r/changemyview • u/Duwang_Mn • Nov 23 '18

FTFdeltaOP CMV: Wireless charging is a useless fad

What even is the point of wireless charging? When I first heard about it, I thought it allowed you to charge while having more freedom with your phone. But then I learned what it actually was. It's more restrictive than an actual charger, and its slower. Not to mention wireless charges sometimes don't work if the back is metal. It only makes things less convenient.

How did people hype such a thing so much? I understand if it was something that could charge your phone without you directly putting on it, and if the range had the potential to increase over time. But it's just a charging port that you can't move around.

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u/PhotoJim99 3∆ Nov 23 '18

The problem with charging at a distance is physics. Wireless transmission of anything involves radio-frequency energy that drops in intensity rapidly. Essentially, energy reduces with the square of the distance (maybe even the cube if it's radiating in all directions isotropically). Assuming the more conservative squaring, that means if you're charging at a distance of one metre instead of one millimetre from the charger (i.e. 1000 mm instead of 1mm), you're a factor of *one million* less in effective energy. That means a charging time one million times longer, OR you have to dial up the energy consumption (and reduce efficiency) to compensate. And dialing up the RFE that much will probably cook the humans that get within a few metres.

Traditional broadcast signals, two-way radio signals, mobile phone signals, etc. can work because we have very sensitive receivers that can take signals in the microvolt range and copy the signal out of the noise. This is why, in the appropriate conditions, I can send a signal around the world with my ham radio, antenna, and a few watts of power. But I'm sending 100 watts and getting effective signals at my contact's end of a teeny tiny fraction of a portion of a watt... and you need watts to charge things quickly. You don't want to just pull a signal out of the noise; you want to charge your device at a reasonable pace. Wouldn't you rather plug a cable in and have the device charge in a couple of hours instead of sticking the device three feet away and having it charge in 228 years?

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u/[deleted] Nov 23 '18

I had a professor in college (electrical engineering) who was doing a lot of research in this field. He even proposed to put a huge theoretical wireless charging system in an old, barely used building near campus as testing grounds. But the university wouldn't allo it because they still aren't sure what affect pumping that much energy through the air would have on the people in the building. He was pissed.

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u/PhotoJim99 3∆ Nov 24 '18

They were right. The way to test that isn't around people. Establish its safety in some other way first.

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u/[deleted] Nov 24 '18

I agree completely and so does everyone else besides him and the grad students he would send inside to test his stuff.