Removing carpet and rear seats

Basildane,

Thanks for the explanation. I've read somewhere that there's a difference between AC vs DC EMF but I'm not sure what the difference is. Could you explain that? And does your meter differentiate between the two types? Also, what is the frequency of the AC driving the Prius motors?

As far as the HV cable is concerned, if you take out the rear seat and remove the carpet section running along the left edge of the car, you can see the cable running along the length of the car. Shielding there would probably make sense. Also, you can easily remove the top cover of the HV battery by removing two screws in the hatch area. Perhaps you could add some shielding material to the underside of that cover piece, as well as to area to the front of the battery (directly behind the rear seat's backrest).

 

Basildine,

You are always going to get a few strange responses, but you also got a lot of respectfully curious questions. Just ignore the responses you dont like.

As far as an alternative "shielding material" have you thought about sound deadening material? One of the best is called "second skin". The material consists of a thin layer of butyl rubber material with an aluminum foil backing. I would think the aluminum foil would be fairly good EMF shielding material and you would get the added benefit of some nice sound deading material. Plus, it would probably be easier to work with than your nickel plating material.

OTOH, the gold foil used on satelites is extremely thin. It might not even be that expensive.

 

<div class='quotetop'>QUOTE(Basildane @ Oct 3 2007, 12:09 PM) [snapback]520670[/snapback]</div>

I'm still not clear on something. Your meter only measures oscillating EMF, correct?
I'm very interested to hear about your before/after measurements.

BTW, I have completely covered my car with Secondskin Damplifier, but I have no clue if it has any EMF shielding effect. Would be way cool if it did! Wish I had a Gaussmeter...

 

the summary on quackwatch looks like an interesting read

http://www.quackwatch.com/01QuackeryRelatedTopics/emf.html

 

if you're seeking peer-reviewed published information, the NIH has a great resource.

here are all the articles that come up, you can access the abstracts through this service. (note: that there are less than 1200 papers in the field says a lot.)

http://www.ncbi.nlm.nih.gov/sites/entrez?d...ch&term=EMF

for available free full-text articles see here.

http://www.ncbi.nlm.nih.gov/sites/entrez?d...ch&term=EMF

not all are exactly what you're looking for, you'll have to do some digging (the pubmed search engine isn't the best) but that's what they pull up for EMF in legitimate scientific journals. i say, make your own conclusions and it's your car so do what you like.

 

California EMF Program

An Evaluation of the Possible Risks From Electric and Magnetic Fields (EMFs) From Power Lines, Internal Wiring, Electrical Occupations and Appliances

The Risk Evaluation analyzes the potential human health risks of magnetic field exposure. Specifically, this document provides an evaluation of the animal, laboratory and human evidence that shows how exposure to 50/60 Hz magnetic fields may or may not increase human health risks. The Risk Evaluation is based on the results of published research studies, with emphasis on new studies, the National Institute of Environmental Health Sciences (NIEHS) Working Group Report, and the results of the California EMF Program Studies.

 

One issue is that the EMF in the Prius is from DC current, and all of the studies are based on EMF's from 50-60hz AC current. I would have no idea how that would affect the risk from exposure, but the EMF's are very different.

Any idea how well the aluminum would shield the EMFs?

I personally did not like that Quackwatch article. The idea where he states that there is no postulated "mechanism" for the EMF's to cause harm is meaningless. It is always easy to poke holes in a hypothesis. It is very very difficult to prove one.

 

<div class='quotetop'>QUOTE(Winston @ Oct 5 2007, 09:52 AM) [snapback]521728[/snapback]</div>

That's why I'm still looking for more info on the DC EMF. I'm not yet convinced that it is a problem. But it wouldn't be imprudent to err on the side of caution if the costs are reasonable.

Also, I checked with Secondskin, they said there's very little (if any) shielding from the aluminum.
Besides, even if there was, putting the material inside the door panels wouldn't help anyhow. You'd have to wrap it around the HV cable and shield the HV battery itself.

 

<div class='quotetop'>QUOTE(Basildane @ Oct 5 2007, 11:59 AM) [snapback]521876[/snapback]</div>

I am an electrical engineer, 30 + years experience in both electric and magnetic field investigations and shielding.

These hybrid cars can produce both:


A. 1000hz.-5000 hz.electric/magnetic fields(primarily from the motor compartment)

and

B.Low frequency(less the 10 Hz.) direct current(D.C.) magnetic fields(primarily from the D.C. battery cables running to the motor)



Comparative field testing will begin shortly on all makes of hybrid cars

 

Thank you Ghostbuster for your valuable information. We certainly need people like you to help us
with this important issue.

As a Prius User Group organizer and Fleet Manager I have become concerned about EMF in hybrids as it relates to human exposure, especially for those that make their living driving these vehicles all day long.

My research to-date shows a strong association with AC and DC EMF levels and human health concerns but not quite a causal relationship. Prudent avoidance seems to be the safest stance to take at this point in time.

Purchasers have a right to know what levels of exposure they can expect from their vehicles particularly if they are buying a hybrid. The Department of Energy in the U.S. has an elaborate testing protocol developed for measuring EMF in hybrid vehicles but to the best of my knowledge has yet to use it on a current hybrid vehicle. Yes there is controversy about the issue but you still have a right to know and to make your own decisions. The hybrid technology is great and we need it in our battle with climate change and the preservation of our environment. EMF exposure can be reduced through proper sheilding albeit at additional cost.

I call for a major automobile publication or the media in general to step up and bring this issue forward by conducting comparative tests between vehicles and making them public. When the automobile manufacturers know the public is concerned about the issue, the solutions will start to flow. Good citizens like Basildane shouldn't have to struggle with retrofitting a sheilding solution on their own.






<div class='quotetop'>QUOTE(ghostbuster @ Oct 5 2007, 07:25 PM) [snapback]522014[/snapback]</div>

 

Do you smoke, eat meat, use cell phones, or fly on commercial jets?

 

[attachmentid=11873]Basildine,

The latest EMF study is here:

http://www.bioinitiative.org/report/index.htm

Save yourself a lot of reading and zero in on Section 17 with the
conclusions.

The report was co-authored by Dr. David Carpenter and Ms. Cindy Sage. It was published
in July-August 2007.


I have also attached a safety note from Triumf which discusses DC EMF fields.

Regards,

RKS

 

<div class='quotetop'>QUOTE(Basildane @ Oct 5 2007, 01:59 PM) [snapback]521876[/snapback]</div>

If your theory is correct then shielding the inverter would make sense.
But if that's not easy to do then perhaps shielding the firewall would help.
Of course, shielding the HV cable itself can't hurt (and should be straightforward).

 

<div class='quotetop'>QUOTE(zenMachine @ Oct 9 2007, 03:31 PM) [snapback]523267[/snapback]</div>

The primary source of EMF in the Prius is indeed the approx. 14 foot wiring harness that runs from the Inverter to the Battery. The cables are encapsulated in a semi-translucent plastic shroud for most of the journey under the vehicle on the driver's side. Also producing EMF is the electric power steering motor mounted near the steering rack inside the dash of the vehicle. The Inverter also produces EMF as you point out.

We have explored a few solutions for controlling the EMF from the wiring harness but to be effective the harness needs to be fully encapsulated most likely by a nickel tube or pipe. The other viable option would be to twist the cables to create a cancelling effect. This would however most likely require additiional cable and would also require the de-rating of the cable. (additional copper content in manufacture). Adding nickel plates under the carpet may reduce EMF levels slightly but to really get it under control you need to fully enclose the wiring harness.

FYI, the Ni-mh battery did not produce significant amounts of EMF in our tests.

Toyota should offer an optional EMF sheilding option package for new customers. An aftermarket kit could also be offered. I suggest "optional" as keep in mind that Toyota is not breaking any laws with respect to EMF exposure for occupants. There aren't any.

 

How about something like this?

[attachmentid=11911]

Wrap wiring, pipes, switches, or electro-magnets. We were able to achieve over 95% reduction of fields from a lamp cord by wrapping it in a single layer of this material! Make shields for your shavers, electric toothbrushes, hair dryers, alarm clocks or lighting ballasts. Even lay it flat (in our experiments, we saw nearly 90% field reduction when a 4" x 4" MetGlas shield was placed flat against an energized lamp cord).

Note: This material tends to saturate easily and is not recommended for shielding strong magnetic fields. This is the material often used in Electronic Article Surveillance systems. Formula 2714AZ, supplied annealed.

Supplied as a ribbon, 1" wide. Specify desired length when ordering.

Metglas (Cat. #A278) ………………….…… $2.50/lin ft

http://www.lessemf.com/mag-shld.html#278

<div class='quotetop'>QUOTE(RKS @ Oct 9 2007, 03:58 PM) [snapback]523286[/snapback]</div>

 

Zenmachine,

I appreciate your efforts. Ghostbuster will need to make some comments but I think you'd find that the material can't handle the current load of the cable and would therefore saturate immediately. According to my contacts at Hymotion Canada (converters of the Prius to PHEV) The Prius wiring harness carries in the range of 100 amps of current at any moment in time. I think a twisting of the cable or a solid nickel sheild is the way to go.

I keep hearing this comment on different blogs that Prius' destined for countries with higher EMF standards for occupant exposure are equipped from the factory with EMF shielding. I have been in touch with Toyota Canada officials on this issue (last week) and have yet to hear back. If it is true, then Toyota already knows the answer and has a solution. Does anyone have any concrete knowledge of this?


<div class='quotetop'>QUOTE(zenMachine @ Oct 9 2007, 04:10 PM) [snapback]523291[/snapback]</div>

 

The link I provided has several other products which have different technical specs. If you click on any of the "specs" links, you'll be able to see more details. I took a look at them but they all sounded like Greek to me.

Regarding "saturation", what is an acceptable level for Prius applications? And what other specs should we look for in these EMF shielding products?

I wonder if/how future versions of the Prius will resolve this issue. Twisted cable, it it works, seems like the simplest solution (from a manufacturing standpoint). I wouldn't hold my breath waiting for an official response from Toyota, however.

<div class='quotetop'>QUOTE(RKS @ Oct 10 2007, 06:51 AM) [snapback]523518[/snapback]</div>