Measuring the EMF

[jcesare]

What is the SAR?

Specific absorption rate (SAR) is a measure of the rate at which energy is absorbed by the body when exposed to a radio frequency (RF) electromagnetic field.

[EVDRIVER]

EMF in the LEAF is about on par with a normal auto, the leaf components must have various forms of shielding to protect the car systems from malfunctioning, this goes two ways to keep other signals like a cell phone from interfering with items like the inverter. A cell phone at your ear has about 1000 times more radiation then one would get from riding in the LEAF, with your cell in the back seat one would emit about 50X the EMF placed there vs the exposure from what the LEAF would emit. EMF exposure in a LEAF is not a big concern, if this concerns anyone they should stop using a cell phone completely.

If I were selling a LEAF vehicle or a dealership selling LEAFs I would not make any specific claims regarding EMF as that could open one up for liability, particularly if one has publicly expressed a concern or question over any adverse effects of EMF. This falls along the lines of dealers giving tax credit advice. I would direct those customers to Nissan or an electrical engineer.

[garygid]

Click on the "SAR" link in your post.

[TomT]

I have an EMF meter that measures both electrical and magnetic fields (it also measures RF but that is not germain here). I've used it in my ICE vehicles and in the Leaf and didn't read anything beyond normal background levels in any of them except when the Leaf was charging - then it was fairly strong. I did once read a very strong magnetic field nearly 100 feet from a 1,000 horsepower AC electric motor however.

Does anyone know if the EMF has been tested/measured for the LEAF? If so, is the data available?

[smkettner]

A cell phone at your ear has about 1000 times more radiation then one would get from riding in the LEAF, (snip).

Is there a reference on that to put actual numbers to the ratio?

[JessEV]

I had the same question about EMF in the Leaf. So after searching around for related info on the Prius, conventional cars and of course the Tesla roadster, I found:

http://www.nytimes.com/2008/04/27/autom ... 27EMF.html
http://www.teslamotors.com/forum/forums/emf-radiation

From these, it looks like Prii and other well made cars are in the sub 5 milligauss range. The Tesla roadster was measured at 10 mG at idle and 50mG on full throttle.

So I bought one of these Triflow measurement devices and did some testing. I managed to get Gudy (Thanks again Gudy!) to let me test his car, compared to a friend's Honda Accord, and my current ICE car which shall remain unnamed. Here are the results:
- Honda Accord: measured at driver head and torso fluctuated at between 1-5mG
- Honda Accord: measured at driver feet fluctuated slightly above 10mG (probably the wiring underneath)
- Leaf: measured at driver head and torso fluctuated between 1-5mG, no noticeable diff whilst accelerating
- Leaf: measured at driver feet hovered around 5-10mG, no noticeable diff whilst accelerating
- Leaf: measured in the back seat area was well sub 3mG, and seemed to jump up a little only when braking
- Leaf: measured in the back hatch area while CHARGING - 100mG - (yeah that was high, but who cares, no one is in the car)
- my ICE car: 100mG+ everywhere in the car

My take away from all this is IF this is a relevant/good/important/useful measure of something (call it EMF, call it non-ionizing radiation, bla bla...) some ICE cars can be much worse than hybrids or electric cars, and the Leaf is in the ball park of other well made cars like the Prii and Accords.

Now, the weird thing is I'm still left wondering why my ICE car is as high as it is. It is also from a reputable manufacturer (German) and the only thing different about it is perhaps because of weight savings they did away with cladding/shielding for the engine bay, alternator, and cables.

(Note: as a basic calibration I used the Triflow on my iPhone and laptops and house breaker box. iPhone blips occasionally from 2mG to 100mG when idle, and when downloading or on a call it is pegged at 100mG. Laptop screen around 10mG. Laptop wifi antenna assembly 100mG but drops off dramatically 1 foot away, breaker box pegged at 100mG but drops off to 2mG at about 2 ft)

[aqn]

I had the same question about EMF in the Leaf.[...]
So I bought one of these Triflow measurement devices and did some testing.

Great job! Thanks!

(And BTW, did you mean "Trifield", not "Triflow"?)

[tbleakne]

I had the same question about EMF in the Leaf.
it looks like Prii and other well made cars are in the sub 5 milligauss range. The Tesla roadster was measured at 10 mG at idle and 50mG on full throttle.
>>
- Leaf: measured at driver head and torso fluctuated between 1-5mG, no noticeable diff whilst accelerating
- Leaf: measured at driver feet hovered around 5-10mG, no noticeable diff whilst accelerating
- Leaf: measured in the back seat area was well sub 3mG, and seemed to jump up a little only when braking
- Leaf: measured in the back hatch area while CHARGING - 100mG - (yeah that was high, but who cares, no one is in the car)
- my ICE car: 100mG+ everywhere in the car

I am impressed that Nissan has been able to achieve magnetic fields this low in the Leaf. Magnetic field is proportional to current. 20KW (during acceleration)/400V = 50A DC going into the car's inverter. The inverter outputs AC to feed the synchronous motor at a frequency proportional to the motor's RPM and vehicle speed.

In addition to shielding, the field can be minimized by short cable lengths and close routing of cables carrying opposing currents, so that their respective magnetic fields cancel out.

I would have more confidence in these readings if the measured field readings did go up with acceleration, but the fact that they decline in the back seat, further from the inverter/motor, makes sense.

Cell phones handle far less current, but they radiate at frequencies many orders of magnitude higher.

[JessEV]

aqn: oops, yes, it was the Trifield (http://www.amazon.com/Trifield-100XE-EM ... 341&sr=8-1)

tbleakne: On the acceleration, it was a bit puzzling to Gudy and myself that it didn't go up much. I should add I didn't measure above the dash much, but when I did that was easily 10mG to 20mG, I was focused on where we were seated. What we did notice is a lot of blipping and movement of the needle on the Trifield meter in when I was holding that unit on my lap. We moved both our iPhones out of our pockets to the backseat, the blipping reduced, and still not much correlation to the many times Gudy gave it full pedal.

I wouldn't mind doing this test again on someone else's Leaf (I'm in "month of April") in the daytime so I can record it on video for folks here. (I'm in the SF Bay Area, Peninsula) Anyone? Anyone?

[PaulScott]

I wouldn't mind doing this test again on someone else's Leaf (I'm in "month of April") in the daytime so I can record it on video for folks here. (I'm in the SF Bay Area, Peninsula) Anyone? Anyone?[/quote]

Marc Geller has a red one. I put in the ask to him. He's got three EVs at his house now. A RAV, an iMiEV and his shiny new red LEAF. For Marc, this is akin to a heaven.