You can change the display to voltage, and check with batteries fresh off of the charger, and again just before the camera shuts down due to low voltage (the canon firmware should start blinking a red battery icon just a little before that)
You may want to set the max slightly lower than "fresh off the charger" level, because that is typically over the nominal "full" voltage and they will drop down to a more reasonable level very quickly.
Note that the voltage is the *total* voltage seen for by the camera, so unless your camera uses 1 AA battery, 1.45 is probably not appropriate!