Here's an interesting issue: FM interference BEFORE motor on

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Here's an interesting issue: FM interference BEFORE motor on

Rob Trahms
Hi all -

1989 VW Cabriolet
Cafe Electric Z1K motor controller
Impulse9 motor

I have been digging into my EV radio interference problem again, and tonight discovered a very interesting distinction between AM and FM radio in the EV.

AM radio is predictably unusable when the motor is engaged, and it does in fact get worse with higher RPMs.

While I previously thought FM radio was the same, I was incorrect.  FM signal is decent with the ignition in position 1 (where you can remove the key), but position 2 (just prior to ignition) a general static noise starts and grows louder until drowning out the FM signal entirely.  There is no difference after ignition - interesting!

What this tells me is that the motor has little or nothing to do with the FM interference I am experiencing!
I am now optimistic I can solve this, at least on the FM side of things.

The working theory I have is that either the Hairball microcontroller or possibly the aux voltage gauge is generating the FM noise (seems unlikely that it would be the TBS e-meter I have, because that is on all the time, even when the ignition is off).

Other theories on why I am seeing FM noise?

Thanks in advance!
Rob
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Re: Here's an interesting issue: FM interference BEFORE motor on

Roland Wiench
In our electrical work in electronics labs and comm rooms, we do a lot of RF
shielding, isolated grounding systems.  I apply this same science to my EV
back in 1980.  Aircraft use this type of isolated and shielding system.

All communication circuits which includes rpm sensor, E-meter, shunts and
speaker wires are all double shield.  The internal shield only grounds at
the senders and device chassis leaving the other end of the shield floating.
The external shield is only grounded at the other end to a chassis plate
that use insulated standoffs that mount to a steel equipment box that houses
the Z1K and all related devices.

The contactors, fuses, and charger meters are install in the rear of the EV
on separated aluminum chassis plates on insulated standoffs inside either
cast aluminum or fiberglass equipment boxes.

A counter poise grounding circuit coming from the B- or a 12 volt accessory
battery runs around the total perimeter of the EV in a complete circle which
is then connected to the B- again.

This counter poise ground wire must be larger than all the combined ground
circuits in the EV.  Tap offs this counter poise is from a cadmium plated
metal standoff using threaded rod couplers that screw in to the existing EV
body bolt connections.  Use a spade wire terminal to bolt the counter poise
wire at every tap off.

The counter poise circuits uses a No. 1 AWG copper stranded and No. 6 AWG
copper stranded for the tap offs.  Two No. 6 wire connects to the fire wall
and two No. 8 AWG copper stranded wire taps off the No. 6 using a standoff
that grounds to the any equipment boxes and internal chassis plates.  A No.
10 AWG copper stranded wire than taps off the No. 8 wire connection on the
equipment box and/or chassis plate.

The a No. 10 wire is connected to the No. 8 wire junction point on the
chassis to the mounting feet of the motor controller and any other devices
use with the motor controller.

This is continuous ground path of the B- 12 volt circuit.  If your EV is a
steel body that uses self grounding devices or ground wires tap to the body,
this may be the cause of your static noise.  Do not relied on the vehicle
body for a return ground.

I also install all wiring circuits of different voltages and comm wires in a
steel wire way that runs through the center of the vehicle from the front
fire wall, through a center fire to the rear equipment panels. Instead of
wireways, you can use aluminum flexible conduit or double shield cables.

Also if you combined different voltages circuits bundle together or in a
conduit or wire way, the insulation of all the wires, must be voltage rated
at the highest voltage circuit.

In all my wire circuits, I prefer to use a 600 volt rating wire type THW 90
degree C. rated, 19 or 39 stranded copper. You can use THWN which has a
extra nylon jacket, but is normally use for ease in pulling in a conduit.
The THW has a thicker and softer insulation design for chassis work.

I do not get any noise on FM and only some light noise on the AM at very low
motor rpm of less 100 rpm.  After 100 rpm, the AM noise go's away.

Roland


----- Original Message -----
From: "Rob Trahms" <[hidden email]>
To: <[hidden email]>
Sent: Friday, May 24, 2013 10:41 PM
Subject: [EVDL] Here's an interesting issue: FM interference BEFORE motor on


> Hi all -
>
> 1989 VW Cabriolet
> Cafe Electric Z1K motor controller
> Impulse9 motor
>
> I have been digging into my EV radio interference problem again, and
> tonight
> discovered a very interesting distinction between AM and FM radio in the
> EV.
>
> AM radio is predictably unusable when the motor is engaged, and it does in
> fact get worse with higher RPMs.
>
> While I previously thought FM radio was the same, I was incorrect.  FM
> signal is decent with the ignition in position 1 (where you can remove the
> key), but position 2 (just prior to ignition) a general static noise
> starts
> and grows louder until drowning out the FM signal entirely.  There is no
> difference after ignition - interesting!
>
> What this tells me is that the motor has little or nothing to do with the
> FM
> interference I am experiencing!
> I am now optimistic I can solve this, at least on the FM side of things.
>
> The working theory I have is that either the Hairball microcontroller or
> possibly the aux voltage gauge is generating the FM noise (seems unlikely
> that it would be the TBS e-meter I have, because that is on all the time,
> even when the ignition is off).
>
> Other theories on why I am seeing FM noise?
>
> Thanks in advance!
> Rob
>
>
>
>
> -----
> Electro, the Cabby-EV
> http://chaosmgmt.blogspot.com
> http://www.evalbum.com/1426
> --
> View this message in context:
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/Here-s-an-interesting-issue-FM-interference-BEFORE-motor-on-tp4663203.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
> For EV drag racing discussion, please use NEDRA
> (http://groups.yahoo.com/group/NEDRA)
>
>
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Re: Here's an interesting issue: FM interference BEFORE motor on

Rob Trahms
Wow, thanks Roland.  That is some thorough shielding!  I am probably not going to replace all of my wiring at this point to solve this problem though - just the offending culprit.

It definitely seems like it is something fairly simple, because my FM radio works fantastic when the key is out (and by the way, the E-meter (including pack voltage, shunt measurements) and Hairball are running all the time, so they do not cause a problem at this point).  

When the key is turned to pre-ignition position, this is typically where all standard auxiliary electronics in the car go on, including the auxiliary voltmeter in the dash.  THIS is when the FM static starts.  The motor contactor isn't even engaged at this point, so the motor and controller are out of the picture.  Interestingly, AM still sounds good at this point, probably because the interference source is more in the FM band and not in AM.

My thinking one of the following culprits:
1) Either my radio isn't properly grounded, or
2) My antenna cable isn't properly shielded, or
3) One of my aux circuits needs a shield.

Does this sound right?

Rob
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Re: Here's an interesting issue: FM interference BEFOREmotor on

Roland Wiench
In reply to this post by Rob Trahms
A lot of car radios use a ground strap connecting to the frame/body of a
vehicle.  That is a lot of resistance for the ground path to the a B- 12
volt ground source.  I first connect a 12 volt B- directly to the radio case
and see what happens.

My radio is a Sony that slides into a second steel case which makes it easy
to remove the radio by unlatching it with a security key.  The steel case
has a large steel case capacitor that is connected to this steel radio case
and to a good ground source to B- of a battery.
The capacitor is a ignition capacitor that is use in distributors in a ICE
vehicle.

The steel enclosure acts as a Faraday shield for many isolated electrical
and communication devices.

With the 12 volt ignition switch off, take a voltage reading across the
battery terminals.  Lets say it reads 13.3 volts just after you turn off the
ignition switch removing a charging source.  Wait about 10 to 12 hours and
the voltage may drop to about 12.8 volts which is normal.

Then connect the volt meter leads from the positive at the battery and a
grounding strap for a device on the fire wall or in the dash.  I have seen
up to 1 to 2 volt drop which is cause by the high resistance of the steel
body parts.

Sometimes a fuse clip, fuses or circuit breaker may cause a voltage drop on
the B+ side of the battery which may cause noise.

Roland




----- Original Message -----
From: "Rob Trahms" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, May 25, 2013 9:01 AM
Subject: Re: [EVDL] Here's an interesting issue: FM interference BEFOREmotor
on


> Wow, thanks Roland.  That is some thorough shielding!  I am probably not
> going to replace all of my wiring at this point to solve this problem
> though
> - just the offending culprit.
>
> It definitely seems like it is something fairly simple, because my FM
> radio
> works fantastic when the key is out (and by the way, the E-meter
> (including
> pack voltage, shunt measurements) and Hairball are running all the time,
> so
> they do not cause a problem at this point).
>
> When the key is turned to pre-ignition position, this is typically where
> all
> standard auxiliary electronics in the car go on, including the auxiliary
> voltmeter in the dash.  THIS is when the FM static starts.  The motor
> contactor isn't even engaged at this point, so the motor and controller
> are
> out of the picture.  Interestingly, AM still sounds good at this point,
> probably because the interference source is more in the FM band and not in
> AM.
>
> My thinking one of the following culprits:
> 1) Either my radio isn't properly grounded, or
> 2) My antenna cable isn't properly shielded, or
> 3) One of my aux circuits needs a shield.
>
> Does this sound right?
>
> Rob
>
>
>
> -----
> Electro, the Cabby-EV
> http://chaosmgmt.blogspot.com
> http://www.evalbum.com/1426
> --
> View this message in context:
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/Here-s-an-interesting-issue-FM-interference-BEFORE-motor-on-tp4663203p4663216.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
> For EV drag racing discussion, please use NEDRA
> (http://groups.yahoo.com/group/NEDRA)
>
>
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Re: Here's an interesting issue: FM interference BEFORE motor on

Lee Hart
In reply to this post by Rob Trahms
On 5/24/2013 11:41 PM, Rob Trahms wrote:
> FM signal is decent with the ignition in position 1 (where you can remove
> the key), but position 2 (just prior to ignition) a general static noise
> starts and grows louder until drowning out the FM signal entirely.
> The working theory I have is that either the Hairball microcontroller or
> possibly the aux voltage gauge is generating the FM noise (seems unlikely
> that it would be the TBS e-meter I have, because that is on all the time,
> even when the ignition is off).

I think you will find that the noise is coming from something with a
microcontroller in an unshielded box (plastic case, bare board, etc.) It
could also come from one inside a metal box, if the metal box isn't
grounded, or if the wires coming out of that box are not shielded or
properly handled so they don't act as antennas.

You should be able to unplug things one at a time until you locate the
offending device.

--
The most dangerous enemy of a better solution is an existing one that
is just good enough. -- Eric S. Raymond
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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Re: Here's an interesting issue: FM interference BEFORE motor on

Cor van de Water
Rob,
If I recall correctly, both Zilla and Hairball have a microprocessor and
the two units are interconnected with an unshielded Ethernet cable. I do
not know what type of signals go over the Ethernet cable, whether it is
Ethernet (balanced) signals or asymmetic signals, but in any case both
processors may leak high frequency noise from out of their metal box via
the cable.
So, it could help to use shielded Ethernet cable and connect the shield
to a good ground (frame) as well as making sure that the two metal boxes
have a good ground (if their mounting screws connect the frame then that
is usually sufficient, but I have seen the units mounted on plastic or
wood, which leaves then floating and able to transmit all kinds of
noise.

As Roland said - you can also improve the radio by giving it a cleaner
power directly from the battery instead of local grounds and noisy
power. Another area to make sure is the shielding of the antenna cable,
since it often travels through areas with high noise (dash and engine
bay) to get to the antenna that is mounted on top of a large shield,
such as a fender. This is done for a reason. If the antenna cable shield
is interrupted, the antenna may still appear to work OK-ish but the
radio will pick up much more noise from inside the car.

BTW, my AM radio will fade out when going under overpasses but will
otherwise still pick up stronger AM stations, even while driving my EV.
But I have to confess that I am not using a Zilla.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email] Private: http://www.cvandewater.info
Skype: cor_van_de_water Tel: +1 408 383 7626


-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of Lee Hart
Sent: Saturday, May 25, 2013 11:37 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Here's an interesting issue: FM interference BEFORE
motor on

On 5/24/2013 11:41 PM, Rob Trahms wrote:
> FM signal is decent with the ignition in position 1 (where you can
remove
> the key), but position 2 (just prior to ignition) a general static
noise
> starts and grows louder until drowning out the FM signal entirely.
> The working theory I have is that either the Hairball microcontroller
or
> possibly the aux voltage gauge is generating the FM noise (seems
unlikely
> that it would be the TBS e-meter I have, because that is on all the
time,
> even when the ignition is off).

I think you will find that the noise is coming from something with a
microcontroller in an unshielded box (plastic case, bare board, etc.) It

could also come from one inside a metal box, if the metal box isn't
grounded, or if the wires coming out of that box are not shielded or
properly handled so they don't act as antennas.

You should be able to unplug things one at a time until you locate the
offending device.

--
The most dangerous enemy of a better solution is an existing one that
is just good enough. -- Eric S. Raymond
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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Re: Here's an interesting issue: FM interference BEFOREmotor on

Cor van de Water
In reply to this post by Rob Trahms
Rob Trahms wrote:
>My thinking one of the following culprits:
>1) Either my radio isn't properly grounded, or
>2) My antenna cable isn't properly shielded, or
>3) One of my aux circuits needs a shield.

That sounds right.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email] Private: http://www.cvandewater.info
Skype: cor_van_de_water Tel: +1 408 383 7626

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Re: Here's an interesting issue: FM interference BEFORE motor on

Martin WINLOW
In reply to this post by Rob Trahms
If you don't thinks it's the motor but suspect the hairball, you could replace the motor temporally with a suitably rated incandescent light bulb and use the controller to power that.  That way you get the controller frequency changing so you can ID it on the radio interference without the motor to confuse things.  Because the bulb load isn't inductive, that won't confuse things either.

MW

On 25 May 2013, at 16:01, Rob Trahms wrote:

> Wow, thanks Roland.  That is some thorough shielding!  I am probably not
> going to replace all of my wiring at this point to solve this problem though
> - just the offending culprit.
>
> It definitely seems like it is something fairly simple, because my FM radio
> works fantastic when the key is out (and by the way, the E-meter (including
> pack voltage, shunt measurements) and Hairball are running all the time, so
> they do not cause a problem at this point).  
>
> When the key is turned to pre-ignition position, this is typically where all
> standard auxiliary electronics in the car go on, including the auxiliary
> voltmeter in the dash.  THIS is when the FM static starts.  The motor
> contactor isn't even engaged at this point, so the motor and controller are
> out of the picture.  Interestingly, AM still sounds good at this point,
> probably because the interference source is more in the FM band and not in
> AM.
>
> My thinking one of the following culprits:
> 1) Either my radio isn't properly grounded, or
> 2) My antenna cable isn't properly shielded, or
> 3) One of my aux circuits needs a shield.
>
> Does this sound right?
>
> Rob
>
>
>
> -----
> Electro, the Cabby-EV
> http://chaosmgmt.blogspot.com 
> http://www.evalbum.com/1426 
> --
> View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Here-s-an-interesting-issue-FM-interference-BEFORE-motor-on-tp4663203p4663216.html
> Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.
> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
> For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
>

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Re: Here's an interesting issue: FM interference BEFORE motor on

Adrian DeLeon
Be aware that the Zilla EM output changes with its temperature. I get  
decent FM reception for about 2 miles until the controller warms up. Then  
I get tons of static when I press the throttle. Sometimes it gets better  
after 8-10 miles as the controller gets even warmer (I have a failing  
cooling pump).

-Adrian

On Sun, 26 May 2013 09:54:00 -0700, Martin WINLOW <[hidden email]> wrote:

> If you don't thinks it's the motor but suspect the hairball, you could  
> replace the motor temporally with a suitably rated incandescent light  
> bulb and use the controller to power that.  That way you get the  
> controller frequency changing so you can ID it on the radio interference  
> without the motor to confuse things.  Because the bulb load isn't  
> inductive, that won't confuse things either.
>
> MW
>
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