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 link 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?
Charging specs are fairly complicated so it is hard to say. Even if your Android phone for example supports faster charging than the iPhone (not hard, the iPhone is one of the slowest charging flagship devices around), it may not support that specific Power Delivery standard. My iPhone for example supports 15W wireless charging. Even though I had a few chargers that supported 15W charging, the iPhone uses a specific PD profile for that and I needed to buy a new charger that supported it to make sure I got the full speed.
So basically without knowing what charger, what specific Android and what specific iPhone you’re using, it is impossible to say. I find it unlikely that the charger itself knows it is connected to an iPhone, let alone would it prioritize it.
Yup. Some chargers support 5V@3A (15W), others 15V@1-4A (15,30,45,65W), [email protected] (65W), some various amps at 9V,11V etc
Some chargers support all of the above voltages at various amps. Others only a subset.
If the OP has a Pixel, those seem to use 9V up to about 2.5A. iPhone similarly does “fast charging” at 9V (apparently up to 3A or so). The Android should charge test, so the limiting factor might actually be the cable. Some older cables don’t support or allow the charger to negotiate higher voltages so the Android cable may be holding things back.