Well, it should be relatively easy to try to reproduce the experiment... but yes, I agree that a battery will be considered "dead" when the device it was poweri

Well, it should be relatively easy to try to reproduce the experiment... but yes, I agree that a battery will be considered "dead" when the device it was powering stops working with the provided voltage, and 0.6 volts is likely far below that voltage (except maybe for traditional flashlights with incandescent bulbs which get dimmer and dimmer, but will probably still work?).