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  1. #1
    Join Date
    May 2009
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    North End Lake Lanier GA
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    8,155

    Default What Voltage is your Trailer At?

    I am working on adding LED run way lights to Bestia. My idea was to have yellow in the front to the just behind the fenders, then it switches to red. This way its legal on the highway and would light the trailer up and also work as evening docking lights.

    I got everything done and was ready to hook it up when i discovered the voltage on my trailer is 7.5V not 12 as i would expect.

    I checked at several light locations and they are all 7.5

    I have all LED lights on my trailer, i checked my truck and its putting out 12.5 to the hitch harness, and then in tongue when it changes from the 7 pin harness to the trailer harness its drops to 7.5. I don't see anything that can cause this drop.

    With only 7.5V my lights don't work as intended. Kinda stumped what direction to go now.
    Malo <--- Means--Evil or Mean One. This explains a lot.
    2013 Mojo 2.5 Skylon Tower. Bestia < Beast >
    [COLOR="#696969"]

  2. #2
    Join Date
    Jun 2012
    Location
    Portland Oregon
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    1,395

    Default What Voltage is your Trailer At?

    Don't led's have built in resistors to keep them from burning out? That's my thought.
    -Jake

  3. #3
    Join Date
    Aug 2010
    Location
    Acworth, GA
    Posts
    1,223

    Default

    Never heard for a voltage drop like that on a boat trailer. Perhaps a badly corroded connection in the connector itself may cause a voltage drop. I would look real closely at the connectors and replace if I suspected one was bad and couldn't be salvaged.
    Kraig - 2010 Outback V

  4. #4
    Join Date
    Jul 2011
    Location
    Murrieta, CA
    Posts
    1,590

    Default What Voltage is your Trailer At?

    At what point in the trailer wiring are you splicing in at?

    Where is the first reading of the lower voltage?
    2018 Max with a little extra weight here and there

  5. #5
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    887

    Default

    Mike,
    There can be multiple causes.
    Corroded or oxidized connections.
    Wire gauge too small for the total draw.
    Too many lights drawing down the voltage in respect to the wire gauge.
    A shorted light or strand down the path that is bringing down the voltage.
    The cause is absolutely measurable so you don't have to speculate.
    So try the following.
    Measure the voltage at various points.
    Measure the voltage with and without a load.
    Run jumpers around suspect areas.
    Clean up the connectors, perhaps with hydrogen peroxide or do a serach?, and coat the disconnects with dielectric grease.
    Upgrade the wire gauge and connections.
    Convert to a Western Electric splice type, soldered and heatshrunk, getting rid of crimps.

    David

  6. #6
    Join Date
    May 2009
    Location
    North End Lake Lanier GA
    Posts
    8,155

    Default

    Quote Originally Posted by EarmarkMarine View Post
    Mike,
    There can be multiple causes.
    Corroded or oxidized connections.
    Wire gauge too small for the total draw.
    Too many lights drawing down the voltage in respect to the wire gauge.
    A shorted light or strand down the path that is bringing down the voltage.
    The cause is absolutely measurable so you don't have to speculate.
    So try the following.
    Measure the voltage at various points.
    Measure the voltage with and without a load.
    Run jumpers around suspect areas.
    Clean up the connectors, perhaps with hydrogen peroxide or do a serach?, and coat the disconnects with dielectric grease.
    Upgrade the wire gauge and connections.
    Convert to a Western Electric splice type, soldered and heatshrunk, getting rid of crimps.

    David
    Will look at these.

    What i have seen so fare.
    Everyhting is first brand new on the boat as its a 2013
    The voltage drop looks to happen when the factory 7pin changes to a 5 pin, i also noticed what they have is the left side and the right side of the trailer run on seperate wire harneses. I can actually unplug just the right side lights or the left. These are both spliced at the 5pin to 7 pin.
    Might be easier with a pic but im working today.

    I tested the rear corner marker lights, the rear Tail lights and the front marker lights. Only thing i didnt test was the license plate light and the etched marker lights.

    As for the LEDs i used they are 12v 300 LED strands, i can power the entire thing with a small hand held 9v battery. I dont think they are placing too much load compared to the normal lights.

    What happens is if i unplug say a marker light, then plug my LEDs into the mix everything goes really DIM. I think this is due to the trailer only having 7.5V but im not positive.

    So fare every connectory i have checked does have dielectric stuff to protect it from corrosion.
    Wire guage too small, trailer wires are all 12-14 as fare as i can tell, the LEDs are 18-22 they are small.
    Malo <--- Means--Evil or Mean One. This explains a lot.
    2013 Mojo 2.5 Skylon Tower. Bestia < Beast >
    [COLOR="#696969"]

  7. #7
    Join Date
    Jan 2008
    Location
    Pensacola, FL
    Posts
    1,585

    Default

    LEDs pull very little power, that's why TVs use them and homes are going to them.

    I don't understand your "factory" 5 pin to 7 pin.

    My trailer has a 5 pin flat connector. I use an aftermarket Round to 5 pin adapter. That adapter was not from the factory. Is your?
    1997 MasterCraft 205

    2008 Moomba Outback
    1999 MasterCraft Sportstar OB
    1992 MasterCraft 205
    1999 Malibu Response LX
    1987 Marlin Magnum Skier

  8. #8
    Join Date
    Jul 2010
    Location
    Vicksburg, MI
    Posts
    1,131

    Default

    Sounds like it is a faulty 7 pin to 5 pin adapter. Try plugging the 5 pin harness from the trailer directly to a vehicle with a standard 4 pin and check voltages again.
    Joe

    2014 LSV
    2010 Outback V - Sold
    1993 Echelon

  9. #9
    Join Date
    May 2009
    Location
    North End Lake Lanier GA
    Posts
    8,155

    Default

    Quote Originally Posted by maxpower220 View Post
    LEDs pull very little power, that's why TVs use them and homes are going to them.

    I don't understand your "factory" 5 pin to 7 pin.

    My trailer has a 5 pin flat connector. I use an aftermarket Round to 5 pin adapter. That adapter was not from the factory. Is your?
    Yes part of the new options is to get a factory 7 pin plug, this is simply a extension to the 5 plug. The 5 plug is now inside the tongue just past the break away section.

    After talking to a couple of the electricians at work they all seem to agree that i have a short in the trailer. The only part of the trailer thats spliced into the factory harness are the Etched lighting on the fenders i have.

    I think ill unplug those, and recheck my Voltages. If everyhting is 12 again then i know my Eteched LEDs are bad. Not too worried about this as i bought new white LEDs for this area because the factory LED strip to too short, I get Moomb on one side and OOMBA on the other LOL.
    Malo <--- Means--Evil or Mean One. This explains a lot.
    2013 Mojo 2.5 Skylon Tower. Bestia < Beast >
    [COLOR="#696969"]

  10. #10
    Join Date
    Oct 2010
    Location
    Lake Wylie NC Area
    Posts
    2,467

    Default

    Quote Originally Posted by mmandley View Post
    I am working on adding LED run way lights to Bestia. My idea was to have yellow in the front to the just behind the fenders, then it switches to red. This way its legal on the highway and would light the trailer up and also work as evening docking lights.

    I got everything done and was ready to hook it up when i discovered the voltage on my trailer is 7.5V not 12 as i would expect.

    I checked at several light locations and they are all 7.5

    I have all LED lights on my trailer, i checked my truck and its putting out 12.5 to the hitch harness, and then in tongue when it changes from the 7 pin harness to the trailer harness its drops to 7.5. I don't see anything that can cause this drop.

    With only 7.5V my lights don't work as intended. Kinda stumped what direction to go now.
    Too lazy to read all the replies, so sorry if this has been mentioned. With the trailer connected to the hitch and harness plugged up, connect your meters ground lead to the trailer and test the voltage on the truck side. If its low, you have a ground issue. If its same as before, then reverse the leads. meters ground lead on trucks chassis, then probe the trailer side and see what the voltage is. If its low, then the there is a problem in the connector.

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