A method for estimating a minimum continuous and transient supply voltage (U min_con, U min_trans) of a battery when the battery is connected and supplying electrical power to a vehicle electrical circuit, the method comprising: performing a first electrical load test of the battery by executing a first battery discharge sequence including a continuous discharge current and at least one transient discharge pulse, while registering parameters characterising a discharge current profile and discharge voltage profile of the battery during the first battery discharge sequence, performing a second electrical load test of the battery by executing a second battery discharge sequence including a continuous discharge current and at least one transient discharge pulse, while registering parameters characterising a discharge current profile and discharge voltage profile of the battery during the second battery discharge sequence, determining a value of a continuous battery coefficient reflecting a ratio of battery internal resistance to continuous discharge current based on said registered parameters, determining a value of a transient battery coefficient reflecting a ratio of battery internal resistance to transient discharge current based on said registered parameters, obtaining information about a maximum expected continuous load current (I con_new) and maximum expected transient load current (I trans_new) of the vehicle electrical circuit, calculating an estimate of the minimum continuous supply voltage (U min_con) from the battery using said continuous battery coefficient and said maximum expected continuous load current (I con_new), and calculating a minimum transient supply voltage (U min_trans) from the battery using said transient battery coefficient and said maximum expected transient load current (I trans_new), when the battery is connected and supplying electrical power to said vehicle electrical circuit. performing a first electrical load test of the battery by executing a first battery discharge sequence including a continuous discharge current and at least one transient discharge pulse, while registering parameters characterising a discharge current profile and discharge voltage profile of the battery during the first battery discharge sequence, performing a second electrical load test of the battery by executing a second battery discharge sequence including a continuous discharge current and at least one transient discharge pulse, while registering parameters characterising a discharge current profile and discharge voltage profile of the battery during the second battery discharge sequence, determining a value of a continuous battery coefficient reflecting a ratio of battery internal resistance to continuous discharge current based on said registered parameters, determining a value of a transient battery coefficient reflecting a ratio of battery internal resistance to transient discharge current based on said registered parameters, obtaining information about a maximum expected continuous load current (I con_new) and maximum expected transient load current (I trans_new) of the vehicle electrical circuit, calculating an estimate of the minimum continuous supply voltage (U min_con) from the battery using said continuous battery coefficient and said maximum expected continuous load current (I con_new), and calculating a minimum transient supply voltage (U min_trans) from the battery using said transient battery coefficient and said maximum expected transient load current (I trans_new), when the battery is connected and supplying electrical power to said vehicle electrical circuit.