RV Converter vs Inverter - What Each Does and Why You Need Both
RV owners mix these up constantly. They do opposite jobs but both live in your electrical system. Knowing which is which saves you money on parts and a lot of troubleshooting headaches.
Converter: AC to DC
A converter takes 120V AC shore power and converts it to 12V DC. Two jobs:
- Charges your house batteries when plugged in
- Powers 12V systems (lights, water pump, fans, slides) from shore power
Every RV with a battery has a converter. It’s usually built into the power center or distribution panel.
Types of Converters
Single-stage: Outputs a fixed voltage (13.6V). Cheap but slow to charge and can overcharge batteries over time.
Three-stage (smart): Adjusts voltage through bulk, absorption and float stages. Charges faster and extends battery life. Worth the upgrade if you camp frequently.
| Stage | Voltage | Purpose |
|---|---|---|
| Bulk | 14.4-14.8V | Fast charge to 80% |
| Absorption | 14.2-14.6V | Top off to 100% |
| Float | 13.2-13.4V | Maintain without overcharging |
Inverter: DC to AC
An inverter takes 12V DC battery power and converts it to 120V AC. This lets you run household appliances — coffee maker, microwave, TV, laptop chargers — without being plugged into shore power.
Pure Sine vs Modified Sine
Modified sine wave inverters ($50-200) produce a choppy approximation of AC power. Fine for basic stuff like phone chargers and incandescent lights. But they can damage sensitive electronics and make motors run hot.
Pure sine wave inverters ($200-800) produce clean power identical to what comes from the wall. Required for:
- CPAP machines
- Laptop computers
- Microwaves
- Variable-speed fans
- Any device with a digital display
Spend the extra money on pure sine wave. Modified sine costs less upfront but damages equipment over time.
Sizing Your Inverter
Add up the watts of everything you’ll run at the same time:
| Appliance | Watts |
|---|---|
| Microwave | 1000-1500W |
| Coffee maker | 600-1200W |
| TV | 50-150W |
| Laptop charger | 60-90W |
| CPAP | 30-60W |
| Hair dryer | 1200-1800W |
Pick an inverter rated 20% above your max simultaneous load. Running an inverter at 100% capacity generates excessive heat and shortens its life.
Inverter/Charger Combos
Modern RVs often use an inverter/charger — a single unit that does both jobs. When plugged into shore power, it acts as a smart converter. Off-grid, it flips to inverter mode automatically.
Popular brands: Victron, AIMS, Progressive Dynamics, Go Power.
These cost more ($500-2000) but save space and wiring complexity. They’re the standard upgrade for serious boondockers.
Common Problems
Converter Fan Runs Constantly
The converter is overheating. Check for blocked ventilation, dust buildup or a failing cooling fan. Clean the area around it and make sure nothing is stacked against the vents.
Inverter Shuts Off Under Load
The battery bank can’t deliver enough current. Check battery connections, state of charge and cable gauge. A 2000W inverter pulls about 170 amps at 12V — thin cables and corroded terminals can’t handle that.
Lights Flicker on Inverter
Modified sine wave inverters cause LED lights to flicker. Switch to a pure sine wave inverter or replace LEDs with inverter-compatible models.
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