Ask HN: Why can’t my iPod case charge my iPhone?

I use a MagSafe charger with my iPhone and find it convenient. But it is expensive so I can’t justify buying more than one.

I wonder what some of the technical challenges would be for using the inductor coils in peer devices to charge one another- specifically the iPod case would be a useful option to me.

Is there an asymmetrical relationship between the coils of the MagSafe charger and the devices, or is the only difference that the MagSafe has stronger magnets in it for alignment?

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I look forward to insightful comments of all sorts - including speculation about Apple’s business practices, marketing, profit strategies. I am also curious how other manufacturers deal with charging issues. My request is that we limit cynical comments about Apple price gouging, etc. Not that I think that opinion is wrong but I would like insightful or detailed commenters to be rewarded and not drowned out by a flood of opinion comments.