FOLGEN SIE UNS
It doesn't deliver as promised in winter
Why batteries need their comfort temperature for optimum performance.
Hello GOFAST team,
Last spring, I decided to sell my old diesel car and switch to a fully electric Hyundai Kona. I chose the variant with the large 64 kWh battery, as I often cover longer distances at the weekends. And for those times, I make use of your fast charging stations. To begin with, everything was great – the Kona was able to charge with almost 80 kW and I was on my way again in 20–30 minutes. But since November there’s been something up with it and I’m getting lower and lower output. Last weekend, when we wanted to make a quick stop to charge at the McDrive in Martigny on the way home from skiing, there was just 20 kW trickling out, whereas you’re always talking about 150 kW. So then of course I have to listen to my friends trotting out the usual preconceptions about electric cars even more than usual. Is there something wrong with your machines, or what’s going on?
Thanks for your feedback and kind regards,
Selina
Hi Selina
Thanks very much for your query and for your visit to GOFAST HPC charging park in Martigny. We’re sorry your charging stop took longer than expected. Our charging points at the Martigny McDrive really do deliver an output of 150 kilowatts and there are currently no restrictions or issues with this. What you describe is a known weakness of electric cars in winter. As with other electric cars, the Kona’s battery will actually limit its charging power depending on the battery temperature. The ideal conditions are a battery temperature of 25°C or more. The Kona will then charge – depending on the battery’s state of charge – with up to 81 kilowatts. If, on the other hand, the battery temperature is under 5°C – as it presumably was after your day of skiing – then it only charges with 20 kilowatts.
Why we don’t skip nimbly through the snow in heavy winter coats and moon boots
It is indeed inconvenient that in winter especially, when electric vehicles already need more energy than in summer for the same distance, vehicles charge more slowly due to a cold battery. But there’s a physical reason for this that sadly cannot be eliminated. Put simply, at a fast charging station, the battery is filled with energy under high pressure. This energy is then saved in the battery in a chemical process. When it is colder, the speed of the chemical reaction is slower – just as we humans don’t exactly skip nimbly through the snow wearing heavy coats and moon boots in winter, but tend to make our way at a slightly more leisurely pace. If high charging outputs didn’t take this temperature-driven sluggishness into account, it would dramatically reduce the service life of the battery. That is why the vehicle’s battery management system (BMS) constantly monitors the battery and communicates the optimum charging output to the fast charging station. Ultimately, therefore, our HPC chargers deliver only the charging output that the battery can effectively tolerate.
Rule of thumb: batteries are just like us humans
There is a simple rule of thumb when it comes to the ideal conditions for batteries: the batteries of electric vehicles are actually similar to us humans. They do best when temperatures are warm and summery, and nights are mild. Say about 25°C. You can find the temperature-adjusted charging behaviour we would expect from a Hyundai Kona in the table below.
Experience values with the Hyundai Kona Electric (2018, 64 kWh)
| Battery temperature | Charging power |
| < 5 oC | ~ 20 kW |
| 5-10 oC | ~ 30 kW |
| 10-25 oC | ~ 50 kW |
| 25 - 35 oC | ~ 75 kW |
| > 35 oC | ~ 50 kW |
So as you can see, there is a little bit of truth to the preconceptions around electric cars experiencing challenges in winter. To make sure you have better charging experiences again in future, we have these three tips for you:
 |
Three tips for charging in Winter
|
Electric greetings,
Your GOFAST team