[prawn]

Could the power/charging issue be handled by a rotatable handle/component that can charge up a battery if it goes flat and leaves you outside? A bit like the wind-up torches you see around the place?

Or would it require minutes and minutes of manpower to realistically charge?

[emhart]

Yes, it is a very good idea. That's precisely how the Mas Hamilton/Kaba Mas X-series safe locks work. The dial is rotated a few times first, at which point the lock powers on and can be operated, solenoids fired, etc.

However, those safe locks get to control many other aspects of the mechanical makeup of the lock, and rely on well defined and reliable standards of production of the doors they are applied to. Consumer smart locks don't get that advantage, so the amount of power required to throw a bolt won't always be consistent. I don't know what it would take to ensure enough human power is transferred to provide enough force to always overcome a stuck bolt.

[Pyrodogg]

Now there's an interesting idea. Instead of a solid axle between the two door handles you could have a split axle and some sort of dynamo. If you gadget dies you just sit there and crank the handle around a few times.

I'm picturing someone with a scarf wrapped around the knob and employing a method similar to starting a stick fire...

[ianburrell]

Another idea to provide backup power is to have backup battery in the "key". The key wouldn't be need to be mechanical, but electronic, and could provide the juice for emergencies. Another option would be a "key" that acts as microUSB adapter to provide power from phone.

[pjc50]

Providing power through the key makes it an attack surface (what if I supply 5kV? can I use it for power-analysis attacks? etc)

[emhart]

Latter idea is mentioned in the post, though...clocking in at ~7500 words I blame absolutely no one for not getting to the end haha