93% efficiency at 1kW and 30kW wireless power delivery (from AC plug to vehicle, not 93% only for the transmission): http://www.deltaenergysystems.com/en/Wireless-Charging-Syste...

This is very close to systems that are using cables and connectors.

The loss associated with wireless charging is in addition to other losses, so this is 7% loss on top of whatever other losses are in the production, delivery and power conversion chain.

Given the sheer amount of power used by vehicles, I would prefer we minimize losses there. Wireless charging for tablets, smartphones and other devices is less of a concern.

It's full system efficiency, not just the wireless charging.

Very close? There's no way you're losing anywhere near 2kW (7% loss in a 30kW charger) to cables and connectors.

It's in the power conversion.

Go educate yourself on the efficiency of power supplies: https://www.extremetech.com/extreme/143029-empowered-can-hig...

Over 90% is amazing.

~5+% in AC > DC is not that uncommon. Which is why wall warts get hot. But yea if this is just about replacing cables then that's poor.

PS: I do wonder about efficiency limits because transformers are effectively wireless power just at cm range.

I'm not sure of what effects you are talking about, but at home a reasonably probable 32 A 400V 10mm cable that is 8m long is about 99.75% efficient. I'm not sure about contacts but let's say it's at least 99%efficient in total.

Fast charging stations is probably worse though.

AC plug to vehicle means you are doing AC > DC conversion which is not 99.75% efficient. So, if this is 93% including AC > DC that's actually fairly good.

Off topic but...Power from solar cells is DC; to the extent these are locally supplying vehicle power you can just cut out the 2-way AC conversion, no?

I have this picture that eventually all parking structures will be fitted with solar power to charge parked vehicles. (Roads would be even better, of course.)

Yes, but the voltage needs boosted up to 300 or 400V, so there's still a DC-DC conversion step + control to ensure the correct current at each range.

As EEVBlog has shown many times, road surfaces are an extremely impractical place to put solar panels on. It needs to be kept clean to work efficiently, and you also need to make a surface with similar friction properties as asphalt, which is not easy when it needs to be transparent and durable enough to take cars and trucks driving over it constantly.

Of course if you meant something like panels on the side of the road, or roofs, or something like that then that's fine, those installations would just be pretty standard solar panel installations. But covering the road surface itself is just a bad idea that would require a significant engineering effort and massive cost to work to any degree at all.

The backup is to simply add a structure over your roads and put solar on that. But, IMO that's just an implementation detail. We have plenty of land for all the solar power we need any time soon without impacting farming.

Agreed heat is the real problem.

I think something between Tesla's snake and a slot track car toy is the inevitable future. Drive on top of something that knows where to put two metal prongs. Very easy problem if you get to design both halves.

The GM EV1 electric car had inductive charging back in the 1990s, using a "paddle" charger.

This is likely because people were terrified of plugging exposed high current high voltage connectors in outdoor setting.

Yes, but the point is, they had it and it worked just fine. Inductive power transmission works fine if the distance is very small (as it was with these paddles).