My xiaomi portable fast charger clearly charges my girlfriend’s iPhone faster than my high end android device. Doesn’t matter which port, which cable or which android phone. It starts by charging fast but as soon as I plug her phone the fast charging speeds go straight to hers and mine just chargers very very slowly.
I’ve got the impression that this may be on purpose or at least has some clear explanation.
Any thoughts?
Are they both using USB PD charging? Chinese brand phones often have weird proprietary charging protocols like OPPO VOOC for example.
Also if the ports are shared on the charger internally, plugging multiple devices in may limit what charging protocols and power levels are available.
It’s not on purpose, but due to the complexity of USB and different charging protocols, and different charger designs.