Removing carpet and rear seats

You are right to be concerned about the EMF levels of your Prius - they are apallingly high (forget about posts from people who are ignorant on this matter). However, I think you will find it very difficult to get them down to a safe level. We tried (my wife is very sick from electro-sensitivity) and gave up. After you have done the battery & cabling etc, you will need to do the conventional things as in any other car - radio, alternator, distributor etc. We ended up with a diesel (no spark plugs, and shielded the alternator).
I'd like to know what the most effective shielding material is though.
Wished we had known all this years ago.....
Jon

 

Hi All,

This is all interesting stuff. I doubt there is a biological effect, but better safe than sorry.

So, I will comment on shielding. The reason the Metglas, or any other magnetic material tape may be of limited usefulness is the currents induced onto the tape. If these currents cannot flow completely, and setup a counter field, the shielding effect will be limited. As the material is a tape, its helically wrapped onto the cable. Each layer of the tape must conduct readily to each other layer. But helical wraps will not maintain internal tension, they tend to unwravel. This results in loss of good high current conductivity from wrap to wrap. This is why the other poster was commenting that a tube from end to end was neccassary.

At RF frequencies such tapes have much more shielding usefulness. Nickel tends to concentrate the current into a thiner layer at RF, than it would be like in copper or silver. This is because of the higher permeability of nickel. Along with the increase resistance of nickel, the current is dissipated into heat. RF currents flowing on the surface of these tapes can dissipate quickly, due to the above comments, and that RF wavelength is short compared to a good conduction length on the surface of the applied tape. At low frequencies, the current will penetrate through the tape, and any unsymetrical flow on the outside of the tape will result in fields outside the enclosure made by the tape. Whereas at RF the current would have to flow along the inside of the tape, reach and edge, then go around the edge. In doing so the RF current is greatly attenuated due to the inch or two of travel for this to occur, rather than the .020" thickness of the tape at low frequency. While there are RF fields from the hybrid drive, they are not strong, or your AM radio would not be able to receive any stations. And of course, the car itself could stall near a strong transmitter if they did not do a good job of RF shielding. I drive past a 50 KW AM broadcast antenna daily without problem.

The magnetic field forms concetrically around the conductor. Its direction depends on the direction of current in the conductor. Having the plus and minus conductors next to each will result in cancellation of the field , as the magnetic field from on conductor is opposite in polarity than from the other conductor. This is the way the Prius is laid out. As the two conductors are not coincident, there is some leakage. Broadside from the pair the fields will be the weakest, as the distance to the two wires in the insulation is the same, and so the field from each exactly cancel. So just turning the pair so that is broadside to an area desired to be at low intensity might help.

DC magnetic fields would cause currents if one were to move physically through the field. But, as the car does not have the field while one is entering or leaving the car, as the main relay is open in the battery comparment, the DC fields should have little effect.

As the cables have to be as big as they are to carry the current, its more likely that higher frequency EMF will leak more readily.

By the way, they do make chain-male like shielding suits. They are used by antenna technicians that need to service broadcast antennas, while other stations at the same site are still in operation.

Is somebody going to measure the motor fields inside the engine comparment next to the transmission, versus at the driver's position?

Has anybody measured the fields in other cars, specifically when the A/C ventilation fan is going full blast, or when the windshield wiper motor is going full ? I would be currious to see how much field these give off.

 

EMF FIELD MEASUREMENTS

With a simulated 16 amps of dc current flow ,the measured dc magnetic field directly beside the conductors was:

A.with the wires together 60 milligauss


B.with the wires seperated 550 milligauss

Note1: As the current increases through the wiring for eg. 30% increase there is an approx. corresponding 30% increase in the magnetic field.
Note2:Refer to scientific medical links already posted for relevance of these readings.

 

For the amount of work you're going to do you might as well do it thoroughly. How about that layer of nickel (is nickel a magnetic shielding material?), a layer of lead foil for any RF component, and a top coat of sound deadening material. I expect you'd want to start all the way up front by the firewall and go back to the rear of the back seat, just cover everything. If you care to it also ought to be possible (tedious, but possible) to come up with a set of seat covers that have the various materials worked into them as a second line of defense.

 

Basildane,

I bought a Gauss meter as well and unfortunately mine isn't as good as yours. The readings from that back seat are alarming. I had no idea it was 100 mG.

Let us know how the shielding goes as I want to do that myself as well.

People should remeber that Asbestos was deemed safe until people got sick. Smoking wasn't deem a health risk until people got sick. Mercury wasn't deemed a health risk and they used it in lipstick. Arsenic was okay too. The list goes on and on. They usually don't find stuff until after there is a body count.

I do share Basildane's concern as I also have young children and I do know that a lot of people on this board have dismissed this idea without looking up or doing some reading on this.

No one has ever sat on top of a battery for hours on end before. You don't really know what the effects are and why take a chance.

Just so the flamers know we all have the same car. I consider the Prius to be a leap ahead in terms of cars. They may not have thought it all the way through.

I also agree Toyota should do something to lower its levels of EMF's.

I highly suspect that a lot of the flamers did not have a Gauss Meter.

Let us know how the nickel plating goes.

 

One other thing I noticed. The steering column also has a lot of EMF's. I don't like this location as it is too close to the jewels.

Just thought I'd bring some levity. Seriously it is pretty high in that particular area for some reason.

 

They used to think tomatoes were poisonous and the insane were possessed. Good luck with your project.

 

This is hilarious! You are aware the earths magnetic field can be as high as 600 mG, and never gets lower than 300 mG right? Better wear a permalloy hat!

 

This may be a stupid question but I'll throw it out there: could you dampen the AC effects in the 12V DC system? Would that lower measured EMF?