A method and system for estimating the state-of-health of a battery The invention relates to a method for estimating the state-of-health, SoHest, of a battery in a vehicle, the method comprising: determining (100) a first battery property and a battery temperature of a battery in a vehicle; calculating (102) a state-of-health, SoHcalc, of a battery cell based on the determined first battery property using a predetermined model; providing (104) a function f estimating a battery cell degradation rate; updating (106) a state-of health estimated in a previous time step according to SoHest←SoHest+ƒ·dt+K·(SoHcalc−SoHest), where K is a gain factor which is dependent on operating conditions of the vehicle, and wherein K is modified (108) for each time step using a reinforcement learning agent.