Charging the Gemini with a non-Gemini cable ?

[Dixit]

Hello,

So I read around the Net that the Gemini charges itself through a dedicated fast-charge protocol. Indeed, mine does: 2 hours and it is full (and hot).

Could someone elaborate on where this magic is physically located ?

My car has a USB port marked "Charge Only" so clearly not a dataport.
I have a charging cable (bought at HEMA).
The Gemini charges, but only 15% during a 2 hour ride.

What slows this down ? The car connection ? The USB-A-to-C cable ? Or both ?

(A pity though... this charger from HEMA is actually a bunch of connectors, being USB A,  C, the one for the iPad and two others. Quite nice to have a one-size-fits-all cable).

[KF6GPE]

I'm guessing that your car USB port is a low-current charging port. The cable shouldn't be the issue.

[DJO]

So I read around the Net that the Gemini charges itself through a dedicated fast-charge protocol. Indeed, mine does: 2 hours and it is full (and hot).
...
What slows this down ? The car connection ? The USB-A-to-C cable ? Or both ?

The special sauce is the fast-charger uses the data lines in the USB for power so it can shove more juice down the same cable, it also carries a higher voltage to get more current across. Look at the charger:
5V @ 2A
7V @ 1.67A
9V @ 1.67A
12V @ 1.25A