Disclosed are a control method for a battery system, device, and a battery system, the method comprising: determining that a state of charge (SOC) and a current of a first battery cluster in N battery clusters meet a first preset condition, the first preset condition including: the SOC of the first battery cluster is greater than a first threshold and the current of the first battery cluster is greater than a second threshold or less than a third threshold, wherein the second threshold is set according to a maximum permissible current of the first battery cluster, and the third threshold is set according to an average current of the N battery clusters; and sending first information to a first DCDC converter connected in series with the first battery cluster., the first information being used to instruct controlling the current of the first battery cluster to reach a first preset current.