Meters tend to use power when they are actually taking a reading, so they are prone to battery drainage if they are left with the power on and the button used to take a reading is compressed in the case. A flash meter would use more power, I suspect, if you normally use it in the non-corded mode, when it is on and waits for the flash to give the reading. If you plug the meter into the strobe sync, and activate it with the button on the meter, it should use less power.