Do portable charges prioritize iphones charging speed over androids?
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.
Assume from the various pd fun that could be occurring, it could be voltage related. Android phones often set their charge current by the input voltage. If the voltage sags, the phone assumes it is overloading the cable and backs off. If the Iphone and Android phone are sharing a 5V rail inside the charger then this could be an issue. If the combined load of both phones causes a voltage sag, the android phone will back off. However, if the Iphone doesn't also slow down at the same rate, you will get a bias. It might be that 90% of the power is going to the iPhone simply because the android phone is being polite, and being screwed by the deal.
The best way to test this is to install a charge monitoring app on the android phone. I personally use AccuBattery. It shows me both the voltage and current draw of my phone. The pulsing effect of a bad cable is very obvious with it. I suspect it would help you diagnose what is going on.
Does the charger display how quickly it is charging? I assume her iPhone's battery might just have a lower capacity as iPhone usually have smaller batteries than comparable Android devices.
Are they both charging through a USB-C port? There are different levels of USB-PD specifications, and the charging speed depends on the maximum supported wattage of USB-PD between either the device, cable, or charger.
What's the model of your high end Android device, jf you don't mind us asking?
USB-A (or what you call regular USB) only supports older versions of the USB power delivery standard, while the charging standard on a lightning port is proprietary.
So, it could be that your charger doesn't support the level of fast charge your phone is capable of: basically, your charger is telling your phone that it doesn't know how to charge your phone super fast safely over USB, so it will try to charge it slowly in the way it knows; it knows how to charge a phone over Lightning slightly faster, so that's what it does.
Try getting a GaN based charger with at least one 45w based USB-C output port. (Anker, if you want a brand recommendation) and your phone should be able to get a much better fast charge from USB-C to USB-C.
I've the exact same issue with my Baseus 100W power bank. It'll charge my S23 ultra super fast. Once I plug iPhone 14 pro, it'll charge it much faster than mine. Even if I unplug/plug again.
I think the issue with the power bank is because I've another 65W wall charger that'll charge both fast.