Tricks For How To Tell If RV Converter Is Bad And What To Do About It

batteries of an RV

Knowing how to tell if your RV converter is bad should be one of the basic components in your arsenal of RV maintenance skills. The converter in your RV is a critical part of the vehicles internal power grid and if it fails, you'll be left without many essential electrical functions.

Let's face it, that's the last thing you want. But in order to know whether your converter is bad or not, you first have to understand your converter.

So, what is a converter and why is it so important?

What Is an RV Converter

Before we start answering the question of how to tell if your RV converter is bad, let's consider the different parts of your RV's electrical system.

You will typically have two distinct sections, or electrical classes, in your RV. The first is 120V alternating current power which will supply most of your larger appliances such as air conditioners, microwaves, and mains outlets.

The second part of your grid is the 12V direct current supply for internal lighting, propane igniters, and electronics charging points.

Let's take a closer look at the differences between these two types of power. Having this knowledge will help you to know how to tell if your RV converter is bad.

Alternating current or AC power

The 120-volt electrical power you draw from the mains grid in your home is known as alternating current and is commonly referred to as AC power.

The electrical power supplied by shore power services or generators is AC power. You will typically have several AC outlets in your RV, and many of your appliances will run on AC power.

Direct current or DC power

Direct current or DC power is most commonly supplied by batteries, transformers or multi-function devices like your converter.

There are many possible voltage options with DC power, the most common of which is 12 volts. Most sensitive electronic devices and a lot of your RV's lighting will run on 12 volt DC power.

So where does the RV converter fit into the picture?

In simple terms, your RV converter takes 120 volt AC power from a generator or shore power supply and converts it into 12 volts DC. The converted energy is then distributed to the DC grid in your RV. In addition, your converter will also charge your RV's batteries.

So, as long as you're hooked up to an AC power source, you'll have DC power without draining your batteries.

Why Do I Need an RV Converter?

Well, if you are camping off the beaten track, you'll in all likelihood use a generator to supply AC mains power to your RV. In a formal campsite, you'll be able to hook up to their shore power service. In either case, you'll be good to go with main power.

Now, if you don't have a converter, your DC power needs will have to be served by your RV's batteries. That means they will eventually run down and you'll need to run your RV to charge them again. That's effective but not the best solution at all.

With a converter in your RV, you're covered for DC power as well. And the converter keeps your batteries topped-up to boot. This why knowing how to tell if your RV converter is bad is important.

How to Tell If an RV Converter Is Bad

The symptoms of a failed or failing converter are often subtle and hard to define. Let's take a look at how to tell if your RV converter is bad.

Symptoms of converter failure

If you lose all DC power, it's safe to assume that your converter has failed, the keywords being "all DC power". If your lights aren't working but your propane igniter is, you probably have a blown fuse or tripped circuit breaker.

However, if you have no 12 volt DC power at all, you may have a bad converter.

Early warning signs of converter problems

The most common initial warning signs of a failing converter are interior lights that start to dim or DC run electronic devices that fail. Propane spark igniters that are too weak to ignite the gas and batteries that run down very rapidly are also reliable ways how to tell if your RV converter is bad.

​Making a positive diagnosis of converter failure

If you want to find out how to tell if your RV converter is bad, here is a quick checklist you can work through.

  • Check if your AC appliances are running. If not, check all the AC circuit breakers
  • Check all your DC fuses and circuit breakers If you do have AC power.
  • If all fuses and circuit breakers are okay, check that the converter AC power light is on if it has one

Now, if you have stable AC power and there are no tripped breakers or blown fuses, the focus is squarely on the converter. At this point, you have a choice to make regarding how you'll proceed. And this choice needs to be carefully considered.

If you have a good working knowledge of electrical power systems you can try to test your converter yourself. If not, we cannot stress enough how important it is to enlist the help of a qualified professional.

The AC power in your RV is as potentially deadly as any other so don't risk injury or worse.

Testing your converter -- the AC side

To know how to tell if your RV converter is bad, you'll need a reliable, accurate multimeter tester. If you don't have one, models such as the Klein Tools 69149 electrical test kit will do the job perfectly.

The first step in testing is to make certain the converter is getting a full 120V AC supply. Find the converter's AC power cable and, if it connects externally, you can test the AC voltage at the connection points. The reading should be between 108 volts and 130 volts.

If the converter's AC supply cable plugs into the unit, trace it back to the point it picks up the AC supply. This will typically be a circuit breaker or fuse where you can test for correct voltage. If you are sure the unit is getting AC power, you can check the converter's DC output.

Testing your converter -- the DC side

blue multimeter

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Locate the converter's output cable and trace it to where it connects into the DC supply panel. Again, this should be a circuit breaker. Set your multimeter to read DC voltage and test the power on the circuit breaker.

If the unit is working correctly, you'll get a reading of 11 to 14 volts.

Making a diagnosis

Now, here's how you can interpret all your findings. If you have 120 volt AC on the converter and 12 volts DC on the panel you have a healthy AC supply and a good converter.

However, if you have no DC power in the RV, your problem lies elsewhere, probably in the DC supply wiring.

If you have AC power on your other appliances but not on the converter, the circuit breaker or supply cable may be faulty. If you have AC power on the converter but no power on the DC panel circuit breaker, then your converter is probably bad.

Replacing a Faulty RV Converter

Before we proceed with this part of the process, let us again stress the importance of safety. If you are not confident about doing this sort of work, don't.

You can have your converter replaced any day, but your family can't replace you so be safe, not sorry.

Choosing a replacement converter

RV converters are available in a wide range of sizes and feature sets. Using your old converter's specifications as a guide is generally a good way of choosing a replacement.

Taking an inventory of all the appliances and the size and number of batteries in your RV is essential knowledge at this point. That will allow you, or sales personnel, to accurately gauge your converter needs. That said, remember that too big is far better than too small, so rather go slightly bigger than you need.

Here are two examples of good converter replacements at opposite ends of the capacity, price, and feature scale.

PowerMax PM3_35

The PowerMax PM3 35 is a 35 Amp deck mount converter suitable for smaller loads. The PM3 35 is frequently sold with the Bayite LCD status display as a handy, complete AC to DC solution.

PowerMax PM4

For large load applications and greater flexibility, the PowerMax PM 4 features 100 Amp output and a 4 stage smart battery charger.

What you will need

If you're going to replace your faulty RV converter yourself, you'll need a couple of basic tools and some consumables. Here's a quick list of the gear you'll need.

  • Two sizes of both flat and Philips insulated shaft screwdrivers
  • A pair of insulated side cutters
  • A pair of insulated needle nose pliers
  • A set of Allen wrenches
  • A good multimeter
  • Electrical insulation tape
  • A selection of cable or zip ties

Replacing the converter

The first step when you're ready to replace your converter is to isolate all power to your RV. That includes any AC power and your batteries. This may seem excessive but as we mentioned previously, safety is paramount.

Your RV will be completely blacked out during installation, so it's good practice to have all your gear ready to go before you disconnect. That will reduce the amount of time your fridge, for instance, is off.

Disconnecting and removing the old converter

Once all power has been disconnected from the vehicle, unplug the old converter's AC power cord. The cord will typically plug into the rear of the unit. You can then move on to the cables that feed the DC cabinet and batteries on the front of the unit.

Before you disconnect the DC cables, take note of which leads are connected to the positive and negative terminals. That's very important, so if there is any doubt, mark the wires clearly beforehand.

There are typically three DC cables which connect to the front of your converter. These are a positive and negative cable and an earth cable, which is usually connected to the converter's frame.

The positive and negative leads are generally fastened with Allen screws so use your Allen wrenches remove these first.

You can then unscrew the earth lead and any mounting screws that secure the old converter and remove it.

​Installing, connecting, and testing the new converter

You may then put the new unit into position and re-insert the mounting screws. Then re-attach the earth cable making sure it makes good tight contact with the case of the inverter.

Now you can go ahead and connect the positive and negative cables. Just make certain that they are in the correct sockets and that the connections are good and tight. Now you can plug the AC supply cable back in.

Now, before you start to reconnect your power switch off the AC circuit breaker that feeds the converter and the main DC circuit breaker in the DC cabinet. You can then reconnect your batteries first and lastly the AC supply to the RV. To test your new installation, switch on the AC circuit break to power up the converter.

Once it's powered up, use your multimeter to check the DC power on top of the main DC circuit breaker. If you are getting around 13 volts you are hot to trot. You may then switch the breaker on to power up your DC circuits.

All that now remains is to monitor the converter and DC circuits for a while to check for potential problems.

 Make sure the converter is not getting overly hot and that all your lighting and appliances are working correctly.

Suggested Reference Material

Now that you have successfully solved your converter issues, here are a couple of really great books for future reference. The first is RV electrical systems: A Basic Guide to Troubleshooting, Repairing and Improvement by Bill Moeller.

And secondly, No Shock Zone: RV Electrical Safety by J Michael Sokol.

​How to Tell If Your RV Converter Is Bad: The Bottom Line

lights on inside an RV

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Well, there you are. Hopefully, our guide has helped demystify how to tell if your RV converter is bad. We'd like to leave you with one bit of advice before we close off though.
Whether in your home, workplace or in your RV, electricity is dangerous, often fatally so. Please, always exercise caution when dealing with any electrical equipment and if you don't know, don't do.

Happy camping!

If you've got any ideas or experiences of how to tell if your RV converter is bad, please use the comments section below.

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