A method comprising: for a battery assembly comprising a first battery interface and a second battery interface connected in parallel: comparing a voltage of a first battery associated with the first battery interface and a voltage of a second battery associated with the second battery interface against a respective reference value; and controlling the current flow to and from each battery interface (111, 113) based on the comparisons; wherein controlling the current flow further comprises: adjusting the current flowing to the second battery interface so as to be compatible with a voltage profile exhibited at the first battery interface and adjusting the current flowing to the first battery interface so as to be compatible with a voltage profile exhibited at the second battery interface; directing a current from the first battery associated with the first battery interface to the second battery associated with the second battery interface while current is flowing from the second battery to a device being powered by the battery assembly; characterized in that, upon detecting that a current is being provided to the battery assembly: directing the current to the second battery interface; and when the voltage level at the second battery interface is greater than or equal to a stop voltage (Vstop) which indicates that charging at the second battery interface may be suspended, directing the current to the first battery interface. for a battery assembly comprising a first battery interface and a second battery interface connected in parallel: comparing a voltage of a first battery associated with the first battery interface and a voltage of a second battery associated with the second battery interface against a respective reference value; and controlling the current flow to and from each battery interface (111, 113) based on the comparisons; comparing a voltage of a first battery associated with the first battery interface and a voltage of a second battery associated with the second battery interface against a respective reference value; and controlling the current flow to and from each battery interface (111, 113) based on the comparisons; wherein controlling the current flow further comprises: adjusting the current flowing to the second battery interface so as to be compatible with a voltage profile exhibited at the first battery interface and adjusting the current flowing to the first battery interface so as to be compatible with a voltage profile exhibited at the second battery interface; directing a current from the first battery associated with the first battery interface to the second battery associated with the second battery interface while current is flowing from the second battery to a device being powered by the battery assembly; characterized in that, upon detecting that a current is being provided to the battery assembly: directing the current to the second battery interface; and when the voltage level at the second battery interface is greater than or equal to a stop voltage (Vstop) which indicates that charging at the second battery interface may be suspended, directing the current to the first battery interface. adjusting the current flowing to the second battery interface so as to be compatible with a voltage profile exhibited at the first battery interface and adjusting the current flowing to the first battery interface so as to be compatible with a voltage profile exhibited at the second battery interface; directing a current from the first battery associated with the first battery interface to the second battery associated with the second battery interface while current is flowing from the second battery to a device being powered by the battery assembly; characterized in that, upon detecting that a current is being provided to the battery assembly: directing the current to the second battery interface; and when the voltage level at the second battery interface is greater than or equal to a stop voltage (Vstop) which indicates that charging at the second battery interface may be suspended, directing the current to the first battery interface.