Originally Posted by jusmee
Actually, I would have hoped that the detection of a battery too low to allow turn on would be independent of the battery gauge. The electronics in the reader will have an absolute minimum voltage specification, and protection against operation below that voltage should against a known voltage reference (not some vague 'calibration' against a partially charged battery). It's an easy, simple, and cheap electronic circuit.
It is and it does, that is why there is still enough power to beep at you and flash the lights. The problem is that there is no warning for the user other than the battery gauge thus it seems to be on full until it fails.