# controller causing static on FM radio



## dtbaker (Jan 5, 2008)

I'm having trouble with static on radio FM when the controller is on... any solutions?

I have a zilla controller. no static when accelerator is off. static starts as soon as I press throttle at all. static does not seem to change with speed.

I tried disconnecting dc-dc, and running the 12v system off the small aux battery thinking perhaps noise was coming back thru the dc-dc. But, it did not change static.

zilla is mounted to plastic, offset from firewall a couple inches, but is pretty much behind the location of the radio. traction battery cables are not very close to antenna wire anywhere I am aware of, but I am not sure where the antenna cable runs in the middle section of car between trunk and front. 

so.... I don't really know how to find what the source of interference is, or how to shield/filter it effectively. I am thinking it is somewhere along the antenna cable because there is no static when I play CDs.

ideas? filters?


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## frodus (Apr 12, 2008)

Might be an unintentional ground somewhere in the HV system. I don't remember if the zilla or hairball case are isolated with respect to pack negative. 

Can you check if you have a ground issue?


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## dtbaker (Jan 5, 2008)

frodus said:


> Might be an unintentional ground somewhere in the HV system. I don't remember if the zilla or hairball case are isolated with respect to pack negative.
> 
> Can you check if you have a ground issue?


how would I check that?
and wouldn't that affect both FM and CD?


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## Caps18 (Jun 8, 2008)

http://www.radioshack.com/product/index.jsp?productId=2062214

Have you tried one of these?


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## frodus (Apr 12, 2008)

Caps, 

Those are for isolating noise on RCA Jacks... Like if he was running amps off the RCA Jacks in the back of his head unit.


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## frodus (Apr 12, 2008)

dtbaker said:


> how would I check that?
> and wouldn't that affect both FM and CD?


It might not... Two different circuits inside and the radio might be more sensitive to noise than the cd side of things. 

My point is that electrical noise has a couple ways in. One is via the antenna. One is because of bad shielding next to something really noisy. Another comes in through the ground/power. 

Since he tried powering with a battery that only proves it wasn't the DC-DC. It doesn't mean that there is not noise coming in from the chassis ground.


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## dtbaker (Jan 5, 2008)

frodus said:


> It might not... Two different circuits inside and the radio might be more sensitive to noise than the cd side of things.
> 
> My point is that electrical noise has a couple ways in. One is via the antenna. One is because of bad shielding next to something really noisy. Another comes in through the ground/power.
> 
> Since he tried powering with a battery that only proves it wasn't the DC-DC. It doesn't mean that there is not noise coming in from the chassis ground.


The thing that is confusing is that the static starts right in as soon as accell is depressed, even with very low amps being pulled thru HV. I would have thought it more likely only under high amps when creating an EMF around the HV cables.... but that doesn't seem to match this case.

I will take some more time to trace the antenna cable to see if it is running close to any HV cable.... if it IS, how far away would be likely to fix the issue? or, is there a way to effectively shield the antenna I can add if proximity cannot be changed?

assuming the hairball is leaking or sharing a ground to chassis somewhere.... how do I find it? just trace every wire coming out of the hairball?


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## dtbaker (Jan 5, 2008)

Caps18 said:


> http://www.radioshack.com/product/index.jsp?productId=2062214
> 
> Have you tried one of these?



no I have not. I have not added any filter or isolator to the radio power/ground in.... but could I guess. the confusing thing is that CDs are fine; which makes me think it is the antenna rather than radio power.


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## dtbaker (Jan 5, 2008)

frodus said:


> Caps,
> 
> Those are for isolating noise on RCA Jacks... Like if he was running amps off the RCA Jacks in the back of his head unit.


i have no aftermarket or separate amps. just stock radio. antenna is on rear fender, so cable runs the length of the car. 

The original builder did put most of the fusing, both LV and HV under the dash, so there might be proximity issues or a ground crossover I have not noticed yet. I doubt the original builder would have intentionally put any HV ground to chassis, he's a very 'electrical' guy, but anything is possible.


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## Roy Von Rogers (Mar 21, 2009)

Have you tried a portable radio to see if you get the noise. It will tell whether or not its rf (antenna) related.

Roy


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## dedlast (Aug 17, 2013)

My guess would be that the controller pot is very close to the antenna and there may a ground issue on the antenna cable itself or even in the radio. Since the static starts as soon as he steps on the pedal, that tells me that as soon as the pedal starts sending a signal (even if it is just a voltage) it's "broadcasting" some noise into the FM antenna. What happens with the radio on AM?

I would check out the connections to the pedal and the antenna. 

Bill


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## dtbaker (Jan 5, 2008)

Roy Von Rogers said:


> Have you tried a portable radio to see if you get the noise. It will tell whether or not its rf (antenna) related.
> 
> Roy


no, I don't have a spare 12v car radio to work with.... but what I guess I might be able to do is pull the power/ground at the back of the installed radio and power that directly from a standalone 12v battery. That should tell me whether the static is coming in thru power/ground to the radio OR coming in thru the antenna.... right?


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## dtbaker (Jan 5, 2008)

dedlast said:


> My guess would be that the controller pot is very close to the antenna and there may a ground issue on the antenna cable itself or even in the radio. Since the static starts as soon as he steps on the pedal, that tells me that as soon as the pedal starts sending a signal (even if it is just a voltage) it's "broadcasting" some noise into the FM antenna. What happens with the radio on AM?
> 
> I would check out the connections to the pedal and the antenna.
> 
> Bill


pedal is a HEPA on drivers side.... wire MAY run along inside of firewall near radio, and out thru firewall to hairball which is on the right. so, the throttle wires may run past both the radio, and the antenna. I will look.

I am still betting on antenna since there is no static playing CDs.


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## frodus (Apr 12, 2008)

I doubt it's the throttle... The throttle is a very low power analog device. Couldn't be more than a few mA. Its probably the pwm switching inside the Controller causing noise. It switches at varying frequency at any throttle position above 0%. The controllers aren't shielded well so it's either Leaking through a ground or its too close to the radio/antenna. 

See if you can get a portable radio or boom box and try it inside the car in the garage while running the motor a little in neutral. 

As far as ground.... Check to see if there's continuity between the chassis and HV battery negative. Put the positive lead on 12v and the negative lead on the traction pack negative. Should not read 12v.


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## piotrsko (Dec 9, 2007)

Try a couple .01 mfd disc caps accross the positive lead and ground of the radio.


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## CKidder (Dec 12, 2009)

I'd second this thought. Controllers can be extremely noisy when they are switching. One other thing to check is how close the input and output HV cables are with respect to plus and minus. Ideally you want your positive and negative wires to be touching or very nearly touching. Any distance between the cables creates a loop antenna. The cables will have super imposed RF noise on them from the switching so making them into a loop antenna is bad news.



frodus said:


> I doubt it's the throttle... The throttle is a very low power analog device. Couldn't be more than a few mA. Its probably the pwm switching inside the Controller causing noise. It switches at varying frequency at any throttle position above 0%. The controllers aren't shielded well so it's either Leaking through a ground or its too close to the radio/antenna.
> 
> See if you can get a portable radio or boom box and try it inside the car in the garage while running the motor a little in neutral.
> 
> As far as ground.... Check to see if there's continuity between the chassis and HV battery negative. Put the positive lead on 12v and the negative lead on the traction pack negative. Should not read 12v.


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## Tesseract (Sep 27, 2008)

dtbaker said:


> I'm having trouble with static on radio FM when the controller is on... any solutions?
> 
> I have a zilla controller.


I've written about this numerous times, most recently here. Other good posts are this reply and this one.

You mentioned that the noise only appeared when throttle was applied, but was constant otherwise, which suggests that this is "E-field" radiation from the motor cables. To be completely sure, try reducing the traction pack voltage to the controller a few cells at a time and note at what voltage the noise disappears.

That said, the only practical solution here is to shield the motor cables with metal - just like coaxial cable. You will likely have to experiment with bonding the shield to the car chassis at one end, both ends or even neither end.


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## dtbaker (Jan 5, 2008)

frodus said:


> As far as ground.... Check to see if there's continuity between the chassis and HV battery negative. Put the positive lead on 12v and the negative lead on the traction pack negative. Should not read 12v.



good news there, I do not have a ground issue, HV+/ LVground shows no continuity.


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## dtbaker (Jan 5, 2008)

CKidder said:


> I'd second this thought. Controllers can be extremely noisy when they are switching. One other thing to check is how close the input and output HV cables are with respect to plus and minus. Ideally you want your positive and negative wires to be touching or very nearly touching. Any distance between the cables creates a loop antenna. The cables will have super imposed RF noise on them from the switching so making them into a loop antenna is bad news.


the long runs under the car have HV +and - cables run together. separating only right where it splits to get the the pos and neg terminals of the battery packs.

hhhmmmmmm.....

this means that the antenna cable will be running 'fairly close' to one side of my middle battery pack where on HV lead is one one side, and the other on the other side. But the antenna cable should have enough shielding at that spot?


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## dtbaker (Jan 5, 2008)

Tesseract said:


> I've written about this numerous times, most recently here. Other good posts are this reply and this one.
> 
> You mentioned that the noise only appeared when throttle was applied, but was constant otherwise, which suggests that this is "E-field" radiation from the motor cables. To be completely sure, try reducing the traction pack voltage to the controller a few cells at a time and note at what voltage the noise disappears.
> 
> That said, the only practical solution here is to shield the motor cables with metal - just like coaxial cable. You will likely have to experiment with bonding the shield to the car chassis at one end, both ends or even neither end.


ok, today I ran a spare antenna cable from the back of the radio, out the passenger door to the trunk to the antenna.... way away from traction pack HV cables... and still get the static when accel is pressed at all, and no static with no accell.

so.... more likely static is coming in thru power to radio, or power to antenna. right?! I disconnected power to antenna, and static is reduced, but so is reception. This doesn't clearly tell me whether the static is coming in from controller via the dc-dc, or from the 12v power being too close to a HV cable, inside a HV loop.

the power tot he radio is hard to access.... I have fairly easy access to the input side of the dc-dc. I am considering adding 100uH inductor(s) inline on dc-dc input. I figure it would probably be good for the health of the dc-dc no matter what?

question is, do I put one on pos, or neg, or both legs for best results?

if THAT doesn't work I guess it would have to be a shielding issue?


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## Caps18 (Jun 8, 2008)

That still sounds like a ground loop. My ICE car had the same problem, and it is a common thing.

Make sure the radio is grounded, and the ground wire is big enough. Or it could be that the frame isn't providing a good enough ground. Here is a lot more info on it:

http://www.caraudio.com/forums/wiri...-engine-whine-ground-loop-fixes-take-two.html


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## Caps18 (Jun 8, 2008)

OK, I re-read this thread again, and might be thinking of something else. I have a radio in my house attached to a powerful stereo and it always had issues with reception. I bought a new antenna, and I also bought an HD radio. I didn't have any static problems when it was playing a DVD or a computer input. But moving the antenna far away from the stereo and closer to the outside helped.

Here is my next suggestion if you don't have RCA plugs, put this in line with your antenna.

http://www.amazon.com/1st-Source-Antenna-Ground-Isolator/dp/B002AU9W48


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## dtbaker (Jan 5, 2008)

Caps18 said:


> OK, I re-read this thread again, and might be thinking of something else. I have a radio in my house attached to a powerful stereo and it always had issues with reception. I bought a new antenna, and I also bought an HD radio. I didn't have any static problems when it was playing a DVD or a computer input. But moving the antenna far away from the stereo and closer to the outside helped.
> 
> Here is my next suggestion if you don't have RCA plugs, put this in line with your antenna.
> 
> http://www.amazon.com/1st-Source-Antenna-Ground-Isolator/dp/B002AU9W48



cheap enough... I'll give it a try. 
considering mounting in the inductors pre-dc-dc regardless as well.

radio itself may or may not be well grounded as it is aftermarket, and original converter pulled the dash and made major changes to accommodate the CycleAnalyst display in the console just above the radio. I have NOT pulled the dash to check all that, and would really like to avoid it.


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## Tesseract (Sep 27, 2008)

dtbaker said:


> ok, today I ran a spare antenna cable from the back of the radio, out the passenger door to the trunk to the antenna.... way away from traction pack HV cables... and still get the static when accel is pressed at all, and no static with no accell.


If the motor cables are the source of noise then it is no surprise that moving the antenna a few feet away from the traction pack cables didn't help much.

Noise from PWM on the motor cables is inversely proportional to voltage rise time. I don't have data on the Zilla controllers, but the rise time for the Soliton controllers is 100-200ns, depending on the model, so the effective frequency of the switching noise will be in the range of ~1.75 to 3.5MHz. 

The FM radio band starts at around 88MHz, so it would take a fairly high harmonic of the switching noise to affect it, but the motor controller is much closer to the radio than any legitimate radio transmitter, hence why it can cause interference.



dtbaker said:


> so.... more likely static is coming in thru power to radio, or power to antenna. right?!


Didn't you report that the CD player in your car stereo works fine? That eliminates noise on the 12V power or chassis ground right there.

You need to be more methodical in your troubleshooting. Change just one thing at a time (for example, moving the antenna) and actually write down some notes on whether the problem got better, worse or changed behavior (e.g. - pitch change, or intensity proportional to throttle, etc.).


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## dtbaker (Jan 5, 2008)

Tesseract said:


> You need to be more methodical in your troubleshooting. Change just one thing at a time (for example, moving the antenna) and actually write down some notes on whether the problem got better, worse or changed behavior (e.g. - pitch change, or intensity proportional to throttle, etc.).


i dunno how much more methodical I can be, but I'll recap what I've done and effects so far....

equipment: zilla controller, ACME dc-dc in motor bay 'always on', plus small 12v aux battery in parallel in trunk wired into where Miatas have their stock battery in trunk. antenna is on rear fender, and is a powered amplified 'stubby' antenna with 12v power pulled from pre-wired 12v+ that was there from original powered antenna motor that would raise/lower stock antenna.

test configurations and observations:

- no static when playing CDs whether accellerator is on or off.

- with everything connected, there is steady static on FM as soon as accell is on. pitch/intensity does not change with motor speed or amp load.

- disconnecting antenna power at antenna base reduces static a lot, but also obviously affects reception for weaker broadcast stations more than is acceptable for long-term use.

- (re-tested today) disconnecting dc-dc and powering 12v system only from aux battery moved to temp hookup directly in place of dc-dc output; still get static on FM ! (had to re-test on a quiet classical station)

addl info: Today I found that the aux batt from its installed location in trunk is not getting power to the system, so it has NOT been in parallel at all as I had assumed, its been doing nothing....


so.... the apparent (clear?) conclusion of the day is that noise is coming in thru the dc-dc, probably mostly thru the antenna amp power. question NOW is what the most effective fix is; 100 uH inductor(s) on the dc-dc input? on both legs from HV?

followup question is.... does anyone have a nice close-up of effective clean installation of these inductors on input to dc-dc? Is a soldered joint the best way to go, etc?


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## frodus (Apr 12, 2008)

Sounds like your DC-DC isn't isolated.... or it's a cheap DC-DC. You shouldn't get much/any noise through it. Try the inductor and see what happens.


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## dtbaker (Jan 5, 2008)

frodus said:


> Sounds like your DC-DC isn't isolated.... or it's a cheap DC-DC. You shouldn't get much/any noise through it. Try the inductor and see what happens.


it is a cheap dc-dc. its an ACME 600 watt, was $200 or so.
I have two inductors I had bought for next build (with Soliton). Is it best to install on both legs of dc-dc input?


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## dtbaker (Jan 5, 2008)

frodus said:


> Sounds like your DC-DC isn't isolated.... or it's a cheap DC-DC. You shouldn't get much/any noise through it. Try the inductor and see what happens.



installed a 100uH inductor on each leg of HV input to dc-dc.... Static returns as soon as I hit the accelerator ?! ;(

....looking at where I hooked in the little aux battery when I disconnected the dc-dc, I am seeing that where I disconnected and plugged in the battery is at an anderson plug on the edge of the motor bay. from there, the run to the dc-dc runs under the battery rack, pretty close to the motor, and then up where I have the dc-dc mounted.... right above the motor, probably 4" above the motor casing.

so, either the inductors are not the appropriate noise suppressors for whatever may be coming in from the zilla, or the interference is being introduced after the dc-dc in the 12v output as it passes close to the motor ? could this be possible ?


.... 30 minutes later ....
crap, I decided to re-test running on battery power only, switched to a really quiet classical station, and there IS still static. It is NOT gone as I had reported just a couple posts ago. This explains why installing the inductors was a waste of time, but leaves me with a likely sheilding problem somewhere along the 12v+ that powers the antenna or the radio.

so now.... will set up to run JUST the antenna power with the battery and see how that goes...

...later...
used external battery to power just the antenna, still get static, so MUST be interference somewhere on 12v in to radio, or a bad ground on radio chassis? right?


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## mora (Nov 11, 2009)

How about this cheap test; wrap some folio over motor cables and make the other end of folio wrapping touch car frame (12V ground). Wrap more than one layer and see if static gets weaker. Leave everything else as per original installation.


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## dtbaker (Jan 5, 2008)

mora said:


> How about this cheap test; wrap some folio over motor cables and make the other end of folio wrapping touch car frame (12V ground). Wrap more than one layer and see if static gets weaker. Leave everything else as per original installation.



what is 'folio' ?

...and by disconnecting dc-dc which is near motor, and connecting battery to dc-dc output far away from motor, I no longer suspect motor/cables/dc-dc. I suspect it is either near the radio, the radio power, or somewhere the antenna/power is in proximity to my HV cables running to mid or rear battery racks.

There is a mess of usual wires behind dash PLUS cable carrying HV to the in-dash cycle analyst, which is mounted just above the radio. the cycleanalyst 4-wire cable I think is shielded, but maybe not. carries TINY amps... so I dunno. not a lot of room to work behind the dash without pulling everything out. thoughts on cycle analyst proximity to radio?

just above the antenna plugin on the back of the radio is a tab that the install manual says is supposed to be a ground wire location.... nothing there. there is ALSO shown one of the wires of the big plug with power in, speakers out, and ground out.... which I can't really see, but I an assuming that ground is in place since the radio is operable. question is, would a second ground on radio chassis really be required? or a probable cause for this issue?


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## PStechPaul (May 1, 2012)

You might try using a small portable radio as a field strength meter and move it all over the car's wiring system to see where it is strongest. It may work best if you tune it between stations so the AGC will max out. The AM band may work better than FM, and you might even find that you can adjust the tuner to get peaks of noise which may indicate a harmonic of the PWM frequency.

If the noise is from a magnetic field, it may not be possible to use copper or aluminum foil or braid shielding to eliminate it. But often it is effective to twist the power cables together to reduce the radiated field, and likewise twist the more sensitive control wires which can serve to cancel out the noise.

It is also important to know if it is differential mode (also called normal mode), or common mode noise. Inductors in series with one or both power leads work for differential mode noise, but for common mode noise the inductors need to be coupled, which is usually accomplished by winding both wires together on the same coil. Here is some explanation:
http://www.murata.com/products/emc/knowhow/pdf/26to30.pdf
http://www.maximintegrated.com/app-notes/index.mvp/id/2045
http://www.butlerwinding.com/store.asp?pid=28349

Another idea is to reduce the higher frequency harmonic energy by using an RC snubber or even an LC low pass circuit out of the controller. The following may help with some ideas (although most are for AC):
http://www.mtecorp.com/pages/wp-content/uploads/PowerQuality99paperAug03.pdf
http://www.ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040172495_2004178258.pdf
http://www.freepatentsonline.com/4673851.pdf


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## kennybobby (Aug 10, 2012)

*Did you ever do this test properly?*



dtbaker said:


> good news there, I do not have a ground issue, HV+/ LVground shows no continuity.


The continuity test was from HV (-) to chassis, not HV (+). The cheap dc-dc may tie the low side of the input and output together (and to chassis). 

Folio is aluminum foil.


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## Tesseract (Sep 27, 2008)

dtbaker said:


> test configurations and observations:
> 
> - no static when playing CDs whether accellerator is on or off.


Noise is not coming in through the 12V power or ground to the stereo, then. It is also not the result of induced currents into the ground loop formed between the powered/amplified antenna and the stereo head unit.

This strongly suggest noise is an electric-field in nature, and not a magnetic one, which means the source is the chopped voltage waveform on the motor cables.



dtbaker said:


> - with everything connected, there is steady static on FM as soon as accell is on. pitch/intensity does not change with motor speed or amp load.


Don't know what "with everything connected" encompasses, but again the observation that the noise does not change pitch/intensity with throttle position, motor speed, etc., strongly suggests that the origin is the chopped voltage waveform on the motor cables.



dtbaker said:


> - disconnecting antenna power at antenna base reduces static a lot, but also obviously affects reception for weaker broadcast stations more than is acceptable for long-term use.


As above, with the additional narrowing down of the actual "victim" to the antenna and the antenna cable.



dtbaker said:


> - (re-tested today) disconnecting dc-dc and powering 12v system only from aux battery moved to temp hookup directly in place of dc-dc output; still get static on FM !...


Because noise is not coming in through power leads.



dtbaker said:


> addl info: Today I found that the aux batt from its installed location in trunk is not getting power to the system, so it has NOT been in parallel at all as I had assumed, its been doing nothing....


Irrelevant.



dtbaker said:


> so.... the apparent (clear?) conclusion of the day is that noise is coming in thru the dc-dc, probably mostly thru the antenna amp power.


Nope, unless you have failed to report an observation which contradicts the conclusion I have drawn (that the motor cables are emitting the noise which is being picked up by the antenna/antenna cable).


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## dtbaker (Jan 5, 2008)

Tesseract said:


> This strongly suggest noise is an electric-field in nature, and not a magnetic one, which means the source is the chopped voltage waveform on the motor cables.


ok, I guess this would explain why adding the inductors to the dc-dc input didn't fix anything. lets assume it IS emitting from the motor cables.... let me ask:

- is it likely to be just the cables between controller and motor, 
or any/all of the HV cables running to battery packs as well?

- what would an effective fix be? to put metal-lined flex conduit on all cables between controller and motor, grounding the metal liner to chassis?

- if I find some other wiring 'near' the motor cables, particularly 12v+, would relocating those wires help or not matter since the e-field is getting picked up by the radio antenna? If relocation might help, how far away would make the difference?

- if it is the motor cables, how come EVERY build doesn't have this FM static problem?


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## mora (Nov 11, 2009)

Tuners (electronics) are different. Antenna locations and motor cabling length/orientation is also different in many builds. I believe most of builds have problems with AM signals at least.

So far my best FM tuner was in a cheap 20$ chinese car radio which was otherwise completely crap. Never had any problems in FM reception. Replaced the whole unit with more expensive stuff and FM problems began. I've replaced antenna few times but have yet to relocate the whole thing. Have also tried different filters and done cable re-runs. Shorter cable between antenna and tuner should do good. But there is no static when pressing pedal. Only poor signal reception. Even with HV side completely disconnected. Maybe I should replace my current radio again.


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## Tesseract (Sep 27, 2008)

dtbaker said:


> ...
> - is it likely to be just the cables between controller and motor,
> or any/all of the HV cables running to battery packs as well?


I already answered this in post 17.



dtbaker said:


> - what would an effective fix be? to put metal-lined flex conduit on all cables between controller and motor, grounding the metal liner to chassis?


See above.



dtbaker said:


> - if I find some other wiring 'near' the motor cables, particularly 12v+, would relocating those wires help or not matter since the e-field is getting picked up by the radio antenna? If relocation might help, how far away would make the difference?


You're getting ahead of yourself here... First reduce the emission of noise, then worry about moving around other potential victim cables.



dtbaker said:


> - if it is the motor cables, how come EVERY build doesn't have this FM static problem?


Whether noise is a problem or not is a random thing because of the multitude of variables involved.


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## dtbaker (Jan 5, 2008)

Tesseract said:


> I already answered this in post 17.



I am just trying to scope the project, and be sure that it is a reasonable approach to start only with the relatively short runs between the controller and motor itself.... ignoring the cable runs between the battery packs for now. I wasn't sure whether 'motor cables' means just the runs from controller to motor, or all of the HV cables everywhere.

adding jackets to the motor cables is going to require pulling and re-installing my battery rack, which could be a full-day project.... I'd love to have some quick test to verify this will do the trick. would a temp 'sheild' between antenna and controller work, or does it have to be an enclosed and grounded conductive container around the motor cables to prevent leakage?

is there some kind of meter I could buy, or perhaps rent if it is very expensive, to help me verify the source of the noise?


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## Tesseract (Sep 27, 2008)

dtbaker said:


> ...I wasn't sure whether 'motor cables' means just the runs from controller to motor, or all of the HV cables everywhere.


When I write "motor cables" I am specifically referring to the cables between the controller and the motor. If I write "battery cables" then I am specifically referring to the cables between the traction battery pack and the controller. There really shouldn't be any confusion here, at least not when it comes to my posts.



dtbaker said:


> adding jackets to the motor cables is going to require pulling and re-installing my battery rack, which could be a full-day project.... I'd love to have some quick test to verify this will do the trick. would a temp 'sheild' between antenna and controller work, or does it have to be an enclosed and grounded conductive container around the motor cables to prevent leakage?


Read post 29 for a cheap/easy way to rig up a temporary electrostatic shield on the motor cables. Keep in mind what I wrote in post 17 about grounding the shield at one end, both ends or even no ends (ie - left floating).



dtbaker said:


> is there some kind of meter I could buy, or perhaps rent if it is very expensive, to help me verify the source of the noise?


Yes there is test equipment that can be used to measure EMI, and it can even be rented, but it is extremely complex to operate. Lest you think I am being patronizing here, *I* would have a tough time using such equipment correctly...


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## dtbaker (Jan 5, 2008)

Tesseract said:


> When I write "motor cables" I am specifically referring to the cables between the controller and the motor. If I write "battery cables" then I am specifically referring to the cables between the traction battery pack and the controller. There really shouldn't be any confusion here, at least not when it comes to my posts.


NOT everyone is so precise, so I thought I'd ask...




Tesseract said:


> Read post 29 for a cheap/easy way to rig up a temporary electrostatic shield on the motor cables. Keep in mind what I wrote in post 17 about grounding the shield at one end, both ends or even no ends (ie - left floating).


sounds like a plan... I MIGHT be able to wiggle my way in or push a length of lined conduit down from the controller end without removing rack, which would be nice. going to be a couple days before I can get to this though.


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## HighHopes (May 29, 2013)

me thinks that you should re-read post #31, #16 and #17. those are the best advice.


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## PStechPaul (May 1, 2012)

You don't want to put steel conduit around individual conductors that are carrying AC current. This will cause induced current and heating and other problems. All the conductors should be bundled together and then the bundle could run through a steel conduit, since the net current flow will be zero. The noise could also be caused by insufficient high frequency filtering across the DC supply close to the controller, or inadequate snubbers on the IGBTs.


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## frodus (Apr 12, 2008)

He's got a Zilla controller ..... i.e. DC


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## dtbaker (Jan 5, 2008)

PStechPaul said:


> You don't want to put steel conduit around individual conductors that are carrying AC current.


my motor cables run about a foot from the zilla controller to my Warp9 DC motor. Tesseract seems to feel that conductive sheilding, perhaps grounded to the chassis is the way to contain the EMI. Do you disagree?


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## PStechPaul (May 1, 2012)

Since it is DC, this should be OK. It is still better to run them close together in a single shield, but for just one foot that might be difficult and unnecessary. A steel jacket would function as somewhat of an inductor, which should round off and slow down the PWM rise and fall edges, and might reduce the radiated harmonics.

I still think it would be worthwhile to try a portable radio to determine where the noise is coming from.


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## dtbaker (Jan 5, 2008)

I didn't try the grounded motor cable conduit yet... but did stick in a 'ground loop isolator' on antenna jack in back of radio. Somewhat surprisingly, it has removed a great deal of the static from most stations, especially in the middle of the dial, but there is *some* still at the low end in particular where the classical stations tend to be like 89.9, 91.9, etc. as well as the upper end above about 102...

I still plan to add a ground from back of radio chassis to chassis, and see if I can slip in motor cable sheilding....


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## dtbaker (Jan 5, 2008)

little update.... the antenna 'ground loop isolator' really is ineffective... there is still the hiss at either end of the dial, and it really ruined reception somehow such that seek can hardly find any stations.

so, I'm back to adding a radio chassis ground (which looks like it might have been skipped when the radio was replaced, then trying to slide some conduit over motor cables, then perhaps conduit over battery cables in middle and rear racks where they separate to reach pos/neg terminals on opposite sides of the sub-packs.


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## nb_mitch (Mar 6, 2016)

I seem to have the same issue, I get static when I touch the accelerator pedal, regardless of how much I push it.

The one thing which might be causing my issue, is I have not completely seated the radio yet, so it may not be grounded to chassis yet. Once I push it all the way in, I don't have the tool to remove it.

NETGAIN MOTORS, WARP9 MOTOR1 
750 Amp Revolt Controller


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## mizlplix (May 1, 2011)

Not trying to over think this but:" 

1- requires throttle input= motor current begins to flow.

2- Motor current is by design, DC, but it is also PWM, (pulsating DC).

So, the controller housing is leaking, the motor leads are leaking, or the motor is leaking.

My roadster is an AC system (still PWM) and AM & FM radios play fine in it.......Strange.

Miz


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