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), 20V@3.35A (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.
Just a note, I’d recommend against fast charging unless you need it. It’s not great for the battery of the phone. I know my phone automatically slow charges when I plug it up at night because it assumes it will stay plugged up for a few hours.
Are you always plugging hers in second? Maybe it’s just giving priority to the most recent thing plugged in.
AFAIK, Xiaomi chargers offer more current over voltage (which is locked to 5V). Other Android phones may charge even faster than Xiaomis and iPhones, provided the charger implements modern standards with variable voltage.
Charging voltages are no longer limited to 5v and haven’t been for a few years. To make things worse there are different fast charging protocols and compatibility is not guaranted. The only real way to measure power throughput is an inline charge meter that can handle voltages over 5v. Modern charging can be very misleading because percentages are not always as useful as we think they are, percent is merely how far between shutoff voltage and top voltage but the curent throughput is not linear during the charge cycle. I’m not a fan of charge speeds over 15w because of how it impacts battery longevity.
There are a number of factors involved. Each phone will support a number of protocols and charging speeds, as will the charger. The two devices will typically perform a handshake to negotiate a charging speed before charging begins. This is what allows the voltage to be adjusted, for example to 9/12/24V rather than the 5V default. Then you have to consider the maximum power to be delivered. Some devices might negotiate a higher power, which at the same voltage will result in slower charging.
Tldr on voltage vs power vs current: power = voltage * current. You want to minimize current in the long wires and connectors/ contacts where there is high resistance because resistance causes power loss, so you use higher voltage until it reaches the end device before dropping it back down.
If the Android device negotiated 18W and the apple device 25W for example (idk what apple does) then the apple device will charge faster. Also, if the apple device has a smaller battery, it will charge faster. You may be able to get faster charging with a different combination of port/cable, charger, or settings on the Android device. For example, I restrict my phone to charge to at most 85% and slow charge because it keeps the battery from degrading as quickly, so I can still use my phone in several year’s time without having to recharge it every few hours.
I think you nailed it in here. Typically, iPhone batteries are smaller. iPhone 15 is 3349 mAh while a Samsung Galaxy S23 is 3900 mAh. The iPhone can get by with a smaller battery due to the OS being developed for specific hardware which allows for better battery life on smaller batteries.
