Our RV Interior Lights Only Work When We Are Plugged In Or Generator Is Running

by Nancy Evans
(Dennisville, NJ)

The inside lights only work when plugged in or on the generator. Batteries are new. Replace the battery isolator switch. What do I check next?

ANSWER Greetings Nancy thanks for submitting your question on our Ask An RV Question Page.

It is apparent that replacing the Battery Isolator Switch may not have been your problem. Let me walk you through some things you can check to see if we can figure out where your electrical problem is.

1. The first thing I would check is to see if your RV is equipped with a battery disconnect switch. The location of this switch varies by RV manufacturer and by model. You need to refer to your RV Owner's manual to determine whether your RV has a battery disconnect switch and where it is located. Once you find it, make sure that it has not been accidently been shut off. If it was turn it back on and check your interior lights, etc. to see if they are now working. If not continue on to the next step.

2. Check all breakers and fuses in your electrical compartment. Reset any tripped breakers and replace any burnt out fuses. If the breakers keep tripping after resetting or the fuses burn out after replacement, then you need to have your RV checked out by a qualified RV Technician to determine where the short is and repair it.

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3. Check your house batteries to make sure that all connections are tight and clean. Also check to make sure that there are no other loose wires that are attached to the battery cables. Clean and tighten wires and cables as needed. Check the electrolyte level in all of your batteries. If they are low top them off with Distilled Water. Even though your batteries are new, you still need to do these checks.

4. Now check to see if the batteries are charged. If your RV has a monitor on it that shows actual
battery voltage then look at the gauge. If your RV does not have a voltage gauge or it has dummy lights, you will need something like the Cen-Tech 7-Function Digital Multimeter to take the readings. With the RV engine and generator off and the RV unplugged from electric, you should have a voltage reading of approx 12.6 volts. If the reading is much lower than that, either the batteries are going bad or they are not receiving a proper charge. Now if you have a solar battery charger on your RV the voltage reading may be higher as the solar charger is applying a trickle charge.

5. Now we are going to check out the charging systems. First start the engine of the RV and then check the voltage at the house batteries either using the RVs built in voltage gauge or your voltage meter. The reading should be around 14.4 volts. Turn off the engine and run the generator; the voltage again should be around 14.4 volts. Now turn off the generator and plug the RV in to electric and check the voltage again it should be around 14.4 volts.

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6. If all the tests above are passed then we know the problem is not with the batteries or the battery charging system. So we have to assume that problem could very well be in the RV’s converter. The converter may not be switching over to battery power when the generator is not running or the RV is not plugged in to electric. If this is the case then you need to have the RV checked out and repaired by a qualified RV Technician. Repairing or replacing a converter is not a Do-It-Yourself job.

Hopefully the above steps will help you isolate your RVs problem. If any of our visitors have additional tips or suggestions for you they can add them by clicking on the add a comment link near the bottom of this page.

Happy RVing

RVing Al

Comments for Our RV Interior Lights Only Work When We Are Plugged In Or Generator Is Running

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my generator shuts off when i turn interior lights on
by: windcruiser

hello all, i was wondering if anyone can help to trouble shoot my problem,

I've 1987 winnibago itasca windcruiser

now my problem is that when I start the generator and switch the vehicle engine off, as soon as I turn any light on, the generator dies!

can anyone help please :))))

RV lights only work plugged in or gen
by: Dan D Corrales

Wow. I can't tell who is posting when and in what order so I don't know if this was asked a week or ten years ago. The answer is definitely not water level in battery. There is a second hidden fuse box with a coach battery breaker. Mine was behind a locked pocket above my propane tank on the Winnebago. Hope this helps

I have 2 New Gel Batteries
by: Anonymous

I just put in 2 brand new gel batteries in my 2003 Pioneer travel trailer They do not take any water.

My Travel Trailer when checking my interior lights works good and so does the refrigerator & the freezer when it is plugged into electricity, but the interior lights will not work alone on just the batteries. My electric jack works and it lights up too with just the new batteries connected to its cables.

Can someone please tell me what is going on or just what I should be looking for? I just bought this trailer but I don't know if it has a disconnect where might I find this.

same problem
by: Anonymous

I have the same problem, My lights won't work unless the main power cable is plugged in to power. But the slides will work but the lights won't work so my battery has power to move the slides in and out and the battery gauge says full power.. I can't get the lights to turn on though, But when the power cable is plugged in the lights will work

specific gravity
by: davr

You might want to check the battery acids' specific gravity occasionally. I bought a specific gravity tester at Auto Zone for about $5.00. Not a bad investment. Be careful not to get the battery acid on you or clothes or anything else. It's very strong. Keep some baking soda handy. It will neutralize the battery acid if you get a spill.

RV Battery water?
by: Jen

One of your suggestions is to check the battery water level. How often should this be done? Is there any type of science to it, or is it as straight-forward as opening a cap and pouring in water?

Reply From RVing Al: As a rule you should check the water level in the house batteries at least once a month. Yes it is simply just pulling off the caps and checking the water level and topping them off.

Remember: Use distilled water only. Tap water contains minerals that can attach to the plates in the batteries which will shorten the batteries lifespan.

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