Ask HN: Who is building credit card size tracker using U1 spec?

Re:Ask HN: Who is building credit card size tracker using U1... by happyopossum on Monday September 12, 2022 @12:56PM (#32813104)

How are you charging a LiPo in a CC sized device? How are you protecting it from the stresses of a wallet? Final problem with this - they'd give you 20-30Mah of power, which is nowhere near what you'd need for a decent battery life in one of these.

tldr; we're not there yet...

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Re:Ask HN: Who is building credit card size tracker using U1... by kube-system on Monday September 12, 2022 @01:13PM (#32813368)

The easiest way to charge something thin would be a proprietary pogo-pin adapter and pads.

Protecting it would certainly be a challenge. If I were to try, my first attempt would be to sandwich it between two sheets of stainless. (0.76-0.4)/2 only leaves .18mm left over... that's 33 gauge. Maybe too thin to add enough rigidity? If you used 28 gauge stainless that would bring the sandwich to 1.04mm, which might be a better compromise.

It would certainly need some prototyping.

Apple gets 1 year of battery life from 225mah. So, it seems reasonable to get a month from 30mah. Not great, but hey, we're just entertaining the packaging requirement.

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