Method for charging at least one low-voltage battery using at least one high-voltage battery during the operation of an electric vehicle

Abstract

The invention relates to a method for charging at least one low-voltage battery (14) using at least one high-voltage battery (16) during the operation of an electric vehicle (10). At least the following method steps are carried out: At least one high-voltage battery (16) is provided, comprising a plurality (82) of battery cells (24) connected in series, each battery cell (24) providing an individual voltage value (58). A voltage tap (80) is arranged on the plurality (82) of the series-connected battery cells (24) such that a number (84) of battery cells (24) remain below the voltage tap (80); furthermore, the at least one low-voltage battery (14) is connected to the voltage tap (80) via a charging switch (86).Then, the charging of the at least one low-voltage battery (14) by the at least one high-voltage battery (16) is started by temporarily closing (90) the charging switch (86) for at least a defined period of time (96, 98), during which a minimum number (85) of battery cells (24) from the number (84) of battery cells (24) remain in a half-bridge or full-bridge circuit (66, 72).

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