That is quite a long story of smartphone makers are trying to create powerful Qi charging devices. And usually, they are all fails. Wireless chargers are still noticeably slower than wired. And also less power-efficient. And also not reliable. With some previous wireless charging docks, you someday waking up with your phone not charged at all. And there are a couple of reasons for that. First is coils misalignment, which reduces all (speed, efficiency, and reliability). The second is power loss and related overheating (affects speed and efficiency). So what is good about Apple MagSafe 15W Qi charger. It solves the first issue. Coils are now aligned. So you can be more or less sure that you will get your phone charged. But it mostly ignores the second. Qi charger is still overheating. And that is slowing down the charging process. Yes, it is an aluminum body, and that is kind of good news. But that is definitely not enough. So for a period of 3-5 hours of wireless charging, you will get 15W only for a short period of time. Usually, it is about 5-7 minutes. And the most interesting part there is 7.5W charger may charge faster than the 15W charger just because of less initial overheating.
So the usual charging may look like graphs below
That is just about 4 hours. But results may vary a lot. That is highly dependent on temperature (room temperature, phone temperature, table temperature), on do you charge with a charger below or above the phone. Do you use a case or does the phone do some background tasks. Do your air moving in the room. It impacts Qi charging speed much more if compared to wired charging.
Wired charging from same 20W power adapter:
It is for the same conditions, same case, same temperature, same table. Just about twice faster. And power consumed is 14.5Wh instead of 22Wh to charge an iphone 10.78 Wh battery (while phone is on, but not in use). That is about 3 times more energy lost on generating heat.
So How to get 15W we pay for? That is easy :). You need to place the phone (without a case) in some cold place with airflow for at least the first 30 minutes of charging.
And if you got proper cooling you will get something like:
Still a bit worse than wire charging in the room. But anyway we got our 15W Qi. It exists and it is fast. (That is kind of sarcasm).
So what is wrong with Apple Magsafe Charger?
- it is slow
- it consumes more power
- it is expensive
One more thing.. about power consumption. Idle power consumption is also might be an issue. Lightning cable inserted in 20W AC adapter consume much less power (0.0025W) in idle mode (when you do not charge anything) than MagSafe charger (0.34-0.5W). So if you kind of eco-friendly person you better plug out the MagSafe charger every time you are done with charging.