An ambulatory infusion device (10), the ambulatory infusion device (10) being designed to be carried by a user external of the body and concealed from view and for an extended time period, (a) the ambulatory infusion device (10) being designed to receive a user-replaceable battery (100) of variable individual characteristics, the battery (100) serving as primary power source of the infusion device (10) and being successively depleted during application, the ambulatory infusion device (10) further including: (b) a dosing unit with an electrically powered actuator, (c) an electronic controller, the controller controlling operation of the ambulatory infusion device (10), (d) a testing unit (110), the testing unit (110) being operatively coupled to the controller, the testing unit (110) being designed to carry out battery tests, a battery test including determining an off-circuit voltage and an internal resistance of the battery (100), (e) an alerting unit, the alerting unit being operatively coupled to the testing unit (110) and/or the electronic controller to provide an alert to a device user in dependence of a battery test result. In a device according to the present disclosure, the alert generation is adopted to the individual battery characteristics. Disclosed are further methods for carrying out battery tests with such devices.
