Dosing device (100) for dispensing a specified vol″ ume of liquid, comprising an electromagnet (1 11) and being adapted to hold a pump (1 12) with a magnetisable pumping member (1 10) displaceable under the action of the electromagnet when the pump is held by the dosing device. The dosing device further comprises a portable voltage source (1 13) adapted to energize the electromagnet by repeated current pulses and to measure the current intensity at least once per pulse, thereby estimating the charge amount in each pulse, until a total charge amount corresponding to the speci″ fied volume of liquid to be dispensed has been supplied. A method including pulse-wise activation of an electromagnet actuating a pump having a magnetisable pumping member is also disclosed.