Discussion When will Wireless Charging become "truly" wireless?

[Gamefreaknet]

When we say "wireless" we mean no more of those cords, cables which technically are still used with those wireless pads. How long however til we get wireless charging that works like a wireless mouse communicates with the USB receiver it comes with.

 

[little_me]

by the time we build tolerance for massive amount of microwaves and power.
Wireless as such now is just eliminating the need to plug cable into the thing and requires you to just place the to be charged thing on top of the charging pad.

the problem with longer distance charging is just that, distance.
by default, most wireless signals are projected fully to all directions but only a tiny fraction of that is received by the receiver.
enter directed antennas, which can reduce or stop power transmit to directions without receivers, saving a LOT of transmit power.

now.. cell phone, while the power to be transmitted is not that huge, it's still enough to cause problems on long term exposure which will happen once/if it's transmitted all around or in between.
(wireless charging detects that there is to be charged item on it before transmitting)

so.. yeah, if you want to fry people in your home, this is the way.
cell towers cap at around 30 to 100W/100Mhz band and are not right next to houses.
also they transmit to wider area.
cell phones on other hand work from 0.6 to 3W in most cases.

To charge cell phone, you need kind of equivalent of USB or so, so 5V/1A meaning 5W or so, minimum, this is about same as two cell phones going all on data transfer for hours. (the time you need to charge cell phone fully at 5W.

this is not same as wireless power since this is for sound but... it's something towards this for non-directed antennas.

Distance Attenuation: How Sound Reduces with Distance

The farther you are from a point of sound, the less sound you hear. This is called distance attenuation. But what is happening to the sound as it travels?

www.acoustical.co.uk

notice that if R doubles, transmitted power drops to 1/4th, so right adjacent is 5W, twice that is 1.25W and that is still finger width or so away.

to make it work across room, power needs to be raised a LOT.
for data transfers it isn't quite as big deal as long as receiver can still perceive transmitted 1's and 0's as intended, power does not need to be high.

so.. yes, you can get around some of that by having directional antennas which also limit where you can wirelessly charge your devices.

 

[Deleted member 14196]

I detest wireless charging in its current state. If your phone isn’t completely flat on the pad, it doesn’t charge and you can’t use it while it’s charging so it’s basically useless.

I really don’t have a need for wireless charging and I think it’s rather stupid and it’s very inefficient if you’re talking about over the air

 

[hotaru.hino]

When we say "wireless" we mean no more of those cords, cables which technically are still used with those wireless pads. How long however til we get wireless charging that works like a wireless mouse communicates with the USB receiver it comes with.

The problem with wireless power transmission are the following:

• Unless the wireless power transmission is directed or is in very short range of the device, the power drop will have an exponential decay due to it spreading out. Think of it like the difference between how bright a laser dot is vs a flash light. For the same amount of power, the laser dot is much brighter than the flashlight because all of the light is directed to more or less a single point rather than spread out.
• It doesn't take a whole lot of power being transmitted before RF exposure becomes a concern. The maximum power out of a cell phone for instance is around 10W/m^2. Now 10W might sound like more than enough for USB devices, but keep in mind it's spread out over a square meter. The little puck that would've been in my wireless mouse for wireless charging would've covered about 0.2% of that, which if my math is right, would mean it'd only be getting about 20mW (assuming it was absorbing RF energy from one direction)
• The amount of RF being blasted around would overwhelm any other RF in the same frequency range. Imagine trying to power a mouse using a 2.4GHz wireless receiver with a 10W output. Meanwhile your WiFI router is basically in the milliwatt range and now it's completely drowned out by the mouse's wireless receiver. And this isn't even accounting for what else this RF would have on electronics in general.

This is also not counting the fact that wireless inductive charging is grossly inefficient compared to wired. As much as 40-50% of the power is lost using inductive transmission.