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Re: [RFI] RFI issues in electric (or hybrid) vehicles

To: rfi@contesting.com
Subject: Re: [RFI] RFI issues in electric (or hybrid) vehicles
From: W0MU Mike Fatchett <w0mu@w0mu.com>
Date: Tue, 10 Apr 2012 19:25:01 -0600
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Maybe the newer cars are better.  My son's is an 04.


Mike W0MU

W0MU-1 CC Cluster w0mu.net


On 4/10/2012 6:51 PM, Roger (K8RI) wrote:
> On 4/10/2012 6:40 PM, Dale Svetanoff wrote:
>> List mates:
>>
>> The link below leads you to an article from Electronic Design magazine.  It 
>> concerns RFI issues in electric drive vehicles (and, by extension, hybrids, 
>> as well).  The primary focus is on the interference caused to the 
>> entertainment system ("broadcast") radios within the vehicles.  My personal 
>> view is that the situation is almost surely applicable to communications 
>> radios, as well, especially those used for HF communications.
>>
>> Here is the link:
> We have a Prius Hybrid: No RFI issues to either the entertainment center
> or the rig.
> Most of the Hybrids I've seen/driven had too small a battery and light
> gauge wiring to run much of a radio. The battery is so small the
> manufacturer recommends you do not wire directly to the battery, but
> either through the switch, or a relay that is energized only when the
> ignition is on.  Two other hams have newer models and they do not have
> any RFI issues either.  I'd suggest a heavy duty battery placed in back
> along with a much larger alternator to keep it charged.
>
> The first sentence is a blanket statement that is not true: "To enable
> radio reception in electric vehicles, manufacturers must install filters
> and insulate cables, since electrical signals will otherwise interfere
> with music and speech transmissions" as I can point to 3 examples from
> different years that have no problems in either the car entertainment
> system, or the ham rigs.  I can understand filters when necessary and
> shielding, but "Insulation"?
>
> Therefor this appears as an article that was not well thought out or
> researched.
>
>> http://www.wirelessdesignmag.com/ShowPR.aspx?PUBCODE=055&ACCT=0000100&ISSUE=1204&RELTYPE=IN&PRODCODE=00000&PRODLETT=AI.html?et_cid=2583485&et_rid=60851216&linkid=http%3a%2f%2fwww.wirelessdesignmag.com%2fShowPR%7ePUBCODE%7e055%7eACCT%7e0000100%7eISSUE%7e1204%7eRELTYPE%7eIN%7ePRODCODE%7e00000%7ePRODLETT%7eAI&CommonCount=0
>>
>> (Note: Due to length of the link, I hope it all comes thru the reflector 
>> intact.  I am in hopes that you will be able to click anywhere on the link 
>> and succeed in getting to the article.)
> It works fine in Thunderbird.
>> To be honest, I was disappointed in the article's lack of substantial 
>> technical detail.  (Although Electronic Design is not a publication devoted 
>> specifically to EMC/EMI issues, it is targeted to the electronic engineering 
>> community.  Therefore, I was a bit surprised that this article is pretty 
>> much at the lay person level.  Nevertheless, I felt that some of the 
>> comments might be of interest to readers on this reflector.)
> The first sentence being a blanket statement that is not true hurt the
> credibility of the article and author.
>
>> One aspect of the automotive RFI issue did catch my interest: A primary 
>> dictum in RFI control is that you do all that you can to contain an RFI 
>> source (in this case, the power converter) so as to minimize propagation of 
>> interference via direct radiation or via the associated wires and cables.  
>> ("Containment" also means that I/O lines should be well-filtered.)  Note 
>> that nowhere in the article is containment of the source mentioned.  
>> Instead, a lot of effort has been placed on routing of wires and insulation 
>> of the high power drive motor from the chassis of the vehicle.  (These 
>> motors are typically electronically commutated DC types, no brushes.)  One 
>> must guess that size, weight, and cost probably factor into the decisions to 
>> work placement and isolation issues, rather than containment.
>>
>> I, for one, would be delighted if someone in the automotive industry would 
>> reply to this posting with some supporting information as to what is being 
>> done in today's electric and hybrid drive vehicles for RFI control, 
>> especially as regards communications (be it for broadcast or two-way 
>> applications).  I would also welcome comments from anyone associated with 
>> the Fraunhofer Institute and the work described in the article.
>>
>> Finally, I am wondering if any list members have installed either a ham rig 
>> (HF and/or VHF/UHF) or a scanner in an electric drive nor hybrid vehicle, 
>> and if so, were there any significant RFI issues to contend with?  Please 
>> post so that we can all share in your experiences.  Thanks.
> As I said above, I know of three hams who drive a Prius (all different
> years). Ours is one of the oldest ones, while a friend drives on about a
> year old.  No RFI issues at all.
>
>
> 73
>
> Roger (K8RI)
>
>> 73, Dale
>> WA9ENA
>> Sr. EMC Engineer
>>
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