Is there electromagnetic field in the Prius?

January 28, 2006 4:21 PM

Anyone has information on possible electromagnetic field inside the Prius (Toyota Hybrid) from the large battery pack?
posted by semmi to travel & transportation (5 comments total)

Wow, no one? Helloooooo?

Ok, I'll take a whack at it.

Yeah, I'm sure that the electronics in your Prius generate some sort of electromagnetic field, but probably not the battery.

Electromagnets generally occur when you have electricity running through wires, particularly lots of them, as in a coil. So it's not your battery that you should worry about, it's the electric motor, which is operated entirely on the basis of electromagnetism.

And even then, I wouldn't bother to worry about it. When you think about it, you walk around on a really big magnet all day, every day, and you haven't died yet. And while it's not a very powerful magnet, at least not in one place, you’re still probably exposed to much stronger magnets (than the Prius) without you knowing it in the course of your day.

I’d imagine that the exhaust from your Prius would be more hazardous to your health than any electromagnetism. I mean, people have MRIs done on them all the time without any harm, right? The electric motor in a Prius is what I'd call a negligible danger.
posted by SlyBevel at 5:19 PM on January 28, 2006

CT and PET scans provide a more or less equivalent dose of radiation to the yearly background radiation for most inhabited locations on Earth, while MRIs are completely different in that the 300X-Earth field magnetism is more a hazard in terms of missle-effect accidents. :)

Along those lines you're more effected by *radiation* (not EMF per se) taking a direct flight over the north pole than you would be sitting in a Prius, as least as far as the Prius contributes -- hell, I'd even say you're better off buying a used car that has completed outgassing of the manufacturing process and new materials if you're that concerned.
posted by kcm at 5:59 PM on January 28, 2006

SlyBevel is correct - stored electricity doesn't generate a magnetic field, but moving electricity does. More precisely, a magnet field is generated at a right angel to the travel of electricity. If you wind a wire around a post many times, you can increase the local magnetic field. That is exactly how you build a simple motor.

The electric power hanging by your house, or burried under the sidewalk probably generate stronger Electro-Magnetic fields than a Prius does.
posted by b1tr0t at 6:15 PM on January 28, 2006

What, more exactly, do you want to know about the electromagnetic field that is specific to the Prius? My wife has driven forty thousand miles in hers and she hasn't had metal buttons ripped off her clothes or chased levitated keys about the interior yet.

More seriously, her cellular phone works in the Prius about as well or bad as it does outside, even considering it's a Bluetooth connection through the car console. If there were nontrivial interactions with an electromagnetic field, I'd expect the connection to be affected. My cell phone works inside the Prius too, and it's a freebie-with-the-plan piece of crap that wants only the slightest excuse to fail. As for other electronics that aren't so sensitive to exernal conditions as cell phones, we've had no problems.

If you want me to run a simple experiment and report back the results -- as long as it doesn't involve me buying something like these little gems -- let me know and I'll give it a shot.
posted by mdevore at 6:23 PM on January 28, 2006

There will be a magnetic field but very close to DC and therefore basically harmless to you, plus the intensity drops off linearly with distance. The field strength is also really really low since the car is pulling (tops) a couple hundred amps through the batteries. Field inside the motor will be much much larger but you're not inside the motor, are you?

There's probably also a sheet of steel between you and the cabling; that will shield you quite effectively.

If you're paranoid, take a magnetic compass in the car and see if it moves when you're running on electric power - I'd be surprised if you can get it to so much as twitch a degree. It won't indicate north correctly since things in the car are magnetised anyway and the steel shell shields you a bit from the earth's field. Even if the compass swings about 45 degrees, that means you're getting about as much field as you are from the earth anyway and you don't worry about that, right?
posted by polyglot at 1:11 AM on January 29, 2006