All EVs have a battery management system(BMS).. The battery management system is the unit that controls voltage, current and temperature. The battery management system also determines how fast the vehicle will charge, i.e. the charging speed. It does this to protect the battery as much as possible.
During a charging session, the battery management system continuously communicates with the charger to tell it how much power it should provide. EVs don’t charge at the same charging speed for the entire charging session, so if the battery is too cold/hot, or is nearly fully charged, fast chargers won’t charge very quickly.
Psst! If the charger is marked with a maximum of 150 kW, and your EV battery can charge at 350 kW, the charger will never provide more than 150 kW.
Our charging speeds
The charging speed says something about how fast the battery will charge. We measure this in kW (kilowatts). All our charging stations are marked with their maximum power. Find your nearest fast charger on our map of charging stations.
- Slow chargers have a maximum power of 3–22 kW.
- Rapid chargers have a maximum power from 50 kW.
- High speed chargers have a maximum power of 150 kW and up.
This is what happens in the battery when you charge
When you charge an EV battery, positive lithium ions are pushed over to a negative electrode until it is full. When the battery approaches a full charge, space also becomes cramped. Then, the electrode takes longer to free up space for the lithium ions that are on their way over.
This is the reason why the charging speed is reduced when you have reached a certain voltage level in the battery cells, usually when the battery is between 70 and 80 per cent charged.
The temperature for optimal battery charging is between 20–24 °C. Charging speed will drop if the temperature is too low or too high. When it is cold, the lithium ions will move more slowly in the electrolyte.
The electrochemical processes are also sensitive to high temperatures; even at the same charging power, the voltage in the battery pack could become higher than at more ideal temperatures. This could damage the cells, so the battery management system must reduce the charging speed.