Most electric cars are equipped with Lithium-ion batteries. The charging process of these batteries can be simplified into two stages. Initially, the battery is charged with a constant current, where the charging current is at its highest and the battery charges the fastest. Once the battery reaches a certain voltage, charging moves to the next stage. A constant voltage is applied to the battery, causing the charging current to gradually decrease. Typically, this transition between the two phases occurs when the battery has reached approximately 80% of its total capacity.

The battery is charged at a maximum speed of up to 80%, but after that, the charging speed is gradually reduced. With fast charging, the battery only goes through the first part of the charging process. Fast charging is safe for the battery pack as long as the charging power (in kW) is 1.5 to 2 times the energy content of the battery pack (in kWh) (rule of thumb). However, it is harmful to the battery pack to only fast charge. It is important to regularly go through the part of the charging process with the constant voltage because this brings the battery cells into mutual balance.

When storing, it is advisable not to keep lithium-ion batteries fully charged. A fully charged battery that is not used can lead to degradation (irreversible reduction of maximum capacity). It is ideal to store the battery in a cool environment and let it rest with a charge of approximately 25% to 50%.