Converter (RV)
An electrical device that converts 120V AC shore power into 12V DC for the house battery and 12V appliances. Standard in every RV.
Also called: converter, RV converter, power converter, AC-to-DC converter
A converter (RV) is an electrical device that converts 120V AC shore power into 12V DC for the house battery and 12V appliances. It’s standard in every RV.
The converter does the opposite of an inverter:
- Converter: 120V AC → 12V DC (when on shore power, charges battery)
- Inverter: 12V DC → 120V AC (when off shore power, runs household appliances)
How the converter works
When the RV is plugged into shore power:
- 120V AC comes in through the power cord
- Distribution panel routes half to AC outlets and appliances
- Other half goes to the converter
- Converter steps down voltage to 12V DC
- Charges the house battery continuously
- Powers 12V appliances (lights, water pump, fan, propane controls)
When the converter isn’t doing its job
If the rig is plugged in but the battery isn’t charging:
- Converter failure (real possibility)
- Battery sulfation (battery can’t accept charge)
- Wiring issue between converter and battery
- Fuses blown
Symptoms in rental:
- Battery slowly drains during plugged-in stay
- Lights dim or flicker when other appliances run
- House battery reading low despite shore power
- Generator works but plugged-in shore power doesn’t charge
Common rental converter issues
- Old converter unable to keep up with modern lithium battery charging
- Burned-out transformer (converter failed)
- Loose wiring at the converter
If you suspect converter failure on a rental, call rental company roadside assistance.
Converter sizes
| Converter capacity | Application |
|---|---|
| 30-50A | Small Class C, travel trailers |
| 60-75A | Standard Class C |
| 75-90A | Larger Class C, smaller Class A |
| 100-120A | Class A motorhomes |
Higher amperage = faster battery charging.
Modern smart converters
Newer rental rigs have “smart” converters that:
- Adjust output based on battery state of charge
- Detect temperature and adjust accordingly
- Show diagnostic info on a display
- Charge more efficiently for lithium batteries
If your rental has a smart converter, the rental staff should explain its operation during the walkthrough.
The converter vs inverter distinction
This trips up first-time renters:
- Converter: when on shore power, makes 12V DC from 120V AC. Always working when plugged in.
- Inverter: when off shore power, makes 120V AC from 12V DC. Required if you want to run household appliances off-grid.
Most rental Class B builds have both. Most rental Class C rigs only have a converter (no inverter) — you can’t run a microwave without shore power or generator.
What renters should verify
- Converter is working (battery charges while plugged in)
- House battery reads correctly on the monitor
- All 12V appliances function when plugged in
If anything seems off, ask during the walkthrough.