Get more out of every charge – the factors that control charging speed

Charging speed describes how quickly an electric car's battery can be recharged and is measured in kilowatts (kW). The higher the power transferred, the faster the charging process. However, this requires that both the car and the charger can handle the same power.

For example, if you use a charging box that can deliver 22 kW, but the car's own charger can only handle 11 kW, the speed is limited to 11 kW. With fast charging, the same principle applies; the car may have a capacity for 150 kW, but if the charging station only provides 100 kW, it cannot go faster than that.

In addition to the technology, the battery's current charge level, the temperature in and around the battery, and the age of the battery also play an important role. Even if the charger has high power, charging can still be slow if the circumstances are not optimal.

“There are many factors that affect charging, but most of it really comes down to planning. By understanding how the car behaves in different situations, you can both charge faster and extend the battery's lifespan,” says Martin Reinholdsson, Operations Development and Product Owner Inspection at Kvdbil .

Two ways to charge – AC and DC

When you charge your electric car, it can be done in two ways: with alternating current (AC) or direct current (DC).

AC charging is the most common way to charge in everyday life, for example via a charging box at home or at work. The power is usually between 3.7 and 22 kW, which means that a full charge can take between four and ten hours depending on the car model and battery size.

DC charging, also known as fast charging, is mainly found at public charging stations along the roads. These chargers offer significantly higher power, from 50 kW and up, and can often charge the battery up to 80 percent in under an hour. However, this type of charging places a higher load on the battery.

Why does charging slow down when the battery is almost full?

When the battery is close to full charge, the speed is automatically reduced. This is done to reduce wear and avoid overheating, which in turn extends the battery's lifespan. Temperature also has a significant impact on charging capacity.

– Cold and heat affect the charging speed. Optimal conditions are around 20–25 degrees, but it is quite rare to have these temperatures all year round, says Martin Reinholdsson.

He explains that many modern electric cars are therefore equipped with a system that can preheat the battery before charging. This allows the charging effect to be optimized even in cold conditions, which both speeds up the process and reduces the risk of wear.

– Preheating the battery is actually what makes the biggest difference to the charging speed while driving, and it is also something that the driver can influence themselves. Generally, it is best to let the car's navigation system plan the preheating, so that the battery is at the right temperature when you arrive at the fast charger.

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How to charge smarter in everyday life

To charge as efficiently and gently as possible, it is important to understand how the battery feels best and adapt your charging pattern accordingly.

– The battery thrives best when the charge level, or SoC (State of Charge), is between approximately 20 and 80 percent. At levels above 80 percent, the voltage in the cells increases, which puts more strain on the battery, explains Martin Reinholdsson.

He therefore recommends that in everyday driving, you should avoid charging to 100 percent, unless absolutely necessary. At the same time, you should avoid completely draining the battery. Regular AC charging is the most gentle.

– Fast charging is a good complement on long trips, but should not be used unnecessarily. And if you need to charge to 100 percent before a longer trip, do it in connection with your departure, for example the night before, says Martin.

Summary: How to max out every charge

Charging an electric car is more than just finding an outlet; it's a combination of technology, temperature and habit. By keeping the battery's charge level between 20 and 80 percent, avoiding unnecessary frequent fast charging and ensuring that the car is at the right temperature when charging, you can both speed up the process and extend the battery's lifespan. Of course, aging cannot be stopped, but with the right charging strategy, wear and tear can be slowed down.

Martin reminds us that many of the most important choices are made in everyday life, not on long journeys.

– It's often the small routines that make the biggest difference. If you get to know your car and plan your charging a little smarter, you'll get a smoother ride while saving time and getting a battery that lasts longer.

By understanding how different factors affect charging, from battery condition to whether you're using AC or DC, it becomes easier to plan trips, reduce wait times, and get more out of each charge.