A battery protector with internal impedance compensation comprises: a logic circuit and delay module, an overcharge comparator, and an over-discharge comparator. The overcharge comparator has a positive terminal connected with a first adjustable reference signal and the over-discharge comparator has a negative terminal connected with a second adjustable reference signal and both of the other terminals of comparator are fed by the same partial voltage of the same voltage divider, which has two terminals, respectively, connected with the two electrodes of the battery. The first adjustable reference signal and the second adjustable reference are varied with the charging current or discharging current and the internal impedance of the battery.