This is probably the single most confused topic in RV electrical systems. Most owners use the terms interchangeably, but they’re completely different devices that do opposite jobs. Misunderstanding which one you have — or which one failed — leads to misdiagnosis every time.
What Does a Converter Do?
A converter takes 120V AC shore power and converts it down to 12V DC to:
- Charge your 12V house battery bank
- Power your 12V DC systems (lights, fans, slides, water pump) directly
Most RVs have a converter. It’s usually built into the main distribution panel and runs silently. You only notice it when it’s broken.
What Does an Inverter Do?
An inverter does the opposite — it takes 12V DC from your batteries and converts it up to 120V AC so you can run household appliances (TV, microwave, CPAP) without shore power or a generator.
Not all RVs have inverters. Many are add-ons. If you don’t know whether you have one, check for a dedicated inverter switch on your control panel or a separate box with cooling fans mounted near your battery bank.
Simple way to remember it: Converter = AC comes in, DC goes out. Inverter = DC comes in, AC goes out.
What Does a Converter/Inverter Combo Do?
Some units do both. These are called inverter/chargers and are common in higher-end RVs and solar setups. They charge the battery from shore power AND provide AC power from the battery bank when not connected. Victron, Magnum, and Xantrex make popular models.
How to Test Your Converter
Set your multimeter to DC volts and measure across your battery terminals while connected to shore power. You should see:
- 13.2V–13.8V = Converter is working and charging the battery
- 12.6V or battery resting voltage = Converter is not charging (check its breaker first)
- 14.8V+ = Converter may be overcharging — can damage batteries
Common Converter Failures
- Fan failure — The converter overheats without cooling and shuts down. You’ll hear the fan stop running.
- Circuit board failure — Older WFCO and Parallax converters are known for board failures. Voltage drops, battery won’t charge.
- Blown fuse or tripped breaker — Check these first before assuming the unit itself is bad.
Common Inverter Failures
- Overload shutdown — Inverters have overload protection. If you tried to run too much, it may have tripped. Look for a reset button.
- Low battery cutoff — Most inverters shut off below 10.5V to protect the battery. If batteries are low, the inverter won’t run.
- Fan or board failure — Same as converters, heat kills electronics.
Important: A failed converter is often misdiagnosed as a bad battery. Before replacing your battery bank, test your converter output voltage as described above.
Electrical System Acting Up?
Converter and inverter diagnosis requires knowing where to look. Thomas comes to you with the right equipment to test the full DC and AC system. Serving South Mississippi within 1.5 hours of Saucier.
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