How to Tell if an RV Converter Is Bad

Is your RV 12-volt electrical system not working correctly?

The culprit is most likely a bad RV converter that regulates the power between the camper’s battery bank and standard shore power within most recreational vehicles.

How to tell if the converter is bad isn’t as tricky as it sounds, especially when you follow this guide that details RV converter troubleshooting tips.

Inside you’ll find how to pinpoint if the RV converter is causing your electrical issue and learn how to fix the problem so your lights, refrigerator, fans, and other 12-volt appliances work as they should.

What Does an RV Converter Do?

The purpose of an RV converter is to convert 120-volt AC power coming from an outside source into 12-volt DC power.

The primary power source coming into your camper wires into the converter. The unit safely alters the voltage before sending it over to charge your house battery bank.

The 12-volt power the battery stores is then sent to certain RV appliances and accessories, so they operate even if you don’t plug into an electrical pedestal.

Understanding how a converter works make it easy to understand why your lights, fans, or RV refrigerator will only run for limited hours when you’re boondocking or not plugged into shore power. Once the battery dies, so do your 12-volt accessories.

Do not confuse the RV converter with an RV inverter.

Large RVs with big battery banks have inverters to take the DC power from the batteries and switch it to AC power to run large appliances when not on shore power.

Signs Your RV Converter is Bad and Needs Replacement or Repair

When the RV converter goes bad, the most obvious signs are:

• 12-volt appliances don’t work at all, or die out quickly
• Flickering alert lights on the converter’s panel
• You don’t hear the cooling fan kicking on and off at the RV’s power center
• Lights dim quickly when not on shore power
• RV fridge display quits working

The number and type of batteries in your RV’s bank will determine how long your 12-volt accessories operate. I have one battery in my RV and know that I can run my 12-volt items for a solid two days before they fade.

If you have two or more batteries, you need to know the average timeline they’ll create power, so you’ll know when things aren’t right. This video has more on proper battery charging that is very informative.

You can also test your batteries after a full charge to see if one or more are working correctly.

A bad converter can cause an RV battery to fail.

Once one battery fails in a bank, the others will eventually follow suit, so swapping out one bad battery instead of many will save you hundreds of dollars.

But, there are some dangerous complications of an older RV converter that you may not know.

Years ago, (as a new RV owner of a vintage camper), I had to learn the hard way about the camper’s original converter.

When packing for our trip, everything seemed to be working correctly.

On the first night of our campground getaway, there was an awful smell coming from the rear of the camper. We thought it was sewer gas because the bathroom was also in the same location.

We did everything we could to inspect our sanitary lines, tanks, and hoses for leaks but couldn’t find anything wrong.

The smell kept intensifying, so I jumped online to search for “causes of bad sewer smell in RVs” and saw a mention of overheating house batteries stinking like sulfur or sewer gas.

I thought I better open up the back compartment to check my new expensive deep-cycle RV battery to be safe, and WOW, the heat that hit my face was scary!

The battery was super hot, and if we didn’t quickly unplug the RV from shore power and carefully unhook the cables, the thing could explode!

After a crash course in “what the hell just happened?!” and drinking a calming beer, I learned my 29-year-old converter was continually charging the 12-volt battery till it boiled.

The old-style converter didn’t have the safety mechanisms newer models have that automatically monitor battery conditions to avoid such danger.

After ordering a new converter and installing it myself (a DIY-suitable project if you’re handy), we bought another expensive battery and tried again. Thankfully everything is still running perfectly years later!

Features to Look for in an RV Converter

The best RV converters have a three-stage or four-stage charging system and have a convenient disconnect switch to turn off power to the battery while your camper is in storage.

These newer RV converters are also known as a smart charger.

My new converter has three automatic charge settings; one for a quick deep-charge of a very low battery, one to trickle charge once it gains some power, and one to “float” once the battery is at full charge so it won’t overheat.

Some converters issue an audible beeping when it senses faults, which is another level of safety, especially when you’re sleeping.

Not having to closely monitor your RV battery is a stress-reliever, and the safety features are worth the few extra dollars for a converter of this type.

Where to Locate the RV Converter

The converter is in the same compartment as your RV breakers. The converter looks like a metal box with a fan on one end.

The cover on this box comes off to access the internal wiring, resistor, and motherboard that control the direct current charging system.

The converter box usually sits below the breaker and fuse panel in the power compartment.

You connect the converter to the fuse panel that connects all the wires that run to your 12-volt appliances, as well as the 120-volt input and the main cables running to your camper’s battery bank.

There are slots for fuses with amperage ratings that correlate to the wire that attaches next to it on the front of the panel.

This panel typically sits next to the camper’s breaker panel, so you can see it all when you open the power panel door.

Will Testing AC Voltage Indicate a Bad Converter?

When you get abnormal voltage readings at the 110 AC wire in the breaker box, it can indicate your RV converter is faulty.

To test, set a multimeter to the 110 AC measurement and test the entry 110 AC wire. The reading should be anywhere between 108-130 volts. A reading above or below this range may point to a malfunctioning RV converter.

To check for faults in the breaker box, switch the setting on the multimeter to the 12 volt DC measurement and look for a reading between 11-13 volts.

Knowing which side of your power system is faulty can eliminate wasting time and money by replacing the RV converter when it’s not the issue.

While I believe RV owners should know all they can about how their camper operates to perform DIY repairs, working with electricity can be dangerous.

If you feel uneasy tackling such projects, please call in a professional RV electrical repair service.

Will a Bad Fuse Cause the RV Converter to Malfunction?

A fuse is a protective element that burns out when it detects too much current, so other components that are more delicate don’t also get damaged.

Fuses in RV converters are usually the same style found in automobiles to run lights and other accessories.

When a fuse blows, the current cannot continue flowing, so your converter may not work as it should, or only certain 12-volt appliances will function.

Some fuses may degrade from age or temperature, or humidity fluctuations, but it is rare.

Replacing converter fuses is simple. Firmly grab the fuse with a pair of needle-nose pliers and pull straight out.

Hold the fuse up to the light to see if has blown. There is a metal tab inside the plastic that should run in an arch between the two legs.

If there is a break in the tab, or there appears to be scorching, the fuse needs replacement. Look at the fuse’s end for the amp rating, and replace the fuse in the socket with one of the same rating.

Changing out a faulty fuse may be the fix to get your RV 12-volt system working correctly again.

If you see a blown fuse, replace it. If it blows again in short order, there’s an electrical issue somewhere else in that wire that needs immediate attention.

Could the RV Circuit Breaker Be the Problem and Not the Converter?

Circuit breakers do go bad, or the wiring loosens, especially under the vibration of travel.

To ensure your circuit breaker is not causing your RV converter issue, you’ll need to inspect the connections.

Start by going to your breaker panel and open all the switches, starting with the main power input breaker.

Do they look okay, or do the switches feel loose or very easy to flip?

If you feel the switch has some play in it, this means you’ll need to replace that breaker.

If everything looks good from the front, go ahead and flip all the breakers to the off position in the reverse order, so the main shut-off is last.

Unplug the RV’s power cord from the pedestal or outlet and return to the breaker box. Unscrew the breaker panel from the housing and carefully bring it forward so you can see all the wiring connections into each breaker.

You’re looking for signs of corrosion or wires that are not entirely seated within the breaker’s clamp.

Reattach loose wires and clean off any corrosion with a baking soda and water mix and a toothbrush. Make sure everything is dry before plugging your RV back into the pedestal.

If your visual inspection of the breakers looks fine, this is more of an indication that the problem is with your RV converter.

Will an RV Converter Work Without the Battery?

Technically the converter will work, but your RV needs the battery to complete the circuit. The two devices go hand-in-hand to bring power to your 12-volt devices.

You’ll only need an RV power converter to charge the RV house battery when you plug into shore power or run a generator.

So while your lights and other appliances will work on shore power alone, you’ll find most RV fridges still rely on the 12-volt battery to operate the panel.

When my battery was out of commission during my converter’s replacement, I could not turn on my fridge.

Since we now own a seasonal RV lot where we can always plug into shore power, I put in a residential fridge. We can unhook our battery during our stay, and everything in the RV operates perfectly without any adjustments to our converter.

When we are ready to go back on the road, we reattach the converter wires to the battery and let it charge, so if we do boondock a night or two, we’ll have operational lights.

The Cost to Replace an RV Converter

Is it smarter to try to fix your converter or replace it instead?

I have to admit I was nervous when I began to shop for a new converter but was pleasantly surprised when the cost was much less than I anticipated.

For such an integral component in the RV’s power system’s operation, the cost was very reasonable.

When you add in the savings of doing the replacement myself, the final total was under $200 and one hour of install time.

For the hassle of trying to replace parts on a converter that still may not fix an issue, buying a new one is a much better choice, especially if your model is old.

My converter was one of the smaller smart-charging models available, as I have a 30-amp 24-foot RV with few lights or appliances. It’s critical you purchase the right size converter for your RV’s needs.

Use an online calculator to make sure you buy the right size replacement converter.

Also, note that some warranties will require you to have a certified RV mechanic install your converter to keep it valid.

A large, powerful converter and installation charges can run over $1,000, so do your homework to ensure you’re getting the best price.

Conclusion

Figuring out if your camper’s converter is bad is a process of elimination.

The electrical system within most RVs is reasonably straightforward, so the more you learn about it, the better you can prepare to troubleshoot converter problems if they arise.

Thankfully, RV converters are not that expensive to replace, nor are they even necessary to have if you don’t mind lighting some candles instead of turning on lights when you boondock.

Bad RV converters are not the end of the world, as long as you know about it and can safely unhook your battery.

With a little patience and using this guide on how to tell if your RV converter is bad, you can troubleshoot and fix your electrical problems so you can hit the road on a new RVing adventure!

Check and Replace a Failed RV Converter (Video)