Jump to content


Photo

Voltage drop


  • Please log in to reply
7 replies to this topic

#1 JustHoward

JustHoward

    FJR Pilot

  • Members+
  • PipPipPip
  • 164 posts
  • Gender:Male
  • Location:memphis, tn
  • Bike: 2013A (Gen III) N. America

Posted 12 April 2012 - 01:22 PM

I am measuring the voltage drop between the output of the voltage rectifier/regulator, and the positive battery post. I'm doing this because my digital voltmeter reads only 13.6volts when cruising.

I stick a needle into the back of the connector (red wire) that connects to the voltage r/r, and put my positive lead there, and then put my negative lead on the positive battery terminal. What kind of voltage drop should I get between these two points?

As best I can tell, the wire from the r/r goes to the main fuse holder, through that 50 amp fuse, then out and travels rearward along the bottom of the battery cable, where it joins the battery cable immediately before the starter relay. So there should be nothing in the way of connections between the two points that I'm measuring.

So...what should be the voltage drop between these two points?

Howard

#2 k1oj

k1oj

    Training Pilot

  • Members+
  • PipPip
  • 75 posts
  • Gender:Male
  • Location:Houston, TX
  • Bike: 2007 ABS (Gen II) N. America

Posted 12 April 2012 - 04:29 PM

I am measuring the voltage drop between the output of the voltage rectifier/regulator, and the positive battery post. I'm doing this because my digital voltmeter reads only 13.6volts when cruising.

I stick a needle into the back of the connector (red wire) that connects to the voltage r/r, and put my positive lead there, and then put my negative lead on the positive battery terminal. What kind of voltage drop should I get between these two points?

As best I can tell, the wire from the r/r goes to the main fuse holder, through that 50 amp fuse, then out and travels rearward along the bottom of the battery cable, where it joins the battery cable immediately before the starter relay. So there should be nothing in the way of connections between the two points that I'm measuring.

So...what should be the voltage drop between these two points?

Howard


In a perfect world, 0v. If all your connections are clean and solid, you should have no resistance and there fore, no voltage drop.
Owen
Owen k1oj & Margaret k5msq
Houston Tx
2007 FJR
IBA 49988

#3 supertankerm60a3

supertankerm60a3

    FJR Pilot

  • Members++
  • PipPipPip
  • 228 posts
  • Gender:Male
  • Location:Pismo Beach
  • Bike: 2003 (Gen I) N. America

Posted 12 April 2012 - 07:17 PM

The voltage drop will vary with the load. A battery that is drawing current recharging will show a lower post voltage while it at a high amp rate. Most vehicles in the Army and many civilian have a feedback wire that will cause the alternator voltage to rise to cover the voltage drop. With the relatively low currents that flow in the FJR that is probably not the case.

Check your connections.

Edited by supertankerm60a3, 12 April 2012 - 07:22 PM.


A bike will keep you young, the wrong bike will stop you from getting older. There is a difference.

#4 3dogs

3dogs

    FJR Pilot

  • Members++
  • PipPipPip
  • 405 posts
  • Gender:Male
  • Location:Hagerstown, MD
  • Bike: 2005 ABS (Gen I) N. America

Posted 13 April 2012 - 05:22 AM

Assuming the battery is not dead u should have a voltage drop around .1 to.3. If the bat was dead the amps would go up and so would the v drop. Also there is no voltage sense wire on the FJR.

#5 wabill

wabill

    FJR Pilot

  • Members++
  • PipPipPip
  • 186 posts
  • Gender:Male
  • Location:Bellingham, WA
  • Bike: 2010 ABS (Gen II) N. America

Posted 13 April 2012 - 10:27 AM

I am measuring the voltage drop between the output of the voltage rectifier/regulator, and the positive battery post. I'm doing this because my digital voltmeter reads only 13.6volts when cruising.

I stick a needle into the back of the connector (red wire) that connects to the voltage r/r, and put my positive lead there, and then put my negative lead on the positive battery terminal. What kind of voltage drop should I get between these two points?

As best I can tell, the wire from the r/r goes to the main fuse holder, through that 50 amp fuse, then out and travels rearward along the bottom of the battery cable, where it joins the battery cable immediately before the starter relay. So there should be nothing in the way of connections between the two points that I'm measuring.

So...what should be the voltage drop between these two points?

Howard


I'm curious, what voltage drop did you measure?
Posted ImagePosted ImagePosted Image

#6 JustHoward

JustHoward

    FJR Pilot

  • Members+
  • PipPipPip
  • 164 posts
  • Gender:Male
  • Location:memphis, tn
  • Bike: 2013A (Gen III) N. America

Posted 13 April 2012 - 11:14 AM

I am getting a 0.5 volt drop between the output positive pin of the regulator and the battery cable. Isn't this too much of a drop?
anybody else with experience like this?

#7 Constant Mesh

Constant Mesh

    FJR Commander

  • Members++
  • PipPipPipPipPip
  • 1,598 posts
  • Location:Tenn
  • Bike: 2004 (Gen I) N. America

Posted 13 April 2012 - 03:27 PM

Now check the drop in the negative side, the return bus. Voltage lost there is just as important.

#8 LAF

LAF

    FJR Commander

  • Members++
  • PipPipPipPipPip
  • 1,130 posts
  • Gender:Male
  • Location:Harrisburg, PA
  • Bike: 2010 ABS (Gen II) N. America

Posted 14 April 2012 - 04:46 PM

Waiting to see how this turns out for you, and what you find.

My '10 will not show over 14.01 with all off. I would run 13.90-13.96 regular running.

My RR output was 15.7 I think.

I even put a brand new, freshly charged Moto Batt in it and now it runs 13.86 by the Datel!

So looking to see what you find out on the reverse check, and you next steps.

I think I never needed to install a Datel :-)