Seems to me this is by design, to avoid wasting massive amounts of power when the hammer wasn't being grasped. A Pro Mini draws a tiny amount of power, I'm tal

Seems to me this is by design, to avoid wasting massive amounts of power when the hammer wasn't being grasped. A Pro Mini draws a tiny amount of power, I'm talking tens of milliamps- he could leave this hammer somewhere for weeks probably without the batteries dying, with the occasional passerby trying and failing to pick it up. To manage that with the magnet running constantly would be impossible.