Wireless Charging

[TEG]

Serious question for the Techies: We have induction loops at just about every traffic light in this area (so the lights only change if someone is waiting); could they be adjusted to provide charging?

Basically I would say no. Starting with the very fine gauge wire loops that are designed to detect nearby ferrous metals, and not used to transmit gobs of energy.

But there is an idea there... Rather than cover the whole road/street with inductive charging, one could just put them at intersections where the vehicles are more likely to be stationary for a while. But better still would be to put them at all parking spaces instead of on the road. There are just too many miles/kms of roads to practically power them all.

[Doug_G]

Serious question for the Techies: We have induction loops at just about every traffic light in this area (so the lights only change if someone is waiting); could they be adjusted to provide charging?

Probably not. It's difficult to share a coil for two purposes, unless the circuit was originally designed to specifically accommodate both. The loop area and number of turns is not optimized for the purpose, either. I believe most of these "air gap transformers" use resonance to boost the transfer efficiency, and that would probably be incompatible with the sensing circuit.

Curious... a quick search for references brought up Nikola Tesla! Apparently he used inductive resonance coupling to provide wireless lighting in his offices.

[TEG]

By the way, on the recent Top Gear EV bashing episode they talked about their "great idea" of putting bumper car style electrified metal fences over all the roads to charge as you go.
Probably more efficient, cheaper and easier to install than inductive under the road. (But still impractical, ugly and possibly dangerous.)
Personally I still think that charging while stopped is the way to go. We ought to have some buffer devices that slow charge themselves at the parking spot, and as soon as someone pulls up and plugs in they get a "quick blast of juice" and get fast charged quickly. Those same devices could be used for backup power when the grid is down, and to even the load between day and night to help reduce the need for new power plants. Having a buffer device means that ubiquitous 240V could still be the source for fast charging, and so we wouldn't have to scramble to provide 400+VAC to all the charge locations.

Inductive charging is probably only good for L2 charge rates. Probably not a good idea to put 50kW+ through such a system.

[vfx]

By the way, on the recent Top Gear EV bashing episode they talked about their "great idea" of putting bumper car style electrified metal fences over all the roads to charge as you go.....

I just thought about all the electric trains and buses that already exist with overhead power.

We had a video here of a bus that would charge it's batteries at it's stop as well.

[TEG]

Yes, I posted various pix of the SF electrified bus system with overhead power lines on some of the earlier threads.
And down near San Jose we have the "light rail" which is overhead electrified too. It works better if the vehicles are a standardized size/shape.
But the Top Gear guys are probably right to mock it as "bumper car like". I don't see individual car owners warming up to having a rod sticking out of their vehicle scraping along an overhead power line. I still thinking charging while parked makes more sense. Those electrified trolleys and buses have a fixed route so they can stay on the power and not need batteries. For individual cars you basically need batteries to go all those places which don't/couldn't have overhead power lines.

[vfx]

. I don't see individual car owners warming up to having a rod sticking out of their vehicle scraping along an overhead power line...

As I watched that segment I kept thinking that someone was going to say "Slot Car". It's bee said about the Roadster many times.

Did the UK go though that craze we had in the 60's/70's here in the US?

[TEG]

Did the UK go though that craze we had in the 60's/70's here in the US?

Apparently

[Nik]

Probably not. It's difficult to share a coil for two purposes, unless the circuit was originally designed to specifically accommodate both. The loop area and number of turns is not optimized for the purpose, either. I believe most of these "air gap transformers" use resonance to boost the transfer efficiency, and that would probably be incompatible with the sensing circuit.

If every vehicle was properly equipped, the sensor would only need to detect that charging was taking place. Legacy vehicles would just have to wait...

[TEG]

In-Road Wireless Electric Vehicle Charging Breakthrough Yields 90% Efficiency | Inhabitat - Green Design Will Save the World

[Talkredius]

Basically I would say no. Starting with the very fine gauge wire loops that are designed to detect nearby ferrous metals, and not used to transmit gobs of energy.

But there is an idea there... Rather than cover the whole road/street with inductive charging, one could just put them at intersections where the vehicles are more likely to be stationary for a while. But better still would be to put them at all parking spaces instead of on the road. There are just too many miles/kms of roads to practically power them all.

+ the cable has to be different, small segments, isolated against each other to avoid the skin effect. The European car makers agreed on a transmission frequency of about 140 kHz