I don’t understand that car manufacturers develop EV’s with thermal heat managemant for their own batteries, but sell wireless charging pads without the same amount of thermal management. It seems they find it normal if you have to buy a new phone every two years cause by overheating the battery. That is definately not durable.
My thoughts exactly.
I have been trying to work out what is going here. I don't think the enclosed space is the issue. The heat normally generated isn't great and I had the compartment open so normal convection currents should be enough to remove the heat. It also isn't easy to work out what is getting hot. Is it the phone or is it the charging pad and that is transferring the heat to the phone as they are in contact.
I am not an expert on Qi charging but I know a little and that it involves communication between the devices. The phone is a fairly passive device in that it is only taking what magnetic field it can get and converting that to power. It controls its own charging and so if it works fine with other wireless pads, I can't see how the BMW can be doing anything that would make the phone itself heat up, so I suspect the heat is coming from the pad and being transferred to the phone.
I suspect that the charging efficiency between the two is not good so the phone requests that the pad ups its power output and consequently it heats up. Why would the efficiency not be very good? I would suggest phone cases and the alignment of the coils of the charger. Because of how it works, the charging efficacy falls off fairly steeply the further the distance between the coil in the charger and phone. More upmarket chargers sometimes have multiple coils to improve the chance of a good alignment. There is a good article explaining how it works here -
Why more coils does not always mean better charging
These are the charging coils on a Samsung S21 (this is an x-ray and you can see the two coils in dark grey in the center:
![Image]()
I believe the larger coil (seen in the centre of the photograph) is the coil that is used when the phone is being charged (the smaller inner coil is because the S21 can be used to charge other devices like ear buds, so it can act as a charger itself). As you can see, it is off centre, closer to the bottom of the phone. When I charge on a pad at home, I offset the position slightly to get the phone charging well. We don't know if the BMW pad has multiple coils or where its coils are located but because of the size of the charging pad enclosure, you can't adjust the alignment if you have a big phone because it only just fits the space. If BMW uses a single coil and it is right in the middle of the pad the charging pad coil and the phone coil are not going to align well. Phone cases also make a difference because they increase the distance between the coils. I have a charging pad on my computer case but it only works when I take my phone case off. It would be interesting to see if removing the case in a BMW makes a difference. It is probably also worth trying to rotate the phone 180 degrees to see if you can get a better alignment.
All said, this is just supposition and may be way off the mark. It would be useful to get some input from BMW, anybody got any good contacts?!
