Air Coupled EV Charging

Specially-built charger and auto setups can insure that the two coils can be large, only a few inches apart, and well aligned. This can greatly simplify the physics of the system. Momentum Dynamics shows a picture, with a low distance-to-diameter ratio.

Talking about "living objects", such as rats, getting in between, they said the air gap "isn't that large". They say f = 80kHz. Also, small systems, like 1.5kW my Prius charges from 120Vac (4 hours for round-trip to work), will be more simple and much cheaper.

I scrubbed thru the vid real quick hoping to see some footage of an actual product in action but unfortunately it's mostly just two guys talking for 'bout a half hour booooooring.

I'm pretty sure I've already seen a product like this available for sale though. but it's one of those things that prolly costs about 10 grand to set up on your EV's undercarriage and in your garage vs. you take 10 seconds to plug in a wire each time you park.

They talk about winter weather show a couple EVs like a Tesla with the charge port on the back iced shut and some other thing with the charge port on the front that's been packed up with blowing snow while driving as a good reason for having this product.

One could also as an electric car company not put the charge port in a dick-headed location, some manufacturers actually did sciencey-type research as to the best location for it to avoid various problems it's on the front quarter panel. Mine's never frozen up or been packed with snow and my Chevy product has sat out in a number of blizzards over the past couple years...

GM may not be "serious" about EVs but at least they have or had an engineer on staff who at some point thought "Hey let's design it so the charge port doesn't get all f***ed up in cold weather"

Your round trip to work is only 15 miles? If everyone had such a short tri p there wouldn't be so large a problem of emissions to solve. I recall yea rs ago California was able to avoid building any new power plants for some years simply by focusing on conservation.

My daily commute is a bit shorter, about 15 miles shorter. But I often tak e trips of 300 to 500 miles. So it balances out.

Rick C.

Here is another example that seems to work well.

Rick C.

No, 22 miles, half hi-way, half city streets. Several big hills, lots of stop-and-go.

How many kWh get into the battery on that 120 volt charge? What is your mi/kWh on the Prius?

Rick C.

If mag chargers require the vehicle to be exactly over the source, why not just connect with brushes or a robotic connector? Electric trains and such use sliding contacts.

Mine is only about three hilly miles each way, but we go up into the mountains, and I wouldn't want to be caught in a 4-hour jam behind some dumb SUV spinout in the snow, creeping 6000 feet uphill at 10F, with nowhere to charge.

Didn't you notice that the wireless is more efficient? That alone is good enough reason. Is there something difficult about positioning a car?

Rick C.

You do resonant charging instead of inductive

Then they can be far apart and still have high efficiency

Resonant isn't inductive? How does that work?

That concept keeps getting rediscovered. Doesn't make sense to me.

How can conversion of DC to high frequency AC, magnetic coupling resonant or not, and rectification be more efficient than a connector?

I bet a lot of things get warm around high intensity high frequency mag fields. Wires in walls. Wheel rims. Dirt.

DC doesn't have a lot of eddy current or skin losses.

I knew San Francisco has some steep hills, but 6000 feet in three miles is pretty impressive.

I don't get what the concern about the backup is. Unlike an ICE you don't need to keep the motor running. Yeah, the heater uses charge, but there's no shortage of chargers along the way. You can keep the heater running ful l blast for many hours on the 100 kWh battery. The elevation change for a model X, the heaviest car Tesla makes takes 12.5 kWh, only 12.5% of my batt ery. 4 hours of sitting in traffic would cost you less than 20 kWh so your total consumption compared to a trip on flag ground for this really ugly t rip is just 32.5% of your total battery capacity.

BTW, there are no less than six charging stations with 84 stalls along your route, not counting the two stations with 19 stalls in Truckee.

Next time you take this trip, try stopping in Rocklin. In addition to the

If you can't figure out how to make this trip in an EV you don't deserve to drive... any car.

Rick C.

Looks like Momentum Dynamics stumped the chump on this one.

Rick C.

Wait until people afraid about WLAN signals, cellular base stations or high voltage power poles hear about all kinds of wireless EV chargers-).

It will never be better efficiently than a connector. Differences in efficiencies are due to different converter topology and components

Inductive is near field

Resonant is matched tanks on both sides, with both frequency and impedance matching

Think of an audio tuning fork. Since it is resonant the distance is not that important since in resonant operation the leakage inductance has reactive power

Cheers

Klaus

What do you base that on? What do you actually know about EV charging and the losses involved? Do you know anything about the cable sizes they use for the current chargers? How much power is lost in the cable and connector?

I think any discussion of the Momentum Dynamics device would require actually learning about how it works. Anything else is just speculation.

Rick C.

They probably won't think about it at all no evidence that that kind of person would see wireless EV charger beams and cellular cancer rays as related phenomena IMO

So it takes about 2 hours round-trip, and 4 hours to recharge? Six hours to go 22 miles? How is that practical?