €0.82 = €2.17.
- Cost for 15,000 km: €325.50 / year.
The difference is abysmal. In Scenario C (the most realistic for most owners with a garage), fuel savings exceed €1,300 per year. Over four years, you recover more than €5,200 in energy alone.
7. The Future of Charging: V2G and Dynamic Tariffs
The landscape of charging costs is constantly evolving. In the coming years, we will see the proliferation of dynamic tariffs (where the price of energy tracks the wholesale market in real-time, allowing you to charge the car for pennies when there is excess wind or solar production on the national grid). Furthermore, Vehicle-to-Grid (V2G) technology will allow your car to be not just a consumer, but a mobile battery for your home. You could charge the car overnight at low prices and use the car's energy to power your house during the late-afternoon peak hours when electricity is most expensive.
Conclusion and Your Next Step
The answer to the question "how much does it cost to charge an electric car" is, as we've seen, highly malleable. It requires a change of habits and a minimum of prior planning. However, the math doesn't lie: with access to home charging or charging at a workplace, electric mobility is undeniably and overwhelmingly more economical than any fossil fuel alternative.
If these numbers have convinced you that it's time to make the transition, or if, on the contrary, you prefer to remain faithful to traditional internal combustion while the public network still grows and matures, the next step is to explore the market.
Don't let your next car be a shot in the dark. To find the right vehicle—with a proven history, safety, and at the best prices on the national market—you need the right partner.