Mastodawn

Perhaps a silly question, but why don't portable power banks (when wired) use the 3.7V that both the battery and device it's charging already have? Why the need to convert to 5V (or higher), necessarily adding nontrivial losses?

Surely it's not only because that's what the USB standard says?

#electronics #technology

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Jason von Nieda 🐀Mar 6

@jhpratt Two things: yes, the USB standard says if you wanna be a USB port you gotta output 5v, and secondly, most batteries charge at about 4.2v. The 3.7 is nominal but charging to 80+% requires above nominal.

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Jacob Pratt

@vonnieda Sure, there would still need to be some level of voltage regulation, not the least because it fluctuates with charge level. It just seems wasteful to always use 5V. There's all sorts of proprietary charging standards out there (still); I'm surprised no one has done this.