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Thread: Grounding a Stebel Horn ('06 R1200GS)

  1. #1
    Registered User bobframe's Avatar
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    Grounding a Stebel Horn ('06 R1200GS)

    I am installing a Stebel Compact Nautilus on my '06 1200GS. I'm using the OEM horn to trigger a relay which is powered directly from the battery. The Stebel will be installed near the spot where the OEM horn was, i.e., in front of forks and behind the oil cooler...up high. I need to add a ground wire nearby. There appears to be a good candidate close by...here's a pic.

    Is this a good choice? Should I somehow prep the bolt or the surface below (like sand it to bare metal??)?

    Thanks...Bob
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    We don't take a trip...the trip takes us.

    2006 BMW R1200GS
    2008 BMW R1200RT

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    I would attach the ground wire to the mounting screw (bolt) of the horn.

    Any solid connection to the frame or engine would be fine.

    David
    2012 R1200R 24,000 MIles
    2011 Versys 14,000 Miles
    2000 R1100RT 140,000 miles
    1976 R75/6 Odometer broken for over 10 years.

  3. #3
    Registered User bobframe's Avatar
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    Quote Originally Posted by DROOT153718 View Post
    I would attach the ground wire to the mounting screw (bolt) of the horn.

    Any solid connection to the frame or engine would be fine.

    David
    The Stebel horn will be mounted to the bike using a bracket sourced from Excel Cycle Werks. Although I don't have the bracket in hand just yet, I believe that the bracket will bolt onto the OEM mounting bolt (welded in place). Then the Stebel should mount onto the bracket.

    It hadn't occurred to me to attach the ground from the Stebel horn directly to the OEM mounting bolt...if this is solid electrically, it would make a very neat install.

    Thanks!!

    Bob

    UPDATE: Got the mounting bracket kit (several parts to it) made by Excel and it was excellent. Really nicely machined parts, vert precisely done, mounting is flawless. This kit contained all the hardware (non-electrical) I needed to install the Stebel horn. Slick.
    Last edited by bobframe; 02-14-2013 at 07:32 PM.
    We don't take a trip...the trip takes us.

    2006 BMW R1200GS
    2008 BMW R1200RT

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    Registered User bobframe's Avatar
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    Just to close this out....I never got comfortable with what my "bolt-to-frame" options were. The installation instructions from Excel also suggested using the horn mounting bolt as a ground...but there's something about using the device itself to ground the device that seems odd. So, I made up a longer ground lead and ran it to the battery.

    Someday, somewhere, somehow...I gotta get an education in 12V electrics.

    PS..The horn is killer.
    Last edited by bobframe; 02-16-2013 at 01:07 PM.
    We don't take a trip...the trip takes us.

    2006 BMW R1200GS
    2008 BMW R1200RT

  5. #5
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    Quote Originally Posted by bobframe View Post
    Just to close this out....I never got comfortable with what my "bolt-to-frame" options were. The installation instructions from Excel also suggested using the horn mounting bol tas a ground...but there's something about using the device itself to ground the device that seems odd. So, I made up a longer ground lead and ran it to the battery.

    Someday, somewhere, somehow...I gotta get an education in 12V electrics.

    PS..The horn is killer.
    First, your horn works.
    Ground is ground. The battery cable is bolted to the frame. The frame is heavier metal than the battery cable so it will
    carry all the - volts and amps you need. Bolting closer to the accessory saves in wire. No loss in voltage is possible as long as each connection along the way is clean. In your case, battery to the frame then to the horn to the frame is fine.

    David
    2012 R1200R 24,000 MIles
    2011 Versys 14,000 Miles
    2000 R1100RT 140,000 miles
    1976 R75/6 Odometer broken for over 10 years.

  6. #6
    Ed Kilner #176066
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    Quote Originally Posted by DROOT153718 View Post

    No loss in voltage is possible as long as each connection along the way is clean.

    David
    Actually, there can be a voltage drop between the ground lug of the horn and the ground lug of the battery. It will be very slight with clean connections as you say. It will be higher with the wire return than with the frame return as the gauge of the wire is smaller than the "gauge" of the frame (being used as a wire). The voltage drop in the return line will be V=IR, where I=current (Amps) and R=resistance (Ohms). The R will be very small, hard to even measure, hopefully, but if the horn's current is large, the drop in that return will be high. Probably will not be a problem.

    That is why the ground return from the starter motor is so important. Very high current flow, so the resistance needs to be as low as possible.

    The power (watts) dropped = I x I x R. It is called the "I squared R loss" and power lines suffer this of course, because they are so long and wire has a resistance of x ohms per foot (or meter if you are metric).

    http://en.wikipedia.org/wiki/American_wire_gauge gives a table of ohms per 1000 feet for wire sizes. Household wiring, 14 AWG is about 2.5 ohms per thousand feet. 20 AWG has about 10 ohms per foot. It's because of the area of the circular cross-section.

    {end of tutorial}
    Ed
    2011 R1200RT Thunder Gray Metallic; 2000 Triumph 900(sold)
    http://triumphantsblog.blogspot.ca/

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