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.

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.

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