Reducing radio interference?

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Reducing radio interference?

Rob Trahms
Hi all -
No drive issues with my EV Cabriolet (Voltsrabbit) conversion, but I wanted to check with the group on a minor issue.  During driving, my AM/FM radio is essentially worthless with the amount of static my system is generating (confirmed that when I am not driving, there is no radio interference).  

Interestingly enough, I can use my iPod connected to the stereo just fine during driving, no static.

I am pretty sure this must be a common problem among EV'ers.

Any simple solutions out there?  Is it typically a magnetic phenomenon from the motor, or is it coming in through the vehicle ground?  Can I suppress the noise on the radio end, and if so, how?

Thanks,
Rob
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Re: Re ducing radio interference?

Roland Wiench
I found that in many metal body vehicles, that the body is use as a ground
return to the battery, which could be a high resistance path and even cause
some capacitance reactance across some bonding of the metal.

I notice this when I dissemble my vehicle and had all the panels and
fittings epoxy painted.  Instead of remove the paint off each grounding
point that the device was using a ground for, I ran a grounding buss system
starting at the 12 volt battery and runs completely around the inside
perimeter of the motor bay, the passenger compartment and the rear equipment
bay.

This is sometimes known as a counterpoise grounding system, where the ground
buss rounds in a complete circuit and both ends connect together at a
junction point.

I use a insulated No. 1 AWG stranded copper wire that terminates at each
grounding point using a brass bolt coupler that screws in a body point,
using a star washer which acts like a standoff.   The ground buss wire is
connected to each standoff using a terminal lug.  Tap off from each ground
point then goes to the device that require a ground.

If the device has a metal enclosure, than the enclosure is also grounded to
this ground buss system.  Do not relied on the enclosures to self ground it
self to the body of the vehicle.

If the enclosures are large, I will ground these enclosures at both ends of
the enclosures.  For a electrical ground, I will run these as a separate
ground buss or even separated ground circuits back to the a large
junction/terminal block as close to the 12 volt source as possible.

I also using separate ground circuits to the motor control, alternator,
inverter, and to the instruments in the console and dash.

The most important thing, is to have a good ground to the frame of the
motor.  My first EV motor mounts and transmission mounts isolated the motor
from the ground frame.  The only path to ground was though the driveline to
the differential which cause a lot of static.

So I install a large 2/0 ground cable to the motor that runs directly to a
large terminal power block where the ground buss ran to.

The radio I have is a Sony unit that is metal case, which slides into
another metal case in the console.  Both of these cases are electrical
ground to a grounding buss that runs directly to the negative 12 volt
battery, not the chassis bonding grounds.

The speaker wires are double shield with the internal shield floating, and
the external shield grounded to the external metal housing.  The speakers
are not in the dash or doors, rather are mounted in a speaker bar that is
normally use for pickups just behind the seats which are mounted on the
steel firewall.

My AM now only gets noise when I first press the accelerator to start
moving, then after that there is no AM noise.  I never had any FM noise with
the mod.

Roland




----- Original Message -----
From: "Rob Trahms" <[hidden email]>
To: <[hidden email]>
Sent: Sunday, October 11, 2009 8:08 AM
Subject: [EVDL] Re ducing radio interference?


>
> Hi all -
> No drive issues with my EV Cabriolet (Voltsrabbit) conversion, but I
> wanted
> to check with the group on a minor issue.  During driving, my AM/FM radio
> is
> essentially worthless with the amount of static my system is generating
> (confirmed that when I am not driving, there is no radio interference).
>
> Interestingly enough, I can use my iPod connected to the stereo just fine
> during driving, no static.
>
> I am pretty sure this must be a common problem among EV'ers.
>
> Any simple solutions out there?  Is it typically a magnetic phenomenon
> from
> the motor, or is it coming in through the vehicle ground?  Can I suppress
> the noise on the radio end, and if so, how?
>
> Thanks,
> Rob
>
>
> -----
> Rob Trahms
> [hidden email]
> Electro - the Cabby-EV
> http://chaosmgmt.blogspot.com chaosmgmt.blogspot.com
>
> --
> View this message in context:
> http://www.nabble.com/Reducing-radio-interference--tp25844182p25844182.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
>
> _______________________________________________
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Re: Reducing radio interference?

Bill Dube
In reply to this post by Rob Trahms
How you route your battery and motor cables makes a significant difference.

It is tempting to route the cables in a big loop around the car. This
is what you often get if you try to make the cables as short as
possible. This makes the RF interference maximum.

If, instead, you have the cables exit and enter each battery box as a
pair, and route them as a tightly-bundled pair, this will result in
minimum RF interference (but the total cable length with be loner.)
This is really the best way to route the cables because your
instruments will be happier (like your radio.)

You really don't have much chance of getting your AM radio to work
very well, unfortunately.

I should also note that often the DC-DC converter will contribute to
radio noise and RFI. Try turning off the controller, but leave on the
DC-DC and see what happens.

Bill Dube'

At 09:08 AM 10/11/2009, you wrote:

>Hi all -
>No drive issues with my EV Cabriolet (Voltsrabbit) conversion, but I wanted
>to check with the group on a minor issue.  During driving, my AM/FM radio is
>essentially worthless with the amount of static my system is generating
>(confirmed that when I am not driving, there is no radio interference).
>
>Interestingly enough, I can use my iPod connected to the stereo just fine
>during driving, no static.
>
>I am pretty sure this must be a common problem among EV'ers.
>
>Any simple solutions out there?  Is it typically a magnetic phenomenon from
>the motor, or is it coming in through the vehicle ground?  Can I suppress
>the noise on the radio end, and if so, how?
>
>Thanks,
>Rob
>
>
>-----
>Rob Trahms
>[hidden email]
>Electro - the Cabby-EV
>http://chaosmgmt.blogspot.com chaosmgmt.blogspot.com
>
>--
>View this message in context:
>http://www.nabble.com/Reducing-radio-interference--tp25844182p25844182.html
>Sent from the Electric Vehicle Discussion List mailing list archive
>at Nabble.com.
>
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Re: Re ducing radio interference?

pgroveTom
In reply to this post by Rob Trahms
It depends on what is generating the RF noise and how its getting into your
radio. Your iPod doesn't utilize the AM/FM radio front end which says the
problem is Radio Frequency noise getting into your radio either via the
antennae, power or ground and not audio frequency noise. If the noise were
audio frequency and getting into the 12V/GND system, the iPod would likely
suffer also. You could try some experiments to see if its being transmitted
and entering your antennae or leaking into your radio via some other route.
If its going the RF route, you need to suppress it via its source. If its
leaking into the 12 volt battery and ground, you can put a filter on its
power input. If its getting in via some ground route, you probably will also
need to stop it at its source.


You need to isolate the :

source(s) Motor, controller, etc..
paths(s) GND, +12V to GND, transmitted RF
signal character RF or Audio
How it gets into the radio - RF through antennae, RF through GND/12V or
both, RF through grounded metal


Two branches in tracking it down are  1) isolating the radio  and 2) Faraday
shielding http://en.wikipedia.org/wiki/Faraday_cage the source.

1) If you can get to the coax that goes from your radio to the antennae,
then disconnect it and try first terminating it to isolate:

Is it getting into the actual antennae that the signal is entering  (
terminate the coax or extend it 50 feet from your car and see what happens)
OR
Is it getting into the radio RF front end via power or ground or both? If so
then an LC filter between the +12V battery -> radio might help or

Temporarily power your radio from a battery outside your car. Disconnect the
radio +12V ( if you can) and use a battery much like you would when jumping
the car except connect GND->GND and +12V -> radio. That eliminates the +12V
as the path.

Make sure all the EV components are properly grounded. Then try and build a
Faraday Shield http://en.wikipedia.org/wiki/Faraday_cage around each
component ( motor, controller etc.. ) one at a time while listening to the
radio. If you shield the actual source with temporary cage and it stops the
noise, you know the source and the path.

Once you know the source and path, you can decide whether to discuss it with
the supplier of the offending part or shield it.

You also might try pulling another car alongside your EV and see if its
radio hears the noise. If it does, and its bad, the path is probably RF
through the air. If it doesn't, then the path may be RF via +12V and GND.
That's an easy quick test. Get a small battery powered radio and place it
near each possible component. If its RF, then the battery powered radio will
behave similar to your EV car radio.

If you are lucky, then its one part via one path and easy to find and fix.

If you are not, it could be multiple parts as sources and multiple paths and
it will be a bummer.

Does any of that make sense?

Tom

.



----- Original Message -----
From: "Rob Trahms" <[hidden email]>
To: <[hidden email]>
Sent: Sunday, October 11, 2009 8:08 AM
Subject: [EVDL] Re ducing radio interference?


>
> Hi all -
> No drive issues with my EV Cabriolet (Voltsrabbit) conversion, but I
> wanted
> to check with the group on a minor issue.  During driving, my AM/FM radio
> is
> essentially worthless with the amount of static my system is generating
> (confirmed that when I am not driving, there is no radio interference).
>
> Interestingly enough, I can use my iPod connected to the stereo just fine
> during driving, no static.
>
> I am pretty sure this must be a common problem among EV'ers.
>
> Any simple solutions out there?  Is it typically a magnetic phenomenon
> from
> the motor, or is it coming in through the vehicle ground?  Can I suppress
> the noise on the radio end, and if so, how?
>
> Thanks,
> Rob
>
>
> -----
> Rob Trahms
> [hidden email]
> Electro - the Cabby-EV
> http://chaosmgmt.blogspot.com chaosmgmt.blogspot.com
>
> --
> View this message in context:
> http://www.nabble.com/Reducing-radio-interference--tp25844182p25844182.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>


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Angle Iron Strength

wjdennis@qwest.net
I'm working on re-doing my front battery box.  Currently, two pieces of
1/4-inch by 1-inch angle iron, spaced 10 inches apart, span 34 inches
from wheel well to wheel well.  Do that sound like enough heft enough to
support about 140 pounds (batteries plus peripherals)?  I've got lots of
angle iron in there from the first battery box, and I think I might have
over-built.  I'd like to remove some of them to reduce the weight under
the hood, leaving just those two pieces of angle iron I'm asking about.

Thanks.

Bill

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Re: Angle Iron Strength

Roland Wiench
Hello Bill,

Type in your search engine:  Deflection Rates of Steel Structures.  There
are many engineering sites  on this.  There is one site that compares
aluminum to steel.  I always use aluminum structures and fittings in my EV.
Aluminum weighs about 8 times less than steel.

In building structures, we like to stay with in a deflection rate of 1/32
inch.

Roland


----- Original Message -----
From: "Bill Dennis" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Sunday, October 11, 2009 12:12 PM
Subject: [EVDL] Angle Iron Strength


> I'm working on re-doing my front battery box.  Currently, two pieces of
> 1/4-inch by 1-inch angle iron, spaced 10 inches apart, span 34 inches
> from wheel well to wheel well.  Do that sound like enough heft enough to
> support about 140 pounds (batteries plus peripherals)?  I've got lots of
> angle iron in there from the first battery box, and I think I might have
> over-built.  I'd like to remove some of them to reduce the weight under
> the hood, leaving just those two pieces of angle iron I'm asking about.
>
> Thanks.
>
> Bill
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>

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Aluminum versus steel strength (was: Angle Iron Strength)

Bill Dube
Aluminum is lighter, but it is also weaker and has a lower modulus
(deflects more under load) than steel.

Aluminum gets its strength from its tempering. If you weld it, and
don't run the welded structure through a tempering furnace, then the
strength degrades severely. Without re-tempering, a welded aluminum
structure  ends up with a much worse strength-to-weight ratio than a
welded steel structure.

This is why aluminum structures in airplanes are riveted together and
not welded together. Steel structures in airplanes are routinely
welded together, however. They use 4130 steel because it retains its
strength even if fully annealed (normalized.) Mild steel tends to
retain its strength after welding also. Annealed 4130 has a tensile
strength of about 70,000 psi. (Ultimate of over 90 ksi)

  6061-T6 aluminum will go from 40,000 psi tensile strength (45 ksi
ultimate) down to as low as 10,000 psi tensile strength in the
heat-effected zone of the weld.

The density of 6061 aluminum is 0.0975 lb/cu in, while the density of
4130 steel is 0.284 lb/cu in. If you don't weld, aluminum can win. If
you weld, then aluminum loses.

The modulus of 6061-T6 is about 10,000 ksi. The modulus of steel is
30,000 ksi, so steel will deflect about 1/3 as much for the same geometry.

Bill Dube'


>Type in your search engine:  Deflection Rates of Steel Structures.  There
>are many engineering sites  on this.  There is one site that compares
>aluminum to steel.  I always use aluminum structures and fittings in my EV.
>Aluminum weighs about 8 times less than steel.

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Re: Angle Iron Strength

Bill Dube
In reply to this post by wjdennis@qwest.net
If the 140 lbs is distributed over the length, then the two 34 inch
spans of 1 inch x 1/4 thick steel angle sounds reasonable.

Bill Dube'

At 01:12 PM 10/11/2009, you wrote:

>I'm working on re-doing my front battery box.  Currently, two pieces of
>1/4-inch by 1-inch angle iron, spaced 10 inches apart, span 34 inches
>from wheel well to wheel well.  Do that sound like enough heft enough to
>support about 140 pounds (batteries plus peripherals)?  I've got lots of
>angle iron in there from the first battery box, and I think I might have
>over-built.  I'd like to remove some of them to reduce the weight under
>the hood, leaving just those two pieces of angle iron I'm asking about.
>
>Thanks.
>
>Bill
>
>_______________________________________________
>General EVDL support: http://evdl.org/help/
>Usage guidelines: http://evdl.org/help/index.html#conv
>Archives: http://evdl.org/archive/
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Re: Angle Iron Strength

storm connors
If you have concerns about the strength, connecting them together near
the center of the span with a piece of barstock will increase the
strength dramatically. The angle has to twist to fail.

On Sun, Oct 11, 2009 at 4:20 PM, Bill Dube <[hidden email]> wrote:

> If the 140 lbs is distributed over the length, then the two 34 inch
> spans of 1 inch x 1/4 thick steel angle sounds reasonable.
>
> Bill Dube'
>
> At 01:12 PM 10/11/2009, you wrote:
>>I'm working on re-doing my front battery box.  Currently, two pieces of
>>1/4-inch by 1-inch angle iron, spaced 10 inches apart, span 34 inches
>>from wheel well to wheel well.  Do that sound like enough heft enough to
>>support about 140 pounds (batteries plus peripherals)?  I've got lots of
>>angle iron in there from the first battery box, and I think I might have
>>over-built.  I'd like to remove some of them to reduce the weight under
>>the hood, leaving just those two pieces of angle iron I'm asking about.
>>
>>Thanks.
>>
>>Bill
>>
>>_______________________________________________
>>General EVDL support: http://evdl.org/help/
>>Usage guidelines: http://evdl.org/help/index.html#conv
>>Archives: http://evdl.org/archive/
>>Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
> _______________________________________________
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>
>



--
http://www.austinev.org/evalbum/1059
http://stormselectric.blogspot.com/
Storm

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Re: Re ducing radio interference?

gottdi
In reply to this post by Roland Wiench
I thought we were supposed to keep the motor isolated? So this says to  
ground the motor case to the car. Never thought of that. What happens  
if I don't have it properly grounded? Static or other dire things?


Pete :)

On Oct 11, 2009, at 9:34 AM, Roland Wiench wrote:

> The most important thing, is to have a good ground to the frame of the
> motor.  My first EV motor mounts and transmission mounts isolated  
> the motor
> from the ground frame.  The only path to ground was though the  
> driveline to
> the differential which cause a lot of static.

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http://onegreenev.blogspot.com/
No need to wait any longer. You can now buy one off the shelf. You can still build one too.
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Re: Re ducing radio interference?

Roland Wiench
The motor enclosure ground is from the 12 volt ground, not from the battery
pack.  The motor case is getting some type of high resistance ground through
the transmission, drive line and differential.  As these unit rotate, you
can get a static build up in these units.

In our electrical work, we always shunt movable and rotating joints with
heavy grounding wires to reduce the static and/or capacitance reactance.

If you connect a speed sensor to the motor which has a tiny ground conductor
that is connected to the motor chassis, this wire will and has build up in
static so much, that it interfere with the speed sensor circuit.  To reduce
this static, I had to install a larger ground wire to the motor to reduce
this static.

This also reduce any interference on temperature sensors that is connected
on and in the motor which required a 12 volt ground path return to work.

If you have a transmission with electronic sensor and speed control, this
also requires a 12 volt grounded return.

Roland


----- Original Message -----
From: <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Monday, October 12, 2009 7:07 AM
Subject: Re: [EVDL] Re ducing radio interference?


> I thought we were supposed to keep the motor isolated? So this says to
> ground the motor case to the car. Never thought of that. What happens
> if I don't have it properly grounded? Static or other dire things?
>
>
> Pete :)
>
> On Oct 11, 2009, at 9:34 AM, Roland Wiench wrote:
>
> > The most important thing, is to have a good ground to the frame of the
> > motor.  My first EV motor mounts and transmission mounts isolated
> > the motor
> > from the ground frame.  The only path to ground was though the
> > driveline to
> > the differential which cause a lot of static.
>
> -------------- next part --------------
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>

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