Dim interior lights: Battery problem or power converter?


By Steve Savage, Mobility RV Service

Here’s a common question that’s worth sharing.

Dim interior lights: Battery problem or power converter?From a reader: Recently my lights in my fifth wheel have started getting dim and sometimes flickering. How can I determine whether my problem is a four-year-old battery or the charger or the converter? I have disconnected my negative battery post while plugged into campground service.

When I disconnected the negative (battery cable) and checked my lights, they were very bright for about two minutes and then went dim. Then I turned on another light switch and they went bright again for a few minutes. How can I check the battery charger? I have a meter to check it, but I don’t know the procedure to check it.

My response: Very simple! Connect your battery and test the voltage with your meter. If you don’t see over 13 volts, your converter is dying. Any time a power converter is plugged in and working, you will always “see” more than 13 volts. The power converter is also the only thing that can make your 12-volt lights flicker, provided your AC power is good. That is to say, as long as you have good power at your receptacles and at your microwave, your power converter is the only possible villain.

It is not unusual that power converters become erratic before they fail completely. The battery is not relevant with an operational converter because it can easily carry the lighting load. You could have a completely dead battery and still have good lights.

You can temporarily work around this by putting a regular battery charger on your batteries, but you need a new power converter. I am not clear why you are using the terms “charger” and “converter.” You have a power converter that converts 120 volts AC to 12 volts DC, and that charges the battery. It also supplies 12-volt power to your lights, etc. The remainder of the panel is called the distribution panel. You either have a distribution panel with the converter built in, or you have a distribution panel with the converter mounted separately and tied to the panel with a red (+) and a white (-) wire.