I have recently acquired a Fluke 289 DMM and would like to make full use of is by logging a battery's voltage under load. I want to measure the change in voltage against time of an AW 18650 battery while powering a flashlight. Does anyone know how to do this safely? I know how to make current measurements, but have never tried measuring voltage while providing current to a flashlight. A diagram or a simplified description of the setup would do.