Welcome to the future

[dpiers1980]

http://www.google.co.uk/url?sa=t&rc...-4HABQ&usg=AFQjCNF-rT9XUlImBIYb6kKTRzNXucoSow

The Japanese are years ahead of most countries regarding their engineering and technology and why make electric cars when you can make grown up boys scaleletrix talk about thinking outside the box.

PS. Carbon is obviously a conductor and one of the reasons cars have it in there tyres are for earthing the my old man has been telling me that for years he's a electrician and the rubber mats you stand on when working live or in switch rooms don't have carbon in them that's what he says because otherwise you could create a earth path.

 

[telectrix]

well then, tyres are useless for earthing. i have had a couple of cars with static build up giving out shocks, and the only way to earth the static was to fit a static strip.

 

[Knobhead]

my old man has been telling me that for years he's a electrician

Don't you believe him?

 

[Darkwood]

Car tyres are good conductors both for the carbon content and some have re-inforcing metal wires wound in, if they weren't coductive your car would charge up from the effect of the tyre driving over the road and thousands of cars would be shooting electric arcs from the body to ground when the charge got high enough to breach the air gap, the static shock a person gets is created usually by the person wearing items that charge up when rubbing against the seating, you are usually isolated from discharging because you dont ground yourself as your shoes, the steering wheel, gear stick etc are all good insulators and its only until you touch the body work you discharge through the bodywork down to ground through the effectively conductive tyres.

 

[telectrix]

so why is it that a static strip fixed to the bodywork of the vehicle eliminates the shocks?

 

[Darkwood]

Soz tel forgot to answer your point, static build up is dependant on how the charge is generated and why is it isolated, some seating fabric can be isolated from the body of the car usually because they are sewn onto a rubber edging on the seat, also to note is a change from carbon heavy tyres to silicone/rubber brands which do insulate although up to press these are uncommon, Anti-static car straps only work when charge is generated in a certain way and car design can play a large part in this but for some people fitting them makes no difference, too many variables can play a part to answer your question fully as its difficult to know exactly what is generating the charge and why it cant discharge in the first place, each situation can be different although we do understand the most common of them.

 

[brman]

darkwood: have you ever tried an IR test on your car tyres?

Out of interest I just have. +500M with the test probes 1" apart......

So either my tyres are strange or it is a myth that they conduct because they are full of carbon.

 

[Darkwood]

LOL Made me chuckle you even tried this but to do a 500v or 1000v is far short of the 20,000 volts which can build up when you wear your nans christmas present ... a big nylon jumper with a snowman on it .

We are talking of the tyres been conductive to static so not you average LV rating and just to add a dampener to it consider a wet road this will bring the tyres dielectrc strength down like a rocket.

I also noted earlier that not all tyres are carbon/rubber mix and those that are will have a dielectric strength relative to many variables including manufacture, quality, remoulds etc etc so dont read into the comment that they all will happily conduct your average household voltage because none of them will.

 

[brman]

LOL Made me chuckle you even tried this but to do a 500v or 1000v is far short of the 20,000 volts which can build up when you wear your nans christmas present ... a big nylon jumper with a snowman on it .

We are talking of the tyres been conductive to static so not you average LV rating and just to add a dampener to it consider a wet road this will bring the tyres dielectrc strength down like a rocket.

I also noted earlier that not all tyres are carbon/rubber mix and those that are will have a dielectric strength relative to many variables including manufacture, quality, remoulds etc etc so dont read into the comment that they all will happily conduct your average household voltage because none of them will.

Don't worry, I have a degree in electronics so I know how conductive materials work
I was responding to this comment:

Car tyres are good conductors both for the carbon content and some have re-inforcing metal wires wound in

No they are not! Conductivity and dilectric strength means different things to me. You can have very low conductivity (i.e. high very resistance) but very poor dielectric strength so low resistance to static. But I guess you know that
Anyway, my IR test proved that, without modifying the dielectric material, the resistance is high. Maybe not high enough to conduct static slowly (it could be GOhms+ and still do that) but certainly not "good conductors".
btw. do you know you can get special, better conducting, tyres for when a vehicle is to be used in an explosive environment?

But relating this back to the initial post, this japanese "invention" is nothing new. As far as I can tell from a quick read it is just using RF to transmit power through the road to pickup coils in the wheels. It is not using the conduction of tyres.

 

[dpiers1980]

Don't you believe him?

Yes I believe him now, I finished level 2 this year and started level 3 Electrical Installation

 

[dpiers1980]

Japan demo shows electricity entering EV through tires

Read again

 

[ferg]

This is way outside my field of knowledge, which is why it's interesting.
I'm pretty sure after reading through it a couple of times that transmitted through is the key phrase. Not conducted through.
I cant see how 4" concrete and a set of car tires could be conductive enough, or such a system safe enough.
I guess the steel bands are the coils brman referred to.

I'm more than happy to be corrected and proved wrong, as every day is a school day

 

[Darkwood]

Although i dont have a field in electronics i do study the quantum nature of electrics and insulation and conductivity become one common measurement irrespective of the waveform of the current flow and although il be happy to debate i see the resistance and the conductivity of a material to be the same thing viewed from the oppposite side.

All insulators have a breakdown voltage but this can be very rapid or gradual so i see your approach as a material can have a high voltage resistance but fail quickly with static, an insulator can also fail with static where it flows across the surface rather than through it, high frenquency electricity can flow over the surface of good insulators. It all comes down to material, voltage, current and frequency,check out how a plasma ball works its usually made of plastic but still attracts to you if you touch it to get to ground.

 

[dpiers1980]

This is way outside my field of knowledge, which is why it's interesting.
I'm pretty sure after reading through it a couple of times that transmitted through is the key phrase. Not conducted through.
I cant see how 4" concrete and a set of car tires could be conductive enough, or such a system safe enough.
I guess the steel bands are the coils brman referred to.)


Ouote from link :''To test how much energy would be lost as electricity traveled through the tire rubber, the researchers also set up a lab experiment with metal plates. "Less than 20 percent of the transmitted power is dissipated in the circuit," said Ohira at that time. With enough power the system could run typical passenger cars, he added.''



The tires sound conductive to me, also one of the major examples in electrical engineering is one of Faraday ie a faraday's cage if you were in a car and it got it by lightening you would be pretty safe as the current would travel through the skin of the car ie metal and then through the tires to earth.

A quote from the link below
''Three basic properties of carbon black are considered to affect the level of conductivity in rubber compounds. These are the particle size (or surface area), the degree of structure
and the corresponding amount of void space between those particles, and finally porosity.
Small particle furnace blacks, with their high degree of chain-like structure or aggregation,
and less void space between the particles, have higher levels of conductivity than thermal
blacks, which have large particles and more space between the particles due to the low
degree of aggregation. The greater amount of structure acts to reduce the distance
between particles or aggregates, thereby allowing electrical flow to pass easily through
along the molecular chains. Thus, an inverse relationship exists between both surface area
and structure and the level of resistivity.''

http://www.google.co.uk/url?sa=t&rc...1oHgCg&usg=AFQjCNHnihcWXqllFeXiS0wuUPi4t9Llqw

 

[Darkwood]

I think your lightning quote is a poor example as at the extreme voltages generated and the fact it can jump through air (in general a very good insulator) i doubt very much that tyres whether good or poor insulators would pose any kind of barrier to a bolt of lighning.
As i have already said there are just too many variables for a yes/no answer to your original query its all dependant on the individual situation and the tyre variables as you have listed above.