On Sunday, April 8, 2018 at 1:44:08 PM UTC-4, passerby wrote:
replying to micky, passerby wrote:
USB style port that allows me to play a flashdrive through the radio -- but
will not charge the phone using the same port. Isn't that very unusual?
Impossible?

The manual for my 2017 Prius specifically says about the USB port - "Not for
charging". I guess they don't want you to plug something large, like a battery
bank and fry the circuit, which they will then be forced to replace during the
warranty. I'm not sure if there's a better explanation as to why, but at the
very least the car USB port that's not able to supply charging current is not
that uncommon.

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for full context, visit https://www.homeownershub.com/mainte...k-1163812-.htm

IDK why they won't allow charging, make no sense with all the phones and stuff, but it should not be over trying to charge something that takes too much current. Max current is limited in the spec and any IC to do the USB interface would have that implemented.