I read something about how we might have the technology for wireless charging, but that it isn't practical as of yet.

How would it work in theory?

:p

The magic of socialism, mainly.

http://en.wikipedia.org/wiki/Inductive_charging

http://en.wikipedia.org/wiki/Wireless_energy_transfer

It's pretty nifty, I thought we had a few topics on this already; the most recent and only topic I found was one about wireless energy transfer from 2006. I remember a topic about getting lights to work without plugs or batteries via this method and I am fairly sure there's a topic on this forum about it.

The subject itself is pretty cool. While the products we have at work don't fly off the shelf, everyone I inform seem legitimately amazed. While I never get into why/how it works - because I'm not that well educated on the matter - I tell them that it's the same as those inductive stove tops you may catch a glimpse of on TV infomercials.

Nice one allyn

The real downside to wireless power is efficiency. Would you rather plug in your device and have it charge in 3 hours, or set it down in a special (and fairly small, or it gets even worse) area and have it take 3 days?

Edit: So think of why Wifi is generally worse than a wired Cat5 cable and you've got it.

*AHelper3 points at hp webOS devices that use wireless charging docks that are just as efficient as USB charging

Is noone else flashing back to the tricorders or other devices in Star Trek TNG that transferred power and data just by being placed on a platform next to a terminal?

Ahelper, but you need the coil in the device and the coil in the mat to be very, very close to each other, and imprecise positioning can greatly influence the power transfer efficiency, as far as I understand. Some of my undergraduate colleagues were working on a medium-range (a few feet) wireless power transfer project based on intel's work on the subject, and their conclusions were fairly negative as far as feasibility.

Now that I think about it, didn't Nikola Tesla envision something like this, on a much, much larger scale, with power being transferred hundreds of feet trough the air above our heads?

Yes, he did.

They need to be directly on top of a specific pad made specifically for that purpose, don't they?

I believe I just said something along those lines a few posts ago. And indeed, Tesla was a pioneer of wireless power transmission.

Tesla's idea was to beam it long distance, as in tens if not hundreds of miles. Nowadays, we can barely figure out how to get it through a quarter inch of petroleum distillate. How does that happen?

We can send it several feet through atmosphere, for artificial lightning experiments, but I don't think anyone has been crazy or high enough to actually build a generator larger than that in open air. If I understand correctly, it could be done, it would just be a profoundly bad idea and require an insane amount of power.

Oh, an the technology is called magnetic induction technology.

Actually Tesla's System was fairly doable if he had been able to overcome the last few hurdles, which many believe he might have been able to do, it just required insanely unsafe amounts of power at the source, and while things like Faraday cages made this a bit safer it wouldn't take much to kill someone with a mis step.

That said Mercury Arc Rectifiers are still may favorite way to die from that era of electronics development.

It would never have been doable after 1940, Jonimus. Sending out that much undirected power would destroy pretty much any attempts at serious radio communication with the white noise.

Iirc his plan was to embed radio communication in the power, and that is where most of his funding was coming from, companies interesting in doing just that.

Interestingly enough, with a big enough antenna you can actually grab enough power out of the air to power a lamp or so (and of course with a smaller antenna a crystal radio). The power is of course coming directly from the radio station's power bill, but it's neat to think about the fact that the radio waves are carrying real power.