Another thought, Peter. Is it possible to use multiple coils to focus
the "beam"? I don't know wave theory but I believe directional radio
transmitters work by having two or more antenae. Can something similar
be done with inductive coils?
If so, then using some sort of directional recognizer, the transmitter
could focus the beam exactly to the receiver area. I'm hoping this
would reduce risk of exposure when humans, animals are in the vicinity
and also improve efficiency.
Peri
------ Original Message ------
From: "Lee Hart via EV" <[email protected]>
To: "Martin WINLOW" <[email protected]>; "Electric Vehicle Discussion List"
<[email protected]>
Sent: 20-Jul-14 11:37:04 AM
Subject: Re: [EVDL] EVLN: BMW&Daimler developing 3-Hour Wireless
Inductive EVSE for i3 EV
From: Martin WINLOW
Not wanting to shoot your work down but I am reminded of (I think it
was) Lee's idea of using
an auto engaging charger connection which would be much more
efficient, much cheaper and only
marginally less practical.
It was actually Bob Rice's solution (although the idea is no doubt even
older). In 1968, Bob had an EV with drive-on charging. It was a
bump-stop that you drove up against. A platform between the front
wheels would slide sideways to center itself between the front wheels.
It had two brush contacts on the top surface, that mated with contacts
on the bottom of the car. The contacts were dead until the car was
present and electrical contact was established. Simple as dirt!
I know that people are often fascinated by complex solutions.
Advertising can often talk them into paying extraordinary prices for
trivial conveniences or hypothetical benefits. Companies like them
because they can make a lot of money selling them (especially if they
can get laws passed to make it a "standard"). But if you actually
expect them to be widely used or survive in the long run, I think we'd
all be better served by working on simpler ways of doing it.
GM's Magnecharger comes to mind. A good idea, expensively implemented,
legislated as a standard, and now a footnote in history.
On an 85 KHz high power inductive charger: As an EE, I can't see how
the charger can detect a 0.1% energy loss to some unexpected device in
the area. And yet, that's enough power to easily heat up unintended
"receivers" and fry sensitive electronics that by chance just happen to
resonate at 85 KHz. How can you reassure me that this won't happen?
When I was designing safety-critical consumer electronics, we'd have
someone on the team whose *job* it was to try to "break" the system. If
the guy was good (and he needed to be) :-) he'd come up with things we
never thought of in our wildest dreams! So... with your inductive
setup, what if you *tried* to find a way to trick the electronics, and
steal 5-10 watts of power from the charger without tripping the safety
shutdowns? If you can do it, then Murphy will probably discover some
mass-produced gadget that just happens to do it.
--
A free whistle given away in millions of boxes of Captain Crunch cereal
just happened to be exactly the right frequency to turn off the phone
company's long-distance billing equipment, so kids could make free
long-distance calls!
--
Lee Hart http://www.sunrise-ev.com/controllers.htm now includes the GE
EV-1 controller
--
Those who say it cannot be done should not interrupt the one who is
doing it. -- Chinese proverb
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net
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