[amluto]

From the Qi Wikipedia article:

> Rather than down-regulate the charging voltage in the device, Qi chargers meeting the A2 reference use a PID (proportional-integral-derivative) controller to modulate the delivered power according to the primary cell voltage.

So... a defective charger could plausibly damage the phone unless the phone contained a suitable protection circuit. Such a circuit could be quite simple - a transistor set up such that switching it would take the resonant receiver out of resonance would do the trick. The designer would need a bit of care to ensure that switching the transistor under wouldn’t fry it.

But IMO this design is a bit nutty. Phones already have voltage converters. Why not just use them?