Electrical dilemma

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glockrow

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Mar 28, 2019
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Toward the end of the season last year, when boondocking I started having a problem with my lights flickering very badly when running the water pump in my travel trailer. I assumed that my batteries were failing so I replaced them. The problem did not go away. I checked all of the wiring that is accessible and cleaned all of the connections including grounds. Still flickering. I thought maybe the pump was drawing too many amps or shorting out so I replaced it with a new one. Lights are still flickering. The lights have always flickered a little when the pump runs but now almost go out. Even when the batteries are fully charged this happens. The idiot lights on the control panel drop all the way into the red but immediately go back to green when the pump stops. I'm just wondering if anyone out there has any ideas about what the problem might be? Just to be clear, the trailer is pretty old (1989).
 

Lou Schneider

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Mar 14, 2005
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Welcome to The RV Forum, glockrow!

Do you have LED lights or incandescent bulbs?  These respond differently to low voltage.  Normal bulbs will dim gradually as the voltage sags, LEDs will stay at full brightness until the voltage reaches a critical level and then go out.

Depending on what kind of bulbs you have, you may or may not have anything that's significantly changed.

The easiest way to isolate the problem area is to take a regular 12 volt light bulb and connect it to the battery wires, then cycle the water pump and see if it flickers.  Start where the battery wires connect to the power panel.  This will tell you if the problem is before (towards the batteries) or after that point.  Then move the light to different places and see if it flickers there until you zero in on the problem.

I suggest using a light bulb instead of a voltmeter because digital voltmeters only check the voltage a few times per second so they may miss the momentary fluctuations caused by the water pump.
 

Hfx_Cdn

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Sep 22, 2006
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Nova Scotia
      Welcome to the world of electrical problems.  It sounds like you have a short in the wiring to the pump.  Before you go replacing any more expensive parts, I would hot wire the pump, that is to say, disconnect the pump and run a wire directly from the battery, if the lights don't flicker you have found the problem.  Then you can try to find the short, try checking from the switch to the pump, then from the box to the switch.

Ed
 

John From Detroit

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Davison Michigan
When you changed out the batteries did you clean the terminals?

Actually when you are plugged in the converter should do the job but in my case I have noticed slides running slower and slower and slower and a few days ago (Saturday Last) I cleaned up the terminals so they were bright and shiny again. then Sunday Sprayed 'em down with terminal spray.. And wed even without being plugged in the slide moved "Smartly" as they say.
 

lynnmor

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May 14, 2013
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If you have a battery switch or circuit breaker, they can have poor connections inside.  I do believe there is a bad connection somewhere.
 

Mike L

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May 13, 2008
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lynnmor said:
If you have a battery switch or circuit breaker, they can have poor connections inside.  I do believe there is a bad connection somewhere.
X2
 

Gary RV_Wizard

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If you have more than one pump on/off switch, you almost surely have a pump controller that actually switches the pump on/off. It does this by closing the ground side of the pump circuit. I'm thinking when that circuit closes, there is a high resistance short that severely lowers the voltage. Could be the pump controller itself, or the wiring from the controller to the eventual ground (battery negative) point.

If you don't have a pump controller, ignore this.
 

glockrow

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Mar 28, 2019
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Thank you everyone for the input. I now have some testing to do, will let you know what I find. :)
 

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