I am getting less than 400 shots on a charge.
Battery recharge performance indicates 3 bars green. battery communicates etc... No GPS, no WIFI running. Using 24 105 L lens . No Live View... No video taking.
Try a different battery, then try a different lens.
Also: will sucking the pics off of the camera via cable v. external card reader use significantly more charge?
My guess is that using the camera as a USB reader will use a lot more power, but that's just a guess. Fortunately, there's an easy way to check: Take the battery out of your camera, and see if your computer can still read files off the card.
If your computer sees the camera without its battery, then the camera was designed to draw power off of the USB bus, in which case using the camera as an interface doesn't run down your camera battery (though it might run down your laptop battery more quickly than a dedicated reader would). If it doesn't work without a battery, then yes, using your camera to transfer photos will drain the camera's battery.