The high frequency switching circuitry causes RF emissions (limited by FCC testing). Externally, the wires are the carriers of any signals (including coupled RF, also tested)
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EMF while Supercharging
- Thread starter Destiny1701
- Start date
The high frequency switching circuitry causes RF emissions (limited by FCC testing). Externally, the wires are the carriers of any signals (including coupled RF, also tested)
Yes. And the amount of EMF in the car while charging at 80amps at home is FAR higher with this meter:
https://www.amazon.com/gp/product/B0013P6ZJQ
Than when supercharging. I've never gotten it to read on a straight DC source, just AC.
Plus the equation is based on an idealized zero cross-section conductor. The strands themselves prevent approaching that distance.
And of course the cable has to complete the electrical circuit by providing a return path back to the supercharger unit.
Two currents flowing side by side in opposite directions along the same cable create magnetic fields which partially cancel each other out, reducing the field strength even further.
thecloud
As rhythm raced inside, the ship came alive
I read the paper you linked, and it says nothing at all about EMF increasing dramatically beyond safe and acceptable levels when charging. What the paper actually concluded was that there's no causal connection between EMF and health issues. Did I miss something?
"Nothing changes my mind" is not a good attitude for a scientist. You're supposed to be open to changing your mind if repeatable tests provide evidence confirming a theory. (In this case, the study in question clearly does not provide such evidence.)My 40 years of electronic engineering experience and knowing the Tesla tells me this is hog wash. Just my opinion. Frequency, Power, Distance from the source, and what's in between you and the source. Think about it some more. You are welcome to disagree, but nothing changes my mind
Just to show that I'm not pointing to a link on Amazon and "claiming" to have done the measurements, here's a video I just took with the same EMF meter while charging at 80 amps. This is the back seat. Notice how it drops to zero when I stop charging.
I bought this meter a week after getting the Tesla for the same concerns. Then I did a little research and realized that health issues related to even extreme levels of EMF have never been proven.
I've thrown the meter in the back of the car again and will repeat the test when I supercharge next. When I did this originally, the reading was 0 in the back seat as DC produces almost nothing.
I bought this meter a week after getting the Tesla for the same concerns. Then I did a little research and realized that health issues related to even extreme levels of EMF have never been proven.
I've thrown the meter in the back of the car again and will repeat the test when I supercharge next. When I did this originally, the reading was 0 in the back seat as DC produces almost nothing.
TBH there's probably a greater risk to health from the calories consumed during the stop, the sanitary condition of the rest rooms and the air quality at the supercharger location.
Still, there's always the portable Faraday Cage, ie the tinfoil beanie with matching underoos.
Still, there's always the portable Faraday Cage, ie the tinfoil beanie with matching underoos.
I don'y usually comment on nutjob babbel, but 600v on over 96cells would mean 6,25v cell voltage, way above the safe/stable/acceptable voltage for Li-Ion cells.
Further comparing a steady magnetic field around DC (superchargers are DC) , to a cell phone is totally nuts as some magnetism /milliGauss produced by DC and and RF power at various frequencies, is not really even in the same domain.
finally, as stated in the post; a cellphone does not generate higher(or none) RF output (on cell tower frequencies) during charge - except if charger is creating some noise, usually at much lower frequencies.
The initial post is on the level of flat-earthers.
Further comparing a steady magnetic field around DC (superchargers are DC) , to a cell phone is totally nuts as some magnetism /milliGauss produced by DC and and RF power at various frequencies, is not really even in the same domain.
finally, as stated in the post; a cellphone does not generate higher(or none) RF output (on cell tower frequencies) during charge - except if charger is creating some noise, usually at much lower frequencies.
The initial post is on the level of flat-earthers.
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FlyF4
Son of a MX
And I am glad you said that
That's because I am not a scientist. I'm an engineer. I don't change my mind on things like that which I know for fact And I will end with a quote "Scientists dream about doing great things. Engineers do them." James A MichenerHow's that for ego
That crazy video posted here, is the same kind toys as "ghost finders" or "hidden camera finders" on ebay.
It's a stupid-simple, way to detect "anything" - except of the annoying sound and red light it emits, it's not in any way related to anything that is bad for your heath, it would go off anywhere near any power outlet too.
It's a stupid-simple, way to detect "anything" - except of the annoying sound and red light it emits, it's not in any way related to anything that is bad for your heath, it would go off anywhere near any power outlet too.
It only goes off near a power outlet if something is plugged in. EMF detectors are cheap and easy to make.
And my point is that it reads NOTHING in the back seat while supercharging. The OP was concerned that supercharging would be dangerous and that charging at home wasn't.
Neither is true, but if ONE of them were, it would be charging at home that was, not supercharging.
thecloud
As rhythm raced inside, the ship came alive
But it did show one thing: when charging stopped, so did the electrical field.
I don't know what the scale of the measurement means, though. I'd like to see comparative experiments, such as what it does outside the car, or in the front seat. Also, as @Ande suggested, does it measure a similar reading near a standard power outlet when something is plugged in and drawing power?
FlyF4
Son of a MX
Absolutely 100% agree! Oh but can you help me understand why the EMF meter sounded why I accidentally sat on it? Too many burritos? No don't answer that. It will cause another conspiracy theory to surface
This particular gauss meter goes up to 50 milliGauss. More expensive digital units have multiple ranges that can go much higher. For the purposes of THIS discussion, as you've just pointed out, the meter is sufficient to show the OP is not on the right track.
Ha, "violent agreement" and all that.
Over the last few decades I've spent too much time with a laptop sitting on my you-know-what, working in data centers, and playing with high power ham gear to worry about a little extra EMF in my car.For those of you still playing along, 1 Gauss = 100 micro Teslas so 50 milligauss is at least 200000 times smaller than the electromagnetic field in a typical hospital MRI machine.
Anyone want to ban hospital MRI?
Thought not.
Anyone want to ban hospital MRI?
Thought not.
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Exactly
(A former job was adjusting wiring in car so that our compass module wouldn't get annoyed. Defroster with chassis ground v.s. 200mgauass earth field...)
Any wires can get induced AC on them and that can cause EMI. Pure DC can create magnetic fields, but there are no signals that will leave the wire. The length for an antenna (the length of wire needed to radiate a signal, or pick one up) ranges from 1/4 to a full wavelength depending on the design of the antenna. The length = c/f. C is the speed of light and f is the frequency. Pure DC has an f of 0.
I don't know if superchargers use pure DC though. DC just means the current flows one direction. In 60Hz AC, the current and voltage are positive half the time and negative the other half of the time. If you run the AC through a regulator, you can flip the negative part positive and instead of a pure sine wave, you have two positive half sine waves after one another.
The Wikipedia article on DC has an image of pure DC (as from a battery), half wave (just chop off the bottom half) and full wave (flip the bottom half on top):
Direct current - Wikipedia
Rectified sine waves still have a frequency and could still radiate off a wire. I don't have a working oscilloscope so I haven't looked at the signals on a li-ion charger (I have some 18650s I use in flashlights), but if I remember correctly a lot of ni-cad chargers use a rectified DC signal. Those cells charge better with a pulsed charge. It's been 30+ years since I studied power supplies and rechargeable batteries and back then there were only two chemistries available: lead acid and ni-cad.
So it is possible there is some kind of alternating signal on supercharger lines.
I won't have time to get to a supercharger in the next week or two, but I suggest next time you supercharge, tune the AM radio first, then start supercharging and listen to the radio after it starts. If the radio fritzes out, there is EMF at the antenna at minumum, but also probably around the cabin. If you want to see where it's strongest, take a portable AM radio with you and hold it various places around the cabin. If there is a lot of EMF, I would expect it to be strongest in the backseat area (on the S, 3rd row on the X), that's where the charging equipment is.
Valid point that DC does not imply constant voltage. The pack itself will prevent large voltage swings on the lines, but there could be current fluctuations.
In the case of battery charging, any deviation from the average value means the peak value is higher. Higher peak currents would likely be less good for the pack, so I'm thinking it's pretty low ripple. Especially given that the pack equivent resistance is very low, so any voltage variation would cause a proportiantly larger current variation.
Sample numbers: If the pack drops 100V on a 1000A acceleration run, the pack is 0.1 ohm, so every volt difference is 10A. For a low voltage 350V pack, that equates to 3.5kW variation. If the pack is more charged it could be 4kW/ volt.
I'm guessing the chargers are constant current output, and possibly interleaved in the SCs to reduce ripple even lower than their normally low value.
/conjecture off
kingjamez
Member
No, they don’t output pack voltage until the taper portion of the charge.
The first part of the charge cycle is constant current which means that the voltage varies in order to keep the current the same. The voltage is raised to increase the current flowing into the pack. The only time that the charger voltage is the same as the pack voltage is when the charge current is zero.
While I haven’t done the math, 600v sounds completely reasonable to me for 120kW.
I too can’t understand EMF coming from the car during supercharging as it’s a pure DC event.
That said, the EMF from the 480 three phase to DC converters in the chargers might be significant. In which case, if that were true, it would be far better to be INSIDE the car. Lots of speculation though.
-Jim
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