Abstract: A battery charger for charging rechargeable batteries and/or battery packs is disclosed. Preferably the charger can apply two modes of charging a battery. In a normal charging mode a battery is charged to full capacity at a low rate. In a boost charging mode the battery is charged very rapidly and preferably only to a certain degree, such as 75% of its maximum capacity. The boost charging mode makes it possible to provide some charge to the battery when the time available for charging is limited. The boost charging method is based on a very high initial charging current (Iinit) The initial current (Iinit) is such that a predetermined maximum charging voltage (Vmax) is reached almost immediately. The charging current is then decreased in such a way that the charging voltage (Vcharge) is maintained substantially constant at the maximum charging voltage (Vmax).

Abstract: A battery charger (1) for charging rechargeable batteries (5) and/or battery packs is disclosed. Preferably the charger (1) can apply two modes of charging a battery. In a normal charging mode a battery is charged to full capacity at a relatively low rate. In a boost charging mode the battery is charged very rapidly and only to maximally 80% of its full capacity. The boost-charging mode makes it possible to provide some charge to the battery (5) when the time available for charging is limited. Due to the partial charging a much higher charging current than allowed at normal charging may be applied during boost charging.