You plug into the fast charger with high expectations: 150 kW should get you to 80% in 20 minutes. But the display shows only 47 kW. What happened? The charging speed of an EV is affected by a whole range of factors — and most of them have nothing to do with the charging station itself. Here we explain everything that determines how fast you actually charge.
The Charging Curve — The Most Important Factor
The single most important factor for charging speed is the battery level (State of Charge, SoC). EVs don't charge at constant power from 0 to 100%. Instead, they follow a charging curve that varies with the battery level.
Typical charging curve for a modern EV:
- 10–30%: Peak power — the car draws as much as the charger can deliver
- 30–50%: Still high power, but starting to taper off
- 50–80%: Gradual reduction — perhaps 60–70% of peak power
- 80–100%: Significant reduction — often only 20–30 kW
The charging curve is unique to each car model. Some cars (like the Hyundai Ioniq 5 with its 800V architecture) maintain high power for longer, while others drop off more quickly.
Battery Temperature — The Cost of Cold
Norwegian EV owners know this well: charging is slower in the cold. Battery temperature has a dramatic impact on charging speed.
Why? Lithium-ion batteries have optimal performance between 20 and 40 degrees. In cold weather, internal resistance in the cells increases, and the battery management system (BMS) reduces charging power to protect the battery.
The effect of temperature:
| Battery temperature | Expected charging power |
|---|---|
| Below -10 °C | 20–40% of max |
| 0 °C | 50–70% of max |
| 10 °C | 70–90% of max |
| 20–35 °C | 90–100% of max |
| Above 45 °C | Reduced (heat protection) |
Tips for Faster Charging in the Cold
- Preheat the battery — many cars have a battery preconditioning function. Activate it 20–30 minutes before you reach the charging station.
- Drive for a while before charging — driving warms up the battery naturally. On road trips, the battery is often already warm when you stop to charge.
- Use the navigation system — cars like Tesla, Hyundai/Kia, and BMW preheat the battery automatically when you navigate to a fast charging station.
- Avoid charging right after long parking in the cold — let the car drive a few kilometres first.
The Car's Maximum DC Power
Each EV has a specified maximum DC charging power. This varies enormously:
- Older/budget EVs: 50–100 kW (Nissan Leaf, VW e-Up, MG4)
- Mid-range: 100–170 kW (VW ID.4, Tesla Model 3 SR, Skoda Enyaq)
- Premium: 200–270 kW (Tesla Model 3 LR, BMW iX, Polestar 2)
- Top models: 250–350 kW (Hyundai Ioniq 5, Porsche Taycan, Lotus Eletre)
Not sure what your car supports? Enter your car model on the homepage and we'll calculate charging costs based on your car's specifications.
The Charging Station's Power
The charging station sets an upper limit for what you can get. The nine major operators in Norway — Recharge, Mer, Eviny, Circle K, Ionity, E.ON, Kople, Uno-X, and Tesla — offer different power levels:
- 50 kW: Older fast chargers, still found in many locations
- 150 kW: Standard at most new charging parks
- 300–350 kW: Ultra-fast chargers (Ionity, Recharge, Tesla Supercharger V4)
If your car supports 250 kW but the charger only delivers 50 kW, you get a maximum of 50 kW. And vice versa: a 350 kW charger won't help if your car can only draw 100 kW.
Rule of thumb: You always get the lower value of the car's max and the charger's max.
Shared Power Between Cars
Many charging stations share power between two charging points. If you plug into a 150 kW charger and someone is already charging at the neighbouring point, you might get 75 kW each.
This is common at:
- Older Circle K stations (50 kW shared = 25 kW per car)
- Some Recharge stations with pairwise sharing
- Older Tesla Supercharger V2 (pairwise A/B sharing)
Cable Limitations
The charging cable can also limit speed:
- Type 2 cable for AC: Most cables are limited to 7.4 kW (single-phase) or 22 kW (three-phase)
- CCS cable for DC: Thinner cables on older chargers can only handle 200 A, which limits power
- Liquid-cooled cables: Newer ultra-fast chargers use liquid-cooled cables that can handle 500 A+, enabling 350 kW
For AC charging, it's also important that the cable matches the car's capacity. An 11 kW wallbox with a 16A cable will limit a 22 kW-capable car to 11 kW.
Grid Capacity
Even the best charger is limited by the power grid it's connected to. In locations with a weak grid (typically in rural areas), the charger may lack the capacity to deliver full power.
Some charging operators use dynamic load balancing to optimally distribute available power between charging points. Others have battery buffers at the station to compensate for grid limitations.
10 Tips for Faster Fast Charging
- Charge between 10 and 80% — that's the sweet spot on the charging curve
- Preheat the battery — use navigation to the charging station or manual preconditioning
- Choose a charger with the right power — a 50 kW charger is wasted time for a 250 kW car
- Avoid shared power — choose a charging point without a neighbouring car when possible
- Charge after driving — the battery is already warm
- Keep the battery between 20 and 80% daily — optimal for battery health and charging speed
- Check the charging curve for your car — some cars have a flat, fast curve; others drop steeply after 50%
- Choose 800V chargers if your car supports it — Hyundai, Kia, and Porsche models benefit from this
- Plan road trips with charging stops — shorter, more frequent stops are faster than one long one
- Compare operators — the price differences are significant, and the most expensive isn't necessarily the fastest
Charging Speed and Price Are Connected
Faster charging is often more expensive. Several operators charge a higher price per kWh at ultra-fast chargers (250+ kW) than at standard fast chargers (50–150 kW).
In 2026, prices vary from approx. 2,49 kr/kWh to 5,99 kr/kWh per kWh among the nine major operators, depending on speed and whether you're a registered user or drop-in.
See all updated prices to find the cheapest operator for your charging speed.
Why does my car charge slower than the stated maximum?
The stated maximum power is a theoretical ceiling under optimal conditions. In practice, power is reduced by battery temperature (especially cold), high battery level (the charging curve drops above 50%), shared power with other cars, and the charging station's capacity. It's normal to see 60–80% of stated maximum under real-world conditions.
Is it better to charge often to 80% than rarely to 100%?
Yes, both for battery health and time efficiency. Charging between 20 and 80% occurs in the most efficient range of the charging curve. Regularly charging to 100% at a fast charger stresses the battery unnecessarily and takes a disproportionately long time (the last 20% can take as long as the first 60%).
What's the difference between 400V and 800V EVs for charging?
800V architecture (used by Hyundai Ioniq 5/6, Kia EV6/EV9, Porsche Taycan, and others) allows higher charging power with lower current. This means faster charging and less heat loss. An 800V car can typically charge from 10 to 80% in 15–20 minutes on a 350 kW charger, compared to 25–35 minutes for a comparable 400V car.
Does the outside temperature affect charging speed even if the car has a heat pump?
Yes. The heat pump helps heat the cabin efficiently, but it has limited ability to quickly heat the battery pack itself. Battery preconditioning (activated by navigating to a charging station) is far more effective at ensuring optimal battery temperature before charging.
How do I find the charging curve for my car?
The charging curve is rarely provided by the manufacturer. The website fastned.nl/benchmark and YouTube channels like Bjørn Nyland test charging curves for most EVs. You can also see real charging speed on the car's display during fast charging — note the values at 20%, 50%, and 80% to get a good overview.
Kilder
- Fastned Benchmark — Independent charging speed tests for EV models
- Bjørn Nyland (YouTube) — Independent EV charging tests and reviews
- CharIN e.V. — CCS charging standards and specifications
- Battery University — Battery technology education — charging curves and temperature effects