The invention relates to an SOH (state-of-health) online
estimation method of a
battery pack. The SOH online
estimation method comprises the following steps of: measuring temperature T,
voltage V and current I of an electric automobile during actual operation to acquire the following function: SOC (state-of-charge)=f(T, V, I) by utilizing a
normalization algorithm, establishing a
database with one-to-one correspondence between the temperature T, the
voltage V and the current I and the SOC, measuring the SOC of a
monomer battery with lowest
voltage in an online manner by utilizing the
database, and further measuring the SOH of the
battery pack. The SOH online
estimation method disclosed by the invention has the beneficial effects that: 1) as the measured SOC is that of the
monomer battery with the lowest voltage, which is a key factor for restricting the
discharge capacity of the
battery pack, a user can know the SOH of the batteries in a more visual manner, the remaining capacity of the batteries can be judged in a more accurate manner by combining with the SOC value, and the continue voyage course of the electric automobile can be estimated in a more accurate manner; and 2) if the problem is caused by attenuation of the
battery capacity, the problem can be obviously seen through the SOH, and the efficiency of after-sale service is improved.