The present invention relates to a medical infusion pump (1), comprising a power source (2), a processor (3) and a voltage supervisor (4), wherein the voltage supervisor (4) is configured to monitor the input voltage (VDD) of the processor (3), the voltage supervisor (4) is configured to respond if the voltage (VDD) drops to a predetermined level which is above the reset voltage level of the processor (3) and the processor (3) is configured to start logging the voltage (Vbat) of the power source (2) when the voltage supervisor (4) responds.
