750km road trip in my electric car

What I learned about EV fast charging

For those unfamiliar with electric vehicle terms, there is a thing called ‘Fast Charging’, also known as ‘DC fast charging’, or ‘rapid charging’ or ‘ultra rapid charging’ depending on which type of marketer you come across.

Before fast charging came along, when the first electric cars became available at the start of this decade, there was just ‘charging’ and it meant plugging the car into mains and it would take overnight if not more to reach full battery. This charging rate is hardly suitable for long distance driving, compounded by the fact that the range of a full battery is already far below the range of a petrol car.

‘Fast Charging’ simply refers to the use of a charger that can supply higher power, therefore enabling you to drive more kilometers in a shorter charge time.

The typical use case for fast chargers is to enable long distance driving. With these chargers placed strategically along highways, the user experience of driving those long distances from A to B in an electric car becomes comparable to driving a petrol car and filling up along the way.

I have recently had the pleasure of driving an Opel Ampera-e (in USA this same car is the Chevrolet Bolt), a fully electric car, in and around Amsterdam city and on a 750km round-trip journey into Germany. This was the first time I’ve spend a good amount of time driving an electric vehicle (EV) and the experience of charging it at a ‘servo’ on the side of the highway, made me realise how close we are to mass adoption.

Currently, Norway has the highest penetration of electric vehicles and charging facilities. Range anxiety is a thing of the past in these select European countries, and major cities and routes around the world should expect the rise of electric cars (autonomous cars which would mostly be electric) and infrastructure within the next decade.

AC charging vs DC charging
To help contextualise the DC fast charging infrastructure I used, it is useful to learn the difference between AC and DC charging.

The battery technology used in EVs today, is Lithium-ion, just like the battery in your laptop or phone, and this is a DC battery.

The electricity on the grid is AC. In order to charge the battery, at some point, there needs to be a converter to change from AC to DC. With AC charging, the electricity coming into the car is AC, and gets converted to DC by a rectifier installed inside the car. The Opel Ampera-e can handle a maximum AC load of 7.4kW (which translates to about 44km of range per hour of charging).

Higher AC inputs are possible, but that would mean the rectifier inside the car would be bulkier and require cooling. Additionally, high power AC outlets are few and far between. These conditions with AC charging makes it difficult to be classed as a fast charging option. At 7.4kW AC (maximum AC power that the Ampera-e can take), the charge time is about 8 hours.

With DC charging, the AC gets converted outside of the car, at the charging station. The newer DC charging stations are wired up to 3-phase AC (unlike the single phase AC at your home) and can deliver much more power. This is why DC charging is alternatively termed ‘Fast Charging’.

The typical DC charger these days can deliver 50kW. The FastNed charges I encountered were all 50kW. The one I used in Germany can supposedly provide a maximum of 350kW, however this is untested as the Ampera-e charges at a maximum of 80kW DC (under factory conditions).

Physically plugging in the charger
In terms of physically charging the car, I was slightly disappointed to learn that the transition from filling up a petrol car, to charging an EV, was so seamless and second nature.

The socket on the Ampera-e hides behind a familiar flap, and the process of charging is involves dislodging a charger plug that is attached to the charging unit with a cable/lead that is similarly sized to a petrol pipe, and plugging it into the car.

I had imagined something a bit more graceful and futuristic than a bulky charger cable. At least, I don’t have to stand there holding it in. Once the plug is connected, the car locks on to it, and it can only be released by pressing the charger release button on the car’s remote.

Interesting fact: The CHAdeMO method was developed in Japan and most of the Japanese EVs use it. “cha demo” is part of a phrase “cha demo ikaga desuka” which translates to “How about a cup of tea” (while you wait for your EV to charge up!)

The vehicle controls the charging rate
Did you know that even your phone has a battery management system (BMS) that governs the charge and usage of the battery? It’s no different in an electric car.

In terms of charging, the BMS ensures the health of battery by ensuring the charging happens at a specific current profile suited to the particular battery.

A relatively discharged Li-ion battery can be charged at a higher current up to a certain battery voltage, and then the charging current should drop off. This profile means it takes longer to charge the battery from half-full to full, than it is to bring it to the midway point. This is evident in the pictures below where the car requests much higher power when the battery is half full as opposed to when it is almost full.

The BMS also disallows charge at very low temperatures and at very high temperatures. The Opel Ampera-e has a thermal management system to heat or cool the battery to keep it in a reasonable temperature range during charge and discharge; some EVs do not have this feature and may have trouble with charging in harsh climates.

I met an ex-Tesla technician who told me the story of his numerous site visits to support Tesla drivers who complained about the car not charging. He explained how it was snowing at -20 deg. C outside and all that was required was a 7 to 10 minute wait for the car to warm up the battery. Apparently, this is not something a salesman would mention.

Forget the ‘fill up the tank’ mentality
If you’re highway driving and 80% full battery will cover the distance to the next charger, then you will experience time savings by not waiting until 100% full. It will also mean that you are taking care of the battery!

How long did it take to charge?
I did not time the operation, rather, I went to the servo toilet and bought some snacks and played soccer with my kids while we waited for the car to charge up to something reasonable like 65 or 70%. The car estimates a range for you based on battery capacity and we judged how long we needed to stay based on how much traveling we would do until our next planned stop.

We used FastNed and Ionity DC charging stations in Germany and the car could request the car’s maximum 50kW / 125A. According to the official Ampera technical specs, 30 minutes of charging at 50kW DC can give you (theoretically) 150km in range.

So, right now, charging up your EV is going to take longer than filling up a petrol vehicle. It’s probably good idea to stop for at least 20 minutes anyway. But for really long-haul drives, it would help if the charge times were faster. For this, both the charging station and the electric cars need to evolve.

The Ionity chargers can supposedly supply 350kW of power, which is much more than the limit of 80kW by the vehicle. I have an inkling it won’t be long until car manufacturers release models that can charge at higher currents. I have no reservations that at some point, charging time will converge to be comparable with that of filling up the tank.

Final words
FastNed was billing at 59 Euro cents per kWh. Ionity was free as we used it during the grace period. Our average electricity usage per 100km was 17.2kWh (easily seen on the driver’s display). Using the FastNed price, this calculates to be €10.15 per 100km, assuming the same driving style.

Final Final words
Please give me a clap if you learned something from this article. Feel free to leave comments or questions.

My next article is on the Opel Ampera-e itself; what it looks like inside, the driving experience and my favourite features. Follow me to be notified.

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