Method and device for charging a battery for a means of transport

A device for charging a battery (30) for a means of transport (90), the device comprising:

• an evaluation unit (10),
• a data input (12), and
• a data output (14),
• wherein the evaluation unit (10) is configured
• to ascertain, in connection with the data input (12), an open-circuit voltage of the battery (30) on the basis of a voltage ramp that is generated by a controllable DC-to-DC converter (40) that is electrically connected to the battery (30),
• to ascertain a differential internal resistance of the battery (30) on the basis of a predefined model for the differential internal resistance and the open-circuit voltage, wherein the predefined model for the differential internal resistance of the battery (30) is checked for plausibility and adapted in a phase in which the open-circuit voltage is ascertained and there is a predefined energy draw from the battery (30),
• to ascertain a target value for an output voltage of the DC-to-DC converter (40) on the basis of
• the open-circuit voltage of the battery (30),
• a predefined charging current of the battery (30), and
• the differential internal resistance of the battery (30), and,
• in connection with the data output (14), to charge the battery (30) using the target value for the output voltage in the DC-to-DC converter (40).