Nowadays, charging an electric vehicle is more accessible than ever. With the arrival of cold winter temperatures, many electric vehicle drivers are wondering about charging their vehicle, in particular about its speed at fast chargers.
Charging speed is one of the determining factors in the intention to purchase an electric vehicle. However, charging can be slowed in cold weather, even at a fast charger! To optimize their charging experience in winter, EV drivers must understand what limits their vehicle's charging speed.
It is essential to know that charging speed depends mainly on two factors: the power of the charging station and the battery characteristics. Le Circuit électrique offers three power levels: 25 kW, 50 kW and 100 kW. These levels correspond to the maximum charging powers that fast chargers can provide. For example, a vehicle plugged into a 50 kW charger can charge at a maximum power of 50 kW.
In the vehicle, the battery management system (Battery Management System or BMS) communicates with the charger and adjusts the power according to the battery's characteristics. Thus, it is the vehicle that determines the power the charger must provide, in order to protect the battery and optimize its lifespan.
Regarding the battery characteristics, two elements must be considered: the state of charge and the battery temperature. First, the higher the battery's state of charge, the more the charging speed decreases, which happens gradually or in steps during charging. Thus, a vehicle's maximum charging speed is maintained for a certain time, which varies depending on the analysis made by the BMS at the start of charging. Afterwards, this speed decreases rapidly to protect the battery. Generally, when the battery is charged to 80%, the charging power requested by the vehicle falls significantly, which limits the usefulness of continuing to charge. After all, why pay the price of fast charging once the charging speed starts to decrease?
As for battery temperature, it should ideally be between 20 °C and 25 °C. If this is not the case, the vehicle will ask the fast charger to limit the power. Thus, the average power provided by the charger will be below its maximum power. This is why charging power is reduced during the hotter periods of summer or the colder periods of winter. In cold weather, EV drivers benefit from arriving at a fast charger with a vehicle whose battery has been warmed during the trip.
Charging tips
Here are three tips to follow to increase the effectiveness of charging at a fast charger in winter:
- Plug into the charger when the battery's state of charge is low, ideally below 30%.
- Park the vehicle inside a garage, when possible, to avoid the battery cooling down.
- Favor fast charging after a long trip, because the battery will have been warmed during its use.
What about ultra-fast chargers?
Currently, the Circuit électrique's 50 kW fast chargers meet the needs of the majority of electric vehicles running on Quebec's roads. Nevertheless, with the arrival of new models on the market, the Circuit électrique must diversify its charging offer to adapt to technological evolution and meet demand, while continuing to serve all regions of the province.
In this spirit, the Circuit électrique put 153 new fast chargers of different powers (25 kW, 50 kW and 100 kW) into service in 2020 in several regions of Quebec. In addition, it has begun testing new technologies as part of test benches. The first is already underway and there will be two others during the year. The Circuit électrique will collect essential data on the use of these new chargers, including actual charging speeds, in order to assess their adaptability to the grid and to our climatic conditions.
Learn more about the Circuit électrique powered by Hydro-Québec >>>
This sponsored content was produced as part of the Impulsion MTL 2020 event – The International Forum on Fleet Management.
