interior lights go dim and then bright

[gmccall]

Just took the fifth wheel for a weeks ride. Stayed in 3 different parks.
amd the interior light problem started
My fifth wheel interior lights go dim for maybe 20 seconds and then will brighten for a while. This sequence of light flutter goes on and on.

When the lights are dim, I here the convertor making a buzzing noise for a few seconds and then I hear the convertor fan come on and the lights go bright for maybe 5 -10 minutes and then the lights go dim again. As I said, all happens over and over.

Is my convertor failing ?

[dalford]

Probably, or the fan is not working properly. Seems the fan should come on before it overheats.

[Brother Les]

Take a volt meter and test the output of your converter. Also, take a standard battery charger and charge your battery outside the unit and then take the battery to a auto parts store and get it load tested. Your battery may be shorted out and causing havoc with your converter. If your converter is fine at this time and your converter keeps trying to compensate for your bad battery (if you have a bad batt) it will mess up your converter in time.

[igor2brvn]

Also, check your converter that nothing is blocking air flow into or out of the converter.

[gmccall]

I have 4 batterys so it will take a while to check them.

I did read in my trailer data that a bad cell in a battery could cause the low/bright light change.

Thank all for your input.
Will heed all suggestions.

[Herk7769]

Originally Posted by gmccall

I have 4 batterys so it will take a while to check them.

I did read in my trailer data that a bad cell in a battery could cause the low/bright light change.

Thank all for your input.
Will heed all suggestions.

Your trailer data is correct.

A short in a battery will cause the converter's "self protection" circuit to cut in and out. While an "open" battery will not effect the converter (you can run items in the camper without a battery as long as total draw never exceeds the converters rated output), a shorted battery will cause the converter to shut down "to save itself" after a while, it will reset itself and try again. This will continue until the converter self destructs (like constantly resetting a house circuit breaker on an overloaded circuit).

[gmccall]

I plan to remove all 4 batteries and have them tested.

I do see some of the connections are corroded so I will clean those.

[gmccall]

Convertor is putting out 13.7 volts without fan kick in.
When fan turns on, the output shows 14.3.

However.......the convertor makes a bad sounding hum for a few seconds before the fan turns on. I think the fan is "dragging" are about to fail.

Am now charging batteries and will have them tested.

[garbonz]

Originally Posted by gmccall

Convertor is putting out 13.7 volts without fan kick in. When fan turns on, the output shows 14.3. However.......the convertor makes a bad sounding hum for a few seconds before the fan turns on. I think the fan is "dragging" are about to fail. Am now charging batteries and will have them tested.

I don't think that means the converter is bad until you verify the batteries are good. 13.7 is normal float voltage and 14.3 is the peak of the absorption phase which should not be held for more than an hour in a healthy battery. Jumping back and forth is definitely not normal, but may be caused by a bad converter or a bad battery bank...

[gmccall]

My four 6 -volt Interstate batteries checked as follows:

Removed the batteries from the trailer.
All batteries had 12.45 volts.

The Hydro meter reading for each cell of the batteries
was between 12.25 (fair) to 12.75 (good).

I could buy a 6 volt charger and charge the batteries more or place them back in the trailer and charge them more.

Should I also have the batteries tested by load ?

Could all my convertor problem be caused by batteries being in a low voltage mode?
We did run the house frig off the invertor while traveling for 6- 7 hours at a time before reaching the RV parks. The bright and dim lights delimna was very obvious after arriving at the parks and connecting to shore power.