Disclosed are ambulatory infusion devices, including: (a) an energy storage (100) for storing electrical energy required for powering the device, (b) a dosing unit with an electrically powered actuator and an electronic controller, the controller controlling operation of the actuator, (c) a testing unit (110) for testing the energy storage (100), the testing unit being designed to repeatedly carry out a test during operation of the device, the test including determining a control variable, the control variable being indicative of a capability of the energy storage (100) for further powering the device (10). In accordance with the invention, the testing unit (110) is configured to vary the testing of the energy storage in dependence of the control variable. Disclosed are further corresponding methods for testing an energy storage of an ambulatory infusion device.
