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Ask Robert Your Own Question
Robert, RV Mechanic
Category: RV
Satisfied Customers: 13511
Experience:  18 yrs. RV experience including Cummins North West, Country Coach, Monaco Coach - vendor certified.
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My lights dim down while I'm plugged in. Sup with that? The

Customer Question

My lights dim down while I'm plugged in. Sup with that?
JA: Just to clarify, what are the exact lights you're talking about?
Customer: The house lights-------chassie batteries are strong.
JA: What is the model/year of your RV?
Customer: 2005 Tropical w/300 CAT-43k miles Original owner
JA: Are you fixing your RV yourself? What have you tried so far?
Customer: Everything !! BUT buy new batteries
JA: Anything else you want the mechanic to know before I connect you?
Customer: No
Submitted: 1 month ago.
Category: RV
Expert:  Robert replied 1 month ago.

Hi, I'm Robert. Welcome to JustAnswer. I'm reviewing your question now and will post back with your reply momentarily.

Expert:  Robert replied 1 month ago.

When you are plugged into power the power converter or inverter will charge the batteries. IF the batteries were in poor condition they might not be able to accept a charge. So the first step is to have the batteries load tested, most auto parts stores can load test them for free. IF they are bad they will need to be replaced. Make sure all your cables are clean and tight as well, no corrison on the cables.

When you are plugged in you should see close to 13 volts at the battery if they are in good condition, if not then you may have a problem with the power converter or inverter. An inverter will allow you to have AC power when you are unplugged, a power converter will not do that but they both will charge the batteries. Sometimes you might find a breaker between the converter and battery, below is a picture, as a general rule they like to stick that 18" from the battery and it can be on the frame. IF you find any check for voltage on eah post to chassis ground, if one side reads much higher then it is the problem.

I would really start off by having the house batteries load checked, just mark the cables and or take a picture of them before you remove them.

Hope this helps if you have more questions or concerns please feel free to contact me.

IF you are satisfied with my efforts please feel free to select a STAR rating on the page...


Expert:  Robert replied 1 month ago.

HI was just checking in to see if my answer helped??? IF you have more questions or concerns please feel free to contact me...